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Troubleshooting a WG 25k7191 no picture blowing fuse
joej85a:
--- Quote from: princess prin prin on March 25, 2020, 12:40:50 am ---
--- Quote from: joej85a on March 24, 2020, 06:30:53 pm ---C38 is shorted, dead. Both pads short to ground when in circuit, when removed, it tests as shorted.
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Is one of the pads on the chassis it was soldered to shorted to ground?
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I installed the new C38 along with the others I ordered and the short is gone. Correction, neither pads for c38 go to ground now. I also found that I had a dead short in c37 as well, which of course I did not order, so I just put an order in for it and c44 just to go ahead and get them all changed. Wish I had seen that full kit with these in it. Anyway, new regulator (ic4) is here. I am going to install and see what I get with Prin's truncated test that isolates the regulator. I also replaced all the recitifier diodes and b+ filter cap. I'm half away to a new board! haha.
Ill keep you all posted.
joej85a:
So, in the midst of my troubleshooting, I searched ebay and found a listing for another k7000 chassis that was verified to be working. However, the seller stated that although it works, the image is too big for the tube. The picture shown shows just that, an image that is going off the sides of the tube. He had it hooked up to a 19" monitor, but as I look at the pictures, it is a P538 board, just like mine for my 25" monitor. Im thinking maybe he just has it hooked up to the wrong tube, and I picked it up for $45.
It came in today and it is indeed a P538 board, model number k7197. It also has the pincushion board attached. Again, searching the 7197 brings up results that say it should be for a 25" from what I can find. It also has the STR30130 regulator.
The main different I see is a different neck board. My neckboard is a P448A (on my original board) and this new board has a P456 board, that is definitely not compatible with my yoke. It is an 8 pin and mine takes the 10. It also appears to have been desoldered and resoldered looking at the connector closest to the HOT.
So question is, are neck boards changeable? Could I disconnect my P448A and attach it to the 7197 board? As I am bringing back this other board to life, I would love to play some GT2k. If it matters my tube is a Philips M08X :dunno
princess prin prin:
P538 is the main chassis board for 25" (and more rarely 27") monitors and P456 is the neckboard for 19" monitors (it wouldn't fit any 25" tube) so this combination doesn't make sense and cannot be original. This P538 would need to be carefully inspected to see if it's still for 25" or if it has been modified. The pincushion board (if that's what it actually is) is necessary for 27" monitors.
Does it have these caps? same values?
joej85a:
--- Quote from: princess prin prin on March 26, 2020, 01:56:38 pm ---P538 is the main chassis board for 25" (and more rarely 27") monitors and P456 is the neckboard for 19" monitors (it wouldn't fit any 25" tube) so this combination doesn't make sense and cannot be original. This P538 would need to be carefully inspected to see if it's still for 25" or if it has been modified. The pincushion board (if that's what it actually is) is necessary for 27" monitors.
Does it have these caps? same values?
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It has a .0036 in C36 and C69 has been replaced at some point with a new smaller brown style that says "602G". So wouldnt that be .00602? Close enough?
If the pincushion is needed for 27 will it work on 25 or would it been to be removed and the cap and resistor at r69 and c28 need to be re-installed?
I also see that the HOT is a "2302 SK9422". Not sure if that is relevant, but someone took the time to write a note, in sharpie above it, it is a "2302" per the identification on it. I do know that the 7191 uses a D1398.
princess prin prin:
C36 and C69 are correct for 25". The HOT has been replaced with a different type (still with damper diode, hopefully compatible enough) and the vertical board can stay (I don't know if it's indeed for pincushion without seeing it). The neckboard can be swapped.