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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Tektronix TDS540 repair
Hi,
I've got my hands on a used TDS540 in hopes that at least once channel would work. No luck. The box comes up with two self-tests failures : FAIL ++ Acquisition FAIL ++ Attn/Acq interface After that, channels 1 and 2 show nothing. Channels 3 and 4 show 'saw' pattern when there's no input signal applied. If I connect it to the probe compensation signal I can see sum of square wave pattern and the 'saw'. I've followed Tektronix' troubleshooting chart and it looks like acquisition module A10 is probably bad. I wonder if anyone here had to deal with the similar issue before. Looking at the ebay, I've noticed that quite a few TDS* scopes sold there had failed acuisition and/or attenuation modules. Looks like it must be a fairly common issue. Does anybody know what are the most common failures for the tds5xx family scopes? Thanks, Artem |
#2
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Tektronix TDS540 repair
Artem Belevich wrote:
Hi, I've got my hands on a used TDS540 in hopes that at least once channel would work. No luck. The box comes up with two self-tests failures : FAIL ++ Acquisition FAIL ++ Attn/Acq interface After that, channels 1 and 2 show nothing. Channels 3 and 4 show 'saw' pattern when there's no input signal applied. If I connect it to the probe compensation signal I can see sum of square wave pattern and the 'saw'. I've followed Tektronix' troubleshooting chart and it looks like acquisition module A10 is probably bad. I wonder if anyone here had to deal with the similar issue before. Looking at the ebay, I've noticed that quite a few TDS* scopes sold there had failed acuisition and/or attenuation modules. Looks like it must be a fairly common issue. Does anybody know what are the most common failures for the tds5xx family scopes? Thanks, Artem Here's what I did to fix mine. Locate all the silver electolytic caps. Remove them ALL. Yes, there are over a hundred of them. They leak and make the board conductive. You must replace ALL of them. Wash the boards in simple green then isopropyl alcohol. Put a .1 1206 SMT cap where each electrolytic was. Bridge the appropriate value aluminum electrolytic across each .1. This made most of the error messages go away. Washed the boards again in simple green then alcohol. Scrub with a stiff toothbrush. This made some more errors go away. Washed the boards a third time with simple green followed by alcohol. Scrubbed HARDER with the stiff toothbrush. Now works great. Fixed two of them this way. On the second one, I tried one board at a time. Had to change ALL the caps on ALL the boards to get it to work. mike -- Return address is VALID. Bunch of stuff For Sale and Wanted at the link below. Toshiba & Compaq LiIon Batteries, Test Equipment Honda CB-125S $800 in PDX Yaesu FTV901R Transverter, 30pS pulser Tektronix Concept Books, spot welding head... http://www.geocities.com/SiliconValley/Monitor/4710/ |
#3
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Tektronix TDS540 repair
mike wrote in :
Artem Belevich wrote: Hi, I've got my hands on a used TDS540 in hopes that at least once channel would work. No luck. The box comes up with two self-tests failures : FAIL ++ Acquisition FAIL ++ Attn/Acq interface After that, channels 1 and 2 show nothing. Channels 3 and 4 show 'saw' pattern when there's no input signal applied. If I connect it to the probe compensation signal I can see sum of square wave pattern and the 'saw'. I've followed Tektronix' troubleshooting chart and it looks like acquisition module A10 is probably bad. I wonder if anyone here had to deal with the similar issue before. Looking at the ebay, I've noticed that quite a few TDS* scopes sold there had failed acuisition and/or attenuation modules. Looks like it must be a fairly common issue. Does anybody know what are the most common failures for the tds5xx family scopes? Thanks, Artem Here's what I did to fix mine. Locate all the silver electolytic caps. Remove them ALL. Yes, there are over a hundred of them. They leak and make the board conductive. You must replace ALL of them. Wash the boards in simple green then isopropyl alcohol. Put a .1 1206 SMT cap where each electrolytic was. Bridge the appropriate value aluminum electrolytic across each .1. This made most of the error messages go away. Washed the boards again in simple green then alcohol. Scrub with a stiff toothbrush. This made some more errors go away. Washed the boards a third time with simple green followed by alcohol. Scrubbed HARDER with the stiff toothbrush. Now works great. Fixed two of them this way. On the second one, I tried one board at a time. Had to change ALL the caps on ALL the boards to get it to work. mike For better cleaning,try running the PCB through your automatic dishwasher using Calgonite (leave the dishwasher's drying heat OFF) and dry in a commercial drying oven or rig up a hot box and a whisper fan or two to pull air out of the box.You don't want to exceed 150 degF in the box.It should dry for about 3 days. -- Jim Yanik jyanik-at-kua.net |
#4
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Tektronix TDS540 repair
Mike,
Thanks a lot for the info. I'll give it a try. --Artem mike wrote: Artem Belevich wrote: Hi, I've got my hands on a used TDS540 in hopes that at least once channel would work. No luck. The box comes up with two self-tests failures : FAIL ++ Acquisition FAIL ++ Attn/Acq interface After that, channels 1 and 2 show nothing. Channels 3 and 4 show 'saw' pattern when there's no input signal applied. If I connect it to the probe compensation signal I can see sum of square wave pattern and the 'saw'. I've followed Tektronix' troubleshooting chart and it looks like acquisition module A10 is probably bad. I wonder if anyone here had to deal with the similar issue before. Looking at the ebay, I've noticed that quite a few TDS* scopes sold there had failed acuisition and/or attenuation modules. Looks like it must be a fairly common issue. Does anybody know what are the most common failures for the tds5xx family scopes? Thanks, Artem Here's what I did to fix mine. Locate all the silver electolytic caps. Remove them ALL. Yes, there are over a hundred of them. They leak and make the board conductive. You must replace ALL of them. Wash the boards in simple green then isopropyl alcohol. Put a .1 1206 SMT cap where each electrolytic was. Bridge the appropriate value aluminum electrolytic across each .1. This made most of the error messages go away. Washed the boards again in simple green then alcohol. Scrub with a stiff toothbrush. This made some more errors go away. Washed the boards a third time with simple green followed by alcohol. Scrubbed HARDER with the stiff toothbrush. Now works great. Fixed two of them this way. On the second one, I tried one board at a time. Had to change ALL the caps on ALL the boards to get it to work. mike |
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