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Pioneer RT-707 reel to reel no sound input, output or meters

daveyh

daveyh

Super Member
I rebuilt the power supply already and the meter don't move. It has no input or output sound. The reels turn in reverse, play and fast forward in both directions, The lights on the meters work. No fuse board! Just wired from the factory without one. So it can not be a fuse. Can someone tell me what to look for? Greatly appreciate any guidance.
 
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Hi Daveyh,

when you turn the machine on, do the VU Meters kick and then settle back to zero?

Cheers

GPS16
 
Hi,

looks like you have lost the 32V supply for the audio electronics. Check around Q307 emitter. I would suggest you check the fuse board for F4 (1A) but you do not seem to have one. It will not have come from the factory without one for legal reasons!!! Also check the raw on C326/7. Have another look with the bottom cover removed!!

Cheers.

GPS16
 
Check this out. Here is what is there. Looks like factory to me. Is this not where the fuse block is suppose to go? Mutl-voltage unit.
Pulled and checked the 2SD526 transistors. All good.


20210220_131109_resized.jpg
 
Oh and by the way, there are just wire posts underneath the board. No fuses. Checked. Also checked the two large caps, Good.
 
Hi Daveyh,

what voltage have you got across the caps when powered? It should be around 45V. Check that R337 3.3 Ohm 1W has not gone open circuit. The Red wires on the PCB where the fuses should be should have 33 V AC.

See what you find.

GPS16
 
GPS16

Got it. Thanks very much!!!! R337 3.3 Ohm 1W was an open circuit .Replaced it and it came to life and now works. Have meters and sound. Wish I had your knowledge and you had more, :king:
 
Hi Daveyh,

glad you now have a runner. As I have said elsewhere on this Forum, the RT-707 is a cracker of a machine. One of the best "domestic" machines on the planet.

Enjoy!

GPS16
 
GPS16.

You seem to know a lot about these units. I have one other problem maybe can help me cure. That would be great if you could. :)

I went to record some music and inserted my RCA plugs into the RCA inputs to adjust the VU meters from my source CD and I have distortion on the right channel. The tape is not even on the heads and the input is distorted on the right channel. It sounds like to much bass. Do you know what could be causing this? In playback it sounds awesome. I have cleaned and double cleaned all inputs and switches with Deoxit 5
 
tapetech:

In the Power and Oscillation Assembly Board (RWR-053) I have already replaced the 2sc1344 transistors or Q301 and Q302 with KSC1845 as well as the Q304 and Q304 with KSC2383.
Did not change anything as far as sound. Still has distortion right channel input.

On the Playback Amplifier Assembly (RWF-069) there are two. Q107 and Q108 I have not changed. There are several in the MIC Assembly Board. Which ones are you referring to?
 
That did it!

I replaced the 2sc1344 on the Playback Amplifier Assembly (RWF-069) Q107 and Q108 and all the ones on the Mic board. Now it records and plays great! Thanks tapetech.
 
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