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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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22nd Sep 2016, 7:55 pm | #1 |
Diode
Join Date: Sep 2016
Location: Vila Real, Portugal
Posts: 4
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Revox A700 problem with PLAY, FF and REW
Hi,
I have a Revox A700 on the bench. After some repairing on the power supply I now have a problem with the PLAY, FF and REW keys. They operate the machine but only while are pressed. If released the A700 stops working. Can you please give me some help? Best Regards Eduardo Fonseca OldBack Productions Portugal Last edited by edmonius; 22nd Sep 2016 at 8:11 pm. |
22nd Sep 2016, 8:13 pm | #2 |
Hexode
Join Date: Jan 2007
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 453
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Re: Revox A700 problem with PLAY, FF and REW
Do you have a tape on the machine? If not, then it might just be the end-of-tape sensor doing its job.
Regards, |
22nd Sep 2016, 8:13 pm | #3 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
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Re: Revox A700 problem with PLAY, FF and REW
You need to check that the EOT sensor is working by following the instructions in the service manual to ensure the threshold level is correct.
Once you've eliminated that, check the output from the tape move module. If that's ok, check that the stop line itself is at 0V. I take it you've replace all the RIFA caps on the speed, capstan and relay boards, if not change them. Let us know your findings. |
22nd Sep 2016, 8:27 pm | #4 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,657
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Re: Revox A700 problem with PLAY, FF and REW
Depending on the age of the machine there may also be microswitches on the tension arms which activate autostop when at the end of their travel. And do replace those Rifas, unless you like firework displays...
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23rd Sep 2016, 1:05 am | #5 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
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Re: Revox A700 problem with PLAY, FF and REW
Was that early versions or late versions? Doesn't seem to be any reference in the service manual
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23rd Sep 2016, 10:47 am | #6 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,657
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Re: Revox A700 problem with PLAY, FF and REW
If memory serves, this was quite late - S/No 15000 or thereabouts. It was standard on the related Studer A67 from the off, and replacement tension arms were so equipped. The mod was simple enough - some wire and a couple of diodes - I have the bit of paper somewhere - but it was a while ago...
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24th Sep 2016, 7:16 pm | #7 |
Diode
Join Date: Sep 2016
Location: Vila Real, Portugal
Posts: 4
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Re: Revox A700 problem with PLAY, FF and REW
Now I have a new problem... the F5 fuse is blowing out as soon as i hit the play/ff/rew... and afert that the capstan motor stops...
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25th Sep 2016, 12:07 am | #8 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,657
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Re: Revox A700 problem with PLAY, FF and REW
A piece of the story missing here - have you fixed the original fault? Did you change the Rifas, and if so, are you confident you haven't introduced a fault in the process?
First thought is that you should check the shunting diode across the brake solenoid - this is the common component which comes to mind for these three operations. |
25th Sep 2016, 8:55 am | #9 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
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Re: Revox A700 problem with PLAY, FF and REW
You should have the service manual, if you don't have it you can download it from various sites including hi fi engine.
F5 is the supply to the -20V and -12V supplies |
25th Sep 2016, 5:53 pm | #10 |
Diode
Join Date: Sep 2016
Location: Vila Real, Portugal
Posts: 4
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Re: Revox A700 problem with PLAY, FF and REW
Hi,
Rifas are out. No more blowing fuses. On to the next step. |
25th Sep 2016, 9:49 pm | #11 |
Diode
Join Date: Sep 2016
Location: Vila Real, Portugal
Posts: 4
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Re: Revox A700 problem with PLAY, FF and REW
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