Kalamazoo Model Two problem

[mresistor]

I've got a Kalamazoo Model Two in because it won't turn on. Well, as luck would  have it the on/off switch is inop. The switch is on the back of a 1M pot and this pot has a split shaft for the knob. I've looked high and low for a suitable sub, without any luck. I do have an Alpha 1M with switch. But is is solid shaft, as all the rest I find. 


Anyone know a source for a 1M (audio or linear) split shaft with a twist on/off switch on it?

[PRR]

Worst-case or quick-fix: slam a hole in the back, put in a toggle on/off switch.

This may even reduce the hum level.

[VMS]

I googled a little and found these options:

not sure if this is lin or log:

http://www.elliottelectronicsupply.com/potentiometers/economy-1-4-shaft-w-switch/1m-meg-ohm-pot-potentiometer-control-with-switch-spst-1-4-inch-diameter-x-5-16-inch-long-shaft.html

Doug has a push-pull pot:

http://hoffmanamps.com/MyStore/perlshop.cgi?ACTION=enter&template&thispage=PotsKnobs&ORDER_ID=!ORDERID!

[eleventeen]

A suitable sub is any old knob with a setscrew. It ain't a '56 Bassman!

[HotBluePlates]

A suitable sub is any old knob with a setscrew. It ain't a '56 Bassman!

Or drill a hole in the side of the knob and add your own set screw?

[eleventeen]

Very difficult. You'd have to drill a slanted and round surface, then tap the hole, no way to know whether the plastic of the knob could withstand the stress. How about changing ALL the knobs?


You could call it a rare variant, instead of a Kalamazoo, it's really a Battle Creek.



There comes a time when you can't spend (and certainly can't charge for) $50 of time to fiddle with a knob. When you can buy chickenhead knobs for $3 which used to cost 25 cents.

[eleventeen]

'nother thing you could do is to go to your local e-recycling joint and swipe some knobs off some trashed piece of gear.

[mresistor]

thanks guys    I have to talk to the owner first  was just trying to find a suitable pot with switch,   I already have another knob for the solid shaft, but it is not a match.
VMS  thank you sir, that pot may just work ..    '

[mresistor]

As well, I am going to ask the owner about opening up the switch portion of the pot and see if it is repairable.  As well I thought about swapping the pot innards with the alpha pot. IOW  taking the old pot shaft and carbon disc and transferring it to the new alpha housing.


guess we'll see

[mresistor]

gonna change out the tone pot and switch  and put a different knob on it.   .

[mresistor]

I changed out the tone pot w/switch, turn it on, and all I get is hum.  Not good.

[HotBluePlates]

I changed out the tone pot w/switch, turn it on, and all I get is hum.  Not good.

Well, you did go from a dead amp to a humming amp (correct?). That seems like progress...

Now you just have to figure out if the amp woulda hummed had it been able to be turned on before.

[shooter]

instead of a Kalamazoo, it's really a Battle Creek

I live about 15 south of BC, It was probably built in a back-room at Kellogg or post, by a disgruntled line worker that wanted to become a Rock-star!

I've brought 2 of them back to life, can't find my notes, I know I re-wired both, swapped out ugly parts, I believe one is still used by a harp guy in OH

[mresistor]

What would you expect?  The first capacitor (20uf) after the rectifier is shorted.   I'll disconnect that section and wire in a replacement (which I already did temporarily) and be done with it. Tremolo is strong as heck on this amp.

[HotBluePlates]

... Tremolo is strong as heck on this amp.

Trem always is on an amp which modulates bias of a preamp tube to inject the trem.

The tradeoff is increased risk the trem will induce background "beating". There's all kinds of trem circuits developed specifically to address that issue.

[mresistor]

Thanks HPB


Eleventeen -  I suggested to owner your suggestion to switch to all chicken head knobs, for instance.   Good call I'd say.