Wells U3000 cap list and questions

ELutz

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I just started on a 27" Wells U3000. This is the first time I've worked on one of these. Does anyone have a cap list?

When powered up, it's doing the deadly tick, tick, tick, etc. I pulled the monitor and noticed the big filter (on the power supply board) cap oozing out it's top. I replaced it....and found the 7watt/10K ohm resistor totally open. I also replaced that and fired it up.....still ticking. I checked the HOT, it's good. Someone has replaced some of the smaller caps on the power supply board and the values do not match the schematics I have.....some are not even close.

I pulled the power supply connector to the main chassis, and fired it up to check the voltages. It no longer ticked, but my voltages were doubled.....the 120V was approximately 240V.....the 22V was 45V. I've never worked on one of these, so I don't know if that is "normal". It seems high to me. I decided to put a load on the power supply. I connected my work light to the 120 volt output at the connnector with the chassis disconnector. With just my work light connected to the power supplies output....I got the tick again.

So, I assume the power supply board is bad? Am I running down the right path? And....anyone have an actual cap list?.....maybe just for the 5-6 caps on the power supply board. Thanks!

Edward
 
I dunno - but fix it! I have one of unknown condition sitting on the floor that I need to get running eventually, but I'm still a week or two from getting to it...
 
I dunno - but fix it! I have one of unknown condition sitting on the floor that I need to get running eventually, but I'm still a week or two from getting to it...

Fixed!
All issues were on the power supply board....mine was a P756 issue.
Filter cap C105 (470uf400V) was ruptured at it's top.
R104 (10K ohm 7watt) was open.
C107 was installed backwards, and thus bad.

This power supply board had shown signs of previous work....specifically C105/C107/C108 and C117.

C107/C108/C117 (which were not original) did not match my schematics.The schematics lists C107 as 10uf50V, C108 as 1uf50V, and C117 as 10uf50V. My board had C107 as 100uf50V, C108 as 10uf160V, and C117 as 22uf100V. I replaced them with these alternate values (I'd really like to know what they're supposed to be. There was a lot of stuff listed in the schematics not installed on my board.....and a few alternate parts, that all looked factory......so, who knows. It's working now. Mod, if you think about it ( and have time)....check what values you have on those three caps.

Also, C107 was silk screened wrong on my board. The "+" symbol was actually marked where the negative leg of the cap goes.....probably why this cap was installed backwards on my board by someone previously.

Edward
 
you'd think Wells would've learned the first time with the K8000. I'm not sure why this chassis is designed this way.

I have to cap a U3000 eventually, does that include any of the power supply caps or is that separate? I have the kit ready, I just never opened it.
 
you'd think Wells would've learned the first time with the K8000. I'm not sure why this chassis is designed this way.

For what it's worth.......this ugly thing looks just like the few K8000 I've seen. I bet they're very similiar.....a la the U2000/U5000.

Edward
 
even the heatsinks on the neck transistors are the same lol.

according to Chad, the K8000 had a separate power supply board if in the event it took a shit, you'd replace it with a different one. whole lot of sense that makes, considering that monster takes 2 isolation transformers to run. that's one difference between the two.

I don't understand why the U3000 emulates the K8000's design after the U5000/U2000 and K7200, all of which had built in power supplies on the deflection board.
 
Did you do a full cap kit for it? if so, post the list for me in case I need it...
 
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