Got this DVD player + combined surround sound system (5.1) (included 6 speakers and sub) for cheap.

Fault: No power. Dead. Fuse is good. Amp area gets power.

Analysis:

At least two bad caps - ones on the left. Caps on the right are also suspect. They are THICON. Not TAICON - they are THICON. This is brilliant. Cheap ripoff caps ripping off another rip-off brand!!

Three 470u/16V and one 100u/16V. Will replace the three 470u's, and maybe the 100u if it doesn't boot without it.

This is a very odd design. It's comprised of several modules - an audio amp, a DVD player, a power supply, a microphone amp, a volume control rotary encoder board (a separate board - even though it's right next to the main front panel board?!) and a few other things... very weird OEM design.

It's full of cheap caps, especially in the audio and main board area, but they seem to be local decoupling and audio coupling, probably not a big deal if they are cheap. Only the PSU is full of them.

 

Probably a dumb question...but what are those black things on the image with the dead caps? It looks like they're designated as caps (at least from the picture), but they look...different.

 

Probably a dumb question...but what are those black things on the image with the dead caps? It looks like they're designated as caps (at least from the picture), but they look...different.

They are inductors. Coils of wire. Very rarely fail. They're pretty good devices, manufacturers like them, because they let them reduce the size of the caps.

 

Ah, cool. The inductors I'm used to are small little air coil ones that I've gotten in random boxes of electronics and some flat packaged ones that we use on Airbag Control Units.

 

Caps replaced with Panasonic FR and FM. Found the 100u was actually a 220u and I had one of those.

But it's still dead......

I did replace the caps with 1000u instead of 470u, which could be the issue, so I will replace them with my newly found 470u's. I have scoped the rails and they are *trying* to rise but failing.

The next possibility is the startup cap, which is a tiny cap required to get the PSU started, on the primary side. It filters the Vcc line for the Fairchild power switch, KA1L0380RB. I suspect this because I measured it going from 8V - 20V using a multimeter and it should ideally assume a fixed voltage.

 

Startup cap replaced. But it still isn't working.

A faint clicking sound can be heard from the PSU even when no outputs connected...

Is the opto perhaps dead?

Also replaced the 1000u 16V cheap cap with a 1000u 16V Panasonic. Wasn't bulging but it might have been at fault.

This calls for some serious debugging...!

 

Replaced the 470k resistor which supplies the Vcc of the power switch -> still no luck.

Other possibilities? Maybe some ceramic caps are busted?

Or maybe the transformer is busted... In which case that would mean the power supply is a no go and needs to be replaced.

 

Found service manual for a similar model - not identical - but has a lot of similarities in the PSU area (page 10): http://www.google.com/url?sa=t&sour...XcAIw6bCw&sig2=QpOguoOUDAeKIdEQi76Tnw&cad=rja

 

Noticed 5V rail was completely dead.

Tested diode (1N5822) - DEAD SHORT, both ways.

The 5V is used by the feedback so if it is dead then it will not start.

Hope this is the only problem but it's faulty either way and it wouldn't work without it.

I'm thinking of clipping a heatsink on it because I suspect the diode failed due to heat.