WG6100 problem

ChaosJohn

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So this 6100 was working mostly fine in my Star Wars for the last year or so. Recently, it went into a mode where you could see the lines from the center of the screen to the edges of every vector it was drawing. You could still see all the elements of the game and play it, but it was way overdrawing.

So I decided to finally install that deluxe 6100 cap/etc kit I got from Bob Roberts.

I replaced all the caps, resistors, transistors (including the chassis mounted ones), and diodes provided in the kit. His kit includes most of the upgrades described in the manuals for repairing 6100 monitors that are floating around the net.

I'm generally very careful about making sure I'm putting the right part in the right place and getting the positive leg of caps in the positive hole, and things like that. But somehow I must have missed something this time. I almost put the ZD902 of the HV board in D902 (apparently a common mistake), but caught myself in time by double checking the board after pulling the old component.

When I put the monitor back together, wired it up to the game and turned it on, I heard a loud CRACK and immediately unplugged it. When I checked, the 3 diodes at D100, D101, and D102 had popped.

I've bought replacements for those (and D103 as well), and I'll re-install those and go over every part I replaced and check all the solder points to make sure I didn't create any shorts (I checked the solder of pins of the 4 transistors on the deflection board verrrry closely, but maybe I missed somewhere else).

Anyway, I'm posting here to see if anyone has an idea what would I might have done wrong that would cause those diodes on the deflection PCB to pop. Or if anyone here has had that problem, and what they did to fix it.

Any help would be appreciated.
 
The first problem you mentioned with all of the trace lines showing is because your brightness is to high or your spot kill circuit has something wrong with it. The bridge's discrete diodes smoked because one or both filter caps (C100, C101) is shorted.
 
check continuity between the bottlecap transistors and the frame. Also make sure the Big filter caps arent in backwards. Something is shorting out.
 
The first problem you mentioned with all of the trace lines showing is because your brightness is to high or your spot kill circuit has something wrong with it. The bridge's discrete diodes smoked because one or both filter caps (C100, C101) is shorted.

Well, considering it was working properly and then started behaving improperly, I'd have to guess it was not just a brightness control issue. I'll check the components in the spot killer section of the boards.

You actually reminded me of something curious.

The two filler caps (C100 & C101) that came with the Bob Roberts cap kit were normal capacitors with a + and a -, and the microfarads and voltage matched the originals (4700 uf, 50v). But the original capacitors had a third pin coming out! That definitely threw me off. Is this some special kind of 3-pin capacitor? I put the replacement cap's legs through the right + & - holes.

Do I need some special component for those? Or would the normal caps work?
 
But the original capacitors had a third pin coming out! That definitely threw me off. Is this some special kind of 3-pin capacitor? I put the replacement cap's legs through the right + & - holes.

Do I need some special component for those? Or would the normal caps work?

The third pin is electrically connected to the negative terminal (or possibly,to nothing at all). It's there for mechanical stability only, to help keep the capacitor mounted solidly, being as it's so large. The newer capacitors don't have this, but it doesn't matter.

-Ian
 
Oh I missed that it was working properly first... See if any of the bottlecaps died.. They will act as shorts, but SHOULD blow the fuse before the diodes. Although I have had a few blow the diodes before the fuse..
 
Okay, I checked all the components I installed through a magnifying glass. It looks like every part was in the right place and there were no solder shorts.

And then I tested the chassis mounted transistors... two of them were shorted to the chassis. I'm an idiot not to have checked BEFORE I turned it on, but hindsight is 20-20. Hope I didn't blow the two transistors in addition to the diodes it blew up.

So I guess that means I need to replace the mica insulators ... Just ordered a set of them and of the bottle caps as well in case I blew one of them.

John
 
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