OUCH! Only 340 thumbs up out of 1,700 views. Come on people don't be stingy with a free thumbs up for Shango066. Just realize what this man has done and produced for us for years! Thanks a million for all of your entertaining videos over the years and take care!!
For our enjoyment, this gentlemen puts in $100 per hour work and then all the reel pruning. This being the core of this channel's culture. One hyper BAKED r c a plastic-rama (better living through chemistry era) console with printed circuit boards hosting 39 toasting vacuum tubes in soft sockets, jumbo color CRT that is like NOS, an HV of not great design, nasty quantum level restoration of resister panel values (that would have been the moment typical shop would call the nice lady), and all the 1960s thought put into the stereo and speakers. RCA engineers were not the hippies and yippies so assume it was Mantovani test vinyl. Deserves TWICE the thumbs up.
Cold heaters on the 6GU7s is endemic to these sets. Re-flow the 2 ground stakes on the far right end of the chroma board to fix. With cold heaters, what happens is - plate voltage on the 6GU7s rises, and since the plates are DC-coupled to the CRT control grids, CRT beam current goes into avalanche, dragging down the HV until the raster blooms out. If left in this condition, the 3A3 and flyback are cooked, the 6JE6 cathode current goes out the roof cooking it too. We always re-flowed them 2 stakes as a matter of course on every CTC-12, 15, 16, 17 and 25. Those ground points exist in one of two states: Failed or gonna fail.
Shango I gotta hand it to you. You can get in the most challenging repairs but its good for the mind. It keeps the mind sharp. I am a repairman for a local TV repair shop that repair the LED TVs with bad backlights. Sometimes I get to have some fun and work on vintage things but I hate it when I have to stop and work on a modern TV with bad backlights every five minutes. Hahahaha 😆. Capacitors used to be the worst part ever made that fails but LEDs beat them out they are even worse
Invitation for next Saturday accepted! As always, thanks for your efforts producing these videos - this is 'must-see-TV' in my world. Had anyone told me as a youngster, that I would be making time every Saturday to watch someone on something called the internet repairing TVs and radios, I'd have sworn they were lying.
It's raining, windy and cool here in Los Angeles right now. Not usually as wet and cloudy as the UK, granted (I lived there briefly), but it is winter here too.
Wow nice find shango, yea youve pretty much got all the parts there now to make one awesome one out of the two, that crt is unbelievably strong, brill.
The trademark for Couplate was filed in 1951 by Globe-Union, Inc. in Milwaukee and expired in 1993. The description is "electronic inter-stage audio coupling units for television and radio receivers comprised of electrically connected capacitors and resistors bonded to a high dielectric ceramic base plate". Globe-Union employed Jack Kilby before he invented the integrated circuit at Texas Instruments, so it's likely his experience with Couplates directly inspired the development of the IC.
My mom had an RCA stereo only from 1968 with the same tuner chassis and record player. It had a 3way speaker system per channel. I remember for years she started the record player and hand pushed the turntable to get it started. When the amplifier started going at lower volume would hum through the speakers, but if you turned it up the hum went away. Once the amplifier was really bad, both channels were operating on the left side of the balance, nothing out of the right. She wanted to get it fixed, at the time there were no service parts available in 1981. It turned into a TV stand.
@11:52 Please excuse me for a moment, I've gotta go outside and set fire to a tide pod so as not to break my sense of immersion... Thanks a lot Shango...
I thought I was the only Nipper fan! My last true home theater was my 1988 RCA Dimensia 30 inch flat screen. It was the final console, very hi tech with the black, chrome, and grey presentation. All of the components were shelved neatly on the right of the monitor. I had the full package. Super VHS, compac disk player, turn table, digital tuner, and 500 watt amp(or whatever the highest amp RCA was selling) to handle the full dimensional sound for the TV and the dual twin tower speakers, consisting of a bass, surround, and tweeter. Of course, the beautiful rectangular RCA remote control that ran everything. I remember looking behind it once, with all the wiring, and cringed! I will try and post a picture. Sadly, RCA, was ahead of its time. (the laserdisc, a simple home theater concept, all controlled Universally. One last comment here, it did have a "universal plug" on the monitor side fo the home computers surfacing at the time, along with "Made in Japan".
That was some good going there with the couplet analysis! Excellent result, goes to show how important it is to have a closer look at those ancient transistor output stages. Big thumbs up from Germany👍👍
I grew up with one of these. I fixed it multiple times. Still have the Sams for it. I fixed TV's long before I could drive. I would like to have met you when I lived down there. My retirement job will be fixing vacuum tube stuff. Your videos are great and bring back childhood memories. I was a different kid. Do you remember ITC in L.A. someplace? I used to get my dad take me there at least once a month to spend my money.
Same, just like Dan: I was working on radios long before high school. There was an ITC store in Chatsworth (San Fernando Valley), years ago. I was in there a couple of times. I was more likely to have my dad take me to Olson Electronics or Apex Electronics, though. If you like some of the stuff Dan runs into in the estate sales in some of his videos, you should watch EEVblog's video #124 of his visit to Apex Electronics (which is still in business). It's a "candy store" for anyone in Los Angeles who loves electronics. Just don't be caught in there during an earthquake, since stuff is stacked to the ceiling and the aisles are narrow.
Had that exact same TV Chassis,(not the stereo part) but it was in a metal cabinet that looked like wood, it lasted clear till 2004. We did change the picture tube once.
I was so excited when I found that same B&K tester at Goodwill last year, then I opened it and it was just the empty case. I still bought it of course.
Fancy consoles and desert sets with weeds growing out of them are the most entertaining ones. IIRC transformer size is related to low frequency response (core saturation, I think... or I could be talking nonsense).
Thanks shango! Appreciate the knowledge shared, even better when grasping a bit what said. Your use of parts & 'phrased' words are noted. re: cleaner, O2 sensor, bulb + stereo, QC ... among others. simple idea in trade: If no invention of Box to carry light bulbs, use a 4 or 6 pack, they even come with handle. I recall you explaining process using Lightbulbs to reform capacitors, but 'lost' how - low vs high W. Will Read more.
The lightbulbs are being used as voltage dividers. The low wattage bulbs have a higher resistance than the higher wattage bulbs. The lower wattage bulbs greatly limit the amount of current that the TV can pull, and the bulb takes up most of the line voltage, so the TV gets much less voltage than 120V. If Dan sees that the TV isn't grossly misbehaving (a short circuit, a shorted plate transformer, severely reforming caps), he puts in a higher wattage (i.e. lower resistance) bulb, which allows the TV to get a bigger percentage of the line voltage, and allows it to pull more current from the line. If there's a severe fault in the TV, the lightbulb limits the maximum current that it can draw (to no more than what the bulb itself draws). It's a way of avoiding dealing with exploding old capacitors, or blowing a transformer winding open, or red-plating a tube and ruining it, or catching the TV on fire. It limits the chance of doing damage to the TV. If things seem to be okay, he hits the bypass switch, which shorts across the bulb and gives the TV the full 120V, at whatever current it wants to draw. It's just an inexpensive and convenient alternative to using a variac (autotransformer) to adjust the line voltage to the TV. If you want to understand the theory behind that, look up "voltage divider" in Wikipedia, and more generally Ohm's Law and Kirchhoff's circuit laws.
Those red-ended capacitors were bad from day one. The red stuffing would melt out in about two years. The corroded PC board, probably due to critter pee. And those 6GH8's were run at 100% plate current and they lasted about a year and a half. Quite the challenge.!
@@InsideOfMyOwnMind 2N2222s and 2N3904s. I used to see 2N3055s everywhere (for audio amps and power supplies) in the 1970s, and 6SN7s and 6U8As before that.
If you need to pull the chassis out, notice the stamped steel bracket that sticks up near the power transformer. The VHF/UHF tuner subchassis will slip off of the metal CRT surround fascia panel by loosening three 5/17" hex-head screws. Then lift the tuner subchassis out and notice there are two slotted ears on the back end of the tuner subchassis metal that will slide under two loosened 1//4" hex-head screws on the TV main chassis. There is another 1/4" hex-head screw on the tuner subchassis that slips into the slot of the stamped steel bracket near the power transformer. That allows for easy handling of the complete TV chassis without the danger of breaking the wires and cables to the TV tuner subchassis. Have fun!
interstage transformer size correlates to frequency response = absolutely. The converse of this is why aircraft run on 400 Hz instead of 60 Hz, so that the transformers can be a fraction of the size.
My aunt and uncle had one of these stereo/TV consoles back in the early 60's, they didn't watch TV much but the record player was going pretty much all day, could that be the reason the CRT is still registering as good? I know absolutely nothing about CRTs but was just a thought.
Thanks for doing TV combo units Shango! I don’t understand why I love them so much yet. They are like Cadillacs, giant and epic! Someday I will acquire/create an ultimate TV combo unit, and I will entertain very successfully. Straight up satori mambo set, full color CRT.
Interesting failure for sure but not surprising given it has those huge 15" duo cone ovals that you know have blasted every genre of music. Those consoles were probably used for shop radios and played loud. The heat alone would start to kill the couplate. I've had success making electrical equivalents using a remote mounted board and ribbon cable back to the main board. By adding a couple of precision pots and you can dial the bias in.
Nice job with diagnosing as usual. So couplets, I'm going to have to keep my eye on those now. I had a CTC17 combo, same issue a few years back. Had I known then...
Cap coupled amp. They sound fantastic. I think they sound tube’bee when operating correctly. Nice observation on the bias. The Pioneer coupled amps of that era had trimmers to set half the voltage of the rail collector. I have the scat for the Pioneer but not the RCA. I’d like to know more about the circuit. There’s probably more drifted resistors? Very well done video!
Couplates, never like them things, without schematics your guessing as to what is inside. Good job on getting the output Germanium transistors bias correctly. Its sounding good with lower distortion! The amount of Iron in an audio transformer does not necessarily limit bass response at low power levels, just that you need more Iron if you need to maintain good bass response at higher output watt levels, because of magnet saturation that limits the low end. Driver transformers are low power so they should have fairly good bass response there.
I bet the original part was slightly under spec wattage wise leading to it to overheat and fail over time. I’m familiar with working on this style of amplifier. I’m really surprised there isn’t a trim pot to set the center voltage as that is normally found on these types of amps. I always upgrade the final coupling caps going to the speakers to 2,200 MFD as it will help with bass response. I doubt a volt difference will cause an issue unless running near clipping and the 15x9” speakers will be hurting your ears by that point anyways.
We worked on a lot of these when we were young.. They were worth fixing then parts were relatively cheap and available. It makes no sense today to do this other than for the challenge of the repair or should I say the fun of it. What you get is a transistor radio with big speakers a 25 Inch color TV with a dim CRT and poor color reproduction. I liked the older 21 Inch round tubes for their better color purity as they used rare earth phosphors which had a better color gamut.
The 6GU7 filament circuit grounds at the right rear eyelet of the Chroma board. The solder develops metal fatigue due to the heat-cooling cycles of the chassis. Just re-solder the eyelet usually corrects that. When the 6GU7s filaments go out the bias of the CRT gets messed up and heavy conduction of the CRT results. The green corrosion of the wire on top of the board near the 6GU7s is a B+ wire and will need to be replaced. The plate load resistors of the 6GU7s may need to all be replaced with new flame-proof 3W resistors. You might be able to carefully tighten the 6GU7 tube socket contacts. A good cleaning of the boards top-side may reveal other issues that need to be addressed. There is a stacked selenium disc rectifier in the Damper circuit that develops B++ voltage for the CRT screen control circuits. If it goes high resistance, you may not be able to get the screen controls to produce a line when the Service SW is in the Service position. Yes the stereo tuner chassis is a bit of a pain to work on. I believe the heat sink that the output transistors mount on can be loosened and allowed to fold aside for access to the electrolytic capacitors. Those OEM electrolytics were not the best quality even when new..
I think the CTC25 was the first color set I ever worked on as a late teener/20 something if you don't count the "Admirable" roundie while in high school where I learned about what filter caps will do to a picture. Memreeez! You gonna delam that jug and make it look all nice n shiny?
On the finish, all the Danish Modern style consoles and stereo console models had a walnut wood veneer and the finish was not a form of varnish, but hand rubbed oil finish. That might be easier to do than using a varnish or polyurethane finish. Other furniture styles had completely different finishes that did use a form of varnish.
Edit: Ok, maybe not in this case. "Make things hard to work on so people will replace rather than repair, or pay a premium to have a "professional" repair it. Even back then. " Btw, interesting video!! 👍
Why fix that radio gem? It sounded pretty good with that buzz. That radio had more hum than my grandmother drunk in church on Sunday morning. That whole set is definitely a real keeper! I bet the smell from it is a smell you don’t forget right away. I love every one of your shows! # baked
Shango, if you wanted you could set a premiere date for the station tour video. It allows people to click on it and get a reminder when it goes live, Or you can use your community tab for reminders for upcoming uploads to help boost the viewership of the video when it comes out. I personally don't use the premier feature but I do use the community posts for reminders and such and it seems to work pretty well. The shorts feature also seems pretty popular when I use it.
Those bias couplates in those radio chassis sucked, had to replace many just like you did with this one, another thing to be careful of is the speaker terminal rivets are aluminum and the heads pop off when you try to disconnect the wires and you end up ripping the voice coil leads off. ☹️
Lot times those units were put in the formal lounge and only used when company came by. Rest the time everyone huddle in the den/family room. Way it was in the house I grew up in. Console stereo and all. Lol.
Great analysis troubleshooting, can’t wait for the next chapter! What a bad design that stereo power amp section is, a couplet resistor package is a terrible choice for power output stage biasing. Of course they’re gonna get hot in that position and need to be able to dissipate heat, that’s a guaranteed failure waiting to happen.
thank man i liked the video .i am curious of upgrading the germanium transistors or i guess one could install a modern sure /wondom amp board just running it offf the pre amp
I still want to see all the best tubes and some other parts ported into one final unit. So many duplicate tubes, one could refine down to best editions. Because I've wanted to start with two old units and make one good. Of course, I lack his tools, knowledge, and experience. I'm stuck running with a 100 watt bulb in series. No bypass.
14v approx across each of those 390s is roughly 0.5w per resistor, so yeah it will run pretty warm, i have an amplifier and a tuner-amp that uses basically the same circuit, and their bias resistors(luckily separates in those😉, both made in Denmark, probably by the same company although differently branded externally) run quite hot
I love those speakers Shango, I wonder how they sound and is the amp powerful ? I love your sense of humor Shango.very interesting point about the small transformers and the sound quality shango.
"Quality Deficit Disorder" another one for the Shango Dictionary, !! good one!!!
Can’t forget “propaganda bulb” and “lithium ion transistors”
I about lost it on the tapping foot. Hilarious.
@Eric Ruud The timing on the edit was perfect.
I came for the information, the humor, the fabulous editing and complaining, and I was not disappointed. 👍🤓
"You are my hero"
I'm pleased to see someone admiring the editing. This is one of the most refined one-person channels I've ever seen.
@@directcurrent5751 👍
OUCH! Only 340 thumbs up out of 1,700 views. Come on people don't be stingy with a free thumbs up for Shango066. Just realize what this man has done and produced for us for years! Thanks a million for all of your entertaining videos over the years and take care!!
They are ungrateful schweinhund !!
LFOD !
Wow ŕeally like that TV a modern marvel
For our enjoyment, this gentlemen puts in $100 per hour work and then all the reel pruning. This being the core of this channel's culture. One hyper BAKED r c a plastic-rama (better living through chemistry era) console with printed circuit boards hosting 39 toasting vacuum tubes in soft sockets, jumbo color CRT that is like NOS, an HV of not great design, nasty quantum level restoration of resister panel values (that would have been the moment typical shop would call the nice lady), and all the 1960s thought put into the stereo and speakers. RCA engineers were not the hippies and yippies so assume it was Mantovani test vinyl. Deserves TWICE the thumbs up.
Done and done!
Thanks for the remainder
Talk about bringing back memories! I grew up with many hours around this model. I thought it was greatest during the late 60s, early 70s.
Can't wait,I use to work for WION 1430 back in the late 90's along with Dan Pentengil,He has sence passed away...Macpherson was the owner..
I watch every Saturday I know I'll tune in next Saturday for that one sounds cool. 👍🏻👍🏻
Cold heaters on the 6GU7s is endemic to these sets. Re-flow the 2 ground stakes on the far right end of the chroma board to fix. With cold heaters, what happens is - plate voltage on the 6GU7s rises, and since the plates are DC-coupled to the CRT control grids, CRT beam current goes into avalanche, dragging down the HV until the raster blooms out. If left in this condition, the 3A3 and flyback are cooked, the 6JE6 cathode current goes out the roof cooking it too. We always re-flowed them 2 stakes as a matter of course on every CTC-12, 15, 16, 17 and 25. Those ground points exist in one of two states: Failed or gonna fail.
Yeah I figured something like that or an open corroded jumper wire. I'll get it out and put it on the jig where I can work on it
Yeah. My experience with them was as a service dealer. By now, you'll no doubt find a lotta other stuff cooked and cracked.
@@shango066 thanks for making these videos.
Ultra-cheezy plastic tuning mechanism only ran for one model year ('66 IIRC).
Dig the am stereo stuff, looking forward to next weeks video!
I'll definately be watching next weeks tour of the station. :)
That amp sounds a hell of a lot better.
Shango I gotta hand it to you. You can get in the most challenging repairs but its good for the mind. It keeps the mind sharp. I am a repairman for a local TV repair shop that repair the LED TVs with bad backlights. Sometimes I get to have some fun and work on vintage things but I hate it when I have to stop and work on a modern TV with bad backlights every five minutes. Hahahaha 😆. Capacitors used to be the worst part ever made that fails but LEDs beat them out they are even worse
I wonder if the physics behind those failures is similar explanation.
Just cheap nasty and overdriven.
Thanks! I'm looking forward to next week's video about the radio station.
Invitation for next Saturday accepted! As always, thanks for your efforts producing these videos - this is 'must-see-TV' in my world. Had anyone told me as a youngster, that I would be making time every Saturday to watch someone on something called the internet repairing TVs and radios, I'd have sworn they were lying.
I wish I could time travel back to 1970s Brea CA to thank Charles E Stone for an incredible stand by education in consumer electronics.
Not only entertaining as usual, but nice to see somewhere warm and sunny. Freezing here in a dim dismal UK.
It's raining, windy and cool here in Los Angeles right now. Not usually as wet and cloudy as the UK, granted (I lived there briefly), but it is winter here too.
Wow nice find shango, yea youve pretty much got all the parts there now to make one awesome one out of the two, that crt is unbelievably strong, brill.
The trademark for Couplate was filed in 1951 by Globe-Union, Inc. in Milwaukee and expired in 1993. The description is "electronic inter-stage audio coupling units for television and radio receivers comprised of electrically connected capacitors and resistors bonded to a high dielectric ceramic base plate". Globe-Union employed Jack Kilby before he invented the integrated circuit at Texas Instruments, so it's likely his experience with Couplates directly inspired the development of the IC.
thanks for watching more than the first 2 minutes.
I resemble that remark
it is all because you LOVE the old electronics, we old-timers want to repeat history, somehow~
My mom had an RCA stereo only from 1968 with the same tuner chassis and record player. It had a 3way speaker system per channel. I remember for years she started the record player and hand pushed the turntable to get it started. When the amplifier started going at lower volume would hum through the speakers, but if you turned it up the hum went away. Once the amplifier was really bad, both channels were operating on the left side of the balance, nothing out of the right. She wanted to get it fixed, at the time there were no service parts available in 1981. It turned into a TV stand.
@11:52 Please excuse me for a moment, I've gotta go outside and set fire to a tide pod so as not to break my sense of immersion... Thanks a lot Shango...
I thought I was the only Nipper fan! My last true home theater was my 1988 RCA Dimensia 30 inch flat screen. It was the final console, very hi tech with the black, chrome, and grey presentation. All of the components were shelved neatly on the right of the monitor. I had the full package. Super VHS, compac disk player, turn table, digital tuner, and 500 watt amp(or whatever the highest amp RCA was selling) to handle the full dimensional sound for the TV and the dual twin tower speakers, consisting of a bass, surround, and tweeter. Of course, the beautiful rectangular RCA remote control that ran everything. I remember looking behind it once, with all the wiring, and cringed! I will try and post a picture. Sadly, RCA, was ahead of its time. (the laserdisc, a simple home theater concept, all controlled Universally. One last comment here, it did have a "universal plug" on the monitor side fo the home computers surfacing at the time, along with "Made in Japan".
Looking forward to the tour of the WION studio and transmitter. Throughly enjoy your video’s.
Propaganda bulb i love that term, my old dad used to call the TV the "Idiots lantern"
My ham radio mentor (W6DDB), a WWII vet, used to call it the "modulated milk bottle".
That was some good going there with the couplet analysis! Excellent result, goes to show how important it is to have a closer look at those ancient transistor output stages. Big thumbs up from Germany👍👍
We had that exact same set when I was a kid. Brings back some memories!
I grew up with one of these. I fixed it multiple times. Still have the Sams for it. I fixed TV's long before I could drive. I would like to have met you when I lived down there. My retirement job will be fixing vacuum tube stuff. Your videos are great and bring back childhood memories. I was a different kid. Do you remember ITC in L.A. someplace? I used to get my dad take me there at least once a month to spend my money.
Same, just like Dan: I was working on radios long before high school. There was an ITC store in Chatsworth (San Fernando Valley), years ago. I was in there a couple of times. I was more likely to have my dad take me to Olson Electronics or Apex Electronics, though. If you like some of the stuff Dan runs into in the estate sales in some of his videos, you should watch EEVblog's video #124 of his visit to Apex Electronics (which is still in business). It's a "candy store" for anyone in Los Angeles who loves electronics. Just don't be caught in there during an earthquake, since stuff is stacked to the ceiling and the aisles are narrow.
I worked at ITC Electronics in Torrance it was my first official job that I lost during the LA riots because the main store in La was burned down
@@shango066 riots? Don't you mean "protesting"?
Had that exact same TV Chassis,(not the stereo part) but it was in a metal cabinet that looked like wood, it lasted clear till 2004. We did change the picture tube once.
I appreciate the mention of my old buddies, the Sanchez brothers, Dirty and Nasty.
Loved the video! Always fun to listen to your commentary. The first 20 minutes you try to talk yourself out of the repair😂
Keep up the good work !
You should definitely restore this.
It seems to be surrendering it's secrets.
Just like my grandparents had. Always needed work.
Nice repair, and good info about transistor biasing.
My favourite quote from shango is ” Its the blambulance ”•
Nice job on that radio Shango! Nice job on finding the problem with the resistors! Can't wait till part 2.
I was so excited when I found that same B&K tester at Goodwill last year, then I opened it and it was just the empty case. I still bought it of course.
Fancy consoles and desert sets with weeds growing out of them are the most entertaining ones. IIRC transformer size is related to low frequency response (core saturation, I think... or I could be talking nonsense).
Thanks shango! Appreciate the knowledge shared, even better when grasping a bit what said.
Your use of parts & 'phrased' words are noted. re: cleaner, O2 sensor, bulb + stereo, QC ... among others.
simple idea in trade: If no invention of Box to carry light bulbs, use a 4 or 6 pack, they even come with handle.
I recall you explaining process using Lightbulbs to reform capacitors, but 'lost' how - low vs high W. Will Read more.
The lightbulbs are being used as voltage dividers. The low wattage bulbs have a higher resistance than the higher wattage bulbs. The lower wattage bulbs greatly limit the amount of current that the TV can pull, and the bulb takes up most of the line voltage, so the TV gets much less voltage than 120V. If Dan sees that the TV isn't grossly misbehaving (a short circuit, a shorted plate transformer, severely reforming caps), he puts in a higher wattage (i.e. lower resistance) bulb, which allows the TV to get a bigger percentage of the line voltage, and allows it to pull more current from the line. If there's a severe fault in the TV, the lightbulb limits the maximum current that it can draw (to no more than what the bulb itself draws). It's a way of avoiding dealing with exploding old capacitors, or blowing a transformer winding open, or red-plating a tube and ruining it, or catching the TV on fire. It limits the chance of doing damage to the TV. If things seem to be okay, he hits the bypass switch, which shorts across the bulb and gives the TV the full 120V, at whatever current it wants to draw. It's just an inexpensive and convenient alternative to using a variac (autotransformer) to adjust the line voltage to the TV. If you want to understand the theory behind that, look up "voltage divider" in Wikipedia, and more generally Ohm's Law and Kirchhoff's circuit laws.
Great repair. Really enjoyed you working on that amp. Almost like we were there with you.
Those red-ended capacitors were bad from day one. The red stuffing would melt out in about two years. The corroded PC board, probably due to critter pee. And those 6GH8's were run at 100% plate current and they lasted about a year and a half. Quite the challenge.!
But they were the 2n2222 of the day. They were everywhere.
@@InsideOfMyOwnMind 2N2222s and 2N3904s. I used to see 2N3055s everywhere (for audio amps and power supplies) in the 1970s, and 6SN7s and 6U8As before that.
Bro, im using this video to remove panic attack
Hang in!
There there.
Pat pat.
If you need to pull the chassis out, notice the stamped steel bracket that sticks up near the power transformer. The VHF/UHF tuner subchassis will slip off of the metal CRT surround fascia panel by loosening three 5/17" hex-head screws. Then lift the tuner subchassis out and notice there are two slotted ears on the back end of the tuner subchassis metal that will slide under two loosened 1//4" hex-head screws on the TV main chassis. There is another 1/4" hex-head screw on the tuner subchassis that slips into the slot of the stamped steel bracket near the power transformer. That allows for easy handling of the complete TV chassis without the danger of breaking the wires and cables to the TV tuner subchassis. Have fun!
When you mentioned how humid a day it is at 19.41 I see mr sparky.
Use a colon (:) instead of a period (.) and you make a tappable link to get to a specific point in a video.
Example: 19:40 😉
Have always learned a lot from you Shango, Merry Christmas happy Hanukkah! Mark.
interstage transformer size correlates to frequency response = absolutely. The converse of this is why aircraft run on 400 Hz instead of 60 Hz, so that the transformers can be a fraction of the size.
Socket 3 was the one for most old crts. Been there accidentally grabbing socket 4.
very enjoyable video loved spending my day watching your videos always look forward to each and every video
Love to see what happen next to this repair....
My aunt and uncle had one of these stereo/TV consoles back in the early 60's, they didn't watch TV much but the record player was going pretty much all day, could that be the reason the CRT is still registering as good? I know absolutely nothing about CRTs but was just a thought.
Thanks for doing TV combo units Shango! I don’t understand why I love them so much yet. They are like Cadillacs, giant and epic! Someday I will acquire/create an ultimate TV combo unit, and I will entertain very successfully. Straight up satori mambo set, full color CRT.
Had one of these back around the year 2000, the stereo had bad filter caps. So I wouldn't doubt that you will have to replace those.
In London it's very cold and in Scotland it's snowing
Interesting failure for sure but not surprising given it has those huge 15" duo cone ovals that you know have blasted every genre of music. Those consoles were probably used for shop radios and played loud. The heat alone would start to kill the couplate. I've had success making electrical equivalents using a remote mounted board and ribbon cable back to the main board. By adding a couple of precision pots and you can dial the bias in.
Potentiometers are because no engineering beats uncertainties.
What a great record player
Nice styling on that 67!
Shango always cheers me up.
Wow top job mister
Thanks for your great videos
Nice job with diagnosing as usual. So couplets, I'm going to have to keep my eye on those now. I had a CTC17 combo, same issue a few years back. Had I known then...
Cap coupled amp. They sound fantastic. I think they sound tube’bee when operating correctly. Nice observation on the bias. The Pioneer coupled amps of that era had trimmers to set half the voltage of the rail collector. I have the scat for the Pioneer but not the RCA. I’d like to know more about the circuit. There’s probably more drifted resistors?
Very well done video!
Couplates, never like them things, without schematics your guessing as to what is inside. Good job on getting the output Germanium transistors bias correctly. Its sounding good with lower distortion! The amount of Iron in an audio transformer does not necessarily limit bass response at low power levels, just that you need more Iron if you need to maintain good bass response at higher output watt levels, because of magnet saturation that limits the low end. Driver transformers are low power so they should have fairly good bass response there.
so i have watching long time . thank you your amazing
I bet the original part was slightly under spec wattage wise leading to it to overheat and fail over time. I’m familiar with working on this style of amplifier. I’m really surprised there isn’t a trim pot to set the center voltage as that is normally found on these types of amps. I always upgrade the final coupling caps going to the speakers to 2,200 MFD as it will help with bass response. I doubt a volt difference will cause an issue unless running near clipping and the 15x9” speakers will be hurting your ears by that point anyways.
We worked on a lot of these when we were young.. They were worth fixing then parts were relatively cheap and available. It makes no sense today to do this other than for the challenge of the repair or should I say the fun of it. What you get is a transistor radio with big speakers a 25 Inch color TV with a dim CRT and poor color reproduction. I liked the older 21 Inch round tubes for their better color purity as they used rare earth phosphors which had a better color gamut.
Impressive troubleshooting guess on the drifty couplet !
Another great video thanks shango
The 6GU7 filament circuit grounds at the right rear eyelet of the Chroma board. The solder develops metal fatigue due to the heat-cooling cycles of the chassis. Just re-solder the eyelet usually corrects that. When the 6GU7s filaments go out the bias of the CRT gets messed up and heavy conduction of the CRT results. The green corrosion of the wire on top of the board near the 6GU7s is a B+ wire and will need to be replaced. The plate load resistors of the 6GU7s may need to all be replaced with new flame-proof 3W resistors. You might be able to carefully tighten the 6GU7 tube socket contacts. A good cleaning of the boards top-side may reveal other issues that need to be addressed.
There is a stacked selenium disc rectifier in the Damper circuit that develops B++ voltage for the CRT screen control circuits. If it goes high resistance, you may not be able to get the screen controls to produce a line when the Service SW is in the Service position.
Yes the stereo tuner chassis is a bit of a pain to work on. I believe the heat sink that the output transistors mount on can be loosened and allowed to fold aside for access to the electrolytic capacitors. Those OEM electrolytics were not the best quality even when new..
New Shango post? LFG!!!!! 😎
Thanks!
I think the CTC25 was the first color set I ever worked on as a late teener/20 something if you don't count the "Admirable" roundie while in high school where I learned about what filter caps will do to a picture. Memreeez!
You gonna delam that jug and make it look all nice n shiny?
I'll check next Saturday
Great video, enjoy your explanations. 73 Leo
42:30 Toxic stuff is the best. The more toxic, the better it cleans.
dude, thank you i learn a lot from you
On the finish, all the Danish Modern style consoles and stereo console models had a walnut wood veneer and the finish was not a form of varnish, but hand rubbed oil finish. That might be easier to do than using a varnish or polyurethane finish. Other furniture styles had completely different finishes that did use a form of varnish.
Edit: Ok, maybe not in this case.
"Make things hard to work on so people will replace rather than repair, or pay a premium to have a "professional" repair it. Even back then. "
Btw, interesting video!! 👍
I like RCA I thought there TVs were cheap but I would take those two and make one good one use the other for firewood
Why fix that radio gem? It sounded pretty good with that buzz. That radio had more hum than my grandmother drunk in church on Sunday morning. That whole set is definitely a real keeper! I bet the smell from it is a smell you don’t forget right away. I love every one of your shows! # baked
Wish I had your skills man, great vid 👍
There are PNP silicon output transistors in 1/2 of each audio output stage in the AM-FM tuner chassis.
Looking forward to nx Saturdays vid already sounds cool
You may want to check the tweeters in that unit. I bet they are similar to the ones in an admiral I had as a kid. One of the tweeters went out in it.
These are best background videos whilst Im writing music.
Dude... you gotta restore this unit... with the CRT in that condition...it would be a shame to strip it
That RCA been through the ringer. But it still works
Shango, if you wanted you could set a premiere date for the station tour video. It allows people to click on it and get a reminder when it goes live, Or you can use your community tab for reminders for upcoming uploads to help boost the viewership of the video when it comes out. I personally don't use the premier feature but I do use the community posts for reminders and such and it seems to work pretty well. The shorts feature also seems pretty popular when I use it.
Those bias couplates in those radio chassis sucked, had to replace many just like you did with this one, another thing to be careful of is the speaker terminal rivets are aluminum and the heads pop off when you try to disconnect the wires and you end up ripping the voice coil leads off. ☹️
Can you change the cabinets with the other console with the broken CRT neck ? Might be less work.
If he gets the tv working he should, I would.
Lotsa work though.
@@JohnShinn1960 Maybe Shango has plans to make the other one work also, even though it's been "Necked" he may have a picture bulb for it yet!!!
Is the radio station "this is a test... this is only a test..." still working?
diaperlicious.....made my day, chap~
Lot times those units were put in the formal lounge and only used when company came by. Rest the time everyone huddle in the den/family room. Way it was in the house I grew up in. Console stereo and all. Lol.
Ours was essentially used at Christmas or games.
Same set made it into the 80’s as I recall.
Your bass speakers in knackered
Great analysis troubleshooting, can’t wait for the next chapter! What a bad design that stereo power amp section is, a couplet resistor package is a terrible choice for power output stage biasing. Of course they’re gonna get hot in that position and need to be able to dissipate heat, that’s a guaranteed failure waiting to happen.
So, after you work your magic, swap it into the nicer cabinet?
thank man i liked the video .i am curious of upgrading the germanium transistors or i guess one could install a modern sure /wondom amp board just running it offf the pre amp
Anymore videos coming on this restoration? Would certainly be nice to see this one completed.
Yes
I still want to see all the best tubes and some other parts ported into one final unit. So many duplicate tubes, one could refine down to best editions. Because I've wanted to start with two old units and make one good. Of course, I lack his tools, knowledge, and experience. I'm stuck running with a 100 watt bulb in series. No bypass.
14v approx across each of those 390s is roughly 0.5w per resistor, so yeah it will run pretty warm, i have an amplifier and a tuner-amp that uses basically the same circuit, and their bias resistors(luckily separates in those😉, both made in Denmark, probably by the same company although differently branded externally) run quite hot
Ohhh, the transistor bulbs in the radio are not all PNP; two (at least) are NPN! Whew. Now I’m more happy-ish. ☺️
Anymore developments in this project? Childhood memories of this set is asking. 😁
I love those speakers Shango, I wonder how they sound and is the amp powerful ? I love your sense of humor Shango.very interesting point about the small transformers and the sound quality shango.
You kept the suspense up with the unknown condition of the CRT. Was there actually any damage to the neck?
No
Do you ever come across old Electrohome television sets? I believe they were made in Canada!
Great channel!
Actually the transistors in the AM-FM tuner are NPN silicon rather than PNP germanium. Silicon was already king by then.