Tenma 72-6905 (similar GW GPS-4303) Repair and schematic

[Irving]

My 2005 Tenma 72-6905 4-channel power supply bought for £75 on eBay a couple of years back finally threw enough faults to make me consider  chucking it, but instead I decided to dismantle and troubleshoot it. I found the schematic for the Tek PS280/PS283 posted elsewhere but it soon became apparent this wasn't very representative though clearly they come from the same stable.  Apart from the relay fault listed elsewhere (RL503 & 504 both OC coils - though given they are both low-power 2800ohm 24v relays running off a regulated 24v rail I find that hard to fathom), i had an o/c zener and a couple of electrolytics that were leaky, plus a few dry joints.

Anyway, while I had it stripped down I drew up the schematic of each of the 3 pcbs in KiCAD, a PDF of which I attach here (mods: if it should go somewhere else feel free to move/copy it). It should be good for the GW-Instik GPS-4303, though the description of the serial/parallel options are slightly different to what actually appears to happen. Enjoy.                                                                                                                           

[shakalnokturn]

Great work!
I don't need it yet but thanks for sharing.

[Irving]

You're welcome. Seems popular...

[Conrad Hoffman]

Must have been a huge amount of work- thanks so much. Don't know if I can fix my 4303, but will give it a shot.