1084S-P Vertical brightness banding on left side of screen

psoma · 30 August 2020, 15:45

Hi all,

Working on a mate's 1084S-P... It's presenting with a set of vertical brightness bands on the left hand side of the screen:

The banding stays in the same spot even if I adjust the H-POS... what's interesting is, if I increase the brightness, for a few seconds, the screen is a uniform brightness, and then the bands "settle" to a darker shade.

It certainly sounds like caps, but I replaced all the "larger" caps on the main board and ALL the caps on the power board but to no avail. I've done 16 of them (C473, C717, C144, C494, C112, C395, C396, C145, C146, C346, C491, C493, C352, C394, C116, C122 for those curious - yes, I know a few were on the audio board) but the banding persists.

Am hoping someone has seen and fixed this before, or is cluey enough to pinpoint the correct caps to try next as I'd rather not blindly do the remaining 30 as, to be honest, I hate working on CRTs!

Cheers.

psoma · 30 August 2020, 15:55

I should add - this happens with or without a signal connected, CVBS or RGB.... it's not in any way input related.

UberFreak · 30 August 2020, 16:32

Check capacitors on the CRT neck board.

psoma · 30 August 2020, 17:03

There’s only one on the neck board: C717 and that was done.

UberFreak · 30 August 2020, 17:41

This problem is usually due to a bad cap on the power supply for the RGB output transistors.
If its not on the CRT neck board, then its somewhere around the Flyback.

UberFreak · 30 August 2020, 17:47

Also check for cracked/open solder joints, this model is notorious for them.

psoma · 31 August 2020, 00:51

Thanks - I can trace it from the schematics, but I'm no CRT guru... this thing is covered in transistors! Do you know which ones the RGB output ones are? http://www.devili.iki.fi/Computers/C...rge/sheet1.gif

Cheers.

f-bone · 15 December 2020, 22:50

Hi psoma! Did you sort this out? I have exactly the same monitor with the same issue. Thanks buddy.

psoma · 20 January 2021, 00:05

Hey f-bone - still having it worked on. Latest guess is that it's an issue with the LOPT itself.

30 August 2020, 15:45	#1
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 170	1084S-P Vertical brightness banding on left side of screen Hi all, Working on a mate's 1084S-P... It's presenting with a set of vertical brightness bands on the left hand side of the screen: The banding stays in the same spot even if I adjust the H-POS... what's interesting is, if I increase the brightness, for a few seconds, the screen is a uniform brightness, and then the bands "settle" to a darker shade. It certainly sounds like caps, but I replaced all the "larger" caps on the main board and ALL the caps on the power board but to no avail. I've done 16 of them (C473, C717, C144, C494, C112, C395, C396, C145, C146, C346, C491, C493, C352, C394, C116, C122 for those curious - yes, I know a few were on the audio board) but the banding persists. Am hoping someone has seen and fixed this before, or is cluey enough to pinpoint the correct caps to try next as I'd rather not blindly do the remaining 30 as, to be honest, I hate working on CRTs! Cheers.

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30 August 2020, 15:55	#2
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 170	I should add - this happens with or without a signal connected, CVBS or RGB.... it's not in any way input related.

30 August 2020, 16:32	#3
UberFreak Registered User Join Date: Sep 2009 Location: the world Posts: 369	Check capacitors on the CRT neck board.

30 August 2020, 17:03	#4
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 170	There’s only one on the neck board: C717 and that was done.

30 August 2020, 17:41	#5
UberFreak Registered User Join Date: Sep 2009 Location: the world Posts: 369	This problem is usually due to a bad cap on the power supply for the RGB output transistors. If its not on the CRT neck board, then its somewhere around the Flyback.

30 August 2020, 17:47	#6
UberFreak Registered User Join Date: Sep 2009 Location: the world Posts: 369	Also check for cracked/open solder joints, this model is notorious for them.

31 August 2020, 00:51	#7
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 170	Thanks - I can trace it from the schematics, but I'm no CRT guru... this thing is covered in transistors! Do you know which ones the RGB output ones are? http://www.devili.iki.fi/Computers/C...rge/sheet1.gif Cheers.

15 December 2020, 22:50	#8
f-bone Registered User Join Date: Sep 2020 Location: Athens Posts: 3	Hi psoma! Did you sort this out? I have exactly the same monitor with the same issue. Thanks buddy.

20 January 2021, 00:05	#9
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 170	Hey f-bone - still having it worked on. Latest guess is that it's an issue with the LOPT itself.

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