Guys and Gals i am having quite a strange issue with one of my C-64 Motherboards.
Datasette do not function reason being a missing 6.9 volt line (From 9Volt DC)
Replaced..
Q1 CR1 R1
Q2 R3 Seem fine.
9 volt unregulated is present Q1 Collector and R1 top
No Signal from R1 to base to base
Same issue with R3 +3 present from U6 to the resistor but no signal from resistor to Q3 base.
Resistors are fine Transistors are fine Diode is fine.
While locating reasons for error i noticed if i remove U7 VIC the circuit all the sudden works perfectly but not if VIC is present.. Question is why ?
I see no reason why it would effect the circuit the way it does.
Any tips would be welcome.
Schematic