Author Topic: [Solved] TTI EX354R Unstable output problem  (Read 1113 times)

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Offline Anachron

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[Solved] TTI EX354R Unstable output problem
« on: December 01, 2013, 09:43:38 pm »
Hello everyone!
Hopefully this is the right place to post that, if not I am sorry!
I own a second hand TTI bench supply model EX354R and lately I am experiencing problems with the stability of the output on both channels, after having it loaded with a big load parallel on both outputs. The actual voltage will jump around a lot, down to 3 volts from the set value and almost all the time it will always undershoot even if it stabilizes finally. When cycling the outputs on and off a few times, it will eventually work properly, mostly on the 1st channel, but there is obviously something wrong with it.
I figured the best place to get advice on what might be going on would be here  :D
If anyone has any clues on where to start investigating I would be really grateful!
Will post pictures/videos if anyone thinks it might help.
Thanks everyone in advance  :)
Anachron
« Last Edit: December 01, 2013, 11:46:47 pm by Anachron »
 

Offline Zbig

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Re: TTI EX354R Unstable output problem
« Reply #1 on: December 01, 2013, 09:55:29 pm »
What kind of load are you using? If it has heavy inductive properties, I'd expect all kinds of weirdness.
 

Offline Anachron

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Re: TTI EX354R Unstable output problem
« Reply #2 on: December 01, 2013, 09:59:16 pm »
Hi, thanks for the reply, it was a 200w CB power amp that I was testing, both channels limited to 4 amps.
This behavior though continues even with both of the channels not loaded, like the load has damaged the voltage sense circuit  :-\

UPDATE: I am pretty sure I found the culprit, it's most likely the on/off output switches. In both channels, possibly from the high current of the load the contacts partially welded together or gunk has accumulated(?). Once you click it in you also have to pull the button out and good contact is made, and then the output is stable and correct once again :D
Further investigation is needed, but now I don't have the time. Teardown and switch replacement will follow, as will pictures for anyone who might be facing the same issue.
Cheers
« Last Edit: December 01, 2013, 11:41:05 pm by Anachron »
 


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