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Pioneer RT707 Problems

J

JamesWmor

New Member
Hi All,

Recently acquired a pioneer RT707 tape recorder. I’m having a weird problem with it where the player won’t sound out of both channels unless i press lightly on the supply reel. I feel like it is tension related as as soon as i add tension this problem disappears. Anyone point me in the right direction? I’m guessing it’s back tension - but every time i try and move a slider it doesn’t seem to fix anything (this is following the service manual with R3-2)

I’m at my wits end trying to get to the bottom of this!
 
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Disconnect the variable resistor and check it. I have seen those green variable power resistor open at one end (opposite where the tap is connected). It is confusing if you measure without disconnecting, due to parallel circuitry (ask me how I know.......wasted a lot of time). If it is open at one end, it can be rewired to use the element at the opposite end, and then reset.
 
AE Bob said:
Disconnect the variable resistor and check it. I have seen those green variable power resistor open at one end (opposite where the tap is connected). It is confusing if you measure without disconnecting, due to parallel circuitry (ask me how I know.......wasted a lot of time). If it is open at one end, it can be rewired to use the element at the opposite end, and then reset.
Click to expand...
How does one rewire them to the fix?
 
Does the unit take up tape properly in the reverse direction? If the take up and back tension are both bad on the left reel, then it is likely that R3 (take up and back tension control for the left reel) is open at the one end. You need to disconnect the resistor and measure it with an ohm meter to determine if it is defective before making any wiring changes. If both take up and supply back tension are bad it is likely the resistor is open at the end, and the fix is to invert the resistor (and swap the taps), so that the opposite end of the resistor is used. If the open is between the taps, you may be able to just connect the opposite end of the resistor to the first tap, so the tap not getting fed, will be fed from the other end.
 
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Yes in reverse the take up is spot on. When you say swap the tabs do you mean just flip the resistor around? I should note the resistors are very. thick in dust, could that be a cause for concern?
 
Do you have a multimeter? You need to troubleshoot this issue. Have you actually measured the back tension with a scale? If take up tension is correct in reverse, but back tension is missing in forward, it could be an open between the taps on R3 or possibly an issue with s8 or s9 or possibly contacts on relay 601. You really need to determine what is going on for sure, before making any changes.
 
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