Faulty Sanwa PM1755C PFX-46T

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capcomguru
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Joined: August 25th, 2008, 6:43 pm
Location: Boston

Faulty Sanwa PM1755C PFX-46T

Post by capcomguru »

My Sanwa PFX is experiencing what appears to be horizontal frame collapse - all I am receiving is a thin beam of light down the center of the monitor. While testing a faulty pcb the monitor squealed while trying to sync to the signal and all I got was garbage on the screen. A few moments later "picture not available" came into focus for a brief moment. Directly after making out the "not available" message,the raster completely collapsed into the thin beam. The monitor fires up to a thin beam, even with known good pcb's.

Doing some quick googling, I came across this repair facility in the UK (i'm in the usa). The recently repaired a PFX showing the same exact fault. I've read about this issue on a few different forums now, seems like a fairly common problem.
http://www.lumaco.co.uk/index.php?modul ... startnum=0"

Is anybody familiar with repairing the Sanwa PFX?

Can anybody recommend a repair facility in the USA?

Information is so limited on these chassis (can't find a schematic).

Please help! Paging the level 10 monitor gurus :D
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grantspain
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Re: Faulty Sanwa PM1755C PFX-46T

Post by grantspain »

later sanwa's act differently than most other chassis
i have seen on quite a few occasions the horizontal output transistor fail and cause horizontal collapse-on most chassis they shut down if this blows
capcomguru
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Joined: August 25th, 2008, 6:43 pm
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Re: Faulty Sanwa PM1755C PFX-46T

Post by capcomguru »

-update-

I concluded the HOT was bad on the chassis, since I had horizontal frame collapse. I sourced an NTE replacement from a local supplier, slightly higher on amps. I installed the HOT, no difference regarding the frame collapse.

Gave up on trying to fix it and decided to send it to Allgood USA in Florida (reputable repair facility that services sanwa and nanao).

Upon inspection, they realized the transistor replacement I used was METAL BACKED, the original plastic body. I foolishly did NOT insulate it, and sent HV DC through ground on the chassis. Crap.

I assume the further damage occured due to my non-insulated transistor. Allgood found a handful of bad diodes and resistors in the horizontal deflection circuit, in addition to some 33ohz resistors. Replacing the bad components, and using an insulated resistor got the chassis up and running again.

So, lesson learned for me. ALWAYS INSULATE METAL BACKED TRANSISTORS WHEN BOLTING TO THE CHASSIS! Assuming I insulated the replacement NTE transistor, I probably would have fixed the chassis the first repair attempt.

Hope this info is helpful.
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