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

psoma · 30 August 2020, 14:45

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, 14:55

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, 15:32

Check capacitors on the CRT neck board.

psoma · 30 August 2020, 16:03

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

UberFreak · 30 August 2020, 16:41

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, 16:47

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

psoma · 30 August 2020, 23:51

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, 21:50

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

psoma · 19 January 2021, 23:05

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

grbrady · 11 June 2021, 08:10

I’m curious if there was any resolution? I have this problem after replacing the flyback, LOPT, and doing a full recap. Of course it was completely dead before so it’s infinitely better now, but still would love a somewhat better picture.

psoma · 30 December 2021, 01:58

Quote:

Originally Posted by grbrady

I’m curious if there was any resolution? I have this problem after replacing the flyback, LOPT, and doing a full recap. Of course it was completely dead before so it’s infinitely better now, but still would love a somewhat better picture.

Took it to an old bloke that did CRT repairs and he fixed it... but refused to tell me what it was which is frustrating as I've worked on about 4 or 5 others since and all but one are suffering from the same ailment!

Will post back if I ever get a fix myself.

Jope · 30 December 2021, 10:05

You can probably see where he's been in with his soldering iron. :-)

idrougge · 31 December 2021, 02:36

Have you tried removing the speaker from the monitor?

lilwshu · 01 January 2022, 15:39

I was using my Philips CM8833-2 yesterday which I normally have set to RGB input - I switched to composite video (with no devices active) and the brightness level increased substantially and the bands seen above were visible. Switching back to RGB lowered the brightness and the bands disappeared.

30 August 2020, 14:45	#1
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	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, 14:55	#2
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	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, 15:32	#3
UberFreak Registered User Join Date: Sep 2009 Location: the world Posts: 439	Check capacitors on the CRT neck board.

30 August 2020, 16:03	#4
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	There’s only one on the neck board: C717 and that was done.

30 August 2020, 16:41	#5
UberFreak Registered User Join Date: Sep 2009 Location: the world Posts: 439	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, 16:47	#6
UberFreak Registered User Join Date: Sep 2009 Location: the world Posts: 439	Also check for cracked/open solder joints, this model is notorious for them.

30 August 2020, 23:51	#7
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	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, 21:50	#8
f-bone Registered User Join Date: Sep 2020 Location: Athens Posts: 4	Hi psoma! Did you sort this out? I have exactly the same monitor with the same issue. Thanks buddy.

19 January 2021, 23:05	#9
psoma Registered User Join Date: Nov 2019 Location: Melbourne, Australia Posts: 193	Hey f-bone - still having it worked on. Latest guess is that it's an issue with the LOPT itself.

11 June 2021, 08:10	#10
grbrady Registered User Join Date: Jan 2020 Location: Baltimore, USA Posts: 1	I’m curious if there was any resolution? I have this problem after replacing the flyback, LOPT, and doing a full recap. Of course it was completely dead before so it’s infinitely better now, but still would love a somewhat better picture.

30 December 2021, 10:05	#12
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	You can probably see where he's been in with his soldering iron. :-)

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

31 December 2021, 02:36	#13
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	Have you tried removing the speaker from the monitor?

01 January 2022, 15:39	#14
lilwshu Registered User Join Date: Mar 2020 Location: UK Posts: 243	I was using my Philips CM8833-2 yesterday which I normally have set to RGB input - I switched to composite video (with no devices active) and the brightness level increased substantially and the bands seen above were visible. Switching back to RGB lowered the brightness and the bands disappeared.