G05-801 cap kit...FAIL.

cwilkson

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I just recapped a G05-801 for a friend and replaced the deflection xtors. He had horizontal collapse. But now the game is playing blind. Spot was on, now there's nothing showing at all. The game looks good on an o'scope. Any suggestions on what to look at?

Yay Thanksgiving. :/

EDIT: Oh yeah. We have neck glow.
 
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Did you reflow the connectors?

Yes, I reflowed the connectors on the deflection board, the supply board, and the EHT (inside the cage). This is my first electrohome job, so don't have a good idea where the problem areas are.

BTW, it was horizontal collapse. (Vertical line showing) I fixed that in my first post. But now...nothing.
 
Pretty sure they are not shorted. Just probed the bottle caps to the chassis with a meter. Not shorted. I checked the 2 fuses that go from the deflection board to the yoke. Are there others I should check?
 
Check all of the fuses.
Are there any inside the cage? G05 newb here. :)

Ooh. Just found F100 and F101. They're vaporized. On the power board in the monitor. Don't have any to replace these with...will have to get them tomorrow. Regular or slow-blow?


We replaced the 2 big filter caps on that board. Are they just going to blow the new fuses every time? Any hints?
 
Stolen from the G05 FAQ

Symptom: Fuses F100 and F101 blow on powerup.​
Test the diode bridge (DB100) with the monitor unhooked from the power input. The diodes take
the AC and convert it to DC. If one or more are shorted you will get blown fuses. The diodes, or
legs of the bridge should cond uct one way, and be open the other way. Verify that b+ and b- are not
shorted to ground. If the diodes are all good, both fuses should blow if there is a short.
Check C100 and C101 for shorts. If one or the other measures shorted, unplug the chassis output
transistors and try again. The output stage transistors should be 2N3716 for Q708 and Q608 and
2N3792 for Q709 and Q609. Make sure they are the correct type, and make certain the transistors
have the mica insulators installed.
If C100 and/or C101 is still shorted, remove the shorted capacitor(s) and check to see if the fuses
still blow. If C100 and/or C101 are not shorted, it could be an overload in the output stage.
Unplug the yoke and power up the monitor without any input from the game board. Measure the
voltage from chassis to F700 and F600. It should be close to zero. If it is as much as 10 volts it's
not a problem (with the yoke unplugged the feedback loop isn't what it should be). But if it reads​
something like 40 volts you have a bad driver stage. Look for Q706 to be shorted. It is a MPSU57.
 
I'm an idiot. I installed the BFC's on the power board backward (C100 & C101)!!

Of course, it isn't really my fault. :) On the side of the can, is printed "POSITIVE +". So I mount the caps with the "+" sign on the positive lead. Only to later find that the polarity is marked on the END of the can, right by the leads. And I had installed them BACKWARDS! I found this after a lot of other unsuccessful troubleshooting to try to find the apparent short. So I reversed them and got a picture right away. With the opposite type of collapse. Traced that to intermittant linearity pots. So now I just need to replace the pots and dial them in. Yay!

I love vectors. B&W vectors anyway. And I mean that. They're so simple and easy to work on. You just gotta keep fools who can't read polarity far away from them. :D

BTW, what does that big boldface POSITIVE mean? Is that a temperature coefficient or something?
 
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