Yep, same issue with the motor on the KENWOOD KX-9010 that I talked about in the DR-2 video. Cleaning didn't help, and it seems that lapping the commutator is not helping either. My theory is that there might be the brushes that are the fault. I did examine them closely, and the black section (which doesn't look like graphite to me, despite what my friend and I initially thought) is scratched unevenly, like very rough. Like it's tearing off the fingers of the brushes, and bellow we see the silver. That might explain why it has a dead spot in play, because of the direction. I mean, I have transplanted brushes before with great results, so this is the next thing for me to try. But if it's the magnet that's gone weaker (which to me at least should struggle to turn in both directions, not just the play/forward), then we are screwed. But I don't think that's the case as of now, it's the brushes IMHO. This excessive current draw and thus voltage drop (I do get 4.8v in FF, 4.2 before I cleaned the motor, where it should be 5.6v) can only be explained with high resistance on the brushes to me. So, option A is to try and "remove/polish" the "black stuff" on the brushes and see if there is a difference. And option B would be to transplant brushes from a different motor. On a few motors I actually cut off the brushes and soldered the contact pieces from another motor, and that "solution" is still working perfectly, it's tricky to align them though, they need to be perfectly straight and perpendicular to the rotor. The obvious other option is a donor motor if those things are not viable, but it needs to be the same motor, because other motors for some reason don't work well in this mechanism - there is noise introduced to the signal. Now, the KENWOOD decks I've mentioned have a couple of inductors in series in addition to the ceramic bypass capacitor between the supply pins, so that's a food for thought. Anyway, thanks for the video as always. At least we have a full disassembly video for this mechanism, which is not complicated, just... very annoying in some aspects.

@mrnmrn1

10 ай бұрын

This is the weirdest issue I've ever seen with a brushed motor. Every motor with a dead spot that I came across had worn and/or oxidized commutators and brushes, and the dead spot was caused by bad contact between them. The fact that this one draws excessive current while stalled on the dead spot is an evidence that the brushes make good contact with the commutator. I don't understand either how a weak spot on the magnet would cause a dead spot in only one direction. Might worth a try to transplant a magnet (together with the motor shell) from a generic motor with the same diameter and same number of poles, if such thing exists/available. The position of the magnet poles relative to the position of the brushes is important, so it might not be an easy task to find a good replacement. And if this is indeed a weak magnet issue, any replacement motor would be questionable, even NOS ones, because they can also have a weak magnet if there was some issue with the magnet material Sankyo used at the time, or with their technology they used to magnetize the virgin magnet rings. I wonder if the reel motor from a Sony TCM-190 transport is a usable substitute. Cheap, dead decks with that transport are avaiable, and the reel motor rarely fails in them (it is probably a Panasonic motor, because the capstan motor they used is also Panasonic). I always buy any Sony TC-W320 decks that are cheap, exclusively for parts. They are useless non-auto-reverse double decks, but usually very cheap because of that, and they have the same transport (two of them!) that Sony used even in some of their 3-head decks, like the TC-K511(S), which is by the way a very good sounding deck with this mediocre, dreaded TCM-190 transport.

The same Sankyo mechanisms have been used in many models of tape recorders. Top Kenwood, Onkyo,Teac,Nakamichi and many others. And in all models, the same problems with the motors appeared over time.A great video can tell you more about tuning a tape recorder using test tapes. Regards.👍🏻👍🏻👍🏻

Thanks for video. many dificult machanism for repair. love from India 🙏

check if the back motor plate is aligned with the motor housing.

@glennlove461 my thoughts exactly. One of the BX300's I have was actually running it's reel motor backwards because the person who cleaned it installed the plate 180 degrees from the original position. The back motor plate must be aligned precisely with the magnet poles to make sure the switching between the coils happens at the right angle between the rotor and magne field. The magnet is a simple N-S magnet, unlike those of brushless motors or hall effect FGs usually found in VCRs, the only way it could be to blame is if had itself become loose from the housing.

@hifirulezzz

10 ай бұрын

Actually I checked the magnetic field of that motor and it just has one magnetic spot, the opposite side almost has no field. In other motors I checked field and it has two strong poles. That why I made this conclusion.

@mihaischitcu1917

10 ай бұрын

@@hifirulezzz Wow that's really strange.... it means that it must have very weak torque to begin with. The only thing I can think of if you want to try it is this: set the voltage to the minimum that supports free rotation, and try to rotate the back plate in small steps, find a position that maximizes the speed (and minimizes the cogging, of course)

@hifirulezzz

10 ай бұрын

@@mihaischitcu1917 back plate has two positions. You can not just rotate it.

The 3 grooves between commutator bushes need to be scraped to remove any contamination or dwarf dust etc

@Astralify

10 ай бұрын

Yes, sadly it doesn't help, because I did clean them really good. As far as I understand the "dirt/dust" is conductive, so it will be sorta shorting the plates. But at least in my situation, that didn't entirely fix the problem sadly.

@hifirulezzz

10 ай бұрын

I did scrap twice and checked with lenses. Did not help.

@darinb.3273

10 ай бұрын

Well you guys covered what I was going to suggest 😂 I suppose magnets will become weak or lose the magnetic field. I had a thermostat that that happened to. It used the same thermal spring but instead of a glass mercury filled bulb it had two magnets and contact points the thermal spring would put enough force to make the center flip to the other magnetic. The material they used for the magnet became weak and the switch part wouldn't maintain enough pressure for a solid contact connection. What was happening, when the call for AC was engaged, it would get close to satisfying and the connection would be lost the switch would reconnect again and the compressor would stall. My particular system needs approximately 3 minutes before the compressor can be started again. I discovered this while I was outside. I heard the contactor flutter then it all made since.

To me, it seems like it might be a problem with the permanent magnetic field in relation to the electric magnetic field. Especially seeing how you have more torque in one Direction. It’s not getting the right push when it’s running in the slow direction. I would mark the back plate of the motor and then rotate it one tab. Try all four positions to see if that makes any difference. If that doesn’t work, I would just rotate the back plate a little at a time and keep checking to see if it seems to work. Specially, seeing how you have nothing to lose.

The brass nut is correct and used as a spacer only

@hifirulezzz

10 ай бұрын

Yes, it is on the diagram. I did show that.

Hi, same problem with TEAC V-5000, some time motor is correctly supply but stuk stop, some knoking on motor an than restart...motor is very under traking load in PB also drive FFWD and FREW...i'm looking for new one...good luck

i had the same on my Teac withy similar transport and same motor, i have replaced the motor for the another one and problem solved, apparently with a time magnets gets weaker but because i found another motor so i didn’t search how to fix motor as all cleaning and polishing didn’t help.

You can find NOS Mabuchi RF-510T. It fits good and works well.

@hifirulezzz

10 ай бұрын

Thank you

@RDM-CassetteDeckRepairs

10 ай бұрын

@@hifirulezzz Also if you get them NOS, they will need oiling. Theese motors don t require opening to oil both bearings. Push the back metal ring so it s slightly horizontal and oil will seep in easily. Apply oil on one bearing and wait 3-5h with the oiled bearing facing up, elsewise the motor will get noisy again in a few months.

@RDM-CassetteDeckRepairs

10 ай бұрын

@@hifirulezzz You will also see as hours pass by, there will be less and less oil.

That brass nut you said wasn't original is actually meant to be there. They fit these as a spacer on all the Sankyo mechanisms as standard for some reason. I've seen this on many of the mechanisms.

@hifirulezzz

10 ай бұрын

I have said that it is original and even displayed that nut on the assembly diagram.

@johnnyg1700

10 ай бұрын

@@hifirulezzz Yeah, I typed it the moment when I saw it in the video. I didn't wait until I'd seen the whole video. I jumped the gun a bit!!

do you know were i might be able to obtain a replacement reel motor for a nakamichi BX-300 cassette deck

@hifirulezzz

6 ай бұрын

I would love to find myself. Nothing yet. Donors likely have the same issues.

The same mechanism as the TEAC model, V-8030S !!!!

@hifirulezzz

10 ай бұрын

Yep, Sankyo transport was installed in multiple brands

Hello! Has a solution been found for that motor issue? Additionally, I'm experiencing a problem with my Onkyo 2570 cassette deck. When I press "Play" or "Fast Forward", the deck stops after about 3 seconds. I've cleaned the motors, but the issue persists. Do you have any idea what might be causing this or any suggestions on how to fix?

@hifirulezzz

7 ай бұрын

As you may seen, control motor issue was solved by cleaning g and lubrication, as for your deck other issue, check if reel motor stops at the dead spot- frequent issue with these tape transports. The only way to solve is a reel motor replacement, as the root cause lies in the demagnetized motor permanent magnet.

@globusglobus1540

7 ай бұрын

@@hifirulezzz Thank you!

@globusglobus1540

7 ай бұрын

@@hifirulezzz Are there any alternative motors available? I believe the original ones are no longer obtainable

@hifirulezzz

7 ай бұрын

@@globusglobus1540 i have not met any. Find a donor deck.

mecha is ALPINE...made...

@hifirulezzz

4 ай бұрын

No, it is Sankyo