WG 27K7502 27" med res cap question

Paladin

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The "WG combo kit" had several discrepancies from my chassis including caps listed where I didn't have them populated on my chassis, and caps on the chassis that weren't listed in the kit.

This didn't really suprise me, since there were probably several revisions, but one of the caps that isn't listed in the cap kit is a 10uf 50v Bi-Polar cap (there's adhesive covering the location label). One of the caps that came with the kit but wasn't populated on my chassis is the same value, but you can see the huge size difference.

Now I realize that newer caps are almost always smaller than older ones, but this difference seems a bit too much. Should I replace the cap with the smaller one, or leave the large one in there?

My neckboard has C774 populated with a 22uf 25V, which isn't on the cap kit list, but I found one locally. The other cap that's on my chassis but not on the cap list is C734 which is a 330uf 63V that I can't find locally. I'm still not good enough with schematics to figure out what it does and if it would be OK to leave the old one in.

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The gray colored BP cap is a high temparature/high frequency cap......the smaller blue one is a standard temparature/non-high frequency cap. I would NOT replace the gray one with the blue one.

Edward
 
pretty weird that grey cap was even listed as one that you replace with one from the kit.

as for that other cap that's not included in the kit you can't find locally... these cap kits are only intended to replace the highest failure prone caps on the chassis, so it's normal for some to not be replaced unless you really want to.

considering you have a 7502, and I don't know the major differences between it and the 7501, I wouldn't have used that combo kit one, probably would've picked Zanen's minds about a specific kit for it. 7502 is the lesser encountered model. I don't know entirely if that was just a 27" chassis or if it was a revision on the old design, and likewise, I don't know what was changed between them, but it was enough that some parts aren't interchangeable to my understanding.
 
The gray cap was not listed, I just figured it would be better to do it while I've got the chassis out.

I ended up not replacing it, and fired up the game. After adjusting the picture a little, it looked great. Unfortunately the focus drifted off after about 5 minutes. I turned the focus pot counter clockwise and it looked good again for about 5 minutes before getting blurry again. Same thing one more time.

I'll be busy at the Seattle show all weekend, so I won't have time to look into it for a while. Fingers crossed that it's not the tube!

Update: just did some quick newsgroup research and found that the K7000 series is known to have flyback issues causing focus problems. I looked at the fly with a flashlight, and sure enough there are cracks above and below the focus pot.
Now I just need to find out if replacements are available for the 27" med res flybacks.
 
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pretty weird that grey cap was even listed as one that you replace with one from the kit.

as for that other cap that's not included in the kit you can't find locally... these cap kits are only intended to replace the highest failure prone caps on the chassis, so it's normal for some to not be replaced unless you really want to.

considering you have a 7502, and I don't know the major differences between it and the 7501, I wouldn't have used that combo kit one, probably would've picked Zanen's minds about a specific kit for it. 7502 is the lesser encountered model. I don't know entirely if that was just a 27" chassis or if it was a revision on the old design, and likewise, I don't know what was changed between them, but it was enough that some parts aren't interchangeable to my understanding.

> I don't know what was changed between them, but it was enough that some parts aren't interchangeable to my understanding.

Yeah, I can testify to that. I had a 7501 that was essentially ruined after being rebuilt with a cap kit, new neckboard, and flyback (and possibly a couple of other items). When it came back it was essentially a 7502 and would no longer work properly with my tube.

Paladin, yes, your focus drift is your flyback and yes they are available.
 
I have found the BP cap to cause a width or pincushion problem
maybe intermittent.
For focus issue replace the fly.
Good Luck!
 
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Update: just did some quick newsgroup research and found that the K7000 series is known to have flyback issues causing focus problems. I looked at the fly with a flashlight, and sure enough there are cracks above and below the focus pot.
Now I just need to find out if replacements are available for the 27" med res flybacks.

Just an FYI....the K7500 is not part of the K7000 series. Yes, the flybacks are available.....just make sure you get one for a 7500 series and NOT a 7000 series.

Edward
 
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