[Solved] Bench top power supply problems

[tabbas]

Hello All

I have a circuit Specialist bench supply - Model CSI3005SM. Bought 2.5 years ago. I've used this thing practically
everyday without any problems.

But a few days ago I noticed that there were huge fluctuations in the voltage readout. If I set it to 12 volts it would go
down to about 5 or 6 volts for a few seconds then jump back up to 12v. It would stay at 12v for about 6 seconds then
repeat the fluctuation - and so on.

Does anyone know what the problem might be ? I consider myself to be at hobbyist level in electronics but I would be
confident enough to replace a mosfet/cap/diode etc if that was the problem.

I do realise this is a cheapo unit (£60 from Amazon) but I would like to repair it if possible.

Any help would be appreciated. Thanks for reading.

[cowana]

Does it seem to be worst when adjusting the voltage?

Often the first thing to go in low-cost power supplies are the potentiometers, which become intermittent and allow the voltage to increase/decrease as the wiper skips across the track.

[Nusa]

Circuit Specialists primarly sells rebranded Chinese stuff.

As for that power supply in particular, you might find this useful: http://hackaday.com/2016/02/16/repairing-and-improving-cheap-bench-power-supplies/

[tabbas]

@cowana

Yes, most definately. Infact it's all over the place now.

[tabbas]

@Nusa

Thanks for your post and the link to that video - I'll try replacing the pots. I think I have 2 suitable 10k pots here and
will order 2 1K pots

[tabbas]

Problem fixed.

It was the pots that failed. I soldered in the 2 10k pots, put everthing back together and all is workoing normally now.

When I receive the 2 1K pots I'll solder them in too.

Many thanks for your help guys - It is appreciated. I will also leave a thanks to the guy who made that video.