(03-01-2016, 10:57 AM)Roman Ships Wrote: Regarding the replacement of the ceramic caps C101 - C104 to 250pF.
What about that big mess of ceramic caps on the end ? ( 1971 v4b )
C108 - C110.. I think. The big discs in row there.
Replace those with Silver Mica as well? Stock values or change?
(03-07-2016, 04:30 PM)Hangman Wrote: which caps are you talking about? I don't see C108-110 on the schematic at first glance.
Sorry I didn't reply sooner. Got lost in the shuffle until Steve replied and I checked into it.
Those are part of the ultra low circuit in a V4*B*, along with C101-104. They cut lows. They're after the tube stage's coupling cap, so you can use LOWER voltage through-hole caps that aren't ceramic, rather than high voltage caps. Those should be even smaller than the originals, per what I have on hand. Might be worth replacing them, as "Some ceramic materials exhibit some piezoelectric effects, they can be electrically sensitive to vibration and shock" - though most people don't use the ultra low, so they'd usually at least be out of circuit. Quote credited to Harry Bissell (a really cool and knowledgable dude who I have traded many emails with), from this link http://analogrules.com/capacitors.html.