Hi,
I presently have a par of PA1002 power amps made by Optimation INC. They are very similar to the PA250 with the same lighting lamps. I have tried to restore these to original operation but have had great difficulty getting information from Henry W. I have the circuit diagrams for the PA250, and others in the series that was built by Optimation. Of course, not the diagram for the PA1002. There are differences and errors on the diagrams! I am driving Dynaudio speakers with no sign of stress, but they are easy to drive compared to what you have. According to the infomation manual I have, these amps should drive + or - 1.0 PF, at 250va. In other words, anything. The lights are lite if you draw excessive plate current, and not being an expert in the tube world I would assume some type of mis-match. My PA1002 had impedance taps for 3.75, 16 and 60 ohms. I have seen a host of different tape position availible on different models. I have moded the units with new signal caps, removal of the input pot and cap., new diodes, new Power supply caps., and some circuit changes. I also didn't have the feedback Transformer t3, so it has cause me a great deal of work to make the units sound good. I have bought a Tektronix 4084 distortion analyzer to do some adjusting of the local, global back/forward feed adjustment, but have just recieved the unit an it was damaged in shipping. So I am repairing it first!!!!
Let me know how you get on with them. Do you have any documentation you could share?
Thanks Rob... Not many of us out here working on these thing i guess. Mine sound really fast and clean for tube types....
I presently have a par of PA1002 power amps made by Optimation INC. They are very similar to the PA250 with the same lighting lamps. I have tried to restore these to original operation but have had great difficulty getting information from Henry W. I have the circuit diagrams for the PA250, and others in the series that was built by Optimation. Of course, not the diagram for the PA1002. There are differences and errors on the diagrams! I am driving Dynaudio speakers with no sign of stress, but they are easy to drive compared to what you have. According to the infomation manual I have, these amps should drive + or - 1.0 PF, at 250va. In other words, anything. The lights are lite if you draw excessive plate current, and not being an expert in the tube world I would assume some type of mis-match. My PA1002 had impedance taps for 3.75, 16 and 60 ohms. I have seen a host of different tape position availible on different models. I have moded the units with new signal caps, removal of the input pot and cap., new diodes, new Power supply caps., and some circuit changes. I also didn't have the feedback Transformer t3, so it has cause me a great deal of work to make the units sound good. I have bought a Tektronix 4084 distortion analyzer to do some adjusting of the local, global back/forward feed adjustment, but have just recieved the unit an it was damaged in shipping. So I am repairing it first!!!!
Let me know how you get on with them. Do you have any documentation you could share?
Thanks Rob... Not many of us out here working on these thing i guess. Mine sound really fast and clean for tube types....