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Hello...
I'm working on a MB DC-3 with a strange problem.
The power supply to the 5 band EQ is out. According to the MB schematics, the low voltage supply (marked 'F') feeds the EQ's transistors with -13 VDC. There is no negative voltage to the transistors in this amp, but all the transistors are OK.
The -13 volt supply drawing shows two 220uf 63V power caps with a 3.3K resistor between the two. One cap has -17 volts, so that one is OK. The other doesn't. You say... then the 3.3K resistor between the two caps is open. I say so too.
Here is the problem... WHERE IS THE RESISTOR??? The amp uses a doublesided PCB and doesn't have the component locations marked on the board... too easy to fix then. I have desoldered the parts in order one at a time looking for the trace, used the 'bright light trick', but no avail.
It's driving me sane...
Does any of you have experience with this amp? Would any of you know where this resistor's actual location is on this PCB?
Thank you,
Ken
I'm working on a MB DC-3 with a strange problem.
The power supply to the 5 band EQ is out. According to the MB schematics, the low voltage supply (marked 'F') feeds the EQ's transistors with -13 VDC. There is no negative voltage to the transistors in this amp, but all the transistors are OK.
The -13 volt supply drawing shows two 220uf 63V power caps with a 3.3K resistor between the two. One cap has -17 volts, so that one is OK. The other doesn't. You say... then the 3.3K resistor between the two caps is open. I say so too.
Here is the problem... WHERE IS THE RESISTOR??? The amp uses a doublesided PCB and doesn't have the component locations marked on the board... too easy to fix then. I have desoldered the parts in order one at a time looking for the trace, used the 'bright light trick', but no avail.
It's driving me sane...
Does any of you have experience with this amp? Would any of you know where this resistor's actual location is on this PCB?
Thank you,
Ken
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