When I work on ceramic hybrids I use solder that has a 2% silver content so that the solder to ceramic bond remains intact. This goes back to the old days when Tek used their famous ceramic terminal strips on their 400 and 500 series scopes.
A relay in my daily driver tds620b just broke I believe, since it stopped working in the larger horizontal scales. Still passes self cal though hmm. Great to have this video.
Thanks for this video. I just replaced the relays on my TDS754A. Noticed that 2 of the 4 hybrids had "1GHz" marked on them. So maybe this one only has 2 channels that can do 1 GHz (if modified). Not sure. They were CH1 and CH3. The other 2 hybrids looked different and mo markings.
Good to hear you got it done! They'll be good for a few more decades. :) Being an 'A' model, be sure to check and replace all the SMD capacitors on the Processor (top) and acquisition (bottom) boards. They have a very bad reputation for leaking, and if they haven't yet, they probably will soon... All the hybrids in these machines are functionally identical, with the exception that the letter at the end of the part number denotes the revision (the later the letter in the alphabet, the later the revision up to version 'J' IIRC). For example a H2462H is an earlier revision than a H2467J. I believe there are G, H, I and J versions, maybe more. In practice they are all interchangeable, but if you have the chance to upgrade to a higher revision, why not? :) Your TDS754A should be able to be upgraded to a TDS784A without much problem (Don't forget to remove the capacitors in the differential pairs from the hybrids to the acquisition chips! See my TDS620B video), you'll just have to calibrate it to 1GHz to be able to rely on measurements past 500MHz.
Greetings from Sydney! I really wish you'd change your RUclips Home Page, and place "New videos" on there at the top. Unless people know to hit "Videos" tab, it looks like you haven't published anything for a year, so they never see that you have new content!
I got a 644B which appears to share most of its components with this model, and particularly those hybrid-ceramic thingy (attenuator according to the service manual). Unfortunately it appears someone already attempted a "fix"... (or something...) on those modules and there were 2 out of the 4 chanels throwing calibration errors (not on power on by the way, but when doing a SPC or acquisition board diag test). I managed to have 3 out of 4 working properly after careful reassembly and cleaning the contacts, so I put the bad module in chanel 4. Interrestingly the acq diag test now does not finish and the scope reboots, I suspect channel 4 is in so bad condition it causes some sort of crash because of unexpected values/conditions/whatever. but at least after SPC rthe first 3 channels behaves properly. This 4th module has multiple issues : gain is completly off and does not react to adjusting the voltage range, and when measuring the input impedence it shows as open (probably stuck in AC or GND) but I hear all the relays clicking so I was considering maybe the ADC for this channel could be damaged. I was wondering what I could do to fix those and hopfully youtube algorythm proposed you video which was spot on ! So I ordered 4 relays at first (those for gain control) and then decided to order another 12 as if this module relays failed there are good chances the relays for the orther module will fail shortly after (and they probably started to fail as when measuring the channel input impedence, channel 1 is spot on for 1M and 50ohms, the other started to deviate and the reading is fluctuating, that could indicate the contacts in the relay being worn). Still looking for the 5th relay (small black one with ref TN2E-12V-H11) but it appears to no longer be available. Any chance you'd have a reference in mind that could fit ? By the way I'm wondering if it's the AC/DC/GND coupling relay or the one that controls the 1M/50ohms input impedence switch, does anyone happen to know ? Anyway, great video, thanks for sharing !
I'm glad the video helped you out! The smaller relay is for switching between AC and DC coupling. The relay is obsolete, but I've not looked for a replacement yet. With some luck, another brand or a different relay in the same form-factor might still be available.
Hi, thanks for the video!! I have bought a TDS 380 a week ago while I'm waiting it will come, I'm looking on YT and varies blog to understand what I will have to replace for a good first maintained so, do you have any advice? Dallas? Thanks in advance for your time.
Yeah, the Dallas chip should be replaced if there is one in the scope. It's easiest to remove it, copy it with a chip programmer (if you have one) then load that onto the new chip and install. I'm not sure on common faults with the TDS300 series as I've never played with one, but check out the eevblog forums and/or make a thread there if you need info and help. There will be someone who knows the info you need for sure.
The cheapest I've found here in Japan is 435yen, which is about US$4.35 each (at December 2021 exchange rate). Digikey and Mouser have them for US$5.434 (about US$87 for all 16) and US$5.18 (about US$83 for all 16) respectively.
Would this apply to the tds 3xx and tds 4xx series as well ?also, is there ANY way to purchase actual SCHEMATICS and not block diagrams for these scopes? Thank You !!!
I'm not familiar with the 3xx and 4xx scopes, I think they are different, but they miiigghhtt use the same relays... I haven't had one on my bench to check though. Check out w140.com/tekwiki/wiki/Main_Page for lots of good Tek info. For the TDS5xx, 6xx and 7xx scopes, you can find some relevant schematic info around the place. For example, the TDS544A had schematics released which is very similar, including the colour CRT.
can ccp batch be trusted found different resistance.. Would you buy it from CCP? Digikey has those relays...but more expensive. Looksing at 100$+ for 16 relays. I'm getting either 356 ohm or 750 ohm on the 12v coil in the same batch with either 17 mA or 33MA - bad relays or normal? Seems like 2 different batches or so - can it be trusted? Link to Osaka pz....? Seems like I'm getting below .030 ohm on the contacts though - just checking with de-5000 @ 1000 herts for resistance on the contact - that seems ok? Seems like Uni-T will have hard time measuring that small of resistance. I'm guessing the coil resistance difference is ok as long as contacts are clean near 0 ohm?
Apparently you can really carefully drill a small hole in the top where the divot is from the moulding of the case so a drop of DeOxit can be applied. Then a dab of hot glue or a bit of Kapton tape to seal it back up again. I haven't tried it as new relays are only $3 or so each locally, and once replaced will be good for another 20 years or so (basically the lifetime of the scope).
All been done. 🙂 Depending on the PSU revision, it may have RIFA capacitors or may not (I think the earlier ones usually have them, later ones don't). Definitely worth checking.
Seems like you're measuring low resistances like contacts quite often, perhaps 4 wire method could be of good use to you, then the readings wouldn't fly all over the place with every clip movement.
When I work on ceramic hybrids I use solder that has a 2% silver content so that the solder to ceramic bond remains intact. This goes back to the old days when Tek used their famous ceramic terminal strips on their 400 and 500 series scopes.
Yes I had that same concern, I remember the free gift solder inside those old valve scopes
Well done! Soldering on the ceramic is always fun.
A relay in my daily driver tds620b just broke I believe, since it stopped working in the larger horizontal scales. Still passes self cal though hmm. Great to have this video.
Thanks for this video. I just replaced the relays on my TDS754A. Noticed that 2 of the 4 hybrids had "1GHz" marked on them. So maybe this one only has 2 channels that can do 1 GHz (if modified). Not sure. They were CH1 and CH3. The other 2 hybrids looked different and mo markings.
Good to hear you got it done! They'll be good for a few more decades. :)
Being an 'A' model, be sure to check and replace all the SMD capacitors on the Processor (top) and acquisition (bottom) boards. They have a very bad reputation for leaking, and if they haven't yet, they probably will soon...
All the hybrids in these machines are functionally identical, with the exception that the letter at the end of the part number denotes the revision (the later the letter in the alphabet, the later the revision up to version 'J' IIRC).
For example a H2462H is an earlier revision than a H2467J. I believe there are G, H, I and J versions, maybe more.
In practice they are all interchangeable, but if you have the chance to upgrade to a higher revision, why not? :)
Your TDS754A should be able to be upgraded to a TDS784A without much problem (Don't forget to remove the capacitors in the differential pairs from the hybrids to the acquisition chips! See my TDS620B video), you'll just have to calibrate it to 1GHz to be able to rely on measurements past 500MHz.
Thanks Jared!, this will come in handy once i have received my 744A and this will happen at some time for sure
Greetings from Sydney! I really wish you'd change your RUclips Home Page, and place "New videos" on there at the top. Unless people know to hit "Videos" tab, it looks like you haven't published anything for a year, so they never see that you have new content!
I had no idea I could do that! Thanks for the suggestion and all done. :)
Gutten tight :) My favourite torque spec
Ja! Ja! Germans always must do things properly.
My oscilloscope is made by Yokogawa. It will do calibration periodically for every 30 minutes. I thought it was annoying, but now I can understand.
Thanks for another great video! So, the replacement relays are identical to the original and still prone to fail?
They are exactly the same, but they should last at least another 20 years. 🙂
I got a 644B which appears to share most of its components with this model, and particularly those hybrid-ceramic thingy (attenuator according to the service manual).
Unfortunately it appears someone already attempted a "fix"... (or something...) on those modules and there were 2 out of the 4 chanels throwing calibration errors (not on power on by the way, but when doing a SPC or acquisition board diag test).
I managed to have 3 out of 4 working properly after careful reassembly and cleaning the contacts, so I put the bad module in chanel 4. Interrestingly the acq diag test now does not finish and the scope reboots, I suspect channel 4 is in so bad condition it causes some sort of crash because of unexpected values/conditions/whatever. but at least after SPC rthe first 3 channels behaves properly.
This 4th module has multiple issues : gain is completly off and does not react to adjusting the voltage range, and when measuring the input impedence it shows as open (probably stuck in AC or GND) but I hear all the relays clicking so I was considering maybe the ADC for this channel could be damaged.
I was wondering what I could do to fix those and hopfully youtube algorythm proposed you video which was spot on !
So I ordered 4 relays at first (those for gain control) and then decided to order another 12 as if this module relays failed there are good chances the relays for the orther module will fail shortly after (and they probably started to fail as when measuring the channel input impedence, channel 1 is spot on for 1M and 50ohms, the other started to deviate and the reading is fluctuating, that could indicate the contacts in the relay being worn).
Still looking for the 5th relay (small black one with ref TN2E-12V-H11) but it appears to no longer be available. Any chance you'd have a reference in mind that could fit ?
By the way I'm wondering if it's the AC/DC/GND coupling relay or the one that controls the 1M/50ohms input impedence switch, does anyone happen to know ?
Anyway, great video, thanks for sharing !
I'm glad the video helped you out!
The smaller relay is for switching between AC and DC coupling.
The relay is obsolete, but I've not looked for a replacement yet.
With some luck, another brand or a different relay in the same form-factor might still be available.
Great work....cheers.
I once found the BNC connector unsoldered from the input on one channel, I hate to think how that happened.
I wonder if it was just a dry joint, or maybe (more worryingly) the result of some sticky fingers getting in there?.....
Great work 👌👏
I have a question please
The resistance you measured, did you measure the coil resistance or a normally closed resistance?
I measured the contact resistance, both the Normally Closed contacts and the Normally Open contacts (with the coil energised).
@@NearFarMedia thank you
Excellent Job !
Hi, thanks for the video!!
I have bought a TDS 380 a week ago while I'm waiting it will come, I'm looking on YT and varies blog to understand what I will have to replace for a good first maintained so, do you have any advice? Dallas?
Thanks in advance for your time.
Yeah, the Dallas chip should be replaced if there is one in the scope. It's easiest to remove it, copy it with a chip programmer (if you have one) then load that onto the new chip and install.
I'm not sure on common faults with the TDS300 series as I've never played with one, but check out the eevblog forums and/or make a thread there if you need info and help. There will be someone who knows the info you need for sure.
@@NearFarMedia Thanks mate!
Realy cool repair Video, but how much does one of the new Relays cost?
It depends, $5.34.
The cheapest I've found here in Japan is 435yen, which is about US$4.35 each (at December 2021 exchange rate).
Digikey and Mouser have them for US$5.434 (about US$87 for all 16) and US$5.18 (about US$83 for all 16) respectively.
Nice fix
Was that scope from Dirwings?
Yep! :D I buy a bit of stuff from them, including my 1GHz TDS784C
Would this apply to the tds 3xx and tds 4xx series as well ?also, is there ANY way to purchase actual SCHEMATICS and not block diagrams for these scopes?
Thank You !!!
I'm not familiar with the 3xx and 4xx scopes, I think they are different, but they miiigghhtt use the same relays... I haven't had one on my bench to check though.
Check out w140.com/tekwiki/wiki/Main_Page for lots of good Tek info.
For the TDS5xx, 6xx and 7xx scopes, you can find some relevant schematic info around the place.
For example, the TDS544A had schematics released which is very similar, including the colour CRT.
@@NearFarMedia thank you !
The answer is no. On the 4xxxx They are 1n2e-12-h11 and are much smaller and harder to replace, 5 per channel.
can ccp batch be trusted found different resistance.. Would you buy it from CCP? Digikey has those relays...but more expensive. Looksing at 100$+ for 16 relays. I'm getting either 356 ohm or 750 ohm on the 12v coil in the same batch with either 17 mA or 33MA - bad relays or normal? Seems like 2 different batches or so - can it be trusted? Link to Osaka pz....? Seems like I'm getting below .030 ohm on the contacts though - just checking with de-5000 @ 1000 herts for resistance on the contact - that seems ok? Seems like Uni-T will have hard time measuring that small of resistance. I'm guessing the coil resistance difference is ok as long as contacts are clean near 0 ohm?
Is there maybe an "El Cheapo" way to Dremel open the relays and refurbish them? Just asking for a friend 😉
Apparently you can really carefully drill a small hole in the top where the divot is from the moulding of the case so a drop of DeOxit can be applied. Then a dab of hot glue or a bit of Kapton tape to seal it back up again.
I haven't tried it as new relays are only $3 or so each locally, and once replaced will be good for another 20 years or so (basically the lifetime of the scope).
@@NearFarMedia Thanks. Thats sounds doable.
Probably should replace the RIFA AC safety caps.
All been done. 🙂
Depending on the PSU revision, it may have RIFA capacitors or may not (I think the earlier ones usually have them, later ones don't).
Definitely worth checking.
Seems like you're measuring low resistances like contacts quite often, perhaps 4 wire method could be of good use to you, then the readings wouldn't fly all over the place with every clip movement.
Yeah, I usually use my Keysight 34461A, but it's up on the shelf out of view of the camera.
The Uni-T meter was 'for demonstration purposes only'... 😃