I've stepped into monitor chassis repair and picked up 4 G07 that all were shipped as 'consider non-working'. I've done a bunch of video watching and thread reading and carefully worked on these chassis. The first three, I got working with great results however the fourth one is giving me a battle. I'm glad this one wasn't the first one I did, otherwise I would have thrown in the towel on chassis repair.
Anyways, here is what I 've done:
washed in water to remove ages of dirt and dust
visual inspection, 901 fuse was blown
flyback looked good with no cracks, some goop on top, no mounting posts to the chassis as these flybacks normally have on G07s, looks like a knock off, may not be for G07
width coil was broken
everything tested ok on the power side with meter as per Amateur Mike's videos
first try powering up the tube and I thought I heard high voltage, but nothing on screen
powered off, went to discharge tube and it had no static sound
filter cap was charged up, when shorting I got a big spark and blew fuse
did a recap with a kit from
www.arcadepartsandrepair.com along with filter cap
did a lightbulb test and voltage was high, moving B+ POT made no difference
after some KLOV research resistor 908 is NG, had to test out of circuit
replaced 908 and did light bulb test and was able to control voltage...voltage only went up to 117 with POT turned all the way .
Replace R517 because it was out of spec, reading 220 K ohms instead of 180 Kohms
Tested B+ pot out of circuit, it wouldn't go below 227 Ohms.
Replaced B+ pot, and voltage was adjustable to 120...
Replaced flyback and chassis worked...image not centered.
Picture stable, but statically shifted left following flowchart shifting image shows x301 and x305 (I assume that means image is moving to the left mine was just statically shifted, but investigated the X301 and X305)..
Checked both X301 and x305 and initially x305 seems bad...ordered 2SC1815 from Digikey
Replace R516 because it was out of spec, reading 0 ohms instead of 180 Kohms (could cause image darkness)
Replace R512 because it was out of spec, reading 7.3K ohms instead of 8.3K Kohms
Received new replacements and checked X301 and X305, pulled them both and compered to news ones and they tested fine.
pulled IC501 and socketed and new IC501 and still same problem (screen shifted to left about 1"+)
I tried to move image with the jumper on the G07 board and it wouldn't move, even if I moved it to each jumper post
I added the Image centering mode from
www.arcadepartsandrepair.com and still very little image movement, not enough to make it a useable chassis
Replaced all 4 pots on board because they were all very touchy, slightest movement created havoc on the screen
went ahead and replaced X301 and X305 because I was out of ideas.
replaced X304
tested X303 out of circuit with a new one and it was identical
I'm stumped, any ideas. Is it possible a bad cap from the kit? I didn't change C402....however that is for a vertical collapse which is not what I'm seeing.
I even stuck GoldenTee 2K on this chassis monitor and get the same image, if I try my other 3 G07 I get a nice centered image on this tube and yoke.
Thanks for any recommendations.