Re: Viewsonic VG150 logic board 0171-2242-0153 3150-0122-0150 repair help

On Mon, 15 Dec 2008 09:03:53 -0800 (PST), Boyan <bbiandov@xxxxxxxxx>
put finger to keyboard and composed:

Thanks Joe

However the power supply in those monitors is external, and in this
case I have lost the oriinal power supply long time ago and I am
feeding the monitor perfect power from my Lambda lab supply so I know
the juice is good

Am I missing you point?

Thanks
Boyan

He was probably referring to the internal 5V and 3.3V supplies. These
are located near the connector for the front panel switches. You'll
see two coils (or transformers?), p/n 0361-1000-0060, amongst a tight
bunch of caps.

You may also like to check the ESR of the surface mounted
electrolytics. These were very unreliable in older equipment, but I'm
not sure how they hold up in gear of your vintage (2001).

I'm assuming that you've tried your monitor with another signal
source, and that you are operating it at its native resolution
(1024x768 ?), and I'm also assuming that you're not describing
ghosting which occurs when using a cable with the wrong characteristic
impedance.

Otherwise you could check the caps around the PLL pixel clock
generator (ICS-1532M):
http://www.idt.com/products/getdoc.cfm?docid=18461836

This IC regenerates the original pixel clock by using the horizontal
sync pulse as a reference. I'm only guessing, but a dirty supply to
this IC may result in a jittery clock which might then upset the A/D
converter in the AmTRANS IC. Still another possibility may be the caps
around the M52743BSP IC.

As for your OSD, I believe it is handled by the MTV118-11 chip:
http://www.myson.com.tw/products.php?op=pdetail&flang=EN&ProductKind=1&ProductNo=18

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
.

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