Hey boombox junkies. A few years back, I got this near mint JVC M70C from a cranky old guy in Waterloo Ontario, Canada which is about 3 hours from my home town of Windsor, Ontario. I met him in the lobby of his building & did not have the opportunity to fully test it out but the deck worked & it got a few stations in stereo so I took a chance & got it home with me since it was so clean & minty looking, overall. About a year ago, I was trying to address the random changing of speed on playback & changed out the motor with one I salvaged from a JVC 838 which has a very similar tape mechanism & the motors are virtually identical in every way between the 2 models. It did not change the behavior at all & it would still start out slow, then speed up after a couple minutes of playing a tape.
As you can guess, I finally got to it in the last couple of weeks & addressed the deck issues it had but all the functions work. I took it apart & discovered the belt had been replaced with a belt that was too thin in cross section which caused the belt to ride one side or the other of the barrel shaped motor pulley. This changed the speed of the tape playback at times, randomly. That's why changing the motor in my previous attempt didn't change a thing. Both motors work properly & it was the incorrect belt causing the issues. I ordered the belts from Turntable Needles as being an FSB 10.2 which worked inconsistently, even though it was the recommended size according the Turntable Needles' belt measurement as verified to be 3-5% smaller than the belt path.
Thanks to other members posting their M70 re-belting experiences, I found out the FBS 9.6 was the correct size for proper operation & ordered the new belts. I installed the proper belts & also oiled the capstan bearings, motor shaft, etc with synthetic machine oil for smooth operation. I cleaned the tape path with rubbing alcohol & tuned the deck using WFGUI & a 3000Hz test tape. It now sounds great & at the correct speed. All functions work great too.
As you can see in the photos & videos, this M70 is very clean & has very low hours of use. The heads look brand new & the sound overall is spectacular, even with a normal bias MAXELL UR60.
The heads are shiny brand new looking & the capstan pinch roller is still soft & has very little tape residue if any at all.
The tires are still good too. Music search, rewind & FF are all working great too.
As you can guess, I finally got to it in the last couple of weeks & addressed the deck issues it had but all the functions work. I took it apart & discovered the belt had been replaced with a belt that was too thin in cross section which caused the belt to ride one side or the other of the barrel shaped motor pulley. This changed the speed of the tape playback at times, randomly. That's why changing the motor in my previous attempt didn't change a thing. Both motors work properly & it was the incorrect belt causing the issues. I ordered the belts from Turntable Needles as being an FSB 10.2 which worked inconsistently, even though it was the recommended size according the Turntable Needles' belt measurement as verified to be 3-5% smaller than the belt path.
Thanks to other members posting their M70 re-belting experiences, I found out the FBS 9.6 was the correct size for proper operation & ordered the new belts. I installed the proper belts & also oiled the capstan bearings, motor shaft, etc with synthetic machine oil for smooth operation. I cleaned the tape path with rubbing alcohol & tuned the deck using WFGUI & a 3000Hz test tape. It now sounds great & at the correct speed. All functions work great too.
As you can see in the photos & videos, this M70 is very clean & has very low hours of use. The heads look brand new & the sound overall is spectacular, even with a normal bias MAXELL UR60.
The heads are shiny brand new looking & the capstan pinch roller is still soft & has very little tape residue if any at all.
The tires are still good too. Music search, rewind & FF are all working great too.
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