Adjusting monitor focus: Sun/Sony GDM-5010 PT

Most Trinitron screens I've worked with have had the focus controls behind two obvious holes in the cabinet, towards the back on the left side. However, this screen doesn't seem to have those.

Can anyone point me in the right direction?

Please post here or email to steve_wechsler(at)yahoo.com

Thanks,

Steve

Reply to
Steve
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Take the cover off, they're still there on most monitors.

Reply to
James Sweet

Open the back cover, and look on the flyback transformer. There may be two or three pots. One will most likely be the beam focus, and the other(s) will be the focus adjustment.

In some sets, the focus control is on the CRT circuit board.

Before touching anything, read carefully what the adjustment does. Use only a plastic or Teflon tip (non conducting) tool to adjust these pots. Using the fingers can be risky, if you are not used to this type of work. If you use a conductive type tool to do the adjustment, and you slip, there is a very good possibility to do circuit damage, as well as possibly get hurt.

If the monitor or TV sets requires the focus to be touched up, this is a sign that either the CRT is going weak, or that there is something failing in the high voltage section.

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Reply to
JANA

Most newer Sony's use an external Digital Alignment System (DAS) connected to a computer to make these adjustments. (Expensive). You might try and trace out the circuit grom the screen (G2) pin on the CRT neck board. There should be a large value resistor in the circuit. Changing the value of this resistor will often change the screen voltage and brightness. You have to experiment a little to find a good value. I use an resistor box and start at the highest value and then go down until I find the best brightness. Then I solder a fixed resistor in the circuit. Hope this helps.... John

Reply to
jdgill

You'd think someone would have hacked together a hobby version of the DAS, how hard could it be to do it with a cheap microcontroller? Of course you'd have to find access to a real DAS unit/software to analyze the protocol it uses.

Reply to
James Sweet

Focus is adjusted using the traditional pots. Here's the extract from the n31s_fcs.stp file that drives DAS for the GDM-5010:

BEGIN SCREEN "FOCUS ADJUSTMENT" 15 1 65 22 message full_screen "Perform the focus adjustment:\ a) adjust the [F2] focus pot for best vertical focus.\ b) adjust the [F1] focus pot for best horizontal overall focus.\ c) repeat [F1] and [F2] as there is some interaction." BUTTON CANCEL BUTTON OK END

G2, however, is adjusted using DAS control.

Mike.

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