Famicom C1 TV 14c-c1r restoration

I'll try to restore a Famicom C1 TV (14c-c1r) with RGB PPU inside.

I found the issue, problem come from secondary transformer (T751 on PCB). This step down transformer is totally corroded at primary pins. After some fixes, bad luck no power at his output. I have a measure of 1300KOhm on primary pins whereas I must should 0 ohm. Not good… secondary shows 0 ohm.

Actually I need a new transformer, but I don't know the output voltage of this transformer. The first capacitor after output is a 25v/1000µF. I suppose this output voltage may be 12v or something.

I have some pics from inside :

- TV's motherboard :
--> bottom right, the 110v input
--> On the right, the 2 holes are the primary input, stripped traces carry 110v.
--> 2 others hole with red inside are output of the transformer.

- components side :
--> Under the white line to the left, there is primary input (110v)
--> Transformer output goes to the 2 holes above the white line.
--> 2 others holes are not connected to the transformer's coil.

- the components beside transformer's output :
--> 1000µF 25v capacitor
--> D325 transistor (don't find excact reference on the web)

If someone know the exact output voltage, I can replace the transformer and revive this typical 80' Japanese TV.

 

Picture of the transformer. By the outlook of the circuitry around, it's not a normal transformer but something like this:



These are special transformers used on switching power supplies.

 

OK transformer fixed. There is a corroded wire inside. But, now the TV turn ON and after 5~10s it shutdown. I suspect a defect component that I can't indentify.

 

Now, you go pursue bad capacitors. Get an esr meter tool and test the capacitors against their indicated rating. Replace any which fail the test with one with identical ratings. It's best to remove them and test them outside the circuit.

 

You should replace ALL of the electrolytic capacitors. Any electronic device that is 30+ years old should have this done.

 

No, that's not true. It depends on the age and make of the capacitors.
I would say that if it was something like a SEGA Game Gear or something similar with *known bad* capacitors but no.

I have 30+ years old stuff which still has the original capacitors and still works properly.

The proper approach to this kind of restoration is "per case" basis. Only people who have no idea what they're doing go replacing parts without doing proper testing.