U23, the CA3046 transistor array to the bottom left, wasn't properly soldered in. So this was one of the first things I fixed. I of course socketed it, which meant that taking it out of the circuit was a no brainer. Not the fault.
Q13 and Q14 also checked out fine. Next instinct was U14, the SN75107 line reciever. I've seen a lot of bad 75 series parts. Taking it out of circuit didn't bring the rail back to 5V either.
Q13 and Q14 also checked out fine. Next instinct was U14, the SN75107 line reciever. I've seen a lot of bad 75 series parts. Taking it out of circuit didn't bring the rail back to 5V either.
It can run on both AC as well as DC. To achieve this it rectifies the AC into DC and then uses the DC in a very early switch mode power supply. The connections that go to the board to the left only go to two rectifier diodes that were placed on there. The board on the right generates an ~8 kHz switching signal to drive T1, T2 which then drive the transformer
Except the oscillator was dead as a dodo.
Except the oscillator was dead as a dodo.
Fixed: my Exact Model 127 Sweep generator.
Really neat thing to have. Where before I used two function generators cobbled together to sweep the IFs of the little Radiola radio, this does everything in one unit, as it provides the ramp of the sweep at an output. You can also precisely dial in the start or stop frequency, and it can do bursts and pulses.
So why didn't I use it? Because it was broken
Really neat thing to have. Where before I used two function generators cobbled together to sweep the IFs of the little Radiola radio, this does everything in one unit, as it provides the ramp of the sweep at an output. You can also precisely dial in the start or stop frequency, and it can do bursts and pulses.
So why didn't I use it? Because it was broken