Tektronix 465B Restoration Part 1 Power Supply and Tube
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- Опубликовано: 27 авг 2024
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In this video we look at the venerable 465B 100 Mhz scope from Tek. This is turning in to a large restoration project so I will be splitting it in to at least 4 videos but I will be making a play list about it so they are all together.
** Repair exposes the Tech to mains electric and should only be done by trained personal. Errors can be fatal. **
I would say excellent but it would not do justice to your video. You easily have the best channel covering tek scopes. I'm looking forward to part 2
Thanks Todd, Glad you are enjoying.
Thank you for the information! Love it!
Thanks! This is great stuff, especially since you've had a decent amount of experience to draw upon that you share while going through it.
Keeping the old ones alive!
Great video! Thanks for showing the attenuator cam switch in detail - really interesting design. Headlight restoring compounds work well for minor scratch removal on instrument panel windows.
There will be a ton of attenuator troubleshooting in part 2. At this point in time I did not know it yet but the channel 1 attenuator was a disaster. But there is some cool stuff on the way.
Thanks so much for this video, you just helped me fix my scope. Channel one v/div control was not working well, I cleaned it just like you did and voila! all working again. Mine was a bit more of a pain to dismantle and get back together because it has a DM44 voltmeter mounted on the top, which kind of interferes with everything fitting easily. I guess that must have been an optional extra.
Thanks for the info. Good job.
Great series - I have a 465 (lightly used)and would like to fix the chan 1 AC/DC switch which seems to be slipping, and a tune up would be great. I wish I could have seen the q-tips when you were cleaning the attenuator contacts (camera angle), but super video.
The attenuator should not be cleaned with Qtips. It is to easy to catch one and bend the contacts out of alignment permanently deforming them. The micro switches are fairly fragile.
The Tek attenuators are specified in terms of their voltage division ratio rather than the normal power division ration in dB. The x2 attenuator is equivalent to 6dB, the x5 attenuator is equivalent to 14dB and the x10 atenuator is equivalent to 20dB.
Thanks Stephen, I kept coming up with 3, 7, and 20, for the dB ratios. I will do a bit more digging. Then get a few ordered.
Thanks
Nice work as always.
Perfect job
By the time you got to 9:42 it would be on my production bench 😊
I'm really enjoying these videos on the 465B since I just bought a used one at a decent price. As far as I can tell so far the unit works. As for calibration, that is a future pursuit of mine.
One problem i have noticed is that the focus pot (R4132...a 5Meg ohm 311-0075-00 clarostat) Is very hard to turn. May as well say seized. I have been in touch with surplus suppliers for this part.
Since this exact part is no longer in production, I was quoted $555 US for a replacement. Was hoping maybe you would know of a suitable newer replacement that would work. The cost of a exact replacement is more than I am willing to spend .
Also, this pot is under the high voltage guard on the power supply board as you well know, so curious as to what voltage is put across this potentiometer.
TIA
Gary
Thanks for
Jeez, you know your getting old when watching RUclips and someone's doing a restoration of something that was you daily workhorse 40 years ago !!! 🤣🤣🤣🤣
I just hope I did it justice, It is going to a young tech who is currently pre-university.
@@ZenwizardStudios Your doing a superb job, for someone pre-uni it's an excellent scope to give a fundamental grounding in the operation of a scope. I find modern scopes an absolute pain, they take ages to boot up, they have a minefield of menu's and submenus of which I think 90% are over complex. I could operate a 465 almost blindfold, the scope I use now I normally shout over the apprentice to help if Im stuck 🤣🤣
@@DiyMech I totally agree the new stuff is nice especially some of the fancy triggering but some times I just want, show me the waveform and let me figure it out from there. It is why I keep the big Tek iron on the bench. To be honest my 7603 is on more than my Rigol is. But for the REALLY fast, and the REALLY slow. Digital is nice. I would not want to try and look at 50s/div on an analog scope. Ill take the digital for that.
Thanks for these really professional videos .. I bought one 465 recently but unfortunately it has very dim display even at max intensity… could you shed some light on how to troubleshoot that issue … thanks again
Glad you are enjoying. Unfortunately I have bad news if the display is really dim it is either grid bias is WAY out of adjustment and is turning the tube off. Or the tube is high hour and very worn. On thing to look for is what is called a double peak of the tube. This happens when you turn the intensity control up. If the tube gets brighter then dimer then brighter again this would be cathode poisoning and repair is unlikely. Brightness trouble shooting could also mean issues in the high voltage section but extreme care needs to be taken when working in that area as there is -4KV exposed when working. Sometimes but rarely I have heard there is some issues with the HV rectifier diodes as well as some times the ceramic capacitors.
@@ZenwizardStudios Thanks for responding
I think you were spot on ... i had this double peaking . But when i was desperately trying to do grid voltage calibration by probing the test point i found the reading was 95 volts which should have been maximum 75 . Unfortunately the probe slipped and i heard a short whine then the HV was gone and i can't get the HV oscillator Q1418 to run again ever since !
I don't konw if there is a way to test the HV multiplier without having to remove the boards ,
Or Should i give up !
@@basemhanna6175 Weather the project has concluded or not really my call, However if you saw the double peaking tube, then short of trying a CRT restorer with out a parts scope there is not much that can be done. The cathode is internal to the tube and in the vacuum envelope. So at minimum a new CRT will need to be sourced.
Zen
@@ZenwizardStudios Many Thanks for your Technical advice. I learn a lot from Your videos . Technically crisp, really above and beyond.
Thanks again
I’m always shocked when they make it through shipping alive. So risky. People like to launder broken gear through a courier.
How are cleaning in between the leaf contact when it is down? Are you only cleaning the top of the leaf contact with the cotton swab ?
😊
Hi , when checking for CRT BurnIn, a dark room with highest trace intensity the best conditions? and are there any other trucks?
Thanks in advance 😊
Thanks! Question = As you know, the mains AC voltage supply has increased to ~120V. The scope is to be calibrated with a 115V supply. Is it better to 1) drop the supply to 115V with a variable autotransformer and adjust the calibrations, or 2) try to make some mathematical calculation for all the various calibration points? 120/115 = 1.04347; so a 10V calibration point should be at 10.4347V. Number two does not feel like the correct method to use, but lots of folks don't have a autotransformer... Your thoughts?
My current practice is to do the alignments with the regulator set to where it will be in operation. Given the increase in line voltage this is usually in HIGH position. For some of the older gear like the type 106 this runs on a double conversion ups to drop the line voltage to 110 and hold it there.
Thanks for the nice video, what replacement did you use for the capacitor indicated in 17:00?
Looks to be an axial leaded cap that I had on hand in the lab. Nichicon or Rubycon, Highest temp 105 degree C, similar capacitance, and a descent voltage bump (if it will physically fit) one thing to note is that axial leaded caps tend to be only available in 85 degree C.
@@ZenwizardStudios Great, thanks. Indeed I took a look at mine and I looks bad. I'm considering to change it. Thanks again :)
Can you someday make a video ,for a broken ac .Gnd.dc slide switch on the channel 1 side. It stuck on DC thanks
How did you get so good on the 465B Scopes?
Interesting video, I learned quite a bit.I've never calibrated my scopes so this will give me some idea of the processes involved. I'm missing several bits of test gear needed though to calibrate my 500 series scopes, like a step gen. For those of us on a budget could you suggest any alternatives to the proper kit, as you go through the alignment process. EG would it be possible to use a 555 IC to knock up a simple step genny, (assuming one could measure accurately ish the resultant frequency) instead of a dedicated bit of test gear to get our scopes better aligned/calibrated. Thanks....DA.
Hi Diabolical Artificer, To do a full scope there are typically 5 sections that need to be addressed. Power supply (Voltages), Tube (General Geometry and beam shape), Vertical (amplitude and frequency response of the X plane of the scope), Triggers (This is really a balance point for the trigger circuit to make sure they behave correctly) and the Horizontal/Time base(This is the timing of the Y plane of the scope.) The true trick to an alignment is knowing your input signals and having confidence in them that they are precise. Absolute precision is not super critical for a 400 series scope as the tolerance is +/- 3%. This was the first video in a multipart series the vertical section will be out tomorrow. I am still shooting the Trigger and Horizontal sections. Ran in to more trouble during the Horz cal. So there is much more information coming on the topic. If it would be helpful I could do a video on what is “special” about each of the signals in how they are used in the calibration process?
@@ZenwizardStudios Thanks. If you have the time a video would be a great help. Watching this series of video's with great interest. ATB...DA.
Glad I could help! There is quite a bit of interest in the calibrators. I do have a video planned for going in to the SG505 TG501 and PG506 in detail. In terms of accurate frequency measurements the easiest way I have found for highly accurate measurements in a home lab Is a GPSDO backed up frequency counter. In this way you could tune a pulse timing to have the correct period then use that to adjust the time base. The GPSDO is self correcting which is great for a home lab. comparing 2 different GPSDO's they agreed with each other within 500 uh or micro hertz. This is plenty good for an analog scope. 500 micro hertz on 10Mhz.
@@ZenwizardStudios Thanks again, I'll look into a GPSDO but think my FC has an oven frequency reference, will look into this...DA
Hi. Do you think the graticule is removable or is it glued to the tube? Thanks
On the 4xx 7xxx 5xxx scopes the graticule is etched in to one of the glass surfaces of the tube and in non removable. In the 500 series I am not sure if this is the case.
@@ZenwizardStudios Many thanks!!!
Where do you get your replacement filter capacitors for 465 tektronix scopes?
Mine were from a parts unit. There is an adapter board that can be used. The impotent part is there are grounds that are carried though on the can case. So the adapter takes it from 5 pin caps to 2 pin form factor.
thank you for the excellent video. I have the Tektronix 475 with the healthy CRT with good focus but the trace does not seem to be as tight has your scope. I have checked the power supply and everything is good there, the high voltage is good at 2460v. Is there an adjustment you know of maybe a capacitor that could be causing the problem or any advice to point me in the right direction.any help would be much appreciated from anybody. thank you in advance.
Hi David, I will have to check if the 475 has a auto focus circuit. If it does Then that might need some adjustment. Also there should be an Astig control some where. Full focus is a balance between HV, Focus control, and the Astig control. The good news is if the Astig control needs to be adjusted it will not throw off the calibration and it tends not to need adjustments often. Also due to the high bandwidth of the scopes the trace will seem a little unfocused at the lower v/Div values this is normal amplifier noise and nothing to worry about. for instance asking a scope to do 500 uV/Div is asking a LOT from the front end.
@@ZenwizardStudios thanks for the quick reply iI have already adjusted the Astig and grid bias, I think the scope will need a full calibration as I have done major work in the power supply section and high voltage section I replaced 6 tantalum's and 4 electrolitic capacitors to get the scope backup running. I was chasing short-circuits all over the damn thing.the trace is not bad just not as good as yours, maybe I will just have to live with it. I have been inspired by your videos to have a go at calibrating it
thanks for your time in replying to my question, much appreciated
Yea major work on the supply would need a full re calibration. There is one power supply that is the reference to all the supplies in the scope if that is out and needs to be adjusted. it effects every circuit in the scope. If i remember right in the 400 series that is the -50V supply. I hope the calibration goes well for you they are great scopes and well worth the effort. Most of the signals you will need are pretty mundane. however there are some exotic signals you will need for the HF calibration of the vertical. Some pretty fast edges are needed for the HF compensation. The faster the scope the faster the rise time needed to calibrate.
Hi m8 about to watch this series as i have a 465m scope...but i have a telinstruments 25mhz CRT scope that was pushed off the bench and took a fall, now when i try and centre the trace(CH1) using the vertical position knob , the trace is only just visible at the bottom of the screen when the vertical position knob is at its maximum, When i inject a sine wave i can still see thst a waveform is being produced at the bottom of the screen(ps channel 2 is working fine?...any ideas where to start my troubleshooting?
Thanks in advance.
I have a concern that one of the deflection plates in the tube became disconnected in the fall. This will unfortunately be a terminal error in the tube. This can be checked by disconnecting each plate one at a time and seeing if you can adjust the position. Also checking the voltage at the deflection pins. If the voltage is moving and the trace is not the tube is the fault. When checking this all high voltage precautions need to be noted and care taken there are very high voltages present around the CRT in to the Kv range.
@@ZenwizardStudios thanks Zenwizard, can it stil, be a tube fault if ch2 works perfectly? , the vertical on ch2 moves up and down as it should,🤔🤔
@@ZenwizardStudios here is a short video on what is happening.thanks for your help ruclips.net/video/ev46QpcK8K4/видео.html
No it would not be a tube fault at that point. The deflection plates drive the tube in the same way Ch1 vs CH2. This would also rule out the plate drive amps as well. And point more to a differential signaling issue in channel 1. After watching the video there is no way this could be a tube fault.
@@ZenwizardStudios thank you very much, i might start visuall inspecting of a cracked solder joint caused by the fall...
Love your channel, was talking to a guy who said he will soon have to replace the cmos bettery on his Tektromix 2445A scope, i refered him to your channel
PeaceN73
using a DMM6500 for this?? LOL
and peel off the plastic!!
you do NOT need this kind of precision LOL LOL
I do agree with not needed the precision for that I have a 7510! However in this case the speed of the meter does make some measurements easier Tek supplies have a fairly tight ripple requirement. Some rails are +/- 1mV of ripple. Depending on the DC offset this can be quite challenging to measure especially when trying to measure accurately. This is not me saying it is needed or necessary. It is quite indeed, overkill.
why bother??