Marantz 2215B: WEIRD Distortion

[kasbah512]

Above I have my scope attached to the volume pot in yellow, and the output of the toneboard in blue. This is with a low volume setting

This is with a high volume setting. Ive tried disconnecting the jumpers on the toneboard output and i still get the same output as before.

The unit was serviced prior, however, the orientation of all the capacitors look correct after a glance at a few original boards on ebay. The treble and base pots are all ok and giving the correct ohm readings. not sure if i should salvage the tone board, or just buy a new one at $35

 

[kasbah512]

*** Update: The previous tech installed two caps incorrectly on the power supply. Fortunately nothing went boom. They are incorrectly marked on the silk screen if anyone runs into the same issue

 

[Mumbles]

Another good reason to always mark the orientation of the caps on the board before removing them. Clear digital photos can also be used for later reference.

Silk screen and service manuals can both have conflicting information as to layout of the components so replacements should be installed the same way as the originals.

 

[kasbah512]

The only strange thing im noticing now is an inverted signal between input and output of the toneboard. Not sure if this is a design issue or not, and if its worth correcting. The signal appears to pass through a ceramic capacitor.