Xerox XA7-19i Died

[Willib]

My Xerox XA7-19i died after several years without a flicker, even if it never would operate in digital mode with a DVI card. No warning except slight disturbance of the picture earlier in the day. It just went black and since then will operate for a few seconds before going black again.

Go easy because I am not that experienced in electronics and have never looked inside one of these before... The power card looks pretty good - nothing scorched, just a little heat stain in one section. I reflowed connections for most of the old style discrete components - transformers, inductors, power resistors, fuses, capacitors, using 60/40 solder, because some looked a bit as if they might be dry. The electrolytics look perfectly normal and I think they are all marked HEC. It might be imagination, but it stays on for about 15 mins now, but same symptoms - for a few seconds the picture looses sync as though there is interference and then black. I have established after reading other posts that the blue LED stays on and under a strong light the desktop is visible, so looks like a backlight problem.

It still looks to me more like a dry joint than a capacitor problem - or am I dreaming? I think the sync is the processor resetting due to interference. I am not familiar with how the backlight is powered - must be the four connectors with flying leads, but not sure why 8 wires. Any ideas what voltages I should see where or how to troubleshoot this? Which bits of the board power the backlight? Any other ideas. Pictures attached.

[PlainBill]

Re: Xerox XA7-19i Died

My Xerox XA7-19i died after several years without a flicker, even if it never would operate in digital mode with a DVI card. No warning except slight disturbance of the picture earlier in the day. It just went black and since then will operate for a few seconds before going black again.

Go easy because I am not that experienced in electronics and have never looked inside one of these before... The power card looks pretty good - nothing scorched, just a little heat stain in one section. I reflowed connections for most of the old style discrete components - transformers, inductors, power resistors, fuses, capacitors, using 60/40 solder, because some looked a bit as if they might be dry. The electrolytics look perfectly normal and I think they are all marked HEC. It might be imagination, but it stays on for about 15 mins now, but same symptoms - for a few seconds the picture looses sync as though there is interference and then black. I have established after reading other posts that the blue LED stays on and under a strong light the desktop is visible, so looks like a backlight problem.

It still looks to me more like a dry joint than a capacitor problem - or am I dreaming? I think the sync is the processor resetting due to interference. I am not familiar with how the backlight is powered - must be the four connectors with flying leads, but not sure why 8 wires. Any ideas what voltages I should see where or how to troubleshoot this? Which bits of the board power the backlight? Any other ideas. Pictures attached.

Good pictures, and the layout makes things easier.

Notice F203. Draw a line horizontally across the board just below F203. Continue the line around to the back of the board. Everything north of that line is the inverter and associated circuits. IC1 is the inverter controller, Q5 and Q6 are the drivers for the transformers.

Possible causes for two seconds to black are bad capacitors, bad (aging or broken) CCFL, wiring problem to the CCFLs, shorted transformer, or problems with the protection circuitry. About half the components are related to the protection circuitry (yeah, that bad).

One simple test. Set the computer to display a white screen, and disable the screensaver. Turn the monitor off with the power button. Leave it off long enough to cool down - at least half an hour. Now turn it on. Do you see a pinkish tinge for a few seconds? If so, that confirms an aging CCFL.

Far and away, the easiest way to troubleshoot the problem is to substitute one good CCFL for each of the original CCFLs one at a time. The test CCFL can be external to the LCD panel. The test CCFL should be similar to the originals, but does not have to be identical. (I used a CCFL from a 23" wide screen KDS monitor to test a 19" Dell narrow screen monitor).

If the monitor always stays on when the test CCFL replaces a particular CCFL, that CCFL is either defective or the wiring is bad. Broken insulation and bad solder joints are common.

Another option is to do a total recap of the power supply.

To me, the symptoms indicate either a bad CCFL (drawing too much current), arcing from a wire to the channel, or a bad capacitor.

PlainBill

[sabre504]

Re: Xerox XA7-19i Died

Further to what Plainbill has said even though the caps look good they would most likely need changing have done a couple of these and caps have been the cause .

Yellow power connector
14v 5v Blon 3.3v (approx)


Caps should be

3 x 220uf 25v (35v)
4 x 680uf 25v (35v)
1 x 470uf 25v (35v)
Cannot remember what the 2 smaller ones are, have put 35v in brackets as have seen both these voltage caps used on these .

As to why 8 wires basically 4 x live and 4 x return

[jetadm123]

Re: Xerox XA7-19i Died

C11 and C12 are a problem with this model board. HEC caps are not known to be great caps and all caps, except for the large 450V one, should replaced as suggested by sabre504.

[Rtech]

Re: Xerox XA7-19i Died

C11 and C12 are a problem with this model board. HEC caps are not known to be great caps and all caps, except for the large 450V one, should replaced as suggested by sabre504.

Totally agree with the C11 and C12 possible failure, even when they look good.Would change these two, and then if that sorts your problem,a total recap as suggested is the next course of action.

[Willib]

Re: Xerox XA7-19i Died

Thanks for all that. There is a tinge of pink on the PlainBill CCFL test, which fades away in a few seconds - does that make the CCFL the clear favorite or are the caps still worth a try? As I don't have access to a good CCFL for a test, I'll have to buy new and they don't seem too cheap in the UK, so prefer not to jump the wrong way.

[PlainBill]

Re: Xerox XA7-19i Died

Thanks for all that. There is a tinge of pink on the PlainBill CCFL test, which fades away in a few seconds - does that make the CCFL the clear favorite or are the caps still worth a try? As I don't have access to a good CCFL for a test, I'll have to buy new and they don't seem too cheap in the UK, so prefer not to jump the wrong way.

Well, I've had two that had the pink tinge when first powered up.

The first was a Dell, the pink tinge was very subtle. It had the original caps; substituting a known good CCFL solved that one.

The other had a complete recap with Panasonic FM caps about a year before the pink tinge first showed up. It got progressively worst for about 3 months before going 'Two seconds to black'. Replacing the CCFL solved that one.

If you want to replace the caps now you might be able to get a few more months before it becomes necessary to replace the CCFL.

PlainBill

[jiangou2007]

Re: Xerox XA7-19i Died

hi , would like to check if it is possible to use CCFL of smaller LCD (eg 15") to test on 19" faulty LCD ?

[PlainBill]

Re: Xerox XA7-19i Died

hi , would like to check if it is possible to use CCFL of smaller LCD (eg 15") to test on 19" faulty LCD ?

Yes, but use it for only a short time (less than 1 minute at a time).

PlainBill

[jiangou2007]

Re: Xerox XA7-19i Died

Yes, but use it for only a short time (less than 1 minute at a time).

PlainBill

thanks.

[jiangou2007]

Re: Xerox XA7-19i Died

hi anyone know where to get these 19"LCD lamps(Proview)?

[PlainBill]

Re: Xerox XA7-19i Died

hi anyone know where to get these 19"LCD lamps(Proview)?

CCFL warehouse.

PlainBill

[tom66]

Re: Xerox XA7-19i Died

I repaired an identical monitor.

Replaced all the caps on the secondary side with Nichicon KMG 470u 25V (including the 220u.)

It works good now.

I think the CCFLs are on their way out, so I set it to 50% brightness and it's lasted at least 6 months so far.

Also my DVI port would never work in digital either... I thought it was my gfx card, but maybe it was my monitor? Any idea on how to fix it?

[PlainBill]

Re: Xerox XA7-19i Died

I repaired an identical monitor.

Replaced all the caps on the secondary side with Nichicon KMG 470u 25V (including the 220u.)

It works good now.

I think the CCFLs are on their way out, so I set it to 50% brightness and it's lasted at least 6 months so far.

Also my DVI port would never work in digital either... I thought it was my gfx card, but maybe it was my monitor? Any idea on how to fix it?

Nope. I routinely test every monitor I repair. If it has a DVI input, I check that too. I've never had one fail to work.

PlainBill

[tom66]

Re: Xerox XA7-19i Died

Nope. I routinely test every monitor I repair. If it has a DVI input, I check that too. I've never had one fail to work.

PlainBill

Mine works on analog mode, but switching it over to digital mode makes it show "no signal" (it switches back after this) and the gfx card doesn't see the digital mode being activated...

[Willib]

Re: Xerox XA7-19i Died

I recapped the board with Panasonic FMs except the big 100 mF 400v one because I can get the caps easily, but that made no difference, so looks like CCFLs.

The monitor has always behaved exactly as tom66 describes. Running moninfo shows that the monitor is declaring itself as analogue on the EDID message. It is dual EDID so it has to look for a digital signal and defaults to putting out an analogue message if it doesn't find one. The snag is I haven't the least idea why it doesn't find one on my Gigabyte 7300 GS card via the DVI-I connector. Xerox, of course, haven't a clue either.

[tom66]

Re: Xerox XA7-19i Died

I recapped the board with Panasonic FMs except the big 100 mF 400v one because I can get the caps easily, but that made no difference, so looks like CCFLs.

The monitor has always behaved exactly as tom66 describes. Running moninfo shows that the monitor is declaring itself as analogue on the EDID message. It is dual EDID so it has to look for a digital signal and defaults to putting out an analogue message if it doesn't find one. The snag is I haven't the least idea why it doesn't find one on my Gigabyte 7300 GS card via the DVI-I connector. Xerox, of course, haven't a clue either.

It's really odd now! I had to reinstall XP on my computer and it now works with DVI, crystal clear picture. But Ubuntu still has issues... Hmm...

[Skeltek]

Re: Xerox XA7-19i Died

Greetings,
I am a bit surprised I only found this forum a few days ago.
Got such an old Xerox monitor from someone years back, which I am using as my tertiary monitor. I had to repair it back then before I got it working. Had to change a few capacitors a few years after, but it has been working for me ever since.
Last week there were electricians in the appartment beneath mine, since my neighbor died or moved. Had a nightshift, so I slept until noon. When I returned to my PC, it was offline and my last nights work including a running calculation was destroyed. The electrician had accidently turned off the main fuse in the ellar for my appartment, when he wanted to do renovations in my old neighbors appartment...
Router showed a restart, NAS system showed several sudden disonnects of harddrives due to power loss, Windows 10 later asked for a restart to repair damaged drives...

...and this XEROX monitor did never turn on again. The display remained black and the power button did not seem to turn it on (the blue lighting of the power button simply remained dark).
I opened up the Monitor, saw the capacitors to the left and right being blown on top, while the middle capacitor was bloated on the underside where the pins are. I replaced the blown capacitors (marked in the picture).

Now, after plugging it into power, the button still remains dark and the display has no lighting either. But on occasions when I plug it into power, the right speaker starts giving a sound periodically every 1 second, which stops after about 10-20 seconds.
I presume either another capacitor went bad and got a short circuit or another part is broken.
The big black capacitor seems to have a stable voltage of about 335V, but the small capacitors on the right side never make it to any noteworthy capacity.
I checked the voltage on the connectors to the graphical board in the bottom right: GND to 14V yields just about 6V, sometimes 4V or less.

I am not sure if the capacitors I switched got blown by the power surge and I missed a few defectove ones, or if they blew up as follow-up damage, after a diode/coil or other part short-circuited and got destroyed.

My experience with anything else but changing capacitors is very limited, and I wouldn't know how to check coils for short-circuits or other components.
Currently I got the options of replacing all remaining capacitors or search the defect somewhere else. Maybe the transformator the middle (right of the large black cap) is broken, or a Diode is failing when some cap reaches a certain voltage? Or something else.
The sound from the monitors right speaker gives me the feeling the thing starts working and gives it some voltage, before it shorts out and the voltage suddenly drops of, because a capacitor suddenly looses its charge.

I would be glad for any hints. I am new to this forum, but I repaired about 12 monitors in my lifetime, along with mobile phones, cars, microwaves and so on. So I guess we will talk a lot in the future.

Greetings from Germany,
Skeltek