allanmatters112
Member
Hmm never mind I found it . It's located in Chennai. Il try to get a schematic
Nakamichi repairing/ servicing professional in India
- Thread starter TD150
- Start date
There are located in Chennai. You need to carry it to them.
allanmatters112
Member
Ok so I got the deck back from the technician . Apparently all work he did was put a jumper wire for the middle leg of transistor q407 as the board was a little worn out . And fixed a motor .
He says q407 and 408 is good and no need to replace them . I had asked him what happened or where he got stuck , he simply answered it's not in his level .
So he fixed a motor he found himself on the chassis (rf 500tb 14415 made in Malaysia) and it's just there fixed in the deck . Plus I purchased 3 more motors from lamington road all different brands . One is 9vdc
So now I have 4 motors including the techs motor he has left in the deck .
But my system is the same . The reel motor runs continuously when you switch on the system without anything pressed I.e play fwd or rwd . And when u attempt to press Play fwd rewind the motor does not respond it's just a spinning continuously until I power off the system .this has happened because I kept touching the negative terminal to the chassis from the motor , so it has short something somewhere . Surprised the technician gave up .
Where should I start ?
He says q407 and 408 is good and no need to replace them . I had asked him what happened or where he got stuck , he simply answered it's not in his level .
So he fixed a motor he found himself on the chassis (rf 500tb 14415 made in Malaysia) and it's just there fixed in the deck . Plus I purchased 3 more motors from lamington road all different brands . One is 9vdc
So now I have 4 motors including the techs motor he has left in the deck .
But my system is the same . The reel motor runs continuously when you switch on the system without anything pressed I.e play fwd or rwd . And when u attempt to press Play fwd rewind the motor does not respond it's just a spinning continuously until I power off the system .this has happened because I kept touching the negative terminal to the chassis from the motor , so it has short something somewhere . Surprised the technician gave up .
Where should I start ?
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allanmatters112
Member
So the technician fixed a Mabuchi RF500TB 14415 motor on the chassis . Is this appropriate?. I am trying to find the voltage rating on the internet but can't seem to find it . Some sites are saying it's a max 9vdc and some are saying it's 12vdc max volts
I read on a thread on tapeheads that someone used the same one for their nakamichi mr1
http://www.tapeheads.net/showthread.php?t=58115
I read on a thread on tapeheads that someone used the same one for their nakamichi mr1
http://www.tapeheads.net/showthread.php?t=58115
TD150
Active Member
The mabuchi motor should be 12v.
Ok if the q407 and q408 are ok you should get +12v reading on all the motor terminal. Please check.
For start, 1). Just observe when play, ffw, rew,stop button is pressed does the cam motor move and take positions and in play mode the head assy moves up and gets engaged. If it's doing its job, it's ok & if not we need to address this first. If the cam is not positioned in play mode then the reel motor will not get instructions (required voltage) to move.
2). When you press play and the cam moves to play position and if the required transistor (I will need to check the transistor number) does not switch on, the reel motor may not move in play mode. That will mean the said transistor is defective & needs replacement.
We may proceed further after checking these two steps.
Ok if the q407 and q408 are ok you should get +12v reading on all the motor terminal. Please check.
For start, 1). Just observe when play, ffw, rew,stop button is pressed does the cam motor move and take positions and in play mode the head assy moves up and gets engaged. If it's doing its job, it's ok & if not we need to address this first. If the cam is not positioned in play mode then the reel motor will not get instructions (required voltage) to move.
2). When you press play and the cam moves to play position and if the required transistor (I will need to check the transistor number) does not switch on, the reel motor may not move in play mode. That will mean the said transistor is defective & needs replacement.
We may proceed further after checking these two steps.
allanmatters112
Member
No the cam is not moving when I press play fwd or rwd . The motor is just spinning out of. Control . The cam is just not even trying to move when I press play fwd rewind . When I press fwd the speed if the motor slows down . Still the cam is not doing anything
The rattling sound u hear in the video is cause the motor is movingfast at full speed
The rattling sound u hear in the video is cause the motor is movingfast at full speed
TD150
Active Member
Fine.
The cam should move the large flywheel and position it according to the buttons pressed (play, ffw, rev, stop). The cam is still and may be in a position of either ffw, rev, rec or pause. Most probably either in ffw or rew position, that is why the motor moves accordingly.
Just check this, switch off the unit and rotate the large flywheel with your fingers to other direction from the still position. Switch on the unit and observe whether the large flywheel moves and returns to the earlier position or not. If it does we need to investigate (will come to it if confirmed)
Now we need to identify why the cam motor is not moving. I will list down some check points which you can check.
1). Cam rubber belt damaged/ broken/ slipped or not rotating the larger flywheel. You may check the small cam motor which is on the right side (down side), whether the motor spindle rotates or not when you press various buttons. If it moves but does not rotate the large flywheel which may happen if the rubber belt is not proper. If the motor dose not react, then it needs to be investigated (will come to it if confirmed).
2). Check the voltage on the cam motor you should get +12v on one wire and a varying voltage on the other wire (depending on the button pressed). If you are not getting the voltage, check for wires connecting to the cam motor to the circuit and if any broken needs to be fixed.
3). There is a 10k potentiometer near the cam motor which is connected with three wires (red, blue & black), see if the three wires are intact or not and the connectivity through the main circuit to the small circuit (mounted near the cam motor) to the potentiometer is ok or not. If it is broken anywhere that needs to be soldered appropriately.
If all the wires and the connections are ok and if still the motor does not react, just check if the shaft of the 10k potentiometer is properly engaged (and in the right way) with the mechanism of the large flywheel. You can do this by observing whether the 10k potentiometer moves in either direction when you move the large flywheel with your fingers (switch off the unit while doing so).
Get back with these observations so that we can concentrate on shortlisted area.
The cam should move the large flywheel and position it according to the buttons pressed (play, ffw, rev, stop). The cam is still and may be in a position of either ffw, rev, rec or pause. Most probably either in ffw or rew position, that is why the motor moves accordingly.
Just check this, switch off the unit and rotate the large flywheel with your fingers to other direction from the still position. Switch on the unit and observe whether the large flywheel moves and returns to the earlier position or not. If it does we need to investigate (will come to it if confirmed)
Now we need to identify why the cam motor is not moving. I will list down some check points which you can check.
1). Cam rubber belt damaged/ broken/ slipped or not rotating the larger flywheel. You may check the small cam motor which is on the right side (down side), whether the motor spindle rotates or not when you press various buttons. If it moves but does not rotate the large flywheel which may happen if the rubber belt is not proper. If the motor dose not react, then it needs to be investigated (will come to it if confirmed).
2). Check the voltage on the cam motor you should get +12v on one wire and a varying voltage on the other wire (depending on the button pressed). If you are not getting the voltage, check for wires connecting to the cam motor to the circuit and if any broken needs to be fixed.
3). There is a 10k potentiometer near the cam motor which is connected with three wires (red, blue & black), see if the three wires are intact or not and the connectivity through the main circuit to the small circuit (mounted near the cam motor) to the potentiometer is ok or not. If it is broken anywhere that needs to be soldered appropriately.
If all the wires and the connections are ok and if still the motor does not react, just check if the shaft of the 10k potentiometer is properly engaged (and in the right way) with the mechanism of the large flywheel. You can do this by observing whether the 10k potentiometer moves in either direction when you move the large flywheel with your fingers (switch off the unit while doing so).
Get back with these observations so that we can concentrate on shortlisted area.
allanmatters112
Member
Before I check all the things you told me to check . Let me tell you how i got here . Everything was working when I installed the new motor (I.e cam flywheel responding ) Fwd rwd play was working, but all in the wrong directions even though I fitted the + and - terminal s correctly. So I interchanged the + and - terminals on the motor . Then fwd and rwd worked in the correct direction . But play wouldn't work . So to make play work I took an extra wire and connected one end to the chassis (the middle flat plate ) and one end to the negative terminal of the new motor . And pressed play . Play started working(I even played a cassette with the new motor installed this way ) . But when I clicked stop the motor would still spin unless I disconnected that extra wire from the chassis . Doing this experimenting, I accidentally touched the extra wire to the wrong chassis of the deck ( the outer most one ). Thats when everything stopped working (cam does not move no matter what ) and led me to where I am stuck .
Hope this can narrow it down
Hope this can narrow it down
TD150
Active Member
As per your facts, I suppose some parts must have failed/ short (most probably the transistor). To identify it we need to investigate as there are lot of transistors and one IC in the control drive circuit.
The reel motor does not have a negative connector on it. It works like this, both the terminals get positive voltage. If the voltage on one wire is more than the other it moves the motor in one direction (depending on the voltage difference the speed of the motor varies).
eg. If the voltage on wire1 is +12v and voltage on wire2 is +24v, the net difference (+12v - +24v) will drive the motor in either rew or ffw direction with speed. If the voltage on wire1 is +12v and the voltage on wire2 is +10v, the net difference (+12v - +10v) will drive the motor in play with low speed. Similarly the cam motor also moves based on the voltage supplied to its wire1 & wire2.
You need to check the voltage on reel motor's wires and also the cam motor's wires in different modes, without which trouble shooting will be difficult.
The reel motor does not have a negative connector on it. It works like this, both the terminals get positive voltage. If the voltage on one wire is more than the other it moves the motor in one direction (depending on the voltage difference the speed of the motor varies).
eg. If the voltage on wire1 is +12v and voltage on wire2 is +24v, the net difference (+12v - +24v) will drive the motor in either rew or ffw direction with speed. If the voltage on wire1 is +12v and the voltage on wire2 is +10v, the net difference (+12v - +10v) will drive the motor in play with low speed. Similarly the cam motor also moves based on the voltage supplied to its wire1 & wire2.
You need to check the voltage on reel motor's wires and also the cam motor's wires in different modes, without which trouble shooting will be difficult.
allanmatters112
Member
Ok will check tomorrow morning. New problem found. When I press forward button transistor 1061 gets super hot and smoke starts coming . . Will check tomorrow
allanmatters112
Member
Here are the voltage measures for reel motor capstan motor and cam motor (rf-260t)
There is one more tiny motor but that has 3 wires . I measure the outter wires with the meter that is black and red . It gave 15v reading
Reel motor
Idle mode (when you turn system on ) - 6volt
Fwd - 11.5v
Rew - 14.5v
Play - 22.5v
Capstan motor
Idle mode - no reading (which is normal)
Play - 6.5v
Fwd - no reading
Rew - no reading
Cam motor
Play - no reading
Rew - no reading
Fwd - no reading
Idle mode no reading
Tiny motor attached to cam arm
15 volt read on idle mode
15v rewd
15v fwd
15v play
There is one more tiny motor but that has 3 wires . I measure the outter wires with the meter that is black and red . It gave 15v reading
Reel motor
Idle mode (when you turn system on ) - 6volt
Fwd - 11.5v
Rew - 14.5v
Play - 22.5v
Capstan motor
Idle mode - no reading (which is normal)
Play - 6.5v
Fwd - no reading
Rew - no reading
Cam motor
Play - no reading
Rew - no reading
Fwd - no reading
Idle mode no reading
Tiny motor attached to cam arm
15 volt read on idle mode
15v rewd
15v fwd
15v play
allanmatters112
Member
The transistor c1061 which was getting extra hot on fwd has loose solder in the middle leg . I resoldered it .. Although still c1061 is getting
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TD150
Active Member
Ok you didn't tell me
1).
2).
The tiny motor which you are mentioning attached to the cam arm is the 10k potentiometer fixed with 3 wires (red, blue & black). This needs to rotate to adjust the voltage.
1).
2).
The tiny motor which you are mentioning attached to the cam arm is the 10k potentiometer fixed with 3 wires (red, blue & black). This needs to rotate to adjust the voltage.
allanmatters112
Member
Sorry
I rotated the large flywheel with my fingers . Switched on the system , but the flywheel dint return back to it s position. Play fwd rwd don't work also when pressed . The cam motor does absolutely nothing. Even the 10k one
There is no motor movement feeling when I feel it with my finger while I switch on the system . Both the motors 10k one too just dead like
The shaft of the 10k motor is properly engaged . I made sure of this position, that is studied it before dissembling the chassis to take out old motor . So I know how that is supposed to fit in mechanical. as I even took a video and took lots of pictures before dissembling the chassis .the connections are all good the wires are all connected soldered well from factory
I rotated the large flywheel with my fingers . Switched on the system , but the flywheel dint return back to it s position. Play fwd rwd don't work also when pressed . The cam motor does absolutely nothing. Even the 10k one
There is no motor movement feeling when I feel it with my finger while I switch on the system . Both the motors 10k one too just dead like
The shaft of the 10k motor is properly engaged . I made sure of this position, that is studied it before dissembling the chassis to take out old motor . So I know how that is supposed to fit in mechanical. as I even took a video and took lots of pictures before dissembling the chassis .the connections are all good the wires are all connected soldered well from factory
TD150
Active Member
Assuming that the 10k potentiometer is fixed properly in the large flywheel.
Move the large flywheel manually with your fingers to play position (check the flywheel marking diagram on page 16 of service manual) and press play. Observe whether the capstan motor rotates or not.
You have mentioned that the cam motor has no readings in various positions, have you checked individual wire1 and wire2 readings or you did a wire1 - wire2 reading.
Check fig 2.3.10 on page 16 of the service manual. The cam motor control circuit. The cam motor is governed by Q405 & Q406. And the 10k potentiometer.
Please check the voltage from there by tracing the circuit diagram.
Move the large flywheel manually with your fingers to play position (check the flywheel marking diagram on page 16 of service manual) and press play. Observe whether the capstan motor rotates or not.
You have mentioned that the cam motor has no readings in various positions, have you checked individual wire1 and wire2 readings or you did a wire1 - wire2 reading.
Check fig 2.3.10 on page 16 of the service manual. The cam motor control circuit. The cam motor is governed by Q405 & Q406. And the 10k potentiometer.
Please check the voltage from there by tracing the circuit diagram.
TD150
Active Member
To check individual wire voltage, touch the +ve probe (red colour) of the multimeter to the wire while the -ve probe (black) to the unit body (any where on the cabinet, preferably hook it into the chassis screw holes ment to fix the cover).
allanmatters112
Member
Cam voltage 6.5 volts when + Ve is on one wire any of them , and -ve is on chassis . When I press play and do the same thing 3 volts and rewind fwd 6.5v . Both the wires
allanmatters112
Member
Q405 showing 22volts . when I press play 25v
Q406 showing nothing
Q406 showing nothing
allanmatters112
Member
So I changed q407 and q408 . Nothing changed . Everything is the same. I have a new update however. I moved the flywheel to the play marker position with my finger ,while the deck was off . Then switched deck on . Nothing happened . I pressed play the cam motor moved to fwd marker position on its own . The whole cam assembly finally showed some sign of movement . Maybe when I reassembled the chassis the second time I may have moved the flywheel by accident ?
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allanmatters112
Member
Basically the cam motor is allowing the flywheel to be positioned on the fwd marker . Which explains why the reel motor is turning continuously when the deck is in idle mode. Every time I place the flywheel at the play marker and switch on the deck it moves back to fwd position .
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