Rhodes Chroma Polaris

> From: skyrunr
> 
> Thank you.  I've soldered chips into memory boards to upgrade 
> RAM, but that was twenty years ago, and it took three 
> attempts because I put the iron through the board near the 
> end of the batch.  I would have to get a better soldering 
> iron for sure.
> 
> My membranes are in great shape as is the board.  I was 
> really frustrated with the grounding cords being so short and 
> even inadvertently pulled on them a few times.  (another WHEW!)
> 
> I've been looking but I can't find much info on how and which 
> caps to replace.  Are they basically all the orange ones 
> mentioned in this photo?  Is it as simple as heating them up, 
> carefully removing them, and replacing them?
> 
> http://www.polkadotdictator.net/kss/polaris_4.jpg

I think the earlier post was probably referring to the big caps on the power
supply. The orange ones are the sample and hold caps, and while they can
make the instrument go out of tune, they can't prevent the computer from
running and the panel working.

The first thing to do is to reseat every connector in sight inside the unit,
since that wipes any accumulated dust or oil off the contacts. That includes
socketed chips, but the only ones that could prevent the CPU from working
would be over on the left side of the main board where the computer is.

But it makes me wanna cry to imagine someone going through the Polaris
replacing things willy-nilly, with no diagnosis. You can't do a full
diagnosis without a scope, but you can diagnose some things with only a
multimeter. You can check the power supply voltages. You can check for bad
power supply ripple if you put the meter on an AC voltage scale and use a
capacitor (maybe 0.1uF) in series with the meter to probe with (it should
say zero, once the cap has charged up). You can check that the DC OK and AC
OK lines from the power supply are going high and not chattering (they
should read a full +5V). You may find one obvious thing wrong, and be able
to fix it, but don't count on it.

-- 

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@...tcom.com