Caps for threshold sl-10

I am planning to change caps on my threshold sl-10.
How do you determine polarity of "Instrument Devices" caps? There is no polarity sign.
If they are of the film type they are not polarized.

Your question suggests that you are not that experienced with this, have you considered having a local electronics repair shop do this for you ? It may cost a few bucks more but could save you a bunch if you don't get it right.

Best of luck

The old Instrument Device electrolytic caps used in the SL-10 are marked on the positive side. When in doubt, you can always take a digital volt-meter and check which side is more positive or negative. Since my memory can be short, when I do a re-cap job, I'll put a small dot with a Sharpee on board at the negative side of the cap prior to pulling it. Be sure to take a few good pictures as well. Also, be careful with the old Threshold boards. Its two-sided board has plated-through holes that can be easily damaged if you use too much heat or/and force. Suck the solder out first, clip the old leads flush, then reheat and remove the cap.

BTW, there is lots of info in the Pass Labs section of from folks restoring their old Thresholds.

Also, you will not believe how good that SL-10 will sound once it's been recapped with some nice Elna Slimic II or Panasonic FC or FM caps.
I finally reconstructed the power supply and replaced the caps with Elna Silmic II as most of you suggested, including Nelson. My! What a difference new caps made...natural timber, improved dynamics, well defined bass, airy highs....My system literally sings!?!
Thank you.