SPOILER: Wasn't capacitors. Lead free solder going moldy probably was.
Although my Sony GDM-W900 24" widescreen CRT isn't quite dead yet I started looking for a replacement. 24" CRTs are extremely rare these days, the couple I've seen in the last year are silly money and far away. I don't trust the seller to crate it up properly or UPS or ParcelForce etc to transport a 41kg fragile object.
I liked the look of the HP LP2475W and nearly bought one for about £75, but then I started looking for faulty monitors I thought I could fix.
Ended up with a Crossover 30Q5 Pro Black 2560 x 1600 30″ IPS for £5. Came with no PSU or dual link DVI so got a cable and made a temp PSU out of 2 ATX PSUs in series. Needs 24V at 7A minimum, my lab supply lacks current as does a 24V DIN rail supply I have.
After desoldering the 4 pin power socket I spliced in a power cable.
Monitor would turn off INSTANTLY, so definitely not the standard 2 seconds to black backlight driver issue.
Long story short after replacing all the electrolytics I could see, plus the HT caps on the CCFL driver PCB (they were all crap brands), checking the voltage regulator outputs etc I was stumped. Checked all the power rails with a scope in case there was any rippling or spikes the DMM couldn't see.
After looking at the board with a little LED microscope I ended up finding tin whiskers between the pins of the main chip on the DigitalWave DW270QDP MP REV.02 DVI to eDP board.
http://nand-hate.com/wp-content/uplo...-MP-REV.02.png
Can't seem to upload an annotated image of the board so here's a link to it.
The attachment error message was:
Request Time-out
Server timeout waiting for the HTTP request from the client.
Apache/2.2.22 (Debian) Server at venture.wssnoc.net Port 80
I reflowed that chip with a DX.com hot air soldering gun after using crapton tape to mask off everything else.
It actually worked!
Personally this is the first encounter I've had with tin whiskers. I hate lead free solder with a cold passion but this is the first time I've seen it do this, seen dry joints a plenty tho.
I've just started a blog at nand-hate.com to share some of my electronics experiences.
There is a much longer writeup on this repair with more images here:
http://nand-hate.com/2015/11/crossov...-repair-notes/
Hopefully this will help anyone else trying to repair one of these bargain Korean IPS monitors. The 27" and 30" share a lot of parts, although the 27" are LED backlight based I think.
Although my Sony GDM-W900 24" widescreen CRT isn't quite dead yet I started looking for a replacement. 24" CRTs are extremely rare these days, the couple I've seen in the last year are silly money and far away. I don't trust the seller to crate it up properly or UPS or ParcelForce etc to transport a 41kg fragile object.
I liked the look of the HP LP2475W and nearly bought one for about £75, but then I started looking for faulty monitors I thought I could fix.
Ended up with a Crossover 30Q5 Pro Black 2560 x 1600 30″ IPS for £5. Came with no PSU or dual link DVI so got a cable and made a temp PSU out of 2 ATX PSUs in series. Needs 24V at 7A minimum, my lab supply lacks current as does a 24V DIN rail supply I have.
After desoldering the 4 pin power socket I spliced in a power cable.
Monitor would turn off INSTANTLY, so definitely not the standard 2 seconds to black backlight driver issue.
Long story short after replacing all the electrolytics I could see, plus the HT caps on the CCFL driver PCB (they were all crap brands), checking the voltage regulator outputs etc I was stumped. Checked all the power rails with a scope in case there was any rippling or spikes the DMM couldn't see.
After looking at the board with a little LED microscope I ended up finding tin whiskers between the pins of the main chip on the DigitalWave DW270QDP MP REV.02 DVI to eDP board.
http://nand-hate.com/wp-content/uplo...-MP-REV.02.png
Can't seem to upload an annotated image of the board so here's a link to it.
The attachment error message was:
Request Time-out
Server timeout waiting for the HTTP request from the client.
Apache/2.2.22 (Debian) Server at venture.wssnoc.net Port 80
I reflowed that chip with a DX.com hot air soldering gun after using crapton tape to mask off everything else.
It actually worked!
Personally this is the first encounter I've had with tin whiskers. I hate lead free solder with a cold passion but this is the first time I've seen it do this, seen dry joints a plenty tho.
I've just started a blog at nand-hate.com to share some of my electronics experiences.
There is a much longer writeup on this repair with more images here:
http://nand-hate.com/2015/11/crossov...-repair-notes/
Hopefully this will help anyone else trying to repair one of these bargain Korean IPS monitors. The 27" and 30" share a lot of parts, although the 27" are LED backlight based I think.
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