Plug Pac-Man board in backward...

Peale

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...normal setup, board not modded for DC. Not sure of board condition prior to this, as I pulled the harness to wash off nasty mouse nests.

Now it's blowing fuses, I forget which.

Ideas?
 
No one has ever plugged a board in backward, before?

Well sure.

Look at the connector pinout. You basically pumped 12 VAC into where 7 VAC
should go. If you're lucky you only took out a couple diodes and the 5 volt
regulator.

JD
 
Last edited:
Well sure.

Look at the connector pinout. You basically pumped 12 VAC into where 7 VAC
should go. If you're lucky you only took out a couple diodes and the 5 volt
regulator.

JD

Yep.....D7 and D8......Q6 and IR1 would be potential suspects too.

Edward
 
Eee...hopefully the board is still good...I accidentally stuck slo-blo fuses into it (I just read the value, and didn't pay attention to the element when I did).
 
While attempting to remove D7, the leg broke. I barely touched it. So, it needed replacing, regardless.

I'd thought that I could replace it with a regular rectifying diode, but the datasheets seem to disagree. What's an acceptable substitute? Aside from an NTE5800.
 
A standard 1N5402 will work fine.


While attempting to remove D7, the leg broke. I barely touched it. So, it needed replacing, regardless.

I'd thought that I could replace it with a regular rectifying diode, but the datasheets seem to disagree. What's an acceptable substitute? Aside from an NTE5800.
 
Bob Roberts has a writeup on it on his site-


ah- actually it's for the sync bus card and vram card
"You plugged it in wrong..no problem..shotgun! "
 
For now, I've modded the board for DC.

I'm fairly sure that there's a short somewhere on the board. However, nothing is smoking.

I start tracing voltage from the harness. At the pin, 5.08VDC. At the diodes, also 5VDC. But, just about every other part I can meter and get 1.7VDC, at the positive pin.

I took advice from Adam from One Circuit, and Ohm'd out every part, between ground and VDC. Every part would start low, and start climing, until I got ~80 Ohms. I was waiting to see one part give me a short, but unless I missed a component (which is possible) I'm not finding the short.

Any other tips to find this drain?
 
Unless I'm misunderstanding......I think you've got something open. I assume you're now running this on a switcher? If you had a short, it would kill/suck down the voltage at the start......you wouldn't have 5VDC anywhere.

Edward
 
I was reading 5VDC at the diodes, but really low elsewhere on the board. Figured it out, finally. The large wirewound resistor in the corner should be 4 Ohms. It's reading 8 Ohms. Once I jumpered that, voltage was normal, and the board boots to garbage.
 
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