U2000 Woes...

Rattanee

New member
Joined
Oct 4, 2010
Messages
111
Reaction score
0
Location
Pest, Hungary
Okay... now that I have that damn K7000 up and running beautifully, time to fry a different kind of fish...

Got an U2000 that I pulled a few things from to fix an U5000...

at L704 there's a small inductivity of 0.82 uH.. how mission critical is the value of this thing? I can't for the life of me find the same value locally... Also in lieu of a parts list, I have no idea how many ohms and how many amps it should be rated...

Would 1uH 0.4ohms 0.27A suffice?
 
Well I did the unorthodox thing and made my own inductivity, it's approx 1uH, and fired it up.

The monitor has a new HOT, new LM1203N, a few new resistors, D706 replaced with an alternative.

My first problem, the picture being off-center is now gone. I can center it perfectly.

Problems:
-Picture fades to black in an approx 1, 1.5 inch area on the right.
-Contrast needs to be cranked to max to get an acceptable picture, and I'm getting interference if any of the gain pots on the neckboard are turned halfway up. The interference is colour specific.

Anyone have any clues what might be going on here? The LA7850 at U701 is also new, so I don't think that has anything to do with the black fade, and the monitor has all fresh lytics.
 
Guess this will be a sort of log then.

Metered all the pins of u500 and found some funky readings... contrast pin is at 2,3 volts instead of 6,7 as per the reference... (with the contrast pot at max!!!) The clamp cap pins are all at 5v which is high, but am fairly certain they would be normal if I fix the contrast.

ATTENTION!
For anyone working on an U2000, don't get scared when pins 28, 23, 20, and 15 of the U500 RGB ampt are rossly out of spec!!! The geniouses at WG have wrote the pin numbers of the second half of the chip BACKWARDS!

Now the thing is, when I jumper the resistor before the contrast pot on the remote PCB, I get pretty sweet contrast... The pot gets 12V from the vertical section, which is a table 11.5V, so as per the schematics, the ABL line is the only thing that can be dragging my contrast pin down. However... the schematics say that line leads to a daughter pcb, but there is no such thing on this chassis... instead it leads to Q808, a transistor that I can't seem to find on the schematics, but of course it's there on the voltage reference... no wonder everyone's hating on this pretty much worse then the U5000...

Anyone know what the ABL line is actually supposed to do ?
 
Well... now's the time for loud cussing... Was metering the ABL pin on the neckboard, had 1.2 volts on it (should be around 11v), then went to check on the chassis, and it had 10.5 or so... so I probably have a bad connection... I would've only had a bad conection that is... damn vidb+ testpin touched my probe as I wa pullin t away, effectively shorting video b+ to the damn abl line on the chassis... now it's in permanent shutdown.... bloody briliant...
 
Lucky me... got away with a fried HOT... metered q808, shorted between two legs... replaced it, and getting 0 volts on the center leg... that's supposed to be at 17 volts or so... D805 is supposed to supply it, but it's emitting 0 volts, which is no wonder, as on the other side there's -100V to ground... this is getting weird... to boot, this part is NOT on the schematics for the u2000, but for the u5000... WG... you guys astound me... and C810, which should be between this and the 15v rail is not even populated...
 
Okay this has been confusing as hell seeing how I needed two schematics, of which neither are completely the same as the actual board... Found R811 (again somethin not on the U2000 manual) open, or at least badly out of spec (12 megaohms!) I'll try to find a replacement and see how this goes...
-----------------------
Well.. funny.. I looked through all my scrapper chassies, and none have a 56K 1/2w resistor... will have to see if I can improvise, or this'll have to wait till monday...
There's another thin fishy, D802 is not populated... but R819 is... as per the schematics
Odd as per the U5000 hematics, it should go R815-R819-D802-R11 with the junction of R819 and D802 not connected anywhere else...
 
Last edited:
Okay so I dug around and pulled a few things from a hantarex chassis that should work fine.

Populated D802, and replaced the open R811. Now I'm certain someone pulled D802, as I lost all brightness control. (Makes sense someone would 'fix' it like this around here... hackjobs galore...)

R817 is fishy as it reads only 170K in circuit (Pulling it soon after some further testing), while it should be 470k.
 
Okay, contrast issues FIXED

Turns out one of the leads was bent sideways and a tiny bit of solder linked one le of R811 to an adjacent component after I replaced it. Removed that, cleaned my mess up, Hooked the chassis up, flyback cup fell off... this is still an original fly, lucky me it had a snap-in bit in the middle of the cup, so I just popped that out, peeled some of the insulation of the end of the HV wire and put it back just like it was. Lucky break that one... pun intended...

So I turn it on, and presto, I have full contrast control, and the brightness lowered in intensity too, which is also well adjustable now. I'll need to calibrate cutoffs and whatnot, as generally the colour bias is too sterile for my liking atm.

The only problem remaining is the faint fade-out on the right side. It's like HV is loosing intensity just a bit earlier then it should before retrace. I'd really appreciate some input on this. It's not near as bad as it was though, for anyone else, it'd probably be unnoticable. (Doesn't really show up too well on photos, I tried taking a pic to show you guys.)
 
Case summary:

Problem: Barely any contrast, washed out picture even with it at maximum, excessive brightness all around
Solution: q808 shorted, D802 missing, R811 open

Additional info:
-WG voltage reference for U500 LM1203 has voltage readings for pins 15-28 in backwards order
-WG U2000 schematics DO NOT MATCH THE BOARD LAYOUT... use the U5000 schematics to troubleshoot components in this section
-Differences between U5000 schematic in this section are: R813 marked 8.2K 1W, board has 10K resistor there, R811A not present, instead single 56K resistor at R811
(U5000 schematics mark a 100K (r811) and a 470K (r811A) resistor in parallel, which equals a 82K resistor, I used a 1W 82K resistor instead of the 56K that was there, and it works fine.)
 
The only problem remaining is the faint fade-out on the right side. It's like HV is loosing intensity just a bit earlier then it should before retrace. I'd really appreciate some input on this. It's not near as bad as it was though, for anyone else, it'd probably be unnoticable. (Doesn't really show up too well on photos, I tried taking a pic to show you guys.)

Check C310, and may C812...
 
Back
Top Bottom