Restoring Toshiba Kt-RS1 - A Naive Endeavor

Valentint. There are two capacitors in the motor governor circuit. Have you ever needed to replae them?

 

Never needed to replace any capacitor on these models, but there is always a possibility of some caps failing.
Generally speaking, high W&F is caused by mechanical problems in the vast majority of situations.
Hence why I usually won't even suspect the servo unless I'm sure the mechanism is working flawlessly.

What brand are the caps ?

 

gears and retainers arrived. No wonder the photo in the ad is not too good. these things are really tiny.

 

Better late than never

 

I've picked this project up again. I bought a FIIO-CP13, measured W&F at 0.27 with NAK-T100 software, and on advice from another user, ran it without tape for twney hours and now W&F is down to 0.193 which is better. I've been assured it will continue to improve, but only slightly, with use. Having this wonderful expereince I decided to rebuild one of the better of the other 4 KT-RS1's I have. From experience with first one which runs, plays with great sound, but had 0.4 W&F which I suspect is from inadequately cleaned rollers - although goo removed, not ll of the corrosion was fixed.

First is to clean up the best motor. On the advice of Perplexity, I soldered a 10 Ohm resistor to the positive lead of each of the three motors I wanted to compare, and hooked up my Tek 2445B Oscope across the resistor while I fed 3 volts to the motor. See screen shots for what sort of plot I got. After oiling each of them, the plots looked a lot better and I was able to choose the motor which had the least corrosion for use in the rebuild. I 3d printed a fixture to hold the motor so that I can use it as a lathe to clean up the pulley, first with a swiss needle file and then 1000 grit crocus cloth. EVER SO GENTLY since I'm looking for the working surface to be concentric to the shaft. I'll drive the large pulleys with a HOTO grinder so I can clean them up. Tech-Moan is right about the Acetone, it mostly works on the black stuff but does nothing to the corrosion. I'm skeptical that he was actually able to get good surfaces through the corrosion doing it as he showed on his genrally excellent uTube demo.

If you haven't already discovered this some AI's can read scehematics, or at least Perplexity.AI, the one I use can. I scanned the governor section of the main-board schematic, uploaded the scan to Perplexity and asked how it worked. I got a terrific response and concluded that the two caps, 901 and 902 are used for different things and not likely to be involved in W&F problem - much more likely problem with the gears or out of round pulleys due to corrosion.

I've ordered two new belts which the seller assures me are the right ones - the first one worked ok on my earlier rebuild. These belts are square in section, but dimension seems to be contraversial. The gooey ones are unmeasurable, the ones I bought from England appear to be 0.85 mm but I suspect the more readily available 1mm size will also work. I'm going to buy a bunvh and see for myself.