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Main => Monitor/Video Forum => Topic started by: Malacus on April 15, 2008, 06:01:06 pm

Title: k4900, no vertical deflection
Post by: Malacus on April 15, 2008, 06:01:06 pm

Heres my story, short and sweet, I saw a k4900 (its a 4906 to be exact) on craigslist, ad said it was working, i went to pick it up, he tested it there, saw his pole position playing on the screen, though the picture was very short, only took the center of the screen, he said "it just needs adjusted" and not knowing much about anything monitor related, I went ahead and got it (it was only 35$)

So, as soon as I get it all hooked up, I power it on, and...
single blue line across the screen...

Following the flowcharts i see that this is a vertical deflection issue.

So here are my questions, where do i get the parts to fix this? would the necessary parts come in a cap kit? Would I be able to head over to http://www.partsexpress.com (they're local to me) and pick up what I need? How do i know if I need q302, q303 or ic 301, i dont know how to check them... i have a multi-meter, but the only thing i know how to do with it is to check if something has a short  :dunno


Thanks,
mal

Title: Re: k4900, no vertical deflection
Post by: grantspain on April 15, 2008, 06:21:59 pm

most likely you have a bad solder joint or a bad circuit track,it is worth checking this first

Title: Re: k4900, no vertical deflection
Post by: Malacus on April 15, 2008, 06:27:14 pm

i resoldered the only thing that looked bad to me, and it didnt seem to do anything...  :dunno

-mal

Title: Re: k4900, no vertical deflection
Post by: Ken Layton on April 15, 2008, 06:37:15 pm

Recap it and also check the giant white resistors near the main filter capacitor for a bad solder joint or if the resistor has gone open circuit.

Title: Re: k4900, no vertical deflection
Post by: qrz on April 16, 2008, 11:19:49 pm

q203 and q303  (2sc2073) will likely need to be resoldered .
check/replace c313  sweep return, c311 supply decoupling,c310,c308,c373. also check r307 220k.
check c303 and c301 near ic301 (ha11423)

should be an easy fix

qrz

Title: Re: k4900, no vertical deflection
Post by: Malacus on April 18, 2008, 11:49:16 am

Well, I looked over the caps, and c313 was visually really old and dirty.

So, I replaced it first. The cap that was there was a 100uf 160v, Lizard Lick Amusements has you replace it with a 100uf 250v, but the k4906 manual says to replace it with a 47uf 160v... So I figured the manual knows best and went with the 47uf 160v, plugged everything back up (the rest of the caps look very recent, and I can replace them when Ive got more time.) and there it was, I could finally see my S.Street Fighter: TNC

-mal

Title: Re: k4900, no vertical deflection
Post by: Lutus on April 18, 2008, 12:05:04 pm

Would probably go ahead and recap the whole thing when you get the chance.  (unless you already have, can't tell from the post)

Otherwise,  congrats!   :cheers: