Strange Symptom VP730b

[xtraelectronics]

Just recapped the video processor boards in two Viewsonic VP730b monitors this week. There are 13 Lelon branded 47uF, 16V caps on each board. The caps were replaced with 100uF 25V units (had them on hand) (can't remember the brand). Both monitors had the slow blinking LED symptom. The PSU was not touched, because it tested fine for both units. They both woke up and worked perfectly on test fro several hours. Now, the first one to be repaired is back with a purple (not pink) picture. Using the Nokia monitor test software, there is no green being displayed. It is NOT the ccfl tubes, because swapping the video board to another similar screen (#3 to be repaired) caused the same purple tinted picture. (no green). Did the use of over valued caps cause this, or did the video proc. crap out just because? As far as I know the other one that was repaired this week has the same 100uF caps installed, ansd is running fine with no strange smptoms (yet). Any ideas?!!!

[Bobdee]

Re: Strange Symptom VP730b

Just recapped the video processor boards in two Viewsonic VP730b monitors this week. There are 13 Lelon branded 47uF, 16V caps on each board. The caps were replaced with 100uF 25V units (had them on hand) (can't remember the brand). Both monitors had the slow blinking LED symptom. The PSU was not touched, because it tested fine for both units. They both woke up and worked perfectly on test fro several hours. Now, the first one to be repaired is back with a purple (not pink) picture. Using the Nokia monitor test software, there is no green being displayed. It is NOT the ccfl tubes, because swapping the video board to another similar screen (#3 to be repaired) caused the same purple tinted picture. (no green). Did the use of over valued caps cause this, or did the video proc. crap out just because? As far as I know the other one that was repaired this week has the same 100uF caps installed, ansd is running fine with no strange smptoms (yet). Any ideas?!!!

Had the Purple picture symptoms on a few Monitors a while back,it was there on some monitors and not others that I was repairing, and even the ones that had the symptoms sometimes came up as working perfect, soon realised that I had bad VGA cable that I was using to test them, when you moved the cable back and forth then the symptoms would come and go, It may be your problem (allthough I dont remember having the blinking LED)

[xtraelectronics]

Re: Strange Symptom VP730b

It does this with both D-sub, and DVI.

[xtraelectronics]

Re: Strange Symptom VP730b

Upate: Going into the menu for colour adjustment, I can't get any response to increase or decrease R,G,or B on the "User Setting" mode. Starting to sound more like a bad video proc. but I will replace the over valued caps back to their original values when the parts shipment comes in.

[kc8adu]

Re: Strange Symptom VP730b

had an industrial lcd with a similar issue.
was a bad eeprom.

[xtraelectronics]

Re: Strange Symptom VP730b

Update #2:
Installed all new, proper value caps today. Including two Lelons' that tested ok previously. I am able to get normal colour balance, but the picture has very poor contrast. Is there any way too boost that up, on a parts mod level, -the screens contrast is all the way up as is the brightness. (I subbed in a 5V on the inverter's brightness pin to no avail this is true even if I use another identical screen, so I doubt there is any problem with the ccfls.) Any ideas would be welcome.

thanks, Dan

[xtraelectronics]

Re: Strange Symptom VP730b

Ok just finished with this hairball. It seems corrupt data from the eeprom to the controller was the issue. I corrected this problem by simply dissconnecting the offending data line. I know it shouldn't work, but it does! he only issue now is the OSD is set for portrait mode so you must always pivot it back to landscape mode through the menu. Big deal. It is now usable!

[xtraelectronics]

Re: Strange Symptom VP730b

Monitor has been running for 12 hrs, no problem. Yay! Fixed it!

[Wizard]

Re: Strange Symptom VP730b

Suggestion:

Turn this on with eeprom disconnected, then link them back on and play with settings and let it save them. See if this fixes this.

Cheers, Wizard