1cm lighter vertical band on right edge of screen

Rather do adjustments, it would be more intelligent to find the defective parts that are causing the problem. Most of the time, it is capacitors that are going high in ESR, that cause these types of faults. Do an ESR test of all the caps in the scan and pin amplifier areas. I am sure you will probably find a number of them that have to be changed.

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Jerry G.

I have a problem with my television set. It's a Daewoo 2594ST model using the CP775 chassis. Service manual can be downloaded for free from here:

by entering the model or chassis number in the datasheet search field, or I can email the whole manual or just the schematics in PDF format upon request.

There's a 1cm vertical band which is lighter than the rest of the screen at the right-hand edge. It tapers slightly as it gets toward the bottom. Also the top-right corner has a couple of columns of pixels not lighting as though corner adjustment is off, and the same towards the middle of this right-hand edge, as though pincushion needs adjusting, although this goes when the overall screen brightness increases and the picture 'breathes'.

I thought maybe the corner and pincushion might need adjusting, or since it tapers slightly, maybe even the trapezium adjustment, but I can't do geometry adjustments without a "Remocon" service remote according to the service manual, and I've never seen this lighter band effect when geometry is out before. I have seen something like it when horizontal linearity was over-adjusted on a set, as though the picture was folding over at the edge or horizontal centering was adjusted too far over to one side causing that side to have a siilar effect to this, but all that seems ok - channel logos are in the correct positions.

Only one thing in the sci.electronics.repair FAQ sounds slightly similar but the cause (electrolytic decoupling the 205V supply to CRT base amps) isn't the case in this set as substitution today of the

10uF, 250V one with a known good replacement made no difference. Two more caps on the same feed on the CRT base itself are also good.

Anyone got any ideas please?

Regards, James

very nice and helpful Larry Z. at daewoo technical (1-800-323-9668)

Daewoo part number DECAKIT011 Picture shift kit can be ordered from Fox International 800-321-6993

The main issue: pix shifted to right leaving black bar on left side: Variable resistor R516 is open and/or D504 open due to excess current. Repair: The below is the mod kit called: decakit011. Change value of R420,C505, replace damaged R516,D504. Repair: R420: 240 ohm/ 1W ---> 1.8K ohm 1W # RS01Z182JF C505 2200PF 50V Mylar -> 1000PF 50V Mylar # CMXB1H102K R516 10 K ohm VR R semi fixed---> #RV5426103P D504 1N4148 # D1N4148--- Order From: Fax 201-935-5004 or call 1-800-323-9668.

r 516 open d504 defective. change r 420 to 1.8k one watt. change c 505 to 1000pf@ 50 volt.(mylar) r516 to 10 k pot. d504 = 1n4148

Dani, thank you very much for the info, however this set has the trouble on the right of the screen. The picture still seems to be centered okay, just this trouble at the right-hand edge. It affects from the middle of the edge to the right corner and is pulled in at any point along the vertical depending on brightness level in picture to left of it, leaving unlit pixels.

I will try to do an illustration of it and include it.

Jerry, of course it's more intelligent to find defective parts if any are, however I got given this set and it had cramped frame affecting top half of frame, cure was new frame IC and replacement of two high ESR caps in its feed lines. Also, one O/C dried-up cap was found by accident which was in circuitry associated with the HT feed to the line-output transistor - it was a 2.2uF 160V type and was also replaced. Thing is, I don't know if this problem on the right edge was always there and the other owners didn't really notice it, as it isn't that bad, it's just I've got a keen eye and don't like it, or if it's new. Others have told me before that they don't notice most picture problems till I point them out.

I have already checked all caps in the line stage and amp area. Those that had even slightly high ESR were replaced. All others were fine in ESR and capacitance value. Also checked for any resistors that may have gone high, none have of those I tested. Also checked all diodes for any leakage but all read fine.

Here is illustration:

May want to do some testing of diodes and resistors while the set is running. I would replace all the caps in the horizontal and drive section because one may show good but can be bad. I would also replace those parts that was mentioned in one of the previous post for parts sometimes test good but can be bad. But it does look like it may have a B+ problem. Is your B+ at the proper voltage ? Also may want to replace your horizontal output if you have a spare one there. What happens when you turn the screen control on the flyback down does it still show the line on that one side ? This problem can also be caused by a bad yoke. I will take a look the schematic over the weekend and see what I may come up with. But check your B+ line.

running. Do you mean checking voltages from them? Or checking voltage drops across them? All voltages marked on the schematics are reading correct for chopper and line stages.

because one may show good but can be bad. I've now done that (used new ones), but to no avail. I've even checked the non-electrolytics.

previous post for parts sometimes test good but can be bad. Also done, but still no joy I'm afraid.

proper voltage ? Yep, spot on at 132V when set is running.

one there. Unfortunately I don't have the necessary 2SD1880. I have a 2SD1887 but it doesn't have the internal damper diode or base-emitter resistor. The datasheets don't say what the resistance should be of the internal resistor, but I'm getting 50 Ohms. I have many variations of BU2508s and BU4808s but the ones with internal damper diodes and resistors measure 30 Ohms B-E.

does it still show the line on that one side ? Yes, it does. I am really starting to think this is a line linearity problem. There is no adjustment in the service mode for line linearity, so at least my lack of "remocon" may not be important since it might not be simply an adjustment needed.

the schematic over the weekend and see what I may come up with. But check your B+ line. Did you have a look over it?

Thanks again, James