Wrong voltage when testing the CORE and SID

MIDIbox SID
1

Hi,

I’ve sorted the PSU and am getting the 14v and 5v needed but my CORE and SID are not showing the right voltages.

The CORE module shows the following:-

IC1:MCLR(1) - IC1:Vss(12) = 5.16v

IC1:Vdd(11) - IC1:Vss(12) = 5.16v

IC1:Vdd(32) - IC1:Vss(31) = 0.06v ???

IC2(8 ) - IC2:(5) = 5.18v

The SID module shows the following:-

IC1:Vcc(25) - IC1:Vss(14) = 0.70v  ???

IC2:Vdd(16) - IC2:Vss(8 ) = 2.55v  ???

IC3:Vdd(16) - IC3:Vss(8 ) = 3.58v  ???

What should i do?

Also there is a kind of crackle noise (like flux melting) when it’s turned on, what could this be?

Thank you

Chris

2

Hi Chris,

it seems, that a track between the 7805 and pin 31/32 is broken, this might affect port J10 as well, accordingly the supply of the SID module

You can follow the tracks with the probes of your measuring instrument in order to find the location, where the track is broken or “interrupted”. It could also be a bad soldering joint, but this is hard to say w/o knowing, which board version you are using

Best Regards, Thorsten.

3

it seems, that a track between the 7805 and pin 31/32 is broken, this might affect port J10 as well, accordingly the supply of the SID module

I’ve taken the 7805 out and bridged holes 1 and 3. Thats right isn’t it?