Adrian, When I worked doing repairs we had a saying "It's never the chip, Always the Cap". We also used to say that "The more legs it has the less likely it would be to be faulty"
I replaced so many of these as an ex-IBM Service Rep. They were quite popular as a bank teller console which did not take up too much room on their banking stations. I did also see them used in point of sale stations but not often, probably due to the high cost of these units.
That "brown gunk" is universally known as "tan glue of death" in the repair field, because in new condition it's tan/beige in color and as it degrades it turns more and more brown-ish. Ontop of that it gets hygroscopic (absorbs moisture) which can lead to shorts especially when used in switchmode PSUs, blowing them up. Manufacturers usually used this stuff to hold thru-hole components to the board before soldering. Best practice is to get rid of all of it when fixing a device
So true is that , allot of it , even almost lost a job over it when in a SVHS deck and called vendor and they acknowledged it. It's in allot of old things and is bad. The Mitsubishi TV oil leaking in caps is the worst. all the tv's leaked oil on caps and corroded pcb boards , some in shop could smell the burning oil as replaced. some times Old flux can cause leakage and cause a problem. SO clean the board before jumping to a no fix condition. That repair would have been a 180 dollar REPAIR at 60 per hour plus parts. It's more per hour now that was cheep. Sad but true. some antique car radios 200 or more. Well I got it still do . Love old tape decks and Console stereo's, and 20's radios. Also welcome to the bad cap thing, I had a large inventory at work of caps, car radio's shorted caps tantalum ones, amps old, new baked in cabinets, always got 105 deg caps to replace so id never see what i fixed back to me, Put 50 or more in a a amp all bad. Also no to mention is the bad cap era. Some manufacture got the wrong formula to make caps. electrolytic Caps are temp and hours rated go see spec sheets also the power rating if in a power supply. so be care in selecting replacement. 55 years of it, broadcast 3 tube cameras, sony Video real to real to to 1 in with pizeo head tracking, on and on, to digital typesetters from auto-logic and beyond, to uni buss and PDP 11 macro programing.
At 21:00, the capacitor that is being glued down does not have venting on the top of its can (the venting will look like slices). That means it is made to vent on the PCB side - and that glue might prevent venting in case the capacitor experiences some fault condition. Not so good design there.
Regarding the one-color color input and the missing red and blue signals, there should be a feature in the VGA standard which is translating the red and blue colors to green. I remember that with my first monochrome monitor i needed to execute a DOS utility which switched something inside the graphics card and made the image quality much better.
That brown gunk is somewhat famous for becoming conductive over time, and causing shorts. From old amplifiers to CyberPower UPS’s, that stuff (whose name escapes me) is a plague.
As you may have discovered, the small VGA monitor (without the base) was used with the IBM Wheelwriter for the high-end models - but, as others have commented, the IBM 47xx-series is for the "Finance Communication System".
When the system remains powered off for decades, the oxide layer in the electrolytic capacitors can crack (it's the voltage applied during normal usage that constantly reconstitutes the oxide). If you then turn the system on, current leaks through the cracks in the oxide; and depending on the voltage applied, there can be so much current leak that it shatters the oxide layer. Since the electrolyte is conductive, at this point the capacitor just becomes a short. This is actually quite common.
@@UnitSe7en yes, and looking for vintage computers on eBay can be really cringe-inducing; hearing in the descriptions people powering things up with absolutely no clue. I'll be happy if computer repair people can someday start making money consulting people with their "antiques", testing power supplies and inspecting caps and such before needlessly frying mainboards.
This is mostly a problem in tube equipment because of the high voltages involved. A filter capacitor can start out with 20mA of leakage current at 200v, and end up with less than 1mA at 200v. When hooked up directly to the voltage, it'll boil dry and/or piss electrolyte all over the chassis. For transistor equipment, the voltages involved are so low that usually, if a cap is leaky, the cap will reform in circuit because the leakage resistance is too big for destructive currents to flow, or just stay as bad as it was. Using a current limited power supply at the full voltage is the right way to go.
The IBM 4707 was a financial terminal monitor, part of the 4700 family of parts. It was typically paired with e.g. a 4704 Model F style keyboard, of which, they came in 50, 62, 77, and 121 key varieties. The 50 key was a typical keyboard for doing 10-key entry.
I have a 4707 and a 50-key keypad with an alphabetic layout, a fun pairing for photos as a cute mini system if I may add. Unfortunately though, my keypad isn't a Model F - I have the PS/2 compatible Model M version (P/N 1395249) presumably used with emulating or migrating from 4700 applications with PS/2 and later systems.
*Very* lucky that power-supply was designed as well as it was. A cheaper PSU would've just kept pumping that 15V into that shorted cap and eventually it would've taken out that chip, no doubt. But that PSU, sensing an overcurrent, essentially disconnected itself and stopped that from happening. Good job, IBM, with this design! And kudos to you for finding this issue and getting it fixed -- excellent video!!
Hi Adrian, this is Ferry from Germany. Thank you so much for your video on this monitor. I had the same issue on my IBM4707! I wanted to exchange the tube in my monitor against a 9" amber CRT. The Monitor was working before the "operation", but afterwards: Nothing. Black screen, obviosly no High-voltage on the tube. I thougt, I maybe broke the flyback-transformer by discharging it without a series resistor. Went to bed very angry and sad. Before sleep i watched your video an got a little hope at least. Today i checked this capacitor on my monitor and what do you know: It was shorted too! Crazy. The cap must have been died yesterday, while i was replacing the CRT. I also checked the other electrolytic caps, but they all measured fine. So my monitor works again, after replacing this cap. I would not have thougt of that without your video. Thanks! :-)
I had a capacitor in an appliance die short the other day. That capacitor had no problem handling mains voltage @ 20+ amps, thank goodness for fuses. It is a pretty rare capacitor and all I could find was a 30 year old replacement that tested good. I figure if it's that old and still works it'll probably continue to work.
Another nostalgia blast for me. I couldn't tell you how many of those I've fixed back in the '90s, must run into the hundreds. I didn't have circuit diagrams for them as they weren't released back then and I'm guessing they never were. It will be interesting to see how long that CRT lasts after rejuvenation. Thanks again for another entertaining repair video.
i saw that model in server rooms and telehouses in both the UK and NL, usually attached to a monitor switch on a rack - late 90s/very early 00s. Often with horrendous burn in, since people often left them on and connected to whatever was misbehaving last. No photos, since they had a tendency to fire you for infrastructure photos in those places.
Generally speaking the term "B+" is a forgotten term these days associated more with tube / valve equipment. It originally referred to the plate voltages on the tubes.
I still hear B+ used quite a lot. Given CRT's are tubes, I guess it is still relevant. B+ technically could be any positive voltage supply, but it is generally associated with the higher voltage lines.
@@wbfaulk LoL The Heater voltage is 2, but all the others would be higher. :P (except cathode of course) But technically B+ is any positive voltage, regardless of usage :). It just happens it was primarily used to differentiate between heater/cathode voltages and the higher voltages in tube days. :) Given the plate of a CRT is the "Anode" that is considerably more than 12 :)
"tan glue of death" was found on my Commodore monitor made for C64 and attached to my Atari 8-bit and Cable TV tuner for years until the same fate - death by Daewoo quality.
I had one of these in the early '90s. Was delivering training for which I would lug a server and one of these monitors in a flight case. To conduct a lab for 10 - 15 attendees, the customer would supply the classroom full of networked PCs. Thanks to bringing my own server I could show up an hour early on a Monday morning, plug into their network and have everything ready to teach once the students arrived. And yes, adorable...
Hi ! The 4707 should have a brightness preset alongside the brightness front dial. In the factory they use differently sensible tubes and they adjusted them with brightness full open to a certain "lumen factor" with the preset as far as I recall. I only had these screens along with the bigger 8503 PS/2 monochrome on the workbench if e.g. cables got damaged or screen size was wrong -or- power supply blew up. Back in around 1990 I had the factory setup sheets for all 85xx monitors. The 4707 was a rare bird and was partially sold for server purposes along with a small size keyboard with integrated IBM Trackstick. The type number 47xx indicates that it belongs to the finance communication equipment line of machines. That was the gear used for banks to replace the IBM 3600 series machines in about 1981. This screen was also used for the IBM Wheelwriter 10 Series II typewriter (Model 6789) along with an external 3.5" / 720KB floppy drive.
@@jaybird57 Hi ! My dementia isn't all that bad for now. I always had a problem remembering names since I was a kid, so it isn't that serious now at the age of 61 .... Err ... what were we talking about ? But seriously: I work as a computer-technician for over 40 years and about 34 years for the same actual company. It was - at a point - Germanys largest IBM systems dealer during the time of PS/2 machines and we had quite a few of them on the desk. Back then gear war really repaired, not only replaced or sub-assemblies changed. So my recollections are still quite good. I hope.
the "Bildröhrenregeneriergerät" print on the Box shows what beautiful things the german language can create by putting four words into one :-) Great video Adrian. I had one of these little Monitors back on that time as a display for a FIDO Node and for diagnosing PCs of friends that I fixed because it was small and could sit in the corner of my desk with a small footprint.
Just came home after celebrating Christmas with the family, and found your new video on RUclips. Sooo relaxing to watch. Merry Christmas and greetings from Germany, home of the Bildröhrenregeneriergeräte.
The tellers at my mother’s bank used these monitors. They were attached to PS/2 machines each linked by thicknet to an IBM 3090 downtown. I remember every year they had a software update I got to play on the 3090 and change the tapes. Truly my first computer.
Are you sure they ran thicknet all the way back to the mainframe? If they were running it such a long distance it would have to go through the telephone network using a T1 line.
@@godslayer1415 NBNTV explains below about "thicknet", and there were also a lot more small banks back before 2008. Why nitpick about that detail, and why assume that meant he didn't get near tapes, no matter what networking cabling involved? Why do you feel this deep seated need for putting people down? Does it have something to do with the militant, fundamentalist atheism you seem to espouse? ;P
That brown goop is a well-known problem. When it turns dark brown, it absorbs moisture from the air and becomes a resistor. Depending on what it bridges, it can cause all kinds of issues.
the label reads ">550V~", so this holds true for 14kV ... and would also for 300kV. Admittedly a slightly strange way to label it, but correct in some sense.
I'm guessing the 14kV is only exposed on the final anode at the "stethoscope" end of the plug and so the CRT was labelled as such. The >550V will be for the focus and exposed on the driver board at the base of the tube.
It might be a regulatory thing where everything greater than 550V needs a label, so they'd just have a bunch of >550V labels rather than needing different labels for each possible voltage.
@@StarkRG I don't recall any regulatory things for stating what potential voltages are, especially back in 1988. Maybe the corps got regulation and testing even back then in order to force smaller biz out but only in industrial markets. Corps use government and taxes for themselves.
Im not all the way through the video but I do recall a similar problem shown on another youtube channel on some modern UPS units made by CyberPower which the vibration protection "gunk" goes off and starts conducting, thus shorting out components on the board. Nice fix Adrian its good another piece of history has been renovated.
The other day I had an issue with a Yamaha keyboard of about the same age. In it, a 470µF cap had turned into a 2.3 Ohms resistor, pulling one of the voltage rails WAY lower than needed. After removing a bunch of other components, I was able to find this one. I replaced it (and a few other caps I had cut out along the way) and it freakin' works! Interestingly, I hooked the same faulty cap up to a capacitance meter (I have access to a very good one at work), and it still has almost full capacity. But Blocking DC... nope. Side note: As a German, I just love seeing "Bildröhrenregeneriergerät" written on that box. :-D
In the early 90s I worked as a developer for branch systems at a top 20 bank. We being an IBM shop, supplied all the tellers in the traditional banks this 9" model since space was often at a premium. Ironically the smaller grocery store kiosk branches got the ubiqutous 14" 8511 color monitor, only because the manager apps were also on those particular boxes easily switchable via OS/2 that was running on them.
A fantastic video, Adrian. I love watching your diagnostic work and of course it’s even better when you have a winner! Have a Merry Christmas and we look forward to more great videos. Cheers!
Knew a guy called TV Bill, had some unorthodox ideas, but he once complained about this assembly glue and explained you could test a resistance value across some of it! His thought was conspiracy planned obsolescence, but my theory is they just used it to put the components on the board and thought nothing of it other than this. Gem from the older generation for you and yours!
We used these 9 inch IBM mono VGA screens in Assembly line controllers. They were the only ones that could handle the magnetic fields from the pick and place units.
Awesome to see a monitor like this being fixed instead of being thrown out. Hopefully it can be given to a collector one day once your use for it reaches an end.
Removing gunk like this can often be speeded up if you have a hot air rework station. Set temperature to, say, 100C and use a fine tip to get right to the gunk. Warming it up can soften it making it much easier to remove. Hot air can also soften the adhesive under stickers, making them much easier to remove, too.
I love the CRT rejuvenation videos because it's just so cool to see a CRT be brought back from near death to a usable state. It is worthwhile to read up on some of the best practices for rejuvenation, though, as I've heard that you should be positioning the CRT in a particular way so that any of the oxides or corrosion from the gun that is blown off during the process will fall away to somewhere it won't readily cause problems in the CRT. Still, if it's burnt to the point that it's unusably dim, then there's no reason not to give it a go with the rejuvenation. You weren't going to be able to use it anyway with such a dim picture, so even if it dies, the outcome would be the same as before: a CRT transplant.
Just a few pointers for future reference from someone who works on vintage electronics regularly: You can't rely on CRTs being the same size with the same shape neck connector as a way of seeing if they're compatible, it's always best to Google the part numbers to make sure voltages, bias values and other parameters are compatible. CRTs often "wake up" after not being used for a period of time, they will get brighter within the first few hours of use. The 550v warning underneath was actually a "greater than 550v" warning, so yes it's very likely that the HT is 10+kv. Shorted capacitors are very common, especially in gear that hasn't been used for 5+ years. Sometimes you may find that a device works perfectly for a while then stops working at all, most likely is that an electrolytic has shorted. I would suspect any electrolytic before pulling an IC in something this old! All that said, I really enjoyed the video as always, keep them coming!
AFAIK 7-pin CRTs should be mostly compatible, with two main variations: heater voltage and position of G2 and G4. I believe the other bias voltages are mostly compatible.
I must be learning so much from watching you Adrian. As soon as you switched it on and the Watts spiked then dropped I thought "Capacitor !". Thanks for all your hard work and interesting content.
I think this is partially because he presents things as though we are doing the work and we are experiencing the pain (where relevant). You learn best by doing (experience is what you get when you didn't get what you wanted). By watching you feel like you're doing. It seems in your brain you are taking part. I am never going to be the expert he is (I'm older than he is), but it is gratifying to feel I continue to learn from him.
Back in the '90s I had a 21" monochrome monitor on my PC. I built a simple resistor divider to take the required portion of R, G and B signals from the PC to avoid the problem of only seeing the green output when playing games.
Hi Adrian, when I was in college (1994) these were being used with PS/2 systems in a computer lab. Standard-size Model M, but these were packed together closely in a line on a desk, and they squeezed as many of us in there as they could.
Caps can definitely short out, I've seen quite a load of them going shorted. Nice fault-finding there!! Merry Christmas and Happy Holidays Adrian! Cheers.
Great work and well done although I am a little surprised that you went and removed the chip rather than the cap as the cap was the easiest by far and very likely the problem, remember a short is also a massive leak ! but I guess a nice desolder gun helped with that decision ! Happy New Year....cheers.
Especially since a shorted chip there would probably have had its plastic body crack or it would have become so hot as to discolor the PCB beneath it. Neither of which were observed.
As an old timer I have seen a lot of shorted capacitors. Specially in low voltage circuits. Just not enough power to blow them open ot the over power safety circuit in power supplies shuts down to prevent capacitor opening up.
I've seen this glue cause so many problems too, but no complaints here as it generated good repair revenue. One use of glue that was very unwelcome however was the silicone type IIYAMA used to glue the EHT anode caps to the bowl of the tube. It was very strong and made it difficult to disconnect the lead from the CRT without causing damage.
I had a shorted 1000µF electrolytic cap on the video mixing board from a Sharp X1 turbo recently. First one I'd ever seen. It pulled the +12V rail down and would not let the computer's power supply switch on as a result. You'll be happy to know that it tested out as having incredibly low ESR.
That yellow glue is known to be conductive and corrosive over time when it turns brown. It is best to remove them if they are in contact with connections.
This was my first monitor, a gift from my uncle after we built my first pc from spares. Was 386sx 25mhz! I spent ages looking for a used VGA to finally embrace colour!
Good diagnosis run, gratz on getting it working again. Resistors go open and capacitors can short. The "glue" that they used to use was changed to a new formula when the original formula was found to become conductive over time. Best to just get rid of it whenever possible. And as always: "thou shall always check voltages" as soon as possible in the diagnosis run. Cheers and Merry Christmas,
Great job, Adrian. As stated by others earlier, suspect and check the simple two-legged varmints before the multi-legged ones. Of course it's easy for me to say that after you've fixed it. :)
I have one of those monitors in my collection. I used it as a service unit for field calls, mostly in data centres. I seem to remember there was one batch with out of spec video connectors that could be plugged in upside down.
10:30 - is that a 50V capacitor? I mean the big Daewoo one. You should mention that if a PSU with a big cap was used recently you should discharge it through some resistors because you can get a nasty shock from the stored charge. For fun I shorted a 400V cap of a PSU in a PlayStation 3 slim after opening it up and I almost sh*t my pants, it was loud and scary. But I'm glad it didn't short while I was taking it into my lap or something. 24:09 - when it showed short at this point I was like probably one of those caps is shorted. But yeah, they usually don't short when dead, tantallum caps do that. I'm glad my hunch wasn't so bad but I would have never figured it out on my own, I was just following your logic to this point.
4:47 I have a 22" NEC Diamondtron CRT made in 2000, and it refuses to power on without a signal, instead it turns its glowing Multisync logo to red. Quite unusual for a proper VGA monitor!
@@StarkRG All other CRT monitors I remember would display "no signal" at least brefly. Especially a higher end monitor like this I'd expect to implement that.
Super nice monitor, I had one like this or the exact same model 12 years ago. I used it as a second screen for an old Win95 Digital Starion machine. I miss when it was easy to pick up this stuff, in good working condition, at a thrift for under $10.
I thought "Duff cap" as soon as it was obviously going into some sort of protection mode. It's maybe the things I tend to work on but I've encountered for more capacitors that have failed short, or become electrically leaky, than have failed open or physically leaked,
I have the same monitor. It came off of an IBM Wheelwriter. I work on Selectrics and Wheelwriters. Some later Wheelwriter models came with these monitors and a swing arm that mounts to the back of the Wheelwriters. They were used by offices and realty stores. I am not sure but I think they were sold as an accessory to the public. Though most of the Wheelwriters that would accept this monitor already had displays built into the front lid. Thanks for the video because I am currently trying to figure out what is wrong with my IBM monitor. I really want to get it going
Programming Databases.... Had them at work on the machines that had been set up for the database design team as you only needed text based, the front office had them for word processing and in the phone centre, the call centre used them as terminal screens to put in service calls. My department eventually got some for the inventory I was responsible for.
I think the 550+ warning label has to do with the National Electric Code. Most regular service electrical insulation and components are rated to a maximum of 600v. That label may be there to notify a service tech that there are systems inside the enclosure that are higher voltage than standard service components can be used for.
The brown "junk" is called silastic... They use the silastic on the caps so that they don't move around and change the Q factor of the circuit, due to mechanical, or thermal movement.
I have an IBM paperwhite VGA monitor half the size (5-inch dia? I've never measured it) that one! The last time I plugged it in, it worked fine... but that was quite a few years ago... I should pull it out and check it again!
We used these monitors as our ANI/ALI screens when I worked 911 in the late 90's... I've repaired more than one of them, and most of the failures were due to the glue of death. I have had one that had that same cap shorted. (no idea why, as it hadn't been sitting for ever unused like yours... that must be a sore spot in the filtering on that rail)
This was a well known problem from back in the 80's!... it's contact cement that goes leaky over time big deal, the HA11235 is a horizontal n vert osc + xray protect driver IC, That picture tube tester is a clone of a old B&K from the 80's.
Awhile ago universal replacement crts for console tv came with no band. You bought a separate band and ears. You set the ears where you needed. High anxiety when tightening the band.
Since the band is part of the implosion protection on a CRT, that can be a risky undertaking - with no guarantee that proper implosion protection ultimately results.
Adrian, When I worked doing repairs we had a saying "It's never the chip, Always the Cap". We also used to say that "The more legs it has the less likely it would be to be faulty"
Oh, you missed an oppertunity there 0rin! "The more legs it has the less likely it is to fall over!" ;-)
-Dx
"The more legs it has the less likely it would be to be faulty"
I replaced so many of these as an ex-IBM Service Rep. They were quite popular as a bank teller console which did not take up too much room on their banking stations. I did also see them used in point of sale stations but not often, probably due to the high cost of these units.
Yeah, it kinda figures that banks would have, ya know, money. 😉
Oh yes
That "brown gunk" is universally known as "tan glue of death" in the repair field, because in new condition it's tan/beige in color and as it degrades it turns more and more brown-ish. Ontop of that it gets hygroscopic (absorbs moisture) which can lead to shorts especially when used in switchmode PSUs, blowing them up. Manufacturers usually used this stuff to hold thru-hole components to the board before soldering. Best practice is to get rid of all of it when fixing a device
So true is that , allot of it , even almost lost a job over it when in a SVHS deck and called vendor and they acknowledged it. It's in allot of old things and is bad. The Mitsubishi TV oil leaking in caps is the worst. all the tv's leaked oil on caps and corroded pcb boards , some in shop could smell the burning oil as replaced. some times Old flux can cause leakage and cause a problem. SO clean the board before jumping to a no fix condition. That repair would have been a 180 dollar REPAIR at 60 per hour plus parts. It's more per hour now that was cheep. Sad but true. some antique car radios 200 or more. Well I got it still do . Love old tape decks and Console stereo's, and 20's radios. Also welcome to the bad cap thing, I had a large inventory at work of caps, car radio's shorted caps tantalum ones, amps old, new baked in cabinets, always got 105 deg caps to replace so id never see what i fixed back to me, Put 50 or more in a a amp all bad. Also no to mention is the bad cap era. Some manufacture got the wrong formula to make caps. electrolytic Caps are temp and hours rated go see spec sheets also the power rating if in a power supply. so be care in selecting replacement. 55 years of it, broadcast 3 tube cameras, sony Video real to real to to 1 in with pizeo head tracking, on and on, to digital typesetters from auto-logic and beyond, to uni buss and PDP 11 macro programing.
At 21:00, the capacitor that is being glued down does not have venting on the top of its can (the venting will look like slices). That means it is made to vent on the PCB side - and that glue might prevent venting in case the capacitor experiences some fault condition.
Not so good design there.
We call it "Gorilla Snot" here...
@@whstark Wow... word salad
@@Knaeckebrotsaege It gets progressively worse :D
Regarding the one-color color input and the missing red and blue signals, there should be a feature in the VGA standard which is translating the red and blue colors to green. I remember that with my first monochrome monitor i needed to execute a DOS utility which switched something inside the graphics card and made the image quality much better.
That brown gunk is somewhat famous for becoming conductive over time, and causing shorts. From old amplifiers to CyberPower UPS’s, that stuff (whose name escapes me) is a plague.
There aren't many people in the world who would spend SO much of their time to restore an item like this. FANTASTIC job!
As you may have discovered, the small VGA monitor (without the base) was used with the IBM Wheelwriter for the high-end models - but, as others have commented, the IBM 47xx-series is for the "Finance Communication System".
When the system remains powered off for decades, the oxide layer in the electrolytic capacitors can crack (it's the voltage applied during normal usage that constantly reconstitutes the oxide). If you then turn the system on, current leaks through the cracks in the oxide; and depending on the voltage applied, there can be so much current leak that it shatters the oxide layer. Since the electrolyte is conductive, at this point the capacitor just becomes a short. This is actually quite common.
Interesting. Never heard of that!
Great post. Powering up long-dormant electronics can be the thing that destroys them.
@@UnitSe7en yes, and looking for vintage computers on eBay can be really cringe-inducing; hearing in the descriptions people powering things up with absolutely no clue. I'll be happy if computer repair people can someday start making money consulting people with their "antiques", testing power supplies and inspecting caps and such before needlessly frying mainboards.
This is mostly a problem in tube equipment because of the high voltages involved. A filter capacitor can start out with 20mA of leakage current at 200v, and end up with less than 1mA at 200v. When hooked up directly to the voltage, it'll boil dry and/or piss electrolyte all over the chassis.
For transistor equipment, the voltages involved are so low that usually, if a cap is leaky, the cap will reform in circuit because the leakage resistance is too big for destructive currents to flow, or just stay as bad as it was.
Using a current limited power supply at the full voltage is the right way to go.
It's interesting how just one bad capacitor can prevent the whole thing from working! 😨
The IBM 4707 was a financial terminal monitor, part of the 4700 family of parts. It was typically paired with e.g. a 4704 Model F style keyboard, of which, they came in 50, 62, 77, and 121 key varieties. The 50 key was a typical keyboard for doing 10-key entry.
I have a 4707 and a 50-key keypad with an alphabetic layout, a fun pairing for photos as a cute mini system if I may add. Unfortunately though, my keypad isn't a Model F - I have the PS/2 compatible Model M version (P/N 1395249) presumably used with emulating or migrating from 4700 applications with PS/2 and later systems.
*Very* lucky that power-supply was designed as well as it was. A cheaper PSU would've just kept pumping that 15V into that shorted cap and eventually it would've taken out that chip, no doubt. But that PSU, sensing an overcurrent, essentially disconnected itself and stopped that from happening. Good job, IBM, with this design! And kudos to you for finding this issue and getting it fixed -- excellent video!!
Hi Adrian, this is Ferry from Germany. Thank you so much for your video on this monitor. I had the same issue on my IBM4707! I wanted to exchange the tube in my monitor against a 9" amber CRT. The Monitor was working before the "operation", but afterwards: Nothing. Black screen, obviosly no High-voltage on the tube. I thougt, I maybe broke the flyback-transformer by discharging it without a series resistor. Went to bed very angry and sad. Before sleep i watched your video an got a little hope at least.
Today i checked this capacitor on my monitor and what do you know: It was shorted too! Crazy. The cap must have been died yesterday, while i was replacing the CRT. I also checked the other electrolytic caps, but they all measured fine.
So my monitor works again, after replacing this cap.
I would not have thougt of that without your video. Thanks! :-)
I had a capacitor in an appliance die short the other day. That capacitor had no problem handling mains voltage @ 20+ amps, thank goodness for fuses. It is a pretty rare capacitor and all I could find was a 30 year old replacement that tested good. I figure if it's that old and still works it'll probably continue to work.
Adrian: Brings out the CRT rejuvenator.
Me: Oh, no, not the CRT Killer 2000!
Glad it worked out well this time, though
Another nostalgia blast for me. I couldn't tell you how many of those I've fixed back in the '90s, must run into the hundreds. I didn't have circuit diagrams for them as they weren't released back then and I'm guessing they never were. It will be interesting to see how long that CRT lasts after rejuvenation. Thanks again for another entertaining repair video.
i saw that model in server rooms and telehouses in both the UK and NL, usually attached to a monitor switch on a rack - late 90s/very early 00s. Often with horrendous burn in, since people often left them on and connected to whatever was misbehaving last. No photos, since they had a tendency to fire you for infrastructure photos in those places.
Generally speaking the term "B+" is a forgotten term these days associated more with tube / valve equipment. It originally referred to the plate voltages on the tubes.
You may have missed the one vacuum tube that existed in this circuit.
I still hear B+ used quite a lot. Given CRT's are tubes, I guess it is still relevant. B+ technically could be any positive voltage supply, but it is generally associated with the higher voltage lines.
@@wbfaulk Adrian was referring to 12V as B+, this is not relevant to the CRT, but also not an uncommon use of B+ terminology.
@@EsotericArctos What? You don't think that it's running the CRT's "plate" off of 12V?
@@wbfaulk LoL The Heater voltage is 2, but all the others would be higher. :P (except cathode of course)
But technically B+ is any positive voltage, regardless of usage :). It just happens it was primarily used to differentiate between heater/cathode voltages and the higher voltages in tube days. :)
Given the plate of a CRT is the "Anode" that is considerably more than 12 :)
Excellent diagnosing skills. Glad to see new life brought back to a monitor that spent its life at a checkout counter.
Wow, man. It's like something from a sci-fi horror movie. Attack of the Creeping Brown Gunk! Nice video. Good troubleshooting.
Very good troubleshooting Adrian!
Thanks! Starting to learn how to "act like an engineer" after watching so many of yours videos.
"tan glue of death" was found on my Commodore monitor made for C64 and attached to my Atari 8-bit and Cable TV tuner for years until the same fate - death by Daewoo quality.
I had one of these in the early '90s. Was delivering training for which I would lug a server and one of these monitors in a flight case. To conduct a lab for 10 - 15 attendees, the customer would supply the classroom full of networked PCs. Thanks to bringing my own server I could show up an hour early on a Monday morning, plug into their network and have everything ready to teach once the students arrived. And yes, adorable...
Hi ! The 4707 should have a brightness preset alongside the brightness front dial. In the factory they use differently sensible tubes and they adjusted them with brightness full open to a certain "lumen factor" with the preset as far as I recall. I only had these screens along with the bigger 8503 PS/2 monochrome on the workbench if e.g. cables got damaged or screen size was wrong -or- power supply blew up. Back in around 1990 I had the factory setup sheets for all 85xx monitors. The 4707 was a rare bird and was partially sold for server purposes along with a small size keyboard with integrated IBM Trackstick. The type number 47xx indicates that it belongs to the finance communication equipment line of machines. That was the gear used for banks to replace the IBM 3600 series machines in about 1981. This screen was also used for the IBM Wheelwriter 10 Series II typewriter (Model 6789) along with an external 3.5" / 720KB floppy drive.
Dude, how the hell you remember all that from 30 years ago....damn. wow..
@@jaybird57 Hi ! My dementia isn't all that bad for now. I always had a problem remembering names since I was a kid, so it isn't that serious now at the age of 61 .... Err ... what were we talking about ?
But seriously: I work as a computer-technician for over 40 years and about 34 years for the same actual company. It was - at a point - Germanys largest IBM systems dealer during the time of PS/2 machines and we had quite a few of them on the desk. Back then gear war really repaired, not only replaced or sub-assemblies changed. So my recollections are still quite good. I hope.
the "Bildröhrenregeneriergerät" print on the Box shows what beautiful things the german language can create by putting four words into one :-)
Great video Adrian. I had one of these little Monitors back on that time as a display for a FIDO Node and for diagnosing PCs of friends that I fixed because it was small and could sit in the corner of my desk with a small footprint.
You really need to sell some t-shirts with your logo and "It freakin' works!" I'd buy one.
Just came home after celebrating Christmas with the family, and found your new video on RUclips. Sooo relaxing to watch. Merry Christmas and greetings from Germany, home of the Bildröhrenregeneriergeräte.
Germany, Home of the best scrabble words :-) You can't miss a double word score with Bildröhrenregeneriergerät.
Adrian, thanks for that year full of interesting stuff! Stay healthy, stay safe but also enjoy the following holidays! :)
Bravo! You saved another life! I might be inspired to bust out the sad SE/30 and have another go!
The tellers at my mother’s bank used these monitors. They were attached to PS/2 machines each linked by thicknet to an IBM 3090 downtown. I remember every year they had a software update I got to play on the 3090 and change the tapes. Truly my first computer.
Sorry but by then it would have been thinnet coax or IBM Token Ring. You did not get anywhere near the tapes.
@@godslayer1415 And how do you know this? Were you there?
Are you sure they ran thicknet all the way back to the mainframe? If they were running it such a long distance it would have to go through the telephone network using a T1 line.
@@douro20 Thicknet locally, then it went downtown by other methods. The branches networked with the mainframe locally through thicknet, though.
@@godslayer1415 NBNTV explains below about "thicknet", and there were also a lot more small banks back before 2008. Why nitpick about that detail, and why assume that meant he didn't get near tapes, no matter what networking cabling involved? Why do you feel this deep seated need for putting people down? Does it have something to do with the militant, fundamentalist atheism you seem to espouse? ;P
That brown goop is a well-known problem. When it turns dark brown, it absorbs moisture from the air and becomes a resistor. Depending on what it bridges, it can cause all kinds of issues.
I'm not sure why, but nostalgia has become my favorite feeling lately. Your channel is a great source.
the label reads ">550V~", so this holds true for 14kV ... and would also for 300kV. Admittedly a slightly strange way to label it, but correct in some sense.
I was going to say that too. He missed the greater than symbol.
@@glen4cindy I was saying, that would be a good general high voltage warning -- they you're dealing with anything far in excess of mains voltage.
I'm guessing the 14kV is only exposed on the final anode at the "stethoscope" end of the plug and so the CRT was labelled as such.
The >550V will be for the focus and exposed on the driver board at the base of the tube.
It might be a regulatory thing where everything greater than 550V needs a label, so they'd just have a bunch of >550V labels rather than needing different labels for each possible voltage.
@@StarkRG I don't recall any regulatory things for stating what potential voltages are, especially back in 1988. Maybe the corps got regulation and testing even back then in order to force smaller biz out but only in industrial markets. Corps use government and taxes for themselves.
Im not all the way through the video but I do recall a similar problem shown on another youtube channel on some modern UPS units made by CyberPower which the vibration protection "gunk" goes off and starts conducting, thus shorting out components on the board. Nice fix Adrian its good another piece of history has been renovated.
The Sierra Christmas Card wraps up an already awesome video! Happy Holidays Adrian!
Wow memories I had one of those with my old 386 in the early 90's
The other day I had an issue with a Yamaha keyboard of about the same age. In it, a 470µF cap had turned into a 2.3 Ohms resistor, pulling one of the voltage rails WAY lower than needed. After removing a bunch of other components, I was able to find this one. I replaced it (and a few other caps I had cut out along the way) and it freakin' works! Interestingly, I hooked the same faulty cap up to a capacitance meter (I have access to a very good one at work), and it still has almost full capacity. But Blocking DC... nope.
Side note: As a German, I just love seeing "Bildröhrenregeneriergerät" written on that box. :-D
In the early 90s I worked as a developer for branch systems at a top 20 bank. We being an IBM shop, supplied all the tellers in the traditional banks this 9" model since space was often at a premium. Ironically the smaller grocery store kiosk branches got the ubiqutous 14" 8511 color monitor, only because the manager apps were also on those particular boxes easily switchable via OS/2 that was running on them.
A fantastic video, Adrian. I love watching your diagnostic work and of course it’s even better when you have a winner! Have a Merry Christmas and we look forward to more great videos. Cheers!
The mother of all small setups
Merry Christmas! These were so common in the 90s and early 2000s! I'd say that yours is about as bright as it gets. Nice and sharp picture!
That's a beautiful IBM specimen. I'm glad it works now.
Knew a guy called TV Bill, had some unorthodox ideas, but he once complained about this assembly glue and explained you could test a resistance value across some of it! His thought was conspiracy planned obsolescence, but my theory is they just used it to put the components on the board and thought nothing of it other than this. Gem from the older generation for you and yours!
We used these 9 inch IBM mono VGA screens in Assembly line controllers. They were the only ones that could handle the magnetic fields from the pick and place units.
A true Christmas miracle !! Nice save and great vid as always Adrian.. Hope you have a great Christmas..
Awesome to see a monitor like this being fixed instead of being thrown out. Hopefully it can be given to a collector one day once your use for it reaches an end.
Removing gunk like this can often be speeded up if you have a hot air rework station. Set temperature to, say, 100C and use a fine tip to get right to the gunk. Warming it up can soften it making it much easier to remove. Hot air can also soften the adhesive under stickers, making them much easier to remove, too.
I love the CRT rejuvenation videos because it's just so cool to see a CRT be brought back from near death to a usable state. It is worthwhile to read up on some of the best practices for rejuvenation, though, as I've heard that you should be positioning the CRT in a particular way so that any of the oxides or corrosion from the gun that is blown off during the process will fall away to somewhere it won't readily cause problems in the CRT. Still, if it's burnt to the point that it's unusably dim, then there's no reason not to give it a go with the rejuvenation. You weren't going to be able to use it anyway with such a dim picture, so even if it dies, the outcome would be the same as before: a CRT transplant.
Just a few pointers for future reference from someone who works on vintage electronics regularly:
You can't rely on CRTs being the same size with the same shape neck connector as a way of seeing if they're compatible, it's always best to Google the part numbers to make sure voltages, bias values and other parameters are compatible.
CRTs often "wake up" after not being used for a period of time, they will get brighter within the first few hours of use.
The 550v warning underneath was actually a "greater than 550v" warning, so yes it's very likely that the HT is 10+kv.
Shorted capacitors are very common, especially in gear that hasn't been used for 5+ years. Sometimes you may find that a device works perfectly for a while then stops working at all, most likely is that an electrolytic has shorted. I would suspect any electrolytic before pulling an IC in something this old!
All that said, I really enjoyed the video as always, keep them coming!
AFAIK 7-pin CRTs should be mostly compatible, with two main variations: heater voltage and position of G2 and G4. I believe the other bias voltages are mostly compatible.
I remember buying three of these from an auction in the 90's. One did sterling service on a server until well into the 2000's.
Starting to like the monitor repair videos, after all! Great production values and content! Could imagine this on educational tv.
I must be learning so much from watching you Adrian. As soon as you switched it on and the Watts spiked then dropped I thought "Capacitor !". Thanks for all your hard work and interesting content.
I've always found the larger caps more suspect than smaller values.
My thoughts exactly.
I think this is partially because he presents things as though we are doing the work and we are experiencing the pain (where relevant). You learn best by doing (experience is what you get when you didn't get what you wanted). By watching you feel like you're doing. It seems in your brain you are taking part. I am never going to be the expert he is (I'm older than he is), but it is gratifying to feel I continue to learn from him.
Adrian the way you can test the power supply is by us a 40 watt bulb as load, then if that's OK go to to line output transitory look for shorts
The only person who can make this kind of diagnoses interesting :)
new channel for older hardware, Adrian's analog attic
Back in the '90s I had a 21" monochrome monitor on my PC. I built a simple resistor divider to take the required portion of R, G and B signals from the PC to avoid the problem of only seeing the green output when playing games.
Hi Adrian, when I was in college (1994) these were being used with PS/2 systems in a computer lab. Standard-size Model M, but these were packed together closely in a line on a desk, and they squeezed as many of us in there as they could.
Caps can definitely short out, I've seen quite a load of them going shorted. Nice fault-finding there!! Merry Christmas and Happy Holidays Adrian! Cheers.
I'm surprised he's never heard of it happening. It's super common in older tube-type equipment.
Great work and well done although I am a little surprised that you went and removed the chip rather than the cap as the cap was the easiest by far and very likely the problem, remember a short is also a massive leak ! but I guess a nice desolder gun helped with that decision ! Happy New Year....cheers.
Especially since a shorted chip there would probably have had its plastic body crack or it would have become so hot as to discolor the PCB beneath it. Neither of which were observed.
Another save! IBM things were all built that way at that time. Tanks!
This channel is a Christmas present for me. Thanks, Adrain.
As an old timer I have seen a lot of shorted capacitors. Specially in low voltage circuits. Just not enough power to blow them open ot the over power safety circuit in power supplies shuts down to prevent capacitor opening up.
Any CRT you'd otherwise ditch is a good candidate for rejuvenation. It's even worth a second try.
And a happy new year to you, too, Adrian! :)
CNC panel cutters & lathes I used in the early 90's used that exact same monitor
Loved every bit of this video -- Thank you Adrian ! Fan for life
I've seen this glue cause so many problems too, but no complaints here as it generated good repair revenue. One use of glue that was very unwelcome however was the silicone type IIYAMA used to glue the EHT anode caps to the bowl of the tube. It was very strong and made it difficult to disconnect the lead from the CRT without causing damage.
Hi Adrian. I hope you and your family (including Rammy!) had a safe and wonderful Christmas holiday! 😍
You could try to adjust the G2 voltage a bit to make it brighter.
I really enjoyed this video, Adrian. Thanks for posting.
I had a shorted 1000µF electrolytic cap on the video mixing board from a Sharp X1 turbo recently. First one I'd ever seen. It pulled the +12V rail down and would not let the computer's power supply switch on as a result.
You'll be happy to know that it tested out as having incredibly low ESR.
That yellow glue is known to be conductive and corrosive over time when it turns brown. It is best to remove them if they are in contact with connections.
Nice repair on a lovely monitor. Brilliant.
Hope you had a good Christmas, and have a Happy New Year.
This was my first monitor, a gift from my uncle after we built my first pc from spares. Was 386sx 25mhz! I spent ages looking for a used VGA to finally embrace colour!
Glad you got it working Adrian! Hope you and your family had a merry Christmas and here's to a LESS interesting new year!
Good diagnosis run, gratz on getting it working again.
Resistors go open and capacitors can short.
The "glue" that they used to use was changed to a new formula when the original formula was found to become conductive over time. Best to just get rid of it whenever possible.
And as always: "thou shall always check voltages" as soon as possible in the diagnosis run.
Cheers and Merry Christmas,
Love that CRT, It's awesome. Great repair :)
Great job, Adrian. As stated by others earlier, suspect and check the simple two-legged varmints before the multi-legged ones. Of course it's easy for me to say that after you've fixed it. :)
Good fix, mate. A charming little thing.
I have one of those monitors in my collection. I used it as a service unit for field calls, mostly in data centres. I seem to remember there was one batch with out of spec video connectors that could be plugged in upside down.
Love the repair. Happy Holidays!
10:30 - is that a 50V capacitor? I mean the big Daewoo one. You should mention that if a PSU with a big cap was used recently you should discharge it through some resistors because you can get a nasty shock from the stored charge. For fun I shorted a 400V cap of a PSU in a PlayStation 3 slim after opening it up and I almost sh*t my pants, it was loud and scary. But I'm glad it didn't short while I was taking it into my lap or something.
24:09 - when it showed short at this point I was like probably one of those caps is shorted. But yeah, they usually don't short when dead, tantallum caps do that. I'm glad my hunch wasn't so bad but I would have never figured it out on my own, I was just following your logic to this point.
The PSU is connected to a transformer which likely sends 20-25v to the DC cap -- no risk there from a shock. :-)
4:47 I have a 22" NEC Diamondtron CRT made in 2000, and it refuses to power on without a signal, instead it turns its glowing Multisync logo to red. Quite unusual for a proper VGA monitor!
Not that unusual for a late CRT like that. From what I remember, all CRTs from the late-90s onward had a standby mode like that.
@@StarkRG All other CRT monitors I remember would display "no signal" at least brefly. Especially a higher end monitor like this I'd expect to implement that.
Super nice monitor, I had one like this or the exact same model 12 years ago. I used it as a second screen for an old Win95 Digital Starion machine.
I miss when it was easy to pick up this stuff, in good working condition, at a thrift for under $10.
@Adrian
I'll say it, Merry Christmas Adrian and a Happy New Year!
Good choice of music Sir - I've seen your Sun & Moon on pause in the background
Happy Christmas Adrian and all the best for 2022.
I thought "Duff cap" as soon as it was obviously going into some sort of protection mode. It's maybe the things I tend to work on but I've encountered for more capacitors that have failed short, or become electrically leaky, than have failed open or physically leaked,
Awesome job at troubleshooting as usual! Great job Adrian! WOOHOOOOOOOOOO!!
I have the same monitor. It came off of an IBM Wheelwriter. I work on Selectrics and Wheelwriters. Some later Wheelwriter models came with these monitors and a swing arm that mounts to the back of the Wheelwriters. They were used by offices and realty stores. I am not sure but I think they were sold as an accessory to the public. Though most of the Wheelwriters that would accept this monitor already had displays built into the front lid. Thanks for the video because I am currently trying to figure out what is wrong with my IBM monitor. I really want to get it going
Programming Databases.... Had them at work on the machines that had been set up for the database design team as you only needed text based, the front office had them for word processing and in the phone centre, the call centre used them as terminal screens to put in service calls. My department eventually got some for the inventory I was responsible for.
Merry Christmas to you, too.
I think the 550+ warning label has to do with the National Electric Code. Most regular service electrical insulation and components are rated to a maximum of 600v. That label may be there to notify a service tech that there are systems inside the enclosure that are higher voltage than standard service components can be used for.
The brown "junk" is called silastic... They use the silastic on the caps so that they don't move around and change the Q factor of the circuit, due to mechanical, or thermal movement.
I have an IBM paperwhite VGA monitor half the size (5-inch dia? I've never measured it) that one!
The last time I plugged it in, it worked fine... but that was quite a few years ago... I should pull it out and check it again!
Nice work! I liked your approach!
Used to HATE fixing monitors!!!!! Just YUK!
Back when we fix monitors and PC power supplies.....
They came with the later Wheelwriter word processors too. I've got a Series 70 with a 4707 and a floppy drive.
underneath R530 there's a ground plane to the left of H- HOLD.... there is a massive broken solder joint.
Hi,
Don't see it. I do see a dark reflection which when he moves the leads you can see that it is a reflection, not a crack.
Do you have a time mark?
A friend of mine gave me a brand new one along with a keyboard. He serviced bank computers at the time. Great memories!
Good result, you must be pleased. Such a sweet little monitor. ✨
We used these monitors as our ANI/ALI screens when I worked 911 in the late 90's... I've repaired more than one of them, and most of the failures were due to the glue of death. I have had one that had that same cap shorted. (no idea why, as it hadn't been sitting for ever unused like yours... that must be a sore spot in the filtering on that rail)
This was a well known problem from back in the 80's!... it's contact cement that goes leaky over time big deal, the HA11235 is a horizontal n vert osc + xray protect driver IC, That picture tube tester is a clone of a old B&K from the 80's.
Awhile ago universal replacement crts for console tv came with no band. You bought a separate band and ears. You set the ears where you needed. High anxiety when tightening the band.
Since the band is part of the implosion protection on a CRT, that can be a risky undertaking - with no guarantee that proper implosion protection ultimately results.