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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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11th Dec 2017, 11:44 pm | #1 |
Triode
Join Date: Sep 2016
Location: Nottingham, Notts. UK.
Posts: 15
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Revox A77 Capstan motor control board schematic
Hi Guys, I have a Revox A77 service manual, but the motor control schematic is the later 555 IC version. Could anyone point me to the early discrete board schematic please.
The problem I have is the motor is permanently running up to full speed irrespective of the speed selected. I am getting +21v on the red AE1 pin on slow select, the 2SC782 tests Ok as does the bridge rectifier. Swapped the 0.47uf Rifa and I am getting AC on the tacho input when the motor is rotating. Help greatly appreciated, Many Thanks, Dave sorry about the typo Revoc = Revox ! |
12th Dec 2017, 5:21 pm | #2 |
Heptode
Join Date: Jul 2012
Location: Bromley, London, UK.
Posts: 702
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Re: Revox A77 Capstan motor control board schematic
I had a look online and can only find the 10th edition service manual at either Electrotanaya or the Studer FTP site. The contents list says it has the circuit for the 1.077.725 board but does not - only showing the later circuit diagram. If you can find an 8th edition manual, this contains both circuits. My manual is not easily accessible at the moment, but someone on here may have what you need to hand.
Mike |
12th Dec 2017, 6:15 pm | #3 |
Nonode
Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
Posts: 2,573
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Re: Revox A77 Capstan motor control board schematic
I've sent Dave a copy of the earlier motor control circuit.
Keith |