... @ Don Hills, was what Amir described your understanding?
No. I misunderstood his original description. But this is worse. O. M. G. Why would they do that? With that, and the overall design, and the safety issues (I agree with Amir's analysis of those on all counts), I wouldn't touch one of these. It puts the lie to the saying that no-one ever died from hi-fi. If that thing caught fire and burned a house down, I suspect the insurance company would be somewhat hesitant about paying...
Amir, please get the permission of the owner to do some safety mods. At a minimum:
- Do the ground connection properly:
- Screw goes in from outside the case. Clean the paint off on both sides of the hole.
- Star washer.
- Nut. Tighten securely.
- Lug with the wire crimped (they got that part right, not soldered.)
- Another star washer.
- Another nut. Tighten securely.
- Redo the mains wiring at the IEC socket - heat shrink over each connection, and a big piece over the whole socket. Do something to stop that X capacitor waving in the breeze.
The output circuitry between the main board and the output terminals is a bit "how ya doin'" as EEVBlog Dave(*) says. That little board with the regulator and the caps appears to be supported only by the legs of the regulator screwed to the heatsink. The caps on the board appear to be floating, and the electro / ceramic combo at the output terminals is a pure bodge job. It's all too dodgy for words. You're right, the output terminals should be moved to the front panel.
I don't know how much heat that regulator dissipates at full output, but the thermal design sucks.
Regulator - silicone pad - paint - steel panel - paint - heatsink.
For the cost of a couple of small components they could have used the big transistor on the heatsink as the pass transistor for the regulator.
(*) Is there someone in Aus who has one of these and could send it to Dave for a teardown? I can see it now... it woud be epic.