Author Topic: Tektronix TDS210 repair - oscillator help needed  (Read 2335 times)

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Offline Burner_357

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Tektronix TDS210 repair - oscillator help needed
« on: June 01, 2017, 03:16:14 pm »
Hello community,

after being a passive member of the forum for a while, mostly reading and looking for interesting and helpful stuff...the time has finally come...I need your help :)

I bought a defective Tektronix TDS210 on eBay. The seller said, the display wouldn't show anything. So i got it for 50€, hoping it would be an easy fix (like pluging back in the powersupply to the main board).
After unboxing and taking the unit apart, I saw that the previous owner has already changed an exploded electrolytic cap. He was even so kind to include the defective one into the package  :-+
Unfordunately the power connector was plugged in correctly, so there vanished my easy fix. So I powered the powersupply up, without connectin anything -> the voltages were within specs. After that I connected the other PCBs and testet it:
The backlight of the display works fine, but the display stays black. So I checked the oscillator and bingo, the output is continuously on 3.3V and no signs of life from the oscillator.
The oscillator is a 60.606 MHz type (see photo) but finding a replacement part seems difficult. I found a possible replacement (see attached datasheet) but these guys cost 15€ plus 18€ shipping on DigiKey.

Here comes my question:
Is it possible to replace the defective oscillator with a 60MHz type? At least for further testing.
Has anyone located in Europe one of these 60.606MHz oscillators at hand and could send me one (to Germany)? This may be cheaper than the DigiKey costs  :)


Thanks,
Alex
 

Offline Samogon

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #1 on: June 01, 2017, 07:29:02 pm »
They are not available at Digi-Key and mouser
 

Offline John_ITIC

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #2 on: June 06, 2017, 03:32:44 am »
Is that an oscillator or just the XTAL? If the latter, then the oscillator is in the chip, which may be bad?
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Offline ArcticGeek

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #3 on: June 06, 2017, 08:43:24 pm »
Assuming this really is an oscillator, you can get a programmable oscillator from Digikey in that frequency.  Go to the digikey website and search on "programmable oscillator".  Digikey will program that part to whatever frequency you want, in this case 60.606MHz.  They are pretty reasonable in price, but I don't know if the package is correct for what you are looking for.   Good luck!
 

Online blueskull

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #4 on: June 06, 2017, 10:46:15 pm »
I do have a few 3.3V programmable MEMS oscillators around me, but the only 7050 ones I have are differential output ones, and the single ended ones are in either SOT23 or 2520 or 5032 packages.

If you think you can bodge a 5032 or SOT23 oscillator to your PCB, then I can give you one for free providing you send me a shipping label.
 

Offline rmm

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #5 on: November 19, 2019, 08:55:51 am »
Hi Alex and all,

I too have a scope with the same simptoms as yours.
I power it on, only blacklight goes on, no screen activity whatsoever.

I need to mention it worked ok, before I started changing the PS caps and the bnc connectors on the MCU board.  :'(  I am more than sure my repairs (new low-ESR caps on the PS rails and BNCs) have 0 contribution to this, however I do think that perhaps stress due taking the mcu board out contributed to this non-start behaviour?

I really don't know, measured the voltages on PS, everything checks out (+5V, -5V, -24V, line trigger). Even the 1kHz probe compensation signal is there.
Did you manage to get yours up and running eventually? And bw do you have a check/repair list I could use and probe for voltages on the MCU board? I looked in http://w140.com/tekwiki/wiki/TDS210, but this applies mostly to powering units. 

Thanks,
Rob
 

Online george.b

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #6 on: November 19, 2019, 11:00:26 am »
Hi Alex and all,

I too have a scope with the same simptoms as yours.
I power it on, only blacklight goes on, no screen activity whatsoever.

I need to mention it worked ok, before I started changing the PS caps and the bnc connectors on the MCU board.  :'(  I am more than sure my repairs (new low-ESR caps on the PS rails and BNCs) have 0 contribution to this, however I do think that perhaps stress due taking the mcu board out contributed to this non-start behaviour?

I really don't know, measured the voltages on PS, everything checks out (+5V, -5V, -24V, line trigger). Even the 1kHz probe compensation signal is there.
Did you manage to get yours up and running eventually? And bw do you have a check/repair list I could use and probe for voltages on the MCU board? I looked in http://w140.com/tekwiki/wiki/TDS210, but this applies mostly to powering units. 

Thanks,
Rob

Rob, you might want to check whether you have -24V on the LCD connector. I've seen two TDS220s (sister model, same main board, 100MHz bandwidth - the TDS210 can be modded into a TDS220, even, but I digress)  that didn't, and the screen would be blank as a result.
I bodged a straight connection from the PSU connector to the LCD connector and that seemed to fix it.
I reported my repair of one of the units here: https://www.eevblog.com/forum/repair/tds220-repair-report/

The presence of the 1kHz probe comp signal, in principle, indicates everything is okay with the logic and that the board passed its POST, so I would think you needn't worry about the other power rails. In any case, if memory serves, there are 4 LDOs on the main board, regulating down to +3.3, +2.5, +1.8 and -2.5 volts.
« Last Edit: November 19, 2019, 11:15:12 am by george.b »
 
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Offline rmm

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #7 on: November 22, 2019, 10:41:15 am »
Hi George,
You were right!!! Thanks!!!!

I traced down the issues caused by the absence of pin1 connection, on that display connector. When restored, that measured eventually around -18V on that display flex. The raw -24V coming off the PS is not directly applied to the pin1, it passes through some scaling resistors, maybe some const. current circuitry, etc.
I noticed that another pin (#11) inside the connector suffered, from inserting/retrieving the flex a few times into the display connector, here's a pic attached showing the initial situation.

All with all, I am very happy with the outcome. The new low-ESR panasonic caps installed perform very well, I measured ripple lower than 20mV pp on the loaded PS rails.
I can move further now and try to source a TDS2CM module (since they're cheaper than TDS2MM); I've read you can mod (changing EPROM and RAM) these into TDS2MM and get FFT and rise/fall time measurements.
 

Offline JFJ

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #8 on: November 22, 2019, 12:36:13 pm »
I noticed that another pin (#11) inside the connector suffered, from inserting/retrieving the flex a few times into the display connector...

Over time, the connector pins do appear to adhere to the ribbon cable (perhaps, a lubricant dries out and sets hard), causing the pins to distort or break when the cable is pulled out. Tektronix, presumably, became aware of the problem, as they changed the connector to a zero insertion force type: Molex "Easy-On"
 

Online george.b

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #9 on: November 22, 2019, 02:54:31 pm »
Glad to be of help! :-+

The raw -24V coming off the PS is not directly applied to the pin1, it passes through some scaling resistors, maybe some const. current circuitry, etc.

Oh yes, you're absolutely right. On mine, the problem was with pin 2 (which also doesn't seem to be originally connected straight to the -24V rail from the PSU); the connector was okay - mine has the ZIF connector JFJ mentions - but it was actually the circuit that had malfunctioned somewhere. Having found nothing obviously damaged, I thought "what the heck" and connected it directly. According to the service manual, -24V on pin 2 is within spec. I've left it continuously on for over a week and nothing bad happened, so the bodge remains there.

Pin 1 is contrast and pin 2 is Vbias, IIRC.

I can move further now and try to source a TDS2CM module (since they're cheaper than TDS2MM); I've read you can mod (changing EPROM and RAM) these into TDS2MM and get FFT and rise/fall time measurements.

Heh, that's exactly what I'm doing. I have acquired a TDS2CM, the RAM of which I've already replaced, and now I'm trying to source the adequate (E)EPROM locally. I'm curious to see what FFT looks like on that old scope :)
« Last Edit: November 22, 2019, 03:40:16 pm by george.b »
 

Offline james_s

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #10 on: November 22, 2019, 04:39:54 pm »
Funny, I recently fixed a TDS3014 that had exactly this symptom and mine was a bad oscillator. It too was a somewhat odd frequency however a bit different than yours, I was able to find a replacement and that fixed the scope. For testing you should be able to use any similar oscillator you have around, I initially tried a much lower frequency part I pulled from a scrap board and my scope booted up. It was not usable like that but it verified the fault.
 

Offline rmm

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #11 on: November 22, 2019, 05:25:42 pm »
Quote
Heh, that's exactly what I'm doing. I have acquired a TDS2CM, the RAM of which I've already replaced, and now I'm trying to source the adequate (E)EPROM locally. I'm curious to see what FFT looks like on that old scope :)

Nice!
Let us try in parallel then.  :-+

Let me get one of those TDS2CM modules first.
I will go the easy way, choose an Eprom (1 time programmable, 27C040, still to get via Ebay) instead of the 29F040 flash some people are also trying. When using the flash one needs to modify how A17 and A18 are connected as well, while for the 27C040 is directly a drop-in.
As for RAM, I am thinking of IS62C1024AL-35QLI, as someone suggested in one of the online posts.
As for programming the hex in the 27C I was thinking of Willem? Saw these around 25$ for sale.

What's your approach for this mod?
 

Offline rmm

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #12 on: November 22, 2019, 05:33:56 pm »
Quote
Over time, the connector pins do appear to adhere to the ribbon cable (perhaps, a lubricant dries out and sets hard), causing the pins to distort or break when the cable is pulled out. Tektronix, presumably, became aware of the problem, as they changed the connector to a zero insertion force type: Molex "Easy-On"
You are right. When I pulled the flex for the first time, it felt like it was welded in there.
In one of the pics you see debris from the flex pcba deposit hanging loose in that connector compartment, I suppose since it was literally scrapped off during one of the connect/disconnect actions of mine.
Thanks for the ZIF pno. I will try to get one of these and install it next time I open it again.
 

Online george.b

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #13 on: November 22, 2019, 07:37:41 pm »
Quote
Heh, that's exactly what I'm doing. I have acquired a TDS2CM, the RAM of which I've already replaced, and now I'm trying to source the adequate (E)EPROM locally. I'm curious to see what FFT looks like on that old scope :)

Nice!
Let us try in parallel then.  :-+

Let me get one of those TDS2CM modules first.
I will go the easy way, choose an Eprom (1 time programmable, 27C040, still to get via Ebay) instead of the 29F040 flash some people are also trying. When using the flash one needs to modify how A17 and A18 are connected as well, while for the 27C040 is directly a drop-in.
As for RAM, I am thinking of IS62C1024AL-35QLI, as someone suggested in one of the online posts.
As for programming the hex in the 27C I was thinking of Willem? Saw these around 25$ for sale.

What's your approach for this mod?

The IS62C1024AL should work just fine, but any standard 32-pin SOP 128k x 8 SRAM will probably do. I found a Sony CXK581001M-85 in my scrap bin, and that's what I went with. I know, it's 15ns slower than the original chip, but meh, it's what I had at hand, and it's working so far. If it gives me headaches later - maybe once FFT is enabled it craps out? -  then I'll replace it.

I feel more inclined towards getting the original 27C040 (or the pin-compatible 27C4001), both because I would rather not modify the board and because the programmer I have available is an old Leap SU-1 that won't program 29F040 EEPROMs.
I actually had some trouble acquiring the EPROMs locally. I bought a lot of 5, the ad said they were blank, but when I went to program one of them... "Device is not blank". What the?
I tried another one from the lot, same thing. I dumped the contents and it was full of crap, including some plain readable strings. It seems the seller, in their infinite wisdom, pulled the parts from some old scrap and thought they could be erased... :palm: at least they accepted to give me my money back. Still, time I would rather not have wasted.
 

Offline rmm

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #14 on: November 22, 2019, 08:30:50 pm »
I see AT27C040-70JU-T from Microchip, available on Mouser.
This could work.
 

Online george.b

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #15 on: November 24, 2019, 03:30:26 pm »
I see AT27C040-70JU-T from Microchip, available on Mouser.
This could work.

It will work :) unfortunately for me, it's not economical to order from Mouser, or any of those other, nice stores. Shipping would cost a few times the price of the EPROMs themselves.
 

Offline james_s

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #16 on: November 24, 2019, 05:59:40 pm »
It shouldn't cost much to stick a few parts in an envelope and send them on to you. For small stuff like that you could order them to a member in the US who can forward them on to you, just another option. Otherwise you should be able to find something suitable from China.
 
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Online george.b

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #17 on: November 24, 2019, 07:36:39 pm »
No worries, I can find them locally, just not as conveniently or professionally, as we don't have any large, online component store like Mouser, Digikey and the like. We used to have Farnell-Newark, but it closed :( so it's either small online stores that don't have much stuff, or individuals on our ebay equivalent.

Our post service is crap anyways. I've been waiting for some parts from China for a couple of months now.
 

Online george.b

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #18 on: December 08, 2019, 09:23:49 pm »
Success!

I bought some 27C040-150. Those didn't work - too slow.
Then a friend brought me a 29F040-70 and we hotflashed the image using a Pentium III motherboard. I had to do the bodge wire mod as described elsewhere on the forum due to the swapped pins 1 and 31 on the EEPROM. Results attached below :)

Edit: you might notice I've replaced the RAM as well - I wasn't sure whether the fact it wasn't working was due to the 85ns RAM or the 150ns ROM. I replaced it with a 70ns part from a HP48G+, which works just fine with the 85ns RAM.
« Last Edit: December 08, 2019, 09:41:38 pm by george.b »
 

Offline Nprod

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #19 on: February 10, 2020, 09:00:07 pm »
Hey, george.b ! I see your scope has version 2.03 of the main firmware, is it possible for you to dump it here? I had asked for it awhile back in the other thread discussing the TDS2CM to MM conversion, but nobody had it.
 

Online george.b

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #20 on: February 10, 2020, 09:44:44 pm »
Hey Nprod, can the firmware be dumped through RS232/GPIB? If so, please tell me how it's done and I'll do it. The EEPROM on mine is BGA, so I can't dump it directly.
 

Offline Nprod

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #21 on: February 11, 2020, 11:26:37 am »
I wasn't aware they had versions with a BGA EPROM, that's unfortunate... If there is a way to dump it through RS232 it's not officially documented, i can't find anything about it in the programmer manual.
« Last Edit: February 11, 2020, 07:04:14 pm by Nprod »
 

Offline TERRA Operative

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #22 on: February 11, 2020, 05:13:47 pm »

Rob, you might want to check whether you have -24V on the LCD connector. I've seen two TDS220s (sister model, same main board, 100MHz bandwidth - the TDS210 can be modded into a TDS220, even, but I digress)


Do tell! :)
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Online george.b

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Re: Tektronix TDS210 repair - oscillator help needed
« Reply #23 on: February 11, 2020, 06:55:50 pm »
Do tell! :)

You mean the TDS210/220 mod? It will change its ID with the usual "pitbull" hack. Seemingly (I read this after writing the post you quoted) that doesn't change the actual bandwidth; I suspect the input filter is hardwired. I will probably get to compare TDS210  and TDS220 boards side by side in the near future and will report back.
The TDS210 is my friend's; he bought a non-functioning unit. The capacitors on the PSU were oozing electrolyte, and the TL2274 on the mainboard was dead. I might do a repair report once it's done (we're waiting for him to get a replacement TL2274). When he brings it back, I'll see about comparing the frontends.
 


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