Wobblestone and wiggy made some efforts with reverse engineering the Mk3 audio here:I really would like to change those SMD Ceramic Caps but unfortunatelly don't know the values. Changed 3x47uf 16v, 2x10uf 16v to new ones and the result is the same.
viewtopic.php?p=401542#p401542
RiscPC doesn't have/use -5V AFAIK. Where are you measuring that?Checked IC34 and it has in some pin +12v and in another -12v ( i'm no expert ). All voltages are present +5, +12, -12 , -5v.
That's a series AC coupling cap - you can't measure voltages at it like that (against ground).Also something strange, in the C159 i measure 2.96v on the + side of the cap and -5.95 on the - side of the cap - ODD!!!
My bet would be the amps have blown. They blow quite readily, IME. I've fixed a good number of boards just by replacing those - IC27, IC34.
Statistics: Posted by IanJeffray — Sun Feb 02, 2025 9:19 pm