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Plus/512/128 AB brightness potentiometer replacement?

cheesestraws

Well-known member
I have a spare AB here that has a broken potentiometer; it's obviously been dropped on that corner at some stage and there's a physical crack through it.  I can see it's 1MΩ and it looks like linear, but does anyone know what power rating it is?  And, indeed, does anyone know of a suitable replacement before I start measuring things?

 

apm

Well-known member
At 1MΩ there won't be any significant power flowing through the pot. On the SE/30 at least, the voltage that drives the brightness circuit is measured at 106V (according to BOMARC). If the whole voltage was applied across the pot you'd have about 10mW of power, but as the circuit is designed, the pot doesn't even see all of that. So just look for something with the right shaft and pin spacing. 

 

cheesestraws

Well-known member
Excellent, thankyou.  I thought that might be the case but I have a standing rule to get a second opinion on any repair I attempt at > 24V ;) .

 
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