464 : Rattling motor and irregular speed

[Tommyjarvis]

Hey everyone,
I just bought a 464 from someone who told me that he just "changed the capstan belt" and replaced the Gear C. Everything seemed fine at first, but after a few hours, the Tascam started to make a strange noise, something like a rattling noise. I suspected the capstan to be the culprit so I opened the machine. Also, the tape were playing very slowly (sometimes it gets so slow that the playheads stops)
Inside, the transport was soaking in some kind of lubricant, (not on the tape heads as far as I can tell) . I took the time to clean as much as I could with isopropyl alcohol.
Once I cleaned the board, the capstan became quiet again but not for long. After a few minutes, the rattling noise came back. At least, speed seem to be normal again but that noise is pretty loud and disturbing (and not normal). I also cleaned the capstan and the belt to no avail, the noise is still here. The tapes are playing normally as far as I can tell. I looked for anything that could generate friction on the belt, the roller or the capstan itself but everything looks fine.
What can I do to make this rattling noise disappear ? New lubrication ? New capstan belt ?

 

[SkywaveTDR]

The rattling noise I have heard from motors come from the cam motors in models not this one. However the same construction of the motor can still be the reason. These motors are cheap and that means not brass bearing in the back. On the motors I have taken out there is a brass cup at the back but it is held in place by nylon ribs that have failed. The motor would spin fine by itself but when a load is placed on it with a belt the noise would be there. I put a motor in a few times with brass bearing on both ends and other than some mounting screw size differences, the motor worked perfectly. This may be your issue- you need to find out where this noise is generated from. Maybe they used garbage lub in the capstan shaft- take flywheel out and clean then use AMSoil 0W30 signature synthetic oil. When I use this oil in decks- a lot of them, the wow and flutter would go down and the speed would have to be adjusted as the friction is reduced a lot. Oil the top bearing of the capstan motor with a drop under the pulley. People that drench a deck in some chemical usually do not know what they are doing which is evident in this unit.

 

[Tommyjarvis]

Hi Skywave,
Thanks a lot for your detailed response and your time. I guess the sounds comes from the flywheel itself (and it is indeed silent when the belt is not on it). I will try to clean and lubricate the capstan mechanism, if that does not work I guess I should find someone that knows this kind of stuff better than I do. Do you know any other brand than AMSoil that could do the job nicely ? (I'm in France and AMSoil is not available in my country).

Also, is it safe to unplug the motor from the board so that it does not spin while I'm using the mixer from the 464 ?

 

[SkywaveTDR]

That would be an extreme doing but the motor being unplugged would not affect the mixer. All you need do is put a switch in line with the 12 Vdc supply to the motor as that would turn it off.
I have not tested other synthetic oils as once I found AMSoil there was no other reason to look further.
Noise from a flywheel is very unusual. I would look for mechanical things rubbing. When grease get hard and this is the grease that should be cleaned out and replaced by Lubriplate 105, the parts that are suppose to return by way of small spring will then return to their proper location while with old grease in there the small spring can not overcome that.