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Pioneer RT-701 Capstan Board Replace RT-707?

zackmc

zackmc

New Member
Hi,
Im having user error (I think) on fixing my RT - 701, and its speed issue. The caps have all been swapped. Initially the machine played to fast. Then I did some recapping and the capstan wasn't spinning enough to move the pinch roller. So I obtained the capstan board from a RT-707. Recapped, at first it was playing too fast and now I'm getting nothing

Reading that the 701 and 707 are similar. I assumed using the 707 board would work. I know the 707 has a relay built into it for the auto reverse.

Any input? Will this simply not work?

Thanks!!!
 
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Hi, it would seem to me that as you have similar problems with both servo PCBs, the problem is on the mainframe somewhere.

Whilst I am familiar with the RT707, any guidance must taken on it's merits. On an RT701 it may not apply!

Do you have a proper circuit diagram to work with or was the blanket cap replacement done on the fly???

Make sure that the connector from the motor does not have any bad connections.

Clean the switches too! The speed selector obviously but also the record switch as this defeats the Pitch control in Record.

GPS16
 
Thanks for the prospective!

I do have the service manual.
I did do a blanket recap of the servo board.
I have cleaned the speed control switch. The record switch? I'll give another shot at it. I'll also focus more on the connetor to the motor. I've given the connector a good cleaning.

The pinch rollers operate fine. The move up and down as prescribed.

Thanks again!!!
 
Hi,

If you have the circuit for the machine, look for the Speed Control pot. There is a fixed tap on the pot which is set to nominal ie the click position. The pot wiper is selected during playback to allow the speed to shift. When the Rec button is pressed, the fixed tap is selected so that nominal speed is enforced during recording no matter what the pitch control is set to. The record switch can, therefore, be a source of speed errors. Also it doe not matter what is done to the servo PCB in those circumstances as that is not where the fault lies.

The connector from the motor is notorious on these machines. The FG feedback for the servo goes bad.

During playback, does the pitch pot have any effect?

How fast is it??? Is the motor going full bore??

Does the speed selector do anything??

The more information, the better advice you will get back.

Keep going at least you have a spare PCB as a source of components.

GPS16
 
GPS16 said:
The connector from the motor is notorious on these machines.
GPS16
Click to expand...

^^ I had a speed issue on one of my 707s and fixed it quick merely by cleaning the molex connector to the control board. Took 5 min and has worked fine for years. A little oxidation and it gets all confused.
 
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