Stereoboy70
Active Member
Hello all in the audio world. Quick question. Does anybody have any experience with the Marantz PM 700 ?? I picked up this unit for about $50 and the right channel was in and out. I have literally replaced pretty much every component in the R channel and I still have a short somewhere. The culprit I thought was R758 and the output transistors. Nope. New Q725-728, and all the other transistors. All new resistors. All new caps. All new diodes except the ones
against the main heat sink. I think theses are some sort of varistor. DBT still glows really bright at power up. I plugged it in to the wall and R 758 (the one in question) smoked. Not sure where to go from here.
The components that I didn’t replace spec out good. I’m pulling out the little hair I have left. Thanks in advance.
PS: There were some diodes on the back side of the board soldered in across some points. They were 2 diodes facing each other. Not sure what this was for. Total of 4 jumpers using diodes face to face. I did not put these back in.
Not on the schematic anywhere.
against the main heat sink. I think theses are some sort of varistor. DBT still glows really bright at power up. I plugged it in to the wall and R 758 (the one in question) smoked. Not sure where to go from here.
The components that I didn’t replace spec out good. I’m pulling out the little hair I have left. Thanks in advance.
PS: There were some diodes on the back side of the board soldered in across some points. They were 2 diodes facing each other. Not sure what this was for. Total of 4 jumpers using diodes face to face. I did not put these back in.
Not on the schematic anywhere.