Mcintosh MC30s Restoration (Looking for correct schematic)
- Thread starter Tysen
- Start date
Here's the cap in question.
Also, don't forget that R19 and R 20 , (12K 2 watt), need to be matched to within 1% of each other, and not just 1% tolerance resistors. Very important.
This version has a lower voltage tap for bias, so a 22uF/ 250V elyticap will be fine here. You could do likewise at C4.
Modern elyticaps are more compact for value than vintage types, a moderate increase is ok and advisable, but no need to go crazy with a huge increase.
It met specs with those type, no reason not to use them if you have them.
The 160P caps are generally ok to keep unless known defective.
You really would benefit from the higher value and reheating the terminals to replace the cap later just stresses the metal. Wait f you can, but not the end of the world.
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The resistor can go to either end, I put it at the output end, which is the non-banded end for a negative bias source. The banded end would go to the AC source.
On those examples, yes.
The 40uf is for C12A. Connect the 80 & 30uF sections together for C12B. The 20uF is C12c. That's how I've wired all of mine. Others may do it differently.
Smoke test? 
Bring it up slowly on your variac and carefully check voltages - with one hand!
Bring it up slowly on your variac and carefully check voltages - with one hand!
That's a cap, just looks a resistor.
