1060 with damaged volume pot, repairable?

[jd3rdcoast]

This 1060 was brought to me with intermittent volume operation on one side. No output until rotated pot to near 11:00 position. Then muted output at that.
Initial inspection of R002 I can see the wipers are mangled on the rear pot.



I was able to remove the cover and it looks like, in addition to bent wiper tips, the wiper base is disconnected from the plastic back piece that is attached to the post.

Since these seem to be unobtanium I’m wondering if it is possible to disassemble further? As in can I remove the top plastic piece without permanent damage. Does that tiny rectangle “keeper” come off somehow? I was hoping to straighten the wiper and figure out a way to reattach to the back piece.

BTW, The owner has confessed it was likely his own doing.
None for sale on the internet. I don’t trust the $90 Vol pot on ePrey.

 

[AE Bob]

The end of the aluminum shaft is "swaged" to hold the plastic part that holds the contacts. It can be ground off with a Dremel tool and cut off wheel. once the expanded part is ground off, the plastic part will pull off the shaft. After straitening the wiper contacts out, you can glue the plastic part (and phenolic washer) back on with a TINY bit of gel CA glue wiped on the inside of the hole in the plastic piece, before putting it back on the shaft. You can also SLIGHTLY expand the end of the shaft by dimpling it with a sharp center punch, for more security.

 

[jd3rdcoast]

The end of the aluminum shaft is "swaged" to hold the plastic part that holds the contacts. It can be ground off with a Dremel tool and cut off wheel. once the expanded part is ground off, the plastic part will pull off the shaft. After straitening the wiper contacts out, you can glue the plastic part (and phenolic washer) back on with a TINY bit of gel CA glue wiped on the inside of the hole in the plastic piece, before putting it back on the shaft. You can also SLIGHTLY expand the end of the shaft by dimpling it with a sharp center punch, for more security.

Thank you AE Bob. I thought that might be the case but wanted to hear from the more experienced folks here before I did something I might regret. This is my first foray into full disassembly of a dual Volume pot. Will post updates.

 

[geespot]

None for sale on the internet. I don’t trust the $90 Vol pot on ePrey.

Stay away from this joker. Many threads on this guy.

 

[jd3rdcoast]

Got the top off without much difficulty. But when I looked at the front pot underneath I see the plastic piece is cracked in 4 pieces. I will try my best to put it all back together with some tiny drops of glue to hopefully hold that bottom piece together.

 

[HPMguy]

What is the rating on the pot? 100K log taper 40% loudness tap is what I would guess since it's typical, and that's an available pot if not identical. The numbers on the side should include the letters for the Alps series, it's a solder lug type which is easier to find than the board mount double sided single gang type I need for my KA-88.

A small amount of JB weld may work to glue the plastic parts together. You will need to find a way to GENTLY clamp it in place while the epoxy sets up overnight -- do not squeeze so hard you extrude all the glue out of the joints, some must remain to properly adhere the parts. Common problem in woodworking is over-tight clamping leaving a dry joint with little or no glue in it.

 

[Lavane]

Ya, I would just buy a new dual pot at this stage. Plenty to choose from at Mouser or Digikey. Nothing magical about the original.

 

[jd3rdcoast]

250K ohm AX2 is side lettering. Plus Marantz part number.
Yes, it has a loudness tap
Could not find anything matching on Mouser or Digi-Key. But I may not be searching correctly for the tap.
This is what it looks like.

 

[tarior]

JB Weld is garbage and has no use in vintage stereo repair. It pretty much doesn't stick to anything, it's weaker than 5 minute epoxy and harder to work with. I hate that product.
For phenolic and plastic repairs on parts that haven't shrunk or don't have gaps, Loctite 401 is the cat's ass. On a proper joint, it's strong, and it's fast.
For anything with a gap, find an epoxy that is specifically designed for the plastic you are working with. ABS is pretty common, as are styrene and nylon.

I'm curious as to how those wipers came to be folded like that.

One of these seems like a cheap gamble. Could phony, or they could have had Alps run off a batch. They don't show up on the Alps website, but Alps will make pots to order if the buyer buys a certain quantity. Almost without a doubt better than one that doesn't work at all.
https://www.ebay.com/itm/154391481168? No affiliation.

 

[AE Bob]

With a pot in as bad a shape as the one in question, I would also try the Ebay one from China.

 

[jd3rdcoast]

QUOTE="tarior, post: 15260171, member: 1439"]I'm curious as to how those wipers came to be folded like that.[/QUOTE]
Yea I didn’t press the owner yet who said he was responsible. I suspect shoved a spray straw into the gap.

I will get one on order from China. In meantime might as well have a shot at gluing the plastic part together. “JB Weld!”, Uhhh, Nope.

 

[AE Bob]

For that type of plastic I typically use Gel type CA glue.

 

[OBMG74]

Many years ago, I replaced my 1060 volume pot with one without a loudness tap.
I think that I had to modify the knob to fit the shaft.

Haven't missed the loudness function.
Not the correct way but it is a way.

 

[tarior]

For that type of plastic I typically use Gel type CA glue.

Loctite 401 is the very best CA glue for plastic that I've ever used. I can't say enough good things about it.

 

[Lavane]

JB Weld is garbage and has no use in vintage stereo repair. It pretty much doesn't stick to anything, it's weaker than 5 minute epoxy and harder to work with. I hate that product.
For phenolic and plastic repairs on parts that haven't shrunk or don't have gaps, Loctite 401 is the cat's ass. On a proper joint, it's strong, and it's fast.
For anything with a gap, find an epoxy that is specifically designed for the plastic you are working with. ABS is pretty common, as are styrene and nylon.

I'm curious as to how those wipers came to be folded like that.

One of these seems like a cheap gamble. Could phony, or they could have had Alps run off a batch. They don't show up on the Alps website, but Alps will make pots to order if the buyer buys a certain quantity. Almost without a doubt better than one that doesn't work at all.
https://www.ebay.com/itm/154391481168? No affiliation.

That should work as long as the shaft is long enough. If the OP does some more searching, some of the ALP volume controls are sold with a small PCB that fits over the pins. The PCB has solder eyes for the wiring. Maybe the board itself can be found?

 

[tarior]

Just search around for "Alps RK27 board". I'm about 95% certain the shaft length is the same, or at least very close.

 

[fromnowon]

FWIW . . . for the cracked piece,
I fixed a sherwood pot by gluing a star washer over it for reinforcement with epoxy (after cleaning and lightly scoring with sandpaper). It worked and is a fix others have used on those pots which always crack there and the on/off switch is therefore broken.
I hope the Alps works out!
There's a 100K ohm with loudness taps at RadioShack but I assume that won't work in this case https://www.radioshack.com/products/radioshack-100k-dual-ganged-stereo-volume-control (?)

 

[jd3rdcoast]

OK, I was successful in repairing the original volume pot! After disassembly I cleaned all the wiper contact points and the carbon tracts with D5 and q-tip. Followed that up with a very thin layer of fader lube on the carbon tracks. I glued the three broken plastic pieces back together using Loctite Ultragel Control glue. Placed the wiper on it and glued it in correct place with same Loctite glue. Then had to file down the peened section of shaft that originally held it in place to get it back onto the shaft. Then used additional E6000 glue and a rubber band to hold it in its place while glue cured overnight. Next was dealing with the front pot/wiper that was bent. Got it straightened back to original shape as best I could. Glued it back on its plastic piece, placed at correct alignment with the back wiper for equal L/R volume control. Adde a bit of E6000 on the shaft and placed the round disk on top with another good dab of glue to hold it all together. I know it's not as strong as original assembly but I'm pretty confident it will hold so long as the volume knob is not yanked on. I did squeeze the knurled end of shaft together just a bit so the volume knob slips on and off with minimal effort and added a touch of silicon lube to facilitate that. Sounds perfect with nice smooth action. Note: I did add a bit of Deoxit L2600Np Mechanical & Electrical grease to the shaft/collar as damping grease before re-assembly.
Overall, I am happy with the outcome. This is a delicate procedure, and I did it in several sessions over a few days so as not to rush it and make any mistakes (and to let glue dry after each application). If good alternatives were available, I would probably not do this again, but these are hard to find viable replacements for. But it's good to know it can be done for my own peace of mind.

Edit: I used a dremel cutting wheel to CAREFULLY grind down the top of shaft to initiate disassembly. I also added a bit if the L2600Np grease on the inner wiper rings what contact with the center tap legs.

Here are some pics of the process:

 

[hofferwood]

 

[tarior]

Nice job!
I've been also using the DeOxit L260NP grease for the last few years with good results.