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Old 02-11-2017, 09:11 PM
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Kevin Kuehn Kevin Kuehn is offline
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Wanted replacement 1 Meg Stackpole Pot Element

This one got smacked hard from the front and it cracked the front element in 4 places, so I'm needing a donor Stackpole 1 meg pot to harvest the element with bushing. I'd prefer to fix this rather than rounding up all the individual aftermarket components to build a complete new control( last time I did that it got very costly). Alternately if someone has a 1948-50 vintage Emerson parts chassis with this same type horz/vert control I'd be happy with a good used replacement. It's for a Emerson 638, but I know these were used in several models. Emerson part number 390036. 1 meg front, 50k rear dual concentric control.



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Old 02-12-2017, 01:47 PM
dieseljeep dieseljeep is offline
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I take it, it's a linear taper! Stackpole's EIA number is 240???
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Old 02-12-2017, 02:44 PM
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Yes linear taper 1 meg.

Stackpole EIA code should be 304.

If you look at the pictures you'll notice Stackpole used a very distinctive tab system(6 small and 2 large) to hold the element to the back cover.

Also worth mentioning is that the front bushing on these long shaft controls is longer than a standard panel mount control, although I believe a standard bushing will still function OK.


Last edited by Kevin Kuehn; 02-12-2017 at 03:02 PM.
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Old 02-12-2017, 04:52 PM
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Kevin,

I have some Stackpole resistance elements that may work. There are a variety of different mechanical designs for the connection to the wiper. And the dual concentric bushing you are showing is different than the bushings used in the single non-ganged pots.

So to replace the front element you will need a 1meg from a front element of a dual ganged pot, of the same vintage. I do not have the exact element needed. And to top that off, it seems that this is a part that was probably prone to failure, because the control I have on my Emerson donor chassis has a bad 1 meg front element.

I could probably transplant your bushing into one of the 1 meg elements shown in the attached photo. But because the bushing is swedged into phenolic wafer, I would have to machine the bushing to get it to fit. Attempting to press your existing bushing into the wafer without reducing the diameter of the swedged end will cause the phenolic wafer to crack.

Could you please remove the broken element and show a photo of the carbon wafer configuration and the wiper assembly.

The older variety elements have a coiled up wire that connects the wiper to the center lug, and the newer variety uses a copper ring riveted to the center lug. I may be able to come up with something that will work, but none of the elements I have come out of a dual concentric If need be, I can probably pull the brass bushing out of the element on the right of my photo and press your bushing into either elements in my photo.
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Old 02-12-2017, 09:10 PM
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Hi Bob,

Thanks for sharing that information. I will remove my wafer and see exactly what I have.
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Old 02-12-2017, 09:38 PM
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OK, here's what we have inside. For some reason I was thinking the resistance element was molded onto the back side of the wafer on these. Bobs picture made me realize it is a separate piece riveted onto the terminals. Amazingly this resistance element looks like it has very low mileage. I suppose if I clean the daylights out of the parts, I could then put the bushing back into the wafer and epoxy the whole mess together. But that probably wouldn't be a very long lasting repair.



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Old 02-12-2017, 10:09 PM
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Clarostat made a series of replacement dual and triple pots - the "RTV-XXX" series. I have a few, but more importantly, I have a cross reference manual.. Play things of the past also has some of the RTV series stuff. They list an many with the same values:

1487-599 IRC QJ-80 50K/1M, DUAL POT, TV USE ? . 1 5.00
1500-226 UNK 131-000 50K/1M, DUAL CONC SHAFTS..... 4 4.00
1503-014 PHIL 33560435 50K/1M, DUAL CONC, W/SW...... 1 5.00
1500-911 UNK 970111-8 50K/1MEG DUAL CONC SHAFTS.... 1 4.00
1487-589 UNK 25B874 50K/1MEG DUAL, CONC SHAFTS... 1 5.00
1503-659 PHILC 3355636 50K/1MEG W/SW, 2 SHAFTS...... 1 5.00
1500-299 CLARO RTV-136 50K/1MEG, DUAL CONC......... 1 4.50
1487-656 UNK 131-0004 50K/1MEG, CONC SHAFTS ....... 5 5.00
1500-731 CLARO RTV-631 50K/1MEG, DUAL CONC TV USE... 1 5.00

I'll check in the morning and post what I find. Been a long day...
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Last edited by Findm-Keepm; 02-12-2017 at 10:16 PM.
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Old 02-12-2017, 10:58 PM
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Hi Brian,

I do have a 1966 Sams TV/Auto Radio cross and was looking at those Play Things Of Past listings on Saturday. My Stackpole unit crosses to an industry no X2262, which then crosses to CTS-IRC QJ-162 or Mallory UE1590. I didn't see either of those listed at PTOP. My Sams cross ref only gives individual components for Centralab controls, and no listings for Clarostat? I guess I could email Gary a picture of my control, but that would mean he'd have the task of digging through all those controls for a possible match. Anyhow I do appreciate you taking the time to look.

Last edited by Kevin Kuehn; 02-12-2017 at 11:30 PM.
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Old 02-13-2017, 09:24 AM
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Quote:
Originally Posted by Kevin Kuehn View Post
Hi Brian,

I do have a 1966 Sams TV/Auto Radio cross and was looking at those Play Things Of Past listings on Saturday. My Stackpole unit crosses to an industry no X2262, which then crosses to CTS-IRC QJ-162 or Mallory UE1590. I didn't see either of those listed at PTOP. My Sams cross ref only gives individual components for Centralab controls, and no listings for Clarostat? I guess I could email Gary a picture of my control, but that would mean he'd have the task of digging through all those controls for a possible match. Anyhow I do appreciate you taking the time to look.
I'm having difficulty finding the RTV manual - I thought it was with my controls, but no joy. I did find my 1967 Sams TV/Auto cross manual, and it has the same as your '66. My money is on the RTV-136 - I'd have Gary check that first.

Counterfacts and Mallory guides turn up nothing as well. My Stackpole stuff is all single controls, 'cept for one dualie with a switch, but the shaft is stubby and the values are 30K/150K

Cheers,
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Old 02-13-2017, 08:09 PM
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Bob Galanter
 
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Kevin,

I think the resistance element on the right in the photo I posted could work. The busing on it will need to be bored out (there is a reduced diameter shoulder in it currently)(fairly simple to accomplish on a milling machine). And you will need to carefully re-attach the coil spring wire from your existing wiper assembly to the center lug.

Do you think you have the ability to do this? If so I will be happy to send you the element.

Otherwise..........

If not I am quite sure I can perform the surgery in my machine shop and lab for you. This is the only resistance element I have like this, so it has to be done correctly the first time, there will be no 2nd chance if the element gets damaged in the process.

FYI also, this element is measuring a bit below 1M at an actual 830K, but it should work. You could always add some fixed resistance externally if need be.

EDIT: I see that Brian seems to have located some possible matches at PTOTP so I would go that route first if possible.
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Last edited by ohohyodafarted; 02-13-2017 at 08:17 PM.
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  #11  
Old 02-13-2017, 10:55 PM
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Bob,

I'm going to hold off on the Stackpole element transplant for the time being.

I did contact Gary at PTOP and I'm waiting to hear back. Problem is Gary has so many unidentified parts and there's really not enough hours in his day to search through his humongous inventory looking for exact matches. Trying to track down all these obscure little pieces can kind of get a guy down if one takes it too seriously. I'm going to sit tight for a while and weight out my options.
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Old 02-14-2017, 01:36 PM
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While I'm waiting on Gary I might as well mention that I'm also in need of one other (likely very difficult to find) item for this Emerson 638 - the channel dial plate is missing. It looks to have originally been held on by three small wood screws. I'm assuming it's a 2-13 plate and likely the same as what's on the model 611 on display at the ETF museum. If by chance anyone has such an item in excess to their needs I would be very grateful to obtain it.




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Old 02-24-2017, 12:28 PM
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Kevin Kuehn Kevin Kuehn is offline
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Bob, While I really appreciated your offer, in the end I chickened out on putting your Stackpole element on the chopping block.

Once again (with the help of my IRC replacement guide) I ended up building this control from individual components. When it's said and done a control like this seems to end up costing $20-30, which seems like a lot. But then a guy's gotta have something to hang his knobs on.

So what are you guys using to lube up a freshly built control like this? These parts are as dry as a bone.

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Old 02-24-2017, 01:17 PM
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I use DeOxit Fader Lube.
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Old 02-24-2017, 01:17 PM
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Caig Faderlube - been using it for some time, and really like the stuff. http://store.caig.com/s.nl/it.A/id.1...2&category=293
I don't usually follow the crowd, but Caig makes great stuff - way better than the Rawn/GC/Chemtronics stuff I've used over the years. I was stuck on Rawn contact cleaner and lube for years, as it was cheaper than anything else - switched to ContactKleen (smells awful) and was finally given a small can of Caig cleaner - and found fader lube later. Expensive as all get out, but it works and works well.
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Last edited by Findm-Keepm; 02-24-2017 at 01:21 PM.
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