Tektronix Technical Forums are maintained by community involvement. Feel free to post questions or respond to questions by other members. Should you require a time-sensitive answer, please contact your local Tektronix support center here.

TDS5054B problem,Need help!

Questions in this forum area are community supported. Tektronix does not regularly monitor posts in this area.
Post Reply
profun
Posts: 39
Joined: November 6th, 2021, 4:56 am
Country: China

TDS5054B problem,Need help!

Post by profun » November 6th, 2021, 5:14 am

Hello !
I recently got a TDS5054b oscilloscope, but it can't pass SPC, and the baseline is offset. I checked the debug log file and it prompted: "SPC returned an error in step trigger hysteresis". I don't know what this means, But In the full test performance, the test completes successfully without any errors.
I don't know how to repair it., Can you help me?
image001.jpg
image001.jpg (81.96 KiB) Viewed 186 times
image002.jpg
image002.jpg (124.7 KiB) Viewed 186 times
image003.jpg
image003.jpg (130.19 KiB) Viewed 186 times
with respect
Profun
Last edited by profun on November 6th, 2021, 8:00 pm, edited 1 time in total.

strick
Posts: 329
Joined: March 22nd, 2016, 11:23 am
Country: United States

Re: TDS5054B problem,Need help!

Post by strick » November 6th, 2021, 7:53 am

Profun,
Self test does a much quicker check of the circuits than SPC (signal path calibration). Unfortunately, unlike the earlier TDS scopes, the 5000 series will not correct any offsets or amplitude settings once SPC encounters a fatal error. That's what you have. You don't have a lot of repair options as the schematics were never released (as far as I know) and the error messages may not help in any diagnosis.

The error step trigger hysteresis may mean that the scope is seeing voltage levels that are not close enough while going up and down with the attenuators. Or, it may mean that the trigger level changes too much do to some internal failure.

On earlier TDS700 series, SPC failures were usually caused by the contacts in the relays on the Attenuators gaining resistance and requiring the scope to put too much voltage through the calibrated resistor (RP911 - see the TDS544A manual from KO4BB's website). The 5000 series probably has a similar circuit but uses RP 1601 on the back side of the ACQ board.

Often the resistance of the faulty attenuator in the 700 series could be reduced by actuating the relays a bunch of times (several hundred). In these scopes, that happens when the scale is changed between 1 and 2 volts and 100 to 200 millivolts. However, on the 5054B the only relays I can hear cycle between 50 and 100 millivolts (and, of course 1 MEG ohm and 50 ohms termination). If that didn't work, then changing the faulty attenuator usually fixed the problem.

So, you might try actuating the relays on every channel and you might be lucky. Changing out the attenuators on a 5000 scope is really difficult (they are soldered in) and even with a good Pace desoldering tool, took a real long time. Breaking the attenuator was highly probable. On errors like this, TEK generally just put in a new ACQ board.

Good luck.

Strick

profun
Posts: 39
Joined: November 6th, 2021, 4:56 am
Country: China

Re: TDS5054B problem,Need help!

Post by profun » November 7th, 2021, 8:07 pm

strick wrote:
November 6th, 2021, 7:53 am
Profun,
Self test does a much quicker check of the circuits than SPC (signal path calibration). Unfortunately, unlike the earlier TDS scopes, the 5000 series will not correct any offsets or amplitude settings once SPC encounters a fatal error. That's what you have. You don't have a lot of repair options as the schematics were never released (as far as I know) and the error messages may not help in any diagnosis.

The error step trigger hysteresis may mean that the scope is seeing voltage levels that are not close enough while going up and down with the attenuators. Or, it may mean that the trigger level changes too much do to some internal failure.

On earlier TDS700 series, SPC failures were usually caused by the contacts in the relays on the Attenuators gaining resistance and requiring the scope to put too much voltage through the calibrated resistor (RP911 - see the TDS544A manual from KO4BB's website). The 5000 series probably has a similar circuit but uses RP 1601 on the back side of the ACQ board.

Often the resistance of the faulty attenuator in the 700 series could be reduced by actuating the relays a bunch of times (several hundred). In these scopes, that happens when the scale is changed between 1 and 2 volts and 100 to 200 millivolts. However, on the 5054B the only relays I can hear cycle between 50 and 100 millivolts (and, of course 1 MEG ohm and 50 ohms termination). If that didn't work, then changing the faulty attenuator usually fixed the problem.

So, you might try actuating the relays on every channel and you might be lucky. Changing out the attenuators on a 5000 scope is really difficult (they are soldered in) and even with a good Pace desoldering tool, took a real long time. Breaking the attenuator was highly probable. On errors like this, TEK generally just put in a new ACQ board.

Good luck.

Strick
strick wrote: ↑
November 6th, 2021, 10:53 pm


Strick
Thank you very much for your reply!
According to the information you provided, is the failure of SPC related to the failure of calibration resistance (RP1601) and a relay in the attenuator?

I also have a TDS5052 oscilloscope. Can I replace RP1601 to diagnose the fault?

TDS5054B has four channels, and there are three relays in the attenuator of each channel. Because debug log does not provide detailed information, it is difficult to determine which relay has failed. As you said, starting the relay hundreds of times may repair the fault. Is there a simple way to make the relay actuate continuously?
Regards
TDS5104 DACs.jpg
TDS5104 DACs.jpg (199.53 KiB) Viewed 179 times

strick
Posts: 329
Joined: March 22nd, 2016, 11:23 am
Country: United States

Re: TDS5054B problem,Need help!

Post by strick » November 8th, 2021, 10:26 am

Your detailed error readout appeared to fail right after varigain was checked. The HF part may have something to do with checking voltages after high frequency is selected. However, I don't know anyone who really knows and TEK doesn't seem to want to explain anything except to replace the board.

I sincerely doubt that your RP1601 is bad, as the initial varigain and limits would have immediately failed. Thus, switching them is probably a waste of time. Also, desoldering and moving the attenuators may or may not fix the problem and is a real hassle and apt to break them.

Yes, you can actuate the attenuators of the 700 series via GPIB and possibly via a serial debug connection. you can probably do it via lan if you try. All you need to do is send the voltage commands to the scope. Let me go down and fiddle with my 5054 and see what works.

BTW, I've never been able to get the self-test and SPC readouts for a TDS5000 series scope. I tried to read the serial output from the PowerPC card and got nothing. What program and hookup did you use?

Strick

strick
Posts: 329
Joined: March 22nd, 2016, 11:23 am
Country: United States

Re: TDS5054B problem,Need help!

Post by strick » November 8th, 2021, 3:59 pm

Profun,
disregard the comment about the log, you were using the log captured when the Register is modified. I thought maybe you had figured out the serial port...

I set my 5054B to debug and noted that the varigain completes prior to the triggers as shown on your log. That means that the varigain probably passed and the attenuators are probably not the problem. Something else is. What, ask TEK, because they are the only ones that know. The triggers are always two separate chips in my experience, so you might be able to id them and do some probing to see if something is not the same on each one. Baring that, I'm not sure what you can do.

If you do want to cycle that attenuators a bunch of times without doing it manually, you can hook up the lan to your computer, connect with TEKVISA and then write the command: CH1:VOLTS 100E-03. this should place channel 1 at 100 mv. Then send CH1:VOLTS 50E-03 which should set channel 1 to 50 mv. If this works, do the same thing for all the channels (turning them on) and save the script. Then load the script and loop it and it will run like crazy with cycling the relays...

The other way to do it is to use the GPIB, but I don't know if you have that.

Strick

profun
Posts: 39
Joined: November 6th, 2021, 4:56 am
Country: China

Re: TDS5054B problem,Need help!

Post by profun » November 9th, 2021, 2:44 am

HI, Strick,

Yes, I activate debug log by modifying the registry.

Now for me, the most important thing is to determine which part of the acquisition board has failed.

Limited to my own technical level, if the relay in the attenuator is aging or some patch components are damaged, I think it is still possible to repair it. If the large-scale integrated circuit is damaged or the whole attenuator needs to be replaced, it is impossible for me to do so.

I don't know what type of trigger chip you mean. I analyzed the debug log file. It seems that SPC made an error in the last few steps. I don't know whether it is related to RP1601 or a relay, or an analog switch IC is damaged.

I haven't found any repair examples of "trigger hysteresis error" on the Internet. In short, I don't have a clue now.

I guess the only thing I can do now is to make the relay run crazy. Thank you for the method "connect the computer with LAN and run it with script" It's still difficult for me, because I've never done a similar operation, but I'll try my best. I have a GPIB card, and there's no problem connecting the oscilloscope. I don't know if you have a simpler way to use the GPIB port to run specific programs.

Regards!

strick
Posts: 329
Joined: March 22nd, 2016, 11:23 am
Country: United States

Re: TDS5054B problem,Need help!

Post by strick » November 9th, 2021, 6:50 am

Profun,
OK. if you have a GPIB connection, you can use the ibic command in a dos window to talk to the scope. if you are using XP or later, you connect to the scope and run the listen/talk utility. Without knowing which version of operating system or type GPIB card, it's hard for me to know the proper command.

Anyway, I'm attaching a zip file with a text file (EX5000.txt) that has the commands to send to the scope over a GPIB connection using IBIC, the interactive communications program in NI-488.2. You can also get to IBIC via TEKVISA. The main thing is to send the commands to the scope to automate the actuation of the relays.

As far as which chip (or chips) are the triggers, I really don't know, but my guess is that the trigger logic chips are probably U1000 and U1200, and that U800 and U900 are the Demultiplexers. That would leave U700 as the most likely candidate as a combined trigger.

So, truly once something goes wrong with one of these boards, there is little to no hope of fixing it that I know of. I tried to fix a 5104 board several years back and failed miserably.

Wish I could be more help...

Strick
Attachments
cycle relays.zip
(643 Bytes) Downloaded 7 times

profun
Posts: 39
Joined: November 6th, 2021, 4:56 am
Country: China

Re: TDS5054B problem,Need help!

Post by profun » November 10th, 2021, 4:11 am

Hi,Stick

Thank you for your reply. I measured the resistance value of the calibration resistance RP1601. The measurement result is the same as the resistance value marked on the circuit diagram of TDS544A, so it can be determined that RP1601 is basically undamaged.

I used an old computer (With Windows XP SP3 and Ni PCI-GPIB card) to connect TDS5054B, and then installed TEKVISA program. Using the script you provided, I can now cycle the relay of the oscilloscope.

Thank you for your help. I hope I can be lucky to repair it, even if there is only a little hope.
QQ图片20211110201051.png
QQ图片20211110201051.png (944.13 KiB) Viewed 147 times
_093NE3_7NXS5YYZTQ8NFYX.png
_093NE3_7NXS5YYZTQ8NFYX.png (121.81 KiB) Viewed 147 times

with respect
Profun

strick
Posts: 329
Joined: March 22nd, 2016, 11:23 am
Country: United States

Re: TDS5054B problem,Need help!

Post by strick » November 10th, 2021, 6:09 am

Profun,
glad you could get the relay routine working. I was pretty sure that RP1601 was good or it would have failed the tests much sooner.
While your voltage paths appear to check good, triggers still might be affected by the relays. I guess you will find out.

It would be really nice if someone really knew the circuit in these boards and could chime in. I don't think anyone from TEK watches this particular "Obsolete" forum...

Strick

profun
Posts: 39
Joined: November 6th, 2021, 4:56 am
Country: China

Re: TDS5054B problem,Need help!

Post by profun » December 7th, 2021, 7:20 pm

Hi,Strick

Today, I replaced RP1601, but the fault is still not eliminated. The error message is still "trigger hysteresis error". Now there is no way

Profun

Post Reply

Return to “Other or Discontinued Oscilloscopes”

Who is online

Users browsing this forum: No registered users and 1 guest