Dead TG16. Hot Transistor. Help?

[Pinwizkid]

Hi gang,

I was given 2 broken Turbo Grafx 16 consoles to "take a crack" at repairing. I fixed the first one by doing some cleaning and solder reflowing, especially on the encased RF output module. I got it working 100%.

The second one, however, is given me a bit more of a problem. When I turn it on, I get a white screen (occasionally a pink screen depending on how tight or loose I put a game in). I reflowed the entire pcb and cleaned the contacts thoroughly. Nothing. It's worth noting that this console doesn't have the silver encasing on the pcb and the black transistor hanging off at the bottom of the pcb grows very hot when the console is powered on. From looking at the other console, it seems as though the silver casing acts as a heat sink since the transistor is screwed into it, but I can't be sure because I don't know how hot that transistor usually gets.

I'm decent at soldering and confident I can repair the pcb, but I just don't know how or what to test in order to figure out what I need to repair. I'll try to get some high res pics of the pcb up soon, but any input you guys have is appreciated.

Thanks!

[ApolloBoy]

It's worth noting that this console doesn't have the silver encasing on the pcb and the black transistor hanging off at the bottom of the pcb grows very hot when the console is powered on. From looking at the other console, it seems as though the silver casing acts as a heat sink since the transistor is screwed into it, but I can't be sure because I don't know how hot that transistor usually gets.

The transistor in question is the 7805 voltage regulator and you absolutely, positively must have a heat sink on it. It gets incredibly hot without it and it'll shut down within a few minutes as a result.

[thesteve]

the white screen is simply a boot fail
look for damaged traces around the hudson chips and ram

[Pinwizkid]

[/quote]
The transistor in question is the 7805 voltage regulator and you absolutely, positively must have a heat sink on it. It gets incredibly hot without it and it'll shut down within a few minutes as a result.
[/quote]

Understood.

What are my options for installing some kind of heat sink here if I can't find the original silver casing? (which I'm guessing is going to be impossible to find...)

[cjameslv]

The transistor in question is the 7805 voltage regulator and you absolutely, positively must have a heat sink on it. It gets incredibly hot without it and it'll shut down within a few minutes as a result.
[/quote]

Understood.

What are my options for installing some kind of heat sink here if I can't find the original silver casing? (which I'm guessing is going to be impossible to find...)
[/quote]

Possibly a square/rectangle piece of aluminum (1/8" thickness or so) then just drill it and tap it for whatever size screw or just use a bolt & nut through hole you drill.

[thesteve]

the plate can be found (just ask me) i wouldnt bother till the system boots tho

[bust3dstr8]

There are probably a half million different TO-220 heatsinks on Ebay China...one of em should fit

[clackattack]

That thing usually does run pretty hot, but without a heatsink it will die. Radioshack has a few different 220 heatsinks, go check those out