I have a couple of these coming to see if I can get it working correctly
HK Citation 1
- Thread starter jefferylhenr
- Start date
The last ALPS I bought in that style has a 8mm bushing (0.315") and a 6mm shaft. In addition to being a small metric diameter, the bushing is shorter than most other pots. Adapters to convert a 6mm shaft to 1/4" are common, but I don't know how the other differences will affect mounting in the Citation. I'm working on a situation now where a 0.354" bushing (TT Electronics 9mm) needs to be centered in a 0.375" panel hole. I've decided to cut a thin strip of 0.010" sheet brass and form it around the bushing to take up the slack. You might be able to do something similar. Have you contacted Jim McShane about this? He's the Citation expert. I would be surprised if he stocks these pots, but maybe he knows of a solution, just in case the ALPS is too troublesome.
Jack
depending on the size differences I might be able to make you a special nut to take up the difference. Basically I'm thinking a thing that looks like a nut with an extended shoulder. It would be threaded, and the shoulder part would center in the hole on the face. There is a practical limit to how thin it can be though. Could possibly do 8mm to a 3/8 hole but I don't think I could do much less and not end up with something that has the structural integrity of tinfoil. Even 8mm to 3/8 its at a 30 thou wall thickness from the root of the thread to the outside of the shoulder.
oh, or just use these
guitarrepairparts.com
and call it a day. I was thinking a nut with that built in essentially.
Potentiometer Hole Reducer Adapter Bushings 3/8” to 8mm (5 pcs)
These plastic adapter washers convert pickguard holes that were originally cut for 3/8" bushings to fit smaller 8mm metric pots. (5 pcs.) Specifications: Inside Diameter: 8mm (0.315") Outside Diameter: 0.375" (9.5mm) Flange Diameter: 0.540" (13.7mm) Professional installation is strongly...
guitarrepairparts.com
and call it a day. I was thinking a nut with that built in essentially.
With this crew… we will get there. Thank you for the insight and input
FWIW, I just received a few 6mm-to-1/4" adapters from AES. They're a perfect fit.
Jack
Jack
Many, many moons ago. The power supply and transformer are what really made the CIT I. But there were lots and lots of parts in the signal path. Never had to replace the vol pot though.
What makes a particularly good preamp transformer? Apart from adequate ratings for voltage and current?
Reliability.
I thought that was generally an issue limited to inadequate ratings?
Not always. Manufacturing processes and quality control affect reliability too.
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I remember occasionally seeing a power transformer back in the day that had a primary-side fuse buried inside. You couldn't get to it without destroying the transformer, so the only option when it blew was a total replacement. Don't remember now which manufacturers did this, but I think it was only the cheaper brands like Lloyds and such.
Jack
Jack
Manufacturers would always recommend a new replacement.
size and current. The transformer in the CIT 1 was oversized for the day. Large enough to run a 25-30 watt power amp off of. Its what gives the ease to the sound on the CIT 1.
Back then that was quite rare. Today much more common.
The potential problem with those is the thickness they add to the panel. A shoulder isn't required for this application, only a washer that can be inserted into the 3/8" hole with an ID the size of the control bushing.oh, or just use these
Potentiometer Hole Reducer Adapter Bushings 3/8” to 8mm (5 pcs)
These plastic adapter washers convert pickguard holes that were originally cut for 3/8" bushings to fit smaller 8mm metric pots. (5 pcs.) Specifications: Inside Diameter: 8mm (0.315") Outside Diameter: 0.375" (9.5mm) Flange Diameter: 0.540" (13.7mm) Professional installation is strongly...
and call it a day. I was thinking a nut with that built in essentially.
I have since realized I can simply make a custom washer approximately the same thickness as the front panel. The CNC mill I use for cutting chassis and panels can do this easily. The washer can be cut from either aluminum sheet or FR4 to be sure there aren't any issues with dissimilar metals. In my case, the washer will be captured between the potentiometer's lock washer on the back side of the panel and the trim washer/attachment nut on the front. Its exact thickness isn't critical; it only needs to be slightly less than the panel.
I'm surprised no one is selling adapters like this for the various bushing sizes. Most front panels are at least .063" thick, so that would probably be a good thickness for generic adapters. 3/8" to 9mm and 3/8" to 8mm would be the only sizes needed for most jobs.
Jack
I'm currently working on one of these & this is one of the issues.......one side measures only 100K, the other 138K. While turning them clockwise (increasing volume), the resistance actually rises up to around 170-175K....& not symmetrically.....til about half volume, then decreases to only bottom out at around 70-100 ohms........& yeah, the balance pot is suspect too.
What was your final fix?
I had the pots rebuilt and new carbon wafers inserted
