RE: Star Wars OVERVOLTAGE

 
 
Well, first off - NEVER NEVER disable the over voltage unless you REALLY know what you are doing and have the PROPER test equipment. Congrats, you probably are shortening your life span through X Ray radiation.
 
If the over voltage protection is on, chances are there is a reason. You currently have no way of knowing if that HVT is putting out 19k or 29k. Checking the +180 may not be an accurate indication of what id going on. Especially when there is +180 produced by the deflection board.
 
Now, what is a MPU401D??? Perhaps you mean a BU406D? That could be part of your problem.. If you dont have a BU, get one or more - they are very cheap on my site - www.joesarcade.com
 
Next, get a HV prob from ebay or wherever. I tend to prefer the type that is self contained where you just shove the steel tip under the cup and ground an alligator clip. The choice is up to you. I picked mine up for about $25 shipped.
 
Now, while that stuff is coming in you have plenty of time to test components......
 
 
JB

________________________________

From: owner-vectorlist@vectorlist.org on behalf of Jonathan Stanley
Sent: Thu 3/25/2004 12:33 PM
To: vectorlist@vectorlist.org
Subject: Re: VECTOR: Star Wars OVERVOLTAGE

Let me add a couple things I've checked since my last post:

The overvoltage LED stays on even when CR1 is pulled and the crt is
working. (That's probably normal)

My MPU401D did not fail when the Wintron did, but I did replace it
with a new one anyway - no change.

Since Q4 MCR100-3 seems to be an important part of the overvoltage
section, I replaced it even though it tested ok. No change.

To see if I really am getting overvoltage, I replaced R6 with a 2.2K
resistor which should have knocked a good 5KV or more off the signal
- overvoltage LED still on, so I put the 3.9K resistor back in.

I checked Q4 from the focus block to the board, solid, ohms out.

I checked the DAG ground wiring, solid, ohms out.

I rechecked all the resistors in the overvoltage circuit - all within
spec.

Remember, the game looks and plays perfectly when I have CR1 pulled,
and plenty of range on my brightness control. It is probably at 45%
so I have lots of range either direction. In fact, both R7 and R17
are just about in their mid-points. (Oh, and I checked R7 and R17
for proper resistance as well).

Is it possible the LED could be "lying" and that I don't really have
an overvoltage problem? What could cause that?

Thanks!

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Received on Thu Mar 25 14:23:40 2004