Skylab
Watcher of the skies
That could very well be because the PR99 being half-track uses more of the tape than the quarter-track 707, and as such is getting enough good tape that the recording sounds fine.
Pioneer RT-707 service & rebuild
- Thread starter smurfer77
- Start date
That could very well be because the PR99 being half-track uses more of the tape than the quarter-track 707, and as such is getting enough good tape that the recording sounds fine.
Dear frends,
Some days ago some noise (quiet periodic rat-tat) appear from the Capstan Motor of my Pioneer RT-707. The device is in good common condition and not used very much. Can some one to advise me how to disassemble and open the capstan motor.
Thank you in advance
Slavi
Some days ago some noise (quiet periodic rat-tat) appear from the Capstan Motor of my Pioneer RT-707. The device is in good common condition and not used very much. Can some one to advise me how to disassemble and open the capstan motor.
Thank you in advance
Slavi
Hi,
if memory serves!!! It was a LONG time ago. The rotor on the rear needs to be removed. There are grub screw(s) at the centre of the rotor. They may be into countersinks so may need to be unscrewed to the point of falling out. To be on the safe side. Remove them and put them safe. The rotor then slides off the shaft backwards. On the inside of the rotor and on the back outside edge of the motor are the two parts which constitute the Frequency Feedback for the Servo. DO NOT damage either component of the Frequency Generator. If you do, then the motor will be scrap as far as a tape machine is concerned. After the rotor has been removed, the shaft comes out from the front of the machine. The small aluminium cover over the capstan shaft may need to be removed first. I lubricated mine with the fairly viscous high quality oil which I used on my Thorens Turntable platter bearing. I delved in because the motor was running virtually dry and the larger tension at the start of a tape was pulling the capstan overspeed!!! There was a gradual increase of speed until the electronic brake kicked in. Then the cycle would repeat until the take up tape diameter was large enough to drop the take up tension for controlled speed.
Before I did this I had to put my finger on the end of the capstan shaft for a few minutes if I needed to do a recording.
Before you do any of this make sure that there is not some foreign body which has come loose and touches the rotor as it is spinning. Delve into the motor only if there is no alternative. I am an Electronic Service Engineer by trade and consequently possess skills which are not generally the norm. This operation got the old sphincter twitching as one wrong move would be it!!! Dead recorder!!!
Cheers.
GPS16
if memory serves!!! It was a LONG time ago. The rotor on the rear needs to be removed. There are grub screw(s) at the centre of the rotor. They may be into countersinks so may need to be unscrewed to the point of falling out. To be on the safe side. Remove them and put them safe. The rotor then slides off the shaft backwards. On the inside of the rotor and on the back outside edge of the motor are the two parts which constitute the Frequency Feedback for the Servo. DO NOT damage either component of the Frequency Generator. If you do, then the motor will be scrap as far as a tape machine is concerned. After the rotor has been removed, the shaft comes out from the front of the machine. The small aluminium cover over the capstan shaft may need to be removed first. I lubricated mine with the fairly viscous high quality oil which I used on my Thorens Turntable platter bearing. I delved in because the motor was running virtually dry and the larger tension at the start of a tape was pulling the capstan overspeed!!! There was a gradual increase of speed until the electronic brake kicked in. Then the cycle would repeat until the take up tape diameter was large enough to drop the take up tension for controlled speed.
Before I did this I had to put my finger on the end of the capstan shaft for a few minutes if I needed to do a recording.
Before you do any of this make sure that there is not some foreign body which has come loose and touches the rotor as it is spinning. Delve into the motor only if there is no alternative. I am an Electronic Service Engineer by trade and consequently possess skills which are not generally the norm. This operation got the old sphincter twitching as one wrong move would be it!!! Dead recorder!!!
Cheers.
GPS16
smurfer77
Super Member
Hi Smurfer,
Fear not!!!!
The PR99 is on no level near to the 707. Slide a clip side ways off the rear of the rotor with small pliers, taking precautions that the clip does not bounce off a wall. Slide the rotor off backwards. The FG part on the rotor are machined slots (like the "cog" mentioned about the C270 rotor). Not easily damaged and the pick up for the FG is a small magnetic head which is fixed on the side of the motor base plate. Also, when was the last time you saw a 707 capstan motor on any auction site???!!! When I did this operation the auction sites did not exist!!!
A PR99 motor would be dealt with, with no hesitation. The 707 motor would still be inducing a twitch or 2. I can't remember why but I still have the feeling that what was seen was fragile!!!
I still have to agree with Skylab. Something rubbing is most likely!!
GPS16
Fear not!!!!
The PR99 is on no level near to the 707. Slide a clip side ways off the rear of the rotor with small pliers, taking precautions that the clip does not bounce off a wall. Slide the rotor off backwards. The FG part on the rotor are machined slots (like the "cog" mentioned about the C270 rotor). Not easily damaged and the pick up for the FG is a small magnetic head which is fixed on the side of the motor base plate. Also, when was the last time you saw a 707 capstan motor on any auction site???!!! When I did this operation the auction sites did not exist!!!
A PR99 motor would be dealt with, with no hesitation. The 707 motor would still be inducing a twitch or 2. I can't remember why but I still have the feeling that what was seen was fragile!!!
I still have to agree with Skylab. Something rubbing is most likely!!
GPS16
Nguyen Thang
New Member
My Pioneer RT-707 play only one direction and that revers, i check relay 601,602 ok, direction lamp light,normal, who can tell me, for what must i check, thanks...
Hi Nguyen,
At power on, Relay RY602 is not powered. One of it's contacts is then fed to the relay on the Servo PCB and gives the Relay on the Servo Board a ground return. So this relay must be on. This should be a visual check with the top cover removed. If the lamp on the front is indicating Fwd then there is a problem with the connection from the direction relay on the Chassis to the Relay on the Servo PCB.
If the Fwd lamp is lit then all seems to be OK from the RY602 end. Check the voltage to ground on Point 56 on the PCB which has the Speed Switch on it. Beware of the Line Voltage in the vicinity as the Power Switch is on the same PCB. Point 56 should be low when Fwd. If this is the case then there is a chance that the Fwd/Rev relay on the servo PCB is the fault (RY901). The coil may be open circuit.
GPS16
At power on, Relay RY602 is not powered. One of it's contacts is then fed to the relay on the Servo PCB and gives the Relay on the Servo Board a ground return. So this relay must be on. This should be a visual check with the top cover removed. If the lamp on the front is indicating Fwd then there is a problem with the connection from the direction relay on the Chassis to the Relay on the Servo PCB.
If the Fwd lamp is lit then all seems to be OK from the RY602 end. Check the voltage to ground on Point 56 on the PCB which has the Speed Switch on it. Beware of the Line Voltage in the vicinity as the Power Switch is on the same PCB. Point 56 should be low when Fwd. If this is the case then there is a chance that the Fwd/Rev relay on the servo PCB is the fault (RY901). The coil may be open circuit.
GPS16
Nguyen Thang
New Member
Hi GPS16, Thank you for reply, i measured point 56 when played and is 25.7 Volt, this is normal? & when i stoped the tape is 26V, direction indicator is normal lite, when stoped the tape, i pressed to change direction normal, but if play every time this start to revert direction, must i check to servo board?
Nguyen Thang
New Member
When i press fw direction buton, relay 901 click but not keeping, lamp lite, & return to revert direction
Hi Nguyen,
then you have something enforcing reverse. Check the first lead post on the head block. It can clearly be seen that it has an upper part and a lower part with a black insulator between. Clean this with alcohol. The foil on the tape shorts the two halves of the post together and RY602 then closes and self latches. Either the sensing post is dirty and conductive or the Rev push button contact is stuck shut. The dirty sensing post is the more likely. The Fwd push button shorts out the relay coil so that it drops out. Do not hold the Fwd button in for a prolonged period as you may burn out R601 which is in series with the coil.
The fact that RY901 changes state is saying it is OK. As you have a meter, measure voltage from top to bottom of the first sense guide post. There should be around 24V there. I don't think you will find that on your machine.
Keep us posted.
GPS16
then you have something enforcing reverse. Check the first lead post on the head block. It can clearly be seen that it has an upper part and a lower part with a black insulator between. Clean this with alcohol. The foil on the tape shorts the two halves of the post together and RY602 then closes and self latches. Either the sensing post is dirty and conductive or the Rev push button contact is stuck shut. The dirty sensing post is the more likely. The Fwd push button shorts out the relay coil so that it drops out. Do not hold the Fwd button in for a prolonged period as you may burn out R601 which is in series with the coil.
The fact that RY901 changes state is saying it is OK. As you have a meter, measure voltage from top to bottom of the first sense guide post. There should be around 24V there. I don't think you will find that on your machine.
Keep us posted.
GPS16
Hi Nguyen,
another possibility is that the mechanical linkage for the two rollers is touching the wiring from the sense post and has worn through the insulation. When the 2 rollers lift it may then short it to ground.
With the machine in STOP mode select Fwd. The lamps should change along with the direction of the capstan. Lift the 2 rollers by hand and see if Rev is enforced.
GPS16
another possibility is that the mechanical linkage for the two rollers is touching the wiring from the sense post and has worn through the insulation. When the 2 rollers lift it may then short it to ground.
With the machine in STOP mode select Fwd. The lamps should change along with the direction of the capstan. Lift the 2 rollers by hand and see if Rev is enforced.
GPS16
Nguyen Thang
New Member
Thanks GPS 16, now i check senzor under the head block, & i post here video for analyza please look...
Hi Nguyen,
The instant change of direction, when play is depressed, still points to a problem with the sensing pole on the left hand side of the head block. All else looks to be working as it should. Fwd is enforced at 9999 on the counter and is selectable by the Repeat button.
The wire to the sensing pole and the sensing pole itself needs to be looked at closely. It has a short to ground on it. Either the wire is trapped and the insulation is compromised or the sensing pole has lost the insulation between the 2 halves which get shorted by the foil as it passes at the end of Fwd play. Follow the wire from pin 40 on the PCB which has the Play Button on it. This goes directly to the Sensing Pole.
GPS16
The instant change of direction, when play is depressed, still points to a problem with the sensing pole on the left hand side of the head block. All else looks to be working as it should. Fwd is enforced at 9999 on the counter and is selectable by the Repeat button.
The wire to the sensing pole and the sensing pole itself needs to be looked at closely. It has a short to ground on it. Either the wire is trapped and the insulation is compromised or the sensing pole has lost the insulation between the 2 halves which get shorted by the foil as it passes at the end of Fwd play. Follow the wire from pin 40 on the PCB which has the Play Button on it. This goes directly to the Sensing Pole.
GPS16
Nguyen Thang
New Member
Hi Nguyen,
Yes! That's it. Examine it closely. There will be a single wire going to the insulated half. The other half is ground anyway. There is a short circuit associated with this. Check the wire for being trapped and/or crushed. The pole looks to be clean. Moderate head wear too!!!! Nice one!!!
GPS16
Yes! That's it. Examine it closely. There will be a single wire going to the insulated half. The other half is ground anyway. There is a short circuit associated with this. Check the wire for being trapped and/or crushed. The pole looks to be clean. Moderate head wear too!!!! Nice one!!!
GPS16
Nguyen Thang
New Member
Hi GPS16, I find this single wire, is blue & broken, that touch to chassis ground, I replace this wire one new and problem is solved !, thank you so much for you enthusiastic consultation!!!! now my Pioneer RT-707 is playing great!
PROBLEM SOLVED! THANK YOU
Last edited:
Hi All,
in a previous post on this thread I said.
After closer examination of the circuit diagram, it is phooey!!! That test will not work as the play button has not been depressed and the return via the sensing pole will have been removed the Play Switch S10-3.
for completeness!!
GPS16
in a previous post on this thread I said.
After closer examination of the circuit diagram, it is phooey!!! That test will not work as the play button has not been depressed and the return via the sensing pole will have been removed the Play Switch S10-3.
for completeness!!
GPS16
Nguyen Thang
New Member
Today i have other issue: capstan motor is stoped, not spin when i turned the deck on, when i moving something of machine, is spin now, but every time when turned on, must be move the deck to spin ??? I check all contact from servo board to Capstan Motor & clean it but, notthing gonna change..., Some one tell me what is wrong? to power on the capstan motor through some swich?
