Q. Why not just run the whole daughterboard off 9V? Or, convert to run off 12, chuck an extra regulator in, to feed the main 5v regulator (12 to 5 would be lots of heat in one place) and maybe a fat diode to drop the 12 to about 11.2 volts for the video daughterboard.
The shimmering/banding I can see changes frequency with voltage - so reckon could be eliminate with a fews caps in right places.
natshaw wrote:Yes please, I have 1 x 4116 that has flat-lined its Q output, so I'd be keen to buy 2 of them, we can split the shipping! You in Auckland? Will PM you my details.
natshaw wrote:Am also after a few 4416 chips for repair & upgrade my 2 x stuffed Basic IIIA cartridges (one gives 2 beeps, one just gives that medium tone) - know a good source of those? Pity my junk Jaycar solder sucker can't deal with through-plated (it's actually crud, I shall return it) - and am hopeless with wick, I want a good vacuum gun!
natshaw wrote:well it turned out it was the power transistors on the video daughterboard, but they were different package transistors, very distinctive-looking (similar to image below). Now I don't know if they were original, or the replacements.
natshaw wrote:Your video issue sounds odd - did those 11.2v readings you took occur during the issue? Interesting you said you had one (brief?) 12v reading too.
natshaw wrote:I would love to start documenting some test points on these Sega circuits, and especially the video parts (of 6 Sega faults I've had, 4 are/were video, and 2 possibly BASIC cartridge). I probably don't have the time, but I will at least write up the ones I've found so far on my working & non-working systems and post them to appropriate forums.
Carcenomy wrote:Desolder gun! Best investment ever! When I'm done pottering around in the shed I'll see if I can find the wee asian chap's email address who sourced mine, it was like $250 for a good clone of a Hakko 474.
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