Janis Interphase 1A schematic
SeleniumFalcon
Posts: 3,690
With the possibility that this information might be helpful to someone who is trying to repair their Janis crossover amplifier here is the schematic drawing of the amplifier section:
Comments
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Since the circuit board doesn't have the part numbers on it I made a parts location guide:
The remaining three transistors, Q8, Q9 and Q10 are located on the two heat sink assemblies, with Q8 and Q9 together. -
Thank you! Now I just have to figure out how to run through and check what's going on. I've never diagnosed an audio circuit before. One thing I do know - watch out for capacitors - particularly big ones. Going to check out YouTube or other self-help sites. Any troubleshooting suggestions would be much appreciated. Even basics. To start I intend to find and test power supply levels - I notice that VCC and VCC1 are at +51V and -51V respectively.
Note: When I turn on the Janis Interphase 1A amplifier when connected to the Subwoofer, I can hear a distinctive thump from the driver/speaker. But when I try to drive the Janis from the subwoofer-out (on the surround sound source amplifier - 3SA) I seem to get nothing. Substituting in a different (working) sub and I do hear the test signal from the 3SA. These components are all original and old - from the very early 80s, late 70s. -
I'm glad the information was helpful, the Janis is an excellent subwoofer and should be preserved, if possible. The turn on thump is a good sign, hopefully the problem is easy to solve.
