Tektronix AWG2020 - Page 1
Forum section: electronics / testgear

author: Khashoggi
author_rank: Contributor
timestamp: October 08, 2013, 02:23:07 am
content: I have a AWG2020 arbitrary waveform generator.One day it displayed an error message on boot up on the CRT."Illegal Configuration. STOP"Looking at the AWG2021 service manual, which appears to be the same or extremely similar, that error message is not listed.The error appears before the standard boot up diagnostics.Pulling it apart, I discover 2 leaking SMD electrolytic capacitors on the CPU board. The electrolyte "acid" has completely eaten two traces one on the top and one on the bottom of the PCB which I repaired and verified. There are several other corroded traces, but they pass continuity checks. I have cleaned everything up.Unfortunately, same problem. I hope inner layer traces weren't eaten...Anyone familiar with that particular error message? And, anyone have a source for the schematics as the service manual is very basic and only covers hardware disassembly.

author: Khashoggi
author_rank: Contributor
timestamp: October 24, 2013, 06:50:41 am
content: Problem solved.The A6 (CPU), A10 (synthesizer), A21 (channel 1), and A31 (channel 2) boards had bad caps. A total of 12 were changed out. And 8 PCB traces repaired from electrolyte corrosion.End results, AWG2020 passes self tests, calibrates, and functions correctly.If you get the "Illegal Configuration" type of error, it means that the A21 and A10 boards likely have bad capacitors also.Caps were all SMD 22uf@35V EMVY350ADA220MF55G

author: AlfBaz
author_rank: Super Contributor
timestamp: October 24, 2013, 07:57:59 am
content: Good fixSeems it's not just their scopes with leaky caps

author: bdivi
author_rank: Regular Contributor
timestamp: October 24, 2013, 12:23:31 pm
content: good fix - can you post some pictures from the process.

author: madshaman
author_rank: Frequent Contributor
timestamp: October 24, 2013, 01:21:23 pm
content: I have a used AWG 2021, it's worked perfectly since I got it. Are dead smd caps a common issue? Should I tear mine apart and do some pre-emptive surgery?

author: AlfBaz
author_rank: Super Contributor
timestamp: October 24, 2013, 01:45:52 pm
content: I don't know about their generators but a lot of their tds5xx/7xx scopes are famous for leaky electrolytics.As Khashoggi's gen has suffered the same fate and its from about the same era as the scopes one can only assume they used the same source for their electrolyitics on all their gear from that time

author: Khashoggi
author_rank: Contributor
timestamp: October 24, 2013, 02:46:22 pm
content: Quote from: madshaman on October 24, 2013, 01:21:23 pmKnowing what I know now, I would change the caps out. It caused a mess and the corrosion was impressive. It leaked all over the place. Soldering jumpers to fix bad traces was laborious.Just going in to swap caps shouldn't take more than an hour start to finish if you don't have to clean up electrolyte and probe traces to find bad ones.Backup your nvram files to disk first, because pulling the CPU board will erase everything as the backup battery is on the backplane. (You may want to change that too when your in, mine was dead. It is a Br2/3 soldered in)

author: Khashoggi
author_rank: Contributor
timestamp: October 24, 2013, 02:49:28 pm
content: Quote from: bdivi on October 24, 2013, 12:23:31 pmI didn't take pics. But, this person went through a similar process with the same unit and did take some-http://www.jvgavila.com/awg-2020.htm

author: free_electron
author_rank: Super Contributor
timestamp: October 24, 2013, 06:01:16 pm
content: i hve a dead awg 2020 as well. sdame problem bad caps.i repaired all of them including traces that were shot but my machine is still stuck during boot... there are traces somewhere that are bad that i have not found yet.bloody craptronix !

author: Khashoggi
author_rank: Contributor
timestamp: October 24, 2013, 07:09:15 pm
content: Quote from: free_electron on October 24, 2013, 06:01:16 pmIf your stuck at the "illegal configuration" stage you need to have at least three boards installed and repaired to even test. Just testing with the cpu board won't work. You need an operational cpu board, synthesizer board, and the channel 1 board.I agree the caps made a damn mess and leaked all over the place.

author: madshaman
author_rank: Frequent Contributor
timestamp: October 25, 2013, 07:07:20 am
content: Quote from: AlfBaz on October 24, 2013, 01:45:52 pmThanks, I've been warned away from trying to acquire and repair tds5xx/7xx scopes by other forum members for the same reason. Sounds like I have little choice; would rather spend the time now.Quote from: Khashoggi on October 24, 2013, 02:46:22 pmThanks kindly for the advice, it's a really nice AWG and I'd rather keep it that way. Yet another thing to add to my lab's "todo soon" list

author: nctnico
author_rank: Super Contributor
timestamp: October 25, 2013, 12:15:53 pm
content: Quote from: AlfBaz on October 24, 2013, 01:45:52 pmIn my experience only the early 90's models are affected. My scopes from 1995 are fine.