RE: GO7 with low B+ voltage

Well, I decided if I was going to fix this, I would have to pull out the
chassis and get a better look at it :). Just for posterity, here is what I
found:

broken resistor leg on R703
R414 shorted open and badly burnt
R415 corroded and badly burnt
FR401 corroded and burnt
2 legs of IC 501 with puckered solder joints

So I guess I should have pulled the chassis BEFORE posting, huh?
(Advice to other new guys: Pull chassis BEFORE posting)

On the plus side, it had already had a cap kit done on it.
I don't have all the parts I need. I'll post if this solves the problem.

Sean McLachlan
MIS Manager
LithoFlexo grafics inc.
801.484.8503

-----Original Message-----
From: owner-rasterlist@synthcom.com
[mailto:owner-rasterlist@synthcom.com]On Behalf Of Sean McLachlan
Sent: Thursday, June 19, 2003 3:30 PM
To: rasterlist@synthcom.com
Subject: RASTER: GO7 with low B+ voltage

I have a GO7-CBO I picked up dead. Replaced the HOT and Voltage Regulator
X04. The new X04 I used is a NTE94, which is supposed to cross to the
original. Now it comes up, but I can't get the horizontal OR the vertical
hold to sync up. The screen just rolls on both axis's. Also, the neck
doesn't glow like other monitors I have, it's dimmer. But this is my first
G07, too, so I don't know if that's normal.

I checked Randy's flow chart, and tested the X301, X302, X305 and X306. I
did them in circut, so I don't trust the results, but they checked out good.

When I test the B+ at one end of R1 I get 98 VDC, instead of 120. At the
other end I get 160 VDC, rather than 145. Turning the B+ adjuster pot
doesn't afect the reading at all. Not even .1 V.

I have a cap kit coming from Bob, and I'll cap it when I get it.

The game has a switcher PS, and the voltages on that are good. Except one
of the AC 115 lines reads 20VAC at the termianl, while the other read 116AC,
but the game coins up and plays, marquee lights up, etc, so I figure that's
OK. Mistake?

I have googled like a madman, and can find tons of posts about low B+
voltage, but none mention a particular fix.

So, now my questions:

1: For X04, has anyone used the NTE94 in place of the original 2SC1106A or
2SC1454? Is this really a suitable replacement or should I get an origianl
part # from Bob? I can't find it local.

2: I see that there is a Filter Cap, C904, that filters the line and I read
the schematics to say that is comes before X901 and X04, but High School
electronics was a long time ago, so maybe its after. Bob's page (God bless
you, Bob) tells how to swap it out, but not why. Will changing this out
help?

3: Anything else I missed, other voltages I should check, etc? This is the
first monitor I have had to do anything to other than a cap kit, so I am not
used to the deep end of the pool.

Thanks guys. And thanks to SteveT for his help on the HOT replacement.

Sean McLachlan
MIS Manager
LithoFlexo grafics inc.
801.484.8503

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Received on Fri Jun 20 00:56:13 2003