R81 Tone Arm Wiring

[jd]

Is it possible to "fix" the phono harness/tone arm or is it in need of replacement when it stops transferring sound on one channel? I see someone has kinda hacked the 7 pin plug by directly soldering 4 jumper leads to hard connect to the tone arm wires. Seems as though this may have been one of the issues that took this juke out of service 30 years ago. The needle has not been changed in at least 30 years, but I don't know if there would be anything in the needle to cause the loss of a channel.

When I switch my tone arm RCA leads in the pre-amp, my problem channel changes sides.

I tried probing the tone arm leads with a Fluke 177 multimeter, but I get resistances that seem to vary from 0 to 670 ohms on every wire which is making what should be a very simple resistance check on 4 wires very difficult.

[Ron Rich]

H JD,
Not quite sure what you are asking here-- Also, I can't recall the tone arm set-up on the R-81. I believe they used the A-MP 4 position connector/header that was used in the later phono's. If true--L@k at the sticky above, citing common plug problems. Have you determined the problem to be on the tone arm side of the plug, or the amp side of the plug? That plug can be jumped-- but then the tone arm is not removable -- wire also can be replaced--but it's difficult to find at this point in time-- The "needle" is most likely not causing this--the cartrige CAN be ? Ron Rich

[jd]

Fixed the problem. Got stumped by multiple problems. Tonearm wiring harness was bad to the preamp. High resistance choked out one channel. Shielding was defeated by the sketchy mods by the last owner on the remaining "good" channel. Power cord for the amplifier ran across the side of the harness giving me a nasty 60 cycle hum on the good side. Then I also had an intermittent connection on the phono coil plug.

I soldered a proper shielded audio harness to the tone arm and now my audio sounds amazing on both channels.