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Recapping a Tuner board

M

MyHeresyIsMe

Well-Known Member
About recapping a tuner board that has never been realigned (Lux R-1050): I see on one of my pc boards ---the tuner board--- that there is evidence of leaking from several caps. If I replaced those caps, will I need to have it realigned even though it has never been realigned since new?

Thanks, everyone.
 
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I would say yes, because alot of those caps are going to have different tolerance values. It will probably work fine, but for optimum, I would get an alignment.
 
Thanks, backinthelou. Forgot about the difference tolerances! You're right about that. I'm in that inbetween place because the tuner is okay, but I know it could be better --- that's when I looked at the boards. Uh-oh---I"m not a tech in that area.(I'm a 'parts replacer!')
 
I'd say no.
The electrolytic are not part of the tuned circuitry.
I recapped my R1120 with no issues in this regard.
Are you sure that it's leaking or is it just the glue?
 
Your question about glue is very apt, w1jim. I posted that same question in another, older thread ('is that a leaking cap?) but got no response. If it is glue, the assembler used it prettly liberally. But, if you've done the recap job on an R1120, you would know. This one particular cap does not show any swelling, bulging, splitting, etc.
 
I completly reacapped my STC-7000 and it woked fine,just as before.If you don't pay attention and touch the trims,you'll have to realign.
Even if it's glue,changing them won't do any harm.
 
I appreciate your comments, costellom5. This will be my total recap job (I've done old Fender amps from the 60's--no pc's though) so I know I've a case of the jitters! I do NOT have a desoldering iron, so I better get one (from what I've been told) before I go any farther with this. If you have done a total recap, does that include the tiniest ceramics? (of course, "completely" by definition means all caps, but just asking....). Thanks!
 
The "leakage" is almost certainly glue, which can have its own problems. You would only replace aluminum electrolytics and tantalums (if present), not ceramics or films or anything else. If the unit works well, this is a case where it would be far smarter not to mess with it. No good will come of it.

caps- at least read the last parts.
 
THAT is my question --- glue, not goo from the cap. Didn't know they used glue on the boards.
That link to "caps" is a great read.
Thanks, Conrad.
 
Absolutely not! Go right ahead with the recap.

I've done this so many times I've lost count (1050 included), and never has the tuner been worse off. It has always been the opposite, if anything (usually there is no change).

There is no glue on the small caps on this tuner board (only the two big 1000uF caps are glued down). These small caps are usually empty of electrolyte. Most of what remains is on the PCB in the form of brown, hardened powder.
 
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For recapping all I usually need in addition to a small soldering iron is a solder sucker and a machinist scribe.
I use the right angle portion of the scribe to tug on the part while heating the solder.
Then I use the pointy end to open up the hole by placing it in the hole while heating the solder.
Often I don't even need the solder sucker.
One of those fancy vacuum pump desoldering irons is nice but I rarely use mine.
I've recapped plenty of big receivers in the past few years, the Luxman shouldn't be particularily dificult - just don't melt the tuner string!
I usually put tape over the string to hold it in place if I have to move the main tuning cap.

Can you post a link to the suspect caps?
 
I only changed the elect. From what I've read,the other caps shouldn't be touched unless necessary.I only used a soldering gun.
Just to have a clue,could you post a picture of the cap?
 
I've never had any issues with it affecting the alignment.

Leaking looks like green corrosion on the leads or board.

I would replace electrolytic and tantalum caps. The others are fine.
Electrolytic caps are not the most precise devices, so I doubt they would be used in places critical to alignment.

I've had good results with solder wick.
 
It would be unusual to see glue under small caps, but it's possible. Try a Q-Tip and some warm water on the brown stuff. If it's insoluble it's probably glue, if it dissolves it's probably electrolyte. The risk with some glue is it's been reported to turn quite corrosive to leads and even boards. Only inspection can tell, and that's hard from here.

If you replace the caps, try to remove any glue around the lead area. Again, I can't diagnose things remotely, so anything is possible, but if the unit performs well and the schmutz really is glue, it's statistically unlikely there's a cap problem.

The paranoia about cap life is astounding. Because of the way most solid state audio components use caps, with minimal ripple currents and at low temperatures, they don't often fail unless the quality was bad to begin with. Even tube equipment does well, other than main filter caps and those in thermally "unfortunate" locations. The lifetime numbers most people bandy about from the manufacturers have nothing to do with how the caps are actually used in audio equipment. Still, if you can't sleep until you change them, do a careful job and it will probably go well. Just for fun, if you're not too far away, send me the old ones and I'll check them for condition and tell you how good or bad they really were.
 
tom3: Gotcha! I've been there, done that, and yes it is a ton of work. I have replaced the dial cord after many hours of replacing a rotary switch with 5 wafers. Ouch.

Can't tell if this is glue or goo. If it is glue, it was applied in a glob, with uneven borders. Looks to me like something that has leaked.
Being a rookie on boards, I'm up in the air to make the call. By the way, this is a 'practice' board on another R-1050. My everyday R-1050 is still hooked up and is played daily. Conrad, I'm not antsy to get in there and hack away! I am just looking if there is something to improve and preserve what I have. Thanks for all you comments!

The picture is blurred -- sorry. My new camera arrives tomorrow with 5 more megapixels.

Here is one picture of the the board PB-1054, C152.
 

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  • Luxman R-150 capacitor leakage 001.jpg
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"Definitely old glue" is an 'all systems go' call to me. I'll replace it and send it to Conrad and see what the verdict is. Thanks, Masterdraco.
 
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