filter trouble

[maththeband]

hi,

i have been through eight 6581s and two 6582s and so far every single one of them are showing faulty filters when testing them with my midibox

very loud background noise when filters are activated, and the oscs are extremely quiet, almost inaudible.

is it possible i have done something wrong in the build? i have made sure the jumpers are correct, i am using a regulated 12 volt supply, i have checked the voltage at all the points, and i cannot see anything wrong

of the sids i have tested, 4 of them were supposedly tested. i just got two from the folks at hardsid. the other 4 sids, i was given for free and figured they were most likely faulty.

has anyone heard of a mistake that could be blowing the filters? i dont want to keep trying sids if there is a chance there is a problem with the build....

[Hawkeye]

Hi,

do you have another means of testing the filters? E.g. a real C64 with MSSIAH would be great...

What kind of capacitors do you use for the filters? They probably should differ from 6581 to 6582/8580.

Other than that, it would be interesting to measure voltages on the SID socket (with plugged in SID), while the MIDIbox is playing and the SID filter is turned on... check between PINs 14 and 28 and 14 and 25.

Bye,

Peter

Edited July 3, 2012 by Hawkeye

[TK.]

very loud background noise when filters are activated, and the oscs are extremely quiet, almost inaudible.

Since you've already tested the 12V voltage, it's very likely related to the caps.

E.g. if no caps are connected at all, it would sound like described.

Best Regards, Thorsten.