Baldwin Discoverer tuning pot

[dukeofearl]

this is not a very common keyboard and i can't seem to find a schematic. when i got it, it was out of tune and i located the tuning pot inside (the silver thing with blue and red stripes). i had no trouble tuning it with an allen wrench. now it's out of tune again and it won't turn at all. must be really soft plastic that stripped because i didn't use much force at all.

anyone have any idea where to find a part like this without a schematic? or a more robust replacement? thanks!

 

[scott2000]

Maybe you can get lucky and get a reading of the outer legs of the trimmer to get a value and try whatever you can find for a replacement to see if it'll work?

 

[Brian Roth]

Those parts require a plastic adjustment tool versus a typical metal allen wrench.

Bri

 

[abbey road d enfer]

anyone have any idea where to find a part like this without a schematic? or a more robust replacement? thanks!

You don't need to replace it with the same exact part. Just usolder it, measure it and then look in Mouser, DigiKey or similar for a trimmer of same value and similar footprint.
You could even replace it with a standard pot wired with leads and install it on the rear panel for immediate access, although I don't think it is necessary.

 

[dukeofearl]

thanks, i'll give that a shot

 

[rogs]

That looks more like an IF style coil or transformer than it does a trimmer pot?
Many keyboards of that era (mid 70s pre MIDI) used a top octave synthesizer chip - like the MK50240 - to act as a master tone generator.
That technique would require a master oscillator that ran at around 2MHz, and often used either a crystal or a hi stab LC oscillator for tuning accuracy.
Sounds like you may have an LC master oscillator here?....

Without a schematic or part number it's going to be difficult to match that coil/transformer precisely.
What you could probably do is find the ferrite core slug from a similar sized device and replace that.
(As already described, you're going to need a non ferrous trimmer tool to tune it.)

When I say 'similar', you may find the core from an IF transformer will do the job? You can find those on Ebay.
(Typical UK source HERE - I'm sure there are similar US sites?... )

 

[JohnRoberts]

+1 Sometimes you need to use plastic tools to adjust such trims so the metal tool doesn't affect the circuit.

JR

 

[Brian Roth]

+1 Sometimes you need to use plastic tools to adjust such trims so the metal tool doesn't affect the circuit.

JR

.....or crack the brittle core.

Bri

 

[dukeofearl]

i think this might be beyond my capabilities and i ought to take it to a professional. or put it in the closet and not think about it.