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Scott LK-72 Selector Switch Siezed

goldswimmerb

goldswimmerb

Failed out of engineering, but look at me now!
Subscriber
Hey, so this is a first for me... Have a Scottkit here with a selector switch that seems to have literally turned to stone.

I've tried applying heat, pliers, and even penetrating oil with no luck. Anyone have luck freeing up a frozen switch like this? Literally seems like the thing is glued in place...
Part number on the switch itself is SRW-33-1
 
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Had same problem with treble tone pot on my Dynaco SCA-80Q. Couldn't turn it with small vise grips. Rather than tear it up or out & apart, thus risking buggering the thing beyond hope, I applied heat & PB Blaster penetrant spray. Started trying to rock it not too forcefully, it started to move. Kept at it until the juice thoroughly worked in around the shaft. Freed up as good as new, it's fine to this day. Try to see if one or more of the switch wafers is damaged, you'll need magnifier & something to poke around with that won't cause damage. Ymmv, but worth patience & persistence, just don't force it too hard. Good luck, post results.
 
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Catmanboo said:
Had same problem with tone pot on my Dynaco SCA-80Q. Couldn't turn it with small vise grips. Rather than tear it up or out & apart, thus risking buggering the thing beyond hope, I applied heat & PB Blaster penetrant spray. Started trying to rock it not too forcefully, it started to move. Kept at it until the juice thoroughly worked in around the shaft. Freed up as good as new, it's fine to this day. Try to see if one or more of the switch wafers is damaged, you'll need magnifier & something to poke around with that won't cause damage. Ymmv, but worth patience & persistence, just don't force it too hard. Good luck, post results.
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I have it soaking in a cup of freall at the moment, will check back in 24h, hopefully I'll have some success
 
hope you don't have the wafers soaking in oil. They tend to absorb oil and then you get conductive paths across the contacts when dirt sticks to it. Make sure you hose that down extremely well if those are saturated.
 
gadget73 said:
hope you don't have the wafers soaking in oil. They tend to absorb oil and then you get conductive paths across the contacts when dirt sticks to it. Make sure you hose that down extremely well if those are saturated.
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I'll be spraying the wafers down with isopropyl most likely, and follow up with contact cleaner. Was able to finally get it free after several hours of soaking and a lot of heat.
 
gadget73 said:
hope you don't have the wafers soaking in oil. They tend to absorb oil and then you get conductive paths across the contacts when dirt sticks to it. Make sure you hose that down extremely well if those are saturated.
Click to expand...

Also, while is would like to keep it fairly original, what modifications, from a reliability standpoint are reccomended? My unit seems to be a later once from what I read, based on the OPTs having equally sized ends.

I was planning to replace the cans, replace the smaller caps (I assume they're film), replace the selenium rectifier, and test resistors as needed.

I noticed there is no bias adjust? Is it OK to leave that as is or should I be modding one in?

I don't get too much tube stuff outside of Dynaco ST-70s around here.
 
I don't know Scott stuff specifically but there are a fair number of Scott owners here. There is also the production equivalent of the LK models. Not sure if this is a 222 or a 299 though.
 
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