Power Designs Power Supply TP325 trouble shooting  - Page 1
Forum section: electronics / testgear

author: ez24
author_rank: Super Contributor
timestamp: September 26, 2015, 04:11:17 am
content: First of all I am not connect with this ad, I am not bidding, and I am not watching. I also have a fully functional TP325http://www.ebay.com/itm/Power-Designs-TP325-Triple-DC-Power-Supply-0-32V-0-1A-0-6V-0-5A-load-tested-/291159164051?hash=item43ca704493The seller lists these vaults:Source A 32V @ .75A (rated at 32v @ 1A)Source B 32V @ .65A (rated at 32v @ 1 A)Source C 6V @ .9A (rated at 6 V @ 5 A )Based on this information is there enough information to determine what is wrong?thanks

author: eas
author_rank: Frequent Contributor
timestamp: September 26, 2015, 04:53:11 am
content: That supply has been listed for a long time. I've considered buying it and its still in my watch list, but for that price, I'm not interested.I don't know enough to know if that's enough information to determine what is wrong. First thing I'd do is check the external current limiters. Then I'd check the internal calibration on the current limits...

author: bitseeker
author_rank: Super Contributor
timestamp: September 26, 2015, 05:19:04 am
content: eas is right. That one, and some others, have been around a while. Send the seller a message and see how much motivation there might be to sell it at a better price.If the current limiters are set too low, those Fault indicators should light up. So, unless the indicators are just not working (in which case the current limiter settings might be all that's wrong), you'd need to open it up to figure out what's up. The sources A and B are pretty close to what they should be so they're probably OK. Source C looks a bit more worrisome, but likely repairable. I'd first do some voltage checks on the two main PCBs while referring to the test points and voltages indicated in the schematics. If things look OK, go through the calibration procedure in the manual to see if that brings things in line with expected meter readings and output.In general, these supplies are quite nice with good specs and lots of discrete components that can be replaced. When I got my TP340A, the bridge rectifier for Source C was shorted and burnt into a blob of black plastic. As a result it was blowing the main fuse. I've pulled the bridge rectifier out and tested sources A and B and they're rock stable. No need to even change any caps. So, overall a pretty easy repair.If you get that one or another (same or similar model) at a good price, post back here with your score and findings.

author: ez24
author_rank: Super Contributor
timestamp: September 26, 2015, 05:27:44 am
content: QuoteI already have one, I am not interested in this one, just repair curiosity.

author: bitseeker
author_rank: Super Contributor
timestamp: September 26, 2015, 05:32:14 am
content: Oh, OK. If the price was right, I'd take a chance on it. Might just take a few turns of the screwdriver and some new neons, or a little soldering.

author: ez24
author_rank: Super Contributor
timestamp: September 26, 2015, 05:40:53 am
content: Quote from: bitseeker on September 26, 2015, 05:32:14 amI guess the guy knows how to use a screwdriver. Why would the neons affect the voltages? My guess is it needs soldering, but what on? Tomorrow I am going to check my neons.

author: bitseeker
author_rank: Super Contributor
timestamp: September 26, 2015, 05:52:01 am
content: The neons don't affect the voltages. If they're dead, then the Fault indicators wouldn't light up in the photos even when they're limiting the current. If that is indeed the problem, then turning up the limiters and replacing the neons would be the fix.Just one of various guesses with limited available information.

author: ez24
author_rank: Super Contributor
timestamp: September 26, 2015, 06:51:03 pm
content: Quote from: bitseeker on September 26, 2015, 05:52:01 amI see and I should have known this - thanks