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Main => Monitor/Video Forum => Topic started by: Tenn_pin on December 23, 2008, 12:46:16 pm

Title: SOLVED! WG 4600 Vertical Collapse help
Post by: Tenn_pin on December 23, 2008, 12:46:16 pm

Did a recap from Bob Roberts, but still have VC.  I have reflowed most all solder joints and checked connections with DMM.  After searching this site, I found where some of the transistors can go bad, mostly, TR305 and TR306.  I can pull them, but what am I looking for and how do I test them with the DMM?  Is there something else I should be looking for?  How can I go to our local electronics supply store and tell them what TR I need?  Can they usuall cross reference the number on the part?

Sorry for the chain of questions, but I feel I am chasing my tail>

R

Title: Re: WG 4600 Vertical Collapse help
Post by: qrz on December 23, 2008, 05:21:12 pm

this vert sweep uses discreet components rather than an ic .....

check r322, c313,c310, c306
tr303, tr307 as well as tr304, tr305

a schematic can be found here : http://www.cityofberwyn.com/manuals/WG-4600.pdf

the voltages you measure should be close to those listed,  when properly operating 

qrz

Title: Re: WG 4600 Vertical Collapse help
Post by: Tenn_pin on December 24, 2008, 10:41:46 am

Can this be done with the input board removed?  It would be easier if it was not in the way, but does that change any values on the board?

R

Title: Re: WG 4600 Vertical Collapse help
Post by: Tenn_pin on January 17, 2009, 02:02:40 pm

Turned out to be TR306.  I measured to resistance values with a known working board and found a large difference.  Ordered the part from Bob Roberts and the XY board worked.  I did have to change one of the resistors on the solder side to a jumper, but that did not take much time.  Thanks for the help.

Title: Re: SOLVED! WG 4600 Vertical Collapse help
Post by: qrz on January 18, 2009, 10:55:09 pm

faulty vert pre driver .
tnx for posting the fix . good job  ;)

qrz