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Main => Monitor/Video Forum => Topic started by: brad808 on September 19, 2016, 07:54:31 pm

Title: PM-1745 - Vertical Collapse Issue
Post by: brad808 on September 19, 2016, 07:54:31 pm

Hey guys,

Have a PM-1745 I'm trying to repair. It has vertical collapse. I've replaced IC302, R315, and D302 checks out OK. When I power up the monitor it fries R315 right away. Any Ideas?

Title: Re: PM-1745 - Vertical Collapse Issue
Post by: Rickn on September 19, 2016, 08:48:08 pm

Schematic would be nice, if you have one e-mail it to rick@niemandisplays.com. Meanwhile going blind, my guess is you have replaced the b+ dropping resistor for the vertical output IC as well as the IC. Going to guess maybe a TDA1745? Check on the line that has the dropping resistor for an electrolytic cap... likely a 35 volt cap. It is likely bad. Good luck Rick

Title: Re: PM-1745 - Vertical Collapse Issue
Post by: brad808 on September 19, 2016, 09:06:15 pm

Thanks, I will send you an email. I'll Also attach here the schematics (they are terrible and blurry but all I have to go on). There is capacitor 330uf 50V @ C314. I'll replace that since I'm already messing with this area. I have just recently discovered that D204 1ss83 diode is bad (physically broken in half). Not sure if that was the original problem, or potentially caused on my end after the fact. Either way I'll need to wait until I get some in (probably a couple of weeks at least, before I can continue unfortunately.

Title: Re: PM-1745 - Vertical Collapse Issue
Post by: brad808 on September 19, 2016, 09:08:33 pm

Oh yes, just as a note vertical IC is LA7832

Title: Re: PM-1745 - Vertical Collapse Issue
Post by: brad808 on October 03, 2016, 09:08:50 am

Going to bump this up. I've now replaced c314 and D204. Still instantly burning up r315 on power up.

Title: Re: PM-1745 - Vertical Collapse Issue
Post by: grantspain on October 06, 2016, 02:25:17 pm

vert pos pot ok?
have you tested q302 yet?
Have check the deflection vertical impedence yet?