Nakamichi repairing/ servicing professional in India

[allanmatters112]

Changed the 9cm belt . It's actually measuring 11 cm on the ruler . Any way put a new belt almost same size just a .05 % smaller one and the forward works now continuously without load (still feel I need to put a slightly smaller tighter belt ). But if you put a tape in , it forwards the tape and the reels move slowly (little faster than. Playback speed )
Play back does not work . Rewind does not work with load or without load . Idler tire needs looking at . I manually turned the take in reel with my finger with the play button pressed and the head stayed up . It was basically playing (with no load ) .minute I stopper turning the reel manually, the play head went down.(auto shut down mechanism)

Also I noticed the reels are pretty stiff as I turn them with my fingers . Is that normal ? They seem like they could use some oil. But I won't apply any until I know where and if it is ok to oil them .

 

[TD150]

At this stage don't use any oil.
It's good to hear the ffw works, this means the belt replaced on auto shut-off mechanism is working. Just find out whether the tape counter is moving or not. If it is moving then both the belts are ok and making work the mechanism. If the tape counter is still not moving then check the second small belt which is behind the counter and connected to the rear flywheel of the auto shut-off mechanism flywheel. It may be hard/ stiff or disintegrated. Anyway if the deck mechanism works the auto shut-off mechanism is signalling the circuit to stay active.

The idler tire rubber must have become hard like a plastic (in my case it had become like that). This leads to slipping/ no proper grip on reel hubs while making them rotate in some functions (play or rew). If you change this idler rubber to a new fresh rubber, it will take control of moving the reel hubs and your deck might work as it should be.

 

[allanmatters112]

Thank you @TD150 . The tape counter also moved along with the "working" fwd . But the reels seems to go slower after running fast in the forward mode . Tape counter belt seems fine the tension is good .
I need to read the manual because taking out the idler tire is gonna be a tough job .
Yes it is hard like plastic and the brass from the top motor knob has colored it golden . So the tire is barely black and is hard as a rock.

 

[allanmatters112]

I took out the idler tire . It's is hard expired

 

[TD150]

Good going. Take the unit and get the rubber tire of the exact size made.

 

[allanmatters112]

How did you manage to take out the old rubber tire as mine is too hard it's difficult to take out .
Also forgot to mention one thing to you . The capstan belts . Although they turn independently without the pinch roller rolling on them sometimes they don't spin when the pinch roller is rolling on it in play mode . I noticed the belt was slipping from the capstan s behind when I looked. My belts are lose I guess and I hope I could find that size in lamington road .

 

[TD150]

The hardened rubber tire needs to be carefully broken at one side. You can use a paper cutter/ knife/ nail cutter/ etc. I personally used a nail cutter to chip off one side so to easily break open and remove it.

If the capstan belt is slipping and very loose, please replace it.

 

[allanmatters112]

Done . It took 2 hours . I boiled it in hot water first then cut it on one side(was a tough one to take out ). I really do wish I find a ready made rubber tomorrow of the same size . I know you said it's not available, but I know a couple of shops where I purchased tape belts .I will try my luck there .
Will go to lamington road tomorrow morning . Yes I will also take the sample of the capstans belt and try to get that also .

 

[allanmatters112]

I have found a person in lamington road who will make the rubber/tire for the idler . Capstan belts he did not have the correct size so he is gonna make that as well . It will take a few days .

Mean time I have something else on my mind. The control motor. The one which connects to the idler tire . The head seems a little lose in the vertical direction , when you move it up down with your finger . Is this normal ? Horizontal wise it's fine the head is rigid .

Reason I am asking this is because when I was looking at the playback FWD rwd mechanism , sometimes the idler tire would not engage on either the take in reel or the supply reel .(with the old plastic tire). This happened before I took everything apart . So I used to give it a little push from the top from my finger and then it would engage with the desired reel .

I just hope it will not occur when I put the new idler tire . Probably the old tire was causing the issue ?
Have you encountered this ?I tried searching in forum s like tapehead etc there was no specific or similar topic i found related to what I have described above .
Is this normal?

 

[TD150]

The "control motor" as you mentioned should be the reel motor (if an not wrong) should not have any play in it. I didn't quite well understand which way is vertical/ horizontal from your explanation. However if in its fixed position (side ways) the vertical direction will mean it has a play around the motor spindle, which should not be there. Wait until your new idler rubber tire is fixed and see if things work out. I had encountered such problem (pushing a bit the motor spindle to start) but it was another problem. Please check the voltage readings on the reel motor wires and revert.

 

[allanmatters112]

Ok I will check that and update . Yes you have u understood correctly.

 

[allanmatters112]

I fixed everything I could. New capstan belt. New idler tire . New auto mechanism shut down belt . Tape plays but muffled sound on the right channel . treble comes and goes on left channel though sound is louder on left . Left channel is louder than right(rightt is barely heard and muffled no treble ) . Sound quality sounds like an ordinary deck . I cleaned the play head with a cotton bud and perfume

Problem s
Tape stops after 1 min of play back .
Muffled unclear playback on right channel . Using a maxell type 1 tape . Normal bais. Tired 3 different tapes same feed back

Control motor not turning sometimes does not engage idler tire (in play mode) unless I push the control motor head with my finger (reel motor from the top a bit)(this was the vertical lose thing i spoke about before )

Rewind forward is not 100% speed . More like 80% to 85%speed. If I press the head of the control motor during fwd rew then the fast forward and rewind give 100% speed more like 97%

 

[allanmatters112]

Ok the motor shaft must be gone as the control motor does not even turn at times

 

[TD150]

Ok, for the sound quality issue there might be 3 things to be checked. 1). Check the play back head condition (whether worn out), 2). There is a record/playback long sliding switch located towards the left side of the PCB connected by a string to toggle between play / record functions. Switch off the unit and with your finger try to push/ release/ toggle this switch (the switch contacts need to be cleaned), 3). The speed of the reel motor must be varying/ slow down resulting in poor sound.

Try the (2) possibility, which seems to be the major cause of the poor sound problem.

 

[allanmatters112]

If I turn the deck upside down it will be towards the left . This is what I found ..is that the one ? I moved it back and fourth. No difference. The play back speed is fine as I checked the same cassette on another deck
However my control reel motor seems to be an additional issue also . Cassette does not play for more than 2 mins . The motor stops for some reason . Did u face similar problem for your motor ?

Thanks so far

 

[TD150]

Yes it is the one. Toggle it continuously for long time so that the contacts are cleaned. If the head is ok then there might be some problem with the play circuit (which you can check last). Is there any possibility that the play head alignment is tampered? If not don't do it at this stage as it would be difficult to recalibrate it again in this condition.

Try to figure out what voltage reading is there on reel motor in play, ffw, rew mode. And also check if the transistor Q407 which has a heatsink - how much hot it becomes.

 

[TD150]

Please also check
1). when the motor stops whether the deck goes in auto shut-off mode or not.
2). Does the pinch rollers have become hard?

 

[allanmatters112]

I already fiddled with the head alignment. Messed it up . Ok I checked q407 which has a heat sink . It gets pretty hot when system is on . And even HOT when in playback mode rwd mode and fwd mode . I can only touch it for 3 -4 secs max (the heat sink ) or else il get burnt . It's always very hot even in idle mode

Also the transistors middle leg from the other side seems like it has less solder . I moved it but but the solder does not seen lose . I will resolder it

I apologize as I really don't know how to use a meter . I have a meter analogue one but it does not work .my dad know s how to use a meter as he is a tech but little old

 

[allanmatters112]

I re edited my post above . Please read it again

 

[TD150]

Was the Q407 transistor replaced at any point of time? Do check it, because new (non Japanese) transistors do tend to get very hot as more current is drawn through them.

Do one thing, try to add/ wrap additional heat sink preferably the black rubber slab type found in the LCD TV screens ( you will find it a TV mechanic shop removed from old TV). Wrap it on the existing aluminium heat sink and see if the unit plays for longer time.