[TechAssist] Re: Mitsubishi VS-4543 PTV N/S correction

Joel, check for leaky caps in general and also for coolant leaks.
Specifically, this is from the mits site:

CONVERGENCE AND RASTER DISTORTION
Cause #1
1. GO TO THE CONVERGENCE MENU (MENU 2 3 5 9) AND CHECK THE ADJUSTMENT
SETTINGS FOR CONVERGENCE. IF ALL ITEMS ARE SET AT "127". THE EEPROM SETTINGS
ARE AT DEFAULT. CLEAR THE CONVERGENCE MENU AND ACCESS THE OPTION MENU (MENU
1 3 7 0) USE THE ADJUST BUTTON TO SELECT E2RESET AND PRESS QV. THIS SHOULD
INSURE THE EEPROM IS CLEAR. AT THIS TIME ALL ADJUSTMENTS, CONVERGENCE
GEOMETRY AND CONVERGENCE SHOULD BE DONE. 2. CHECK FOR 20 VPP VERTICAL PULSE
TO PIN 9 OF THE "GL" CONNECTOR TO THE CONVERGENCE PCB, IF MISSING, WEAK OR
DISTORTED, CHECK PULSE AT SOURCE PIN 7 OF IC401 (PUMP UP OUTPUT) ON THE
SIGNAL PCB, IF THE PULSE IS NOT CORRECT AT PIN 7 CHECK C402 100 UFD 50V AND
IC401 PART # 270P064020. 3. CHECK FOR -5 VDC TO THE CONVERGENCE PCB AT "GM"
CONNECTOR PIN 10, IF LOW, MISSING OR NOISY, CHECK C936 (1000 UFD 16 V) AND
C935 (100 UFD 16 V) IN THE -8 VOLT SUPPLY CIRCUIT ON THE MAIN PCB. 4. CHECK
C924 (1000 UFD 36V 105 C) AND C925 (100 UFD 50 V) IN THE -24 VOLT SUPPLY
CIRCUIT ON THE MAIN PCB.

Leonard G. Caillouet
Service Manager
Electronics World
Gainesville, FL
352-332-5608
352-332-5668 (fax)

----- Original Message -----
From: "Joel Jacobs" <jj@xxxxxxxxxx>
To: "TechAssist" <techassist@xxxxxxxxxxxxx>
Sent: Saturday, March 29, 2003 12:34 PM
Subject: [TechAssist] Mitsubishi VS-4543 PTV N/S correction


>
> Hello,
> Received this PTV with no HV - was shutting down.  Found bad vertical IC
> LA-7845 and two open pico fuses z900 and z903 - both 6.3a on +34 and -24
> supplies.
>    Now it comes up and has a picture but the raster is stretched
vertically
> and has severe bow at top and bottom.  E/W correction is weak also.
>    I don't have a lot of info regarding the service mode on this set and I
> couldn't find a N/S or PIN adjustment.  I can get into the convergence
menus
> and the adjustments there seem to be working.  There are only red and blue
> adjustments though and the green is bowed too.
>   On the print, I don't see any raster correction circuitry in the
vertical
> circuit which keeps leading me back to the convergence circuit being the
> problem.  I believe side and top/bottom PIN correction is done through the
> convergence circuit - is this true?
>   If I scope the signals on the convergence yokes I find there is no
signal
> on the green vertical winding.  Tracing it back I also don't have a signal
> at connector 'VY' from the digital convergence module so I don't think the
> problem is the STK392-020.  Then again, the red green and blue convergence
> is not bad, the entire raster is whacked out.
>   Sorry for joining this list and diving right in with a help request
before
> I've had a chance to contribute.  I just been beating my head on this one
> for a week now.  Any help greatly appreciated!
>
> Joel Jacobs CET
> Ohio Consumer Electronics
> 31 Hill Rd. S.
> Pickerington, Ohio 43147
> 614-833-9696  M-F 10-6 EST
>
>
>
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