Teardown - old dodgy satellite receivers!

[hun_yeti]

I got a few old satellite receivers from a friend,to use them as parts, as they have no value anymore and some of them where very "interesting" (at least to me).

The first one was interesting because it was the biggest, it had a huge PCB, the micro-controller was on another PCB above the main one( those nice wires...), but half of that huge PCB was completely empty...





I know, that might be because they had more expensive models with more function and it was maybe cheaper for them to use the same board, box.
It was also the first time for me to see those vertical PCB pieces, at the SMPS and at the empty area, the are totally empty, so maybe for physical isolation?

The second box was strange, it had plastic straps visible on the bottom.



when i opened the box, it was chaotic, all those wires across the board







Than i looked at the power supply, at first glance, it seemed that it has nice, individual mains transformers that i can easily use.
Notice, the plastic straps... interesting solution i have to say...



But my happiness ended soon, as i looked more closely at those boards





As i started to suspect that these are individual switching supplies, or something like that.
The two smaller board are identical, exept the color of the caps and one of them have a 5 volt regulator on it (?)



those dip 8 chips are opto couplers, the to-92 is a  TL431 regulator, on the bigger board, the heatsinked to-220 devices are an N channel mostfet and a low drop rectifier.

on the back side the smaller devices have an opamp and a diode in an SMD high power packed (don't know the exact name) and a few diodes resistors, capacitors and a 4 pin device i could not identify (probably an opto coupler)



The bigger one has an opto coupler instead of a diode,and it has an unmarked transistor (i guess).



I'm not really big on PSU-s but it seemed very unusual to me.

I hope you enjoyed this post and please share your thoughts!

[Short Circuit]

First box is probably an analog only device, with all the unpopulated stuff for pay-tv decoders. Notice the smartcard socket location in the upper right of the pcb?

Second one... Well, it clearly is from a time when electronics were valued quite a lot higher than nowadays Lots of effort for fixing a defective power supply.

[Fallingwater]

The second one seems to have been subject to some ghetto repairs. I mean, it's obviously bodge-happy from stock, but I don't think the factory would use a screw connector in place of a simple solder joint (or, y'know, just a longer wire).

[Chasm]

The second one definetly has some after market modifications. I'd say replacing the original SMPS with what you see.