Not seeing any DC voltage at those points
MixBuzz500 build/support tHread
- Thread starter Igor
- Start date
Help Support GroupDIY Audio Forum:
I checked the continuity through the attack and release resitor banks throught the switch onto the C & B headers. Everthing looks good up to IC7.
moamps
Well-known member
Check that the D6 diode is correctly oriented and that its anode is connected to the attack switch.
Diodes are correctly orientated changing switch from 400 to gssl mode I lose connection with anode of D6 on one board.
Attachments
Probably cold solder joint around switch pad or bad switch which I doubt.
In 4000 mode both CTL 1-10 & 2-10 Make contact with attack switch in GSSL mode only CTL 1-10 makes contact.
moamps
Well-known member
So, is the anode of D6 connected to IC7 pin 12 via attack resistors?
Yes I get a steady buzz from my continuity meter tracing the circuit from D6 anode to CTR pin 10 to attack pole. From there through the various position to ther corresponding resistors R51 through R66 to Pin 12 of IC7.
moamps
Well-known member
Ok, if that's ok, then on pin 12 of IC7 you need to get DC voltage which is negative and depends on the magnitude of the input voltage and the position of the threshold potentiometer.
Still not reading anything on that pin.
Seeing -5.54 volts at CTL Pin 10 full on threshold. Same thing on Attack Switch Pole.
Voltage seems to get lost in the switch going to resistors.
moamps
Well-known member
Is the switch working properly? Check also that pin 12 of IC7 is not accidentally grounded.
Pin 12 is not grounded.
Not sure how the switch could be broken.
Ugh it seems the center pole of the attack switch were I see negative voltage is going to pads on the back of the board that don't have traces to the B header.
Ok adjusted switch back one position with the stop out replaced the stop now I've got connection to traces go to B header.
It's working now.
Thank you so much Moamps for steering me in the right direction to find the error.
moamps
Well-known member
Congratulations! I have to admit you were a great assistant. You owe me a beer 
Similar threads
