DK PP7B Power Supply Issue

ted429

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Donor 2011-2012
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Hello all,

I tried to set up my DK parts outside of the cab to make sure the board I have works and I played for about 5 mins and then a pop and some smoke came from the power supply. I have recapped it and I noticed that R1 resistor was white and burnt looking and it was fried. I replaced that 20 ohm resistor and hooked it all up and it fried that same resistor. Any ideas. Also could use a power supply PM me if you have a spare you would sell me! lol

Thanks
Ted
 
Please do NOT hook that up to your boards again. Something is wrong and test WITHOUT boards hooked up. Something is pulling a lot of current and/or there is a short of some kind. It would be a good idea to see what is on the +5 line.
As for a power supply, this one is a switching power supply and they don't cost much. They are not too hard to replace with existing supply. I replaced my Heavy barrel one with this.

http://cgi.ebay.com/15A-Arcade-Swit...387?pt=LH_DefaultDomain_0&hash=item4cf793ca23
 
Oh I didn't hook my DK board back up to it. I just turned it on and it smoked that same resistor. I have heard bad things about those power supplies because they cause sprites.

Ted
 
I do NOT have a schematic for that supply yet as it takes me a long time on dial up. I do go to the library on hot days (like today) and download them to a thumb drive. I need to be careful some of the sites don't want you to post the schematics to a website. Mikes Arcade is one I need to find out about this. I think posting a link to them is fine but I am not shure and will talk to them before I post a link to their site.
As for right now I would look at transistors and diodes with a simple meter. Follow the outputs backwards and look for anything that would "short" the outputs. In my cabinet there was all kinds of washers broken locks and loose nuts and bolts. Any of these gets on/into your supply and hey look it's somking. In ham radio we have a saying "tune for maxium smoke" but with arcade games and power supplies that doesn't apply.
Also you said you had it out of the cabinet....what did you have it sitting on?
When I have done a repair on computers and such and put it back together I always hold above my head and shake it. This way if anything is loose I know it and can remove before it causes any problems.
After I see a schematic I will be able to help you more but there is not much to a supply. You can readily test parts easy. If you are not shure how to test them there is a sticky on pcb repair and I think it also refs. the Atari Book.
 
Ok so I am at the library and looked at supply schematics.
Check

br1, c6, c7, scr1, r2, r3, d1, tr1.

visually check c5, c8.

If nothing there is shorted to grnd then we will have to look after the xformer

d4, d5, d6, ic3, tr2

Check them there critters and let us know what u get.
 
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