TECH: Black Hole resets

Betelgeuse

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I am having trouble with my Black Hole pin lately. It started with resets after extended operation, but now the resets have become more frequent. I am not a sys80 expert by any stretch, but all the solder on the power supply connectors has been reflowed and looks good. I have noticed that the problem may be with the large filter cap in the bottom right of cabinet. Originally this would have been a large orange cap, but it seems it was replaced at some point. There is a diode across the top that gets VERY hot. How can I test this cap and where can I get a suitable replacement? Anything else worth checking?
 
I'd replace that cap anyway, 10,000 at 25v or higher. It's a problem item, no sense in fooling around, just pop a new one it.

The "diode" should be a resistor. A bleed resistor to be exact, it discharges the cap when power is turned off. It's normal for it to get warm, as it passes current all the time, but it shouldn't be hot. Might have beed replaced with a lower value at some point, you don't really need to have it there.

Actually, you should have 2 caps under there(?), one with the resistor, one without(?). One without would be the 5/12 filter cap, the one with the resistor would be the solenoid cap (shouldn't need to replace this one, it's not critical)

For the resets, there are numerous causes, connections being the most common. Sys80's are plagued with connection, and to be specific, ground issues. If you haven't done the mods, start there. It's all documented here: http://www.pinrepair.com/sys80/

Outside of that, a power supply rebuild, including replacing the adjustment pot and the 5/12 bridge in the bottom of the cab, is probably in order.


D
 
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Thanks for the info D_Zoot! The ground mods were completed about a year ago, along with reflowing solder on the connector pins. I will look into the things you mentioned and post a followup.
 
I would also take a look at the cables running from the power supply to the CPU. Those pins can be troublesome. Also how about checking the +5V to the CPU, it might just be low.
This company sells the rebuild kits for Power supplies:
http://www.bigdaddy-enterprises.com/

Not the cheapest, but VERY convenient!
-Mark
 
You hit it on the head tec9. I reseated the J1 connectors on the power supply and we have lift off! It took me a while to get back into the backbox because I need someone's help to move it out from between other machines and move it back. At least now I know where the issue lies. Thanks for your help guys!
 
You may want to ask forum member "crank" as well.

He just finished a major rebuild of his Black Hole and had lots of wiring and board issues - all resolved now.

RussM
 
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