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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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21st Feb 2018, 12:28 am
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#1 |
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Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,222
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Revox PR99 MkIII no output
I am trying to restore this machine.
This version has 2 VU meters, no input or output controls except headphones, more importantly when monitoring the input, there is no sound, so you cant do an A/B comparison. In fact the Input/Reproduce switch only seems to affect the VU meters! To make matters more complicated there is an extra board fitted next to the output board, for which I cannot find any diagrams whatsoever. It is connected between the output loom which would have gone to the headphones and monitor volume with that plug plugging into the board. I'm very tempted to modify the machine, by connecting the VU meter input on the reproduce board to the audio input of the output amplifiers (Isolating the pins of course. I have included a PDF of the output board, but note that the headphone level control is not wired as per the diagram. The blue lines indicate the new connections if I went ahead with this. Does anyone have a diagram for that rather odd board? I have included a couple of pictures |
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22nd Feb 2018, 1:35 pm
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#2 |
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Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,222
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Re: Revox PR99 MkIII no output
I've been asked for pictures of this module also the details of the recorder itself by Ted Kendal.
The board is marked Preco 210-177-010 The front looks like any PR99 without any markings except a stick on Revox badge. |
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28th Feb 2018, 11:13 pm
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#3 |
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Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,222
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Re: Revox PR99 MkIII no output
An update:
I removed the additional board and referring to the service manual restored the links and resistors that were removed for the modification. That part of the machine now works correctly, now onto the next fault, no recording on CH2 |
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1st Mar 2018, 4:12 am
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#4 |
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Octode
Join Date: Jul 2006
Location: Perth, Western Australia
Posts: 1,969
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Re: Revox PR99 MkIII no output
Is it possible the machine was modded to only record on the left channel? Maybe a link was removed.
Tim |
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1st Mar 2018, 11:19 pm
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#5 |
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Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,222
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Re: Revox PR99 MkIII no output
No, It should record and playback on both channels. It has a full track erase head.
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2nd Mar 2018, 9:12 am
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#6 |
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Hexode
Join Date: Jun 2014
Location: Chelmsford, Essex, UK
Posts: 386
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Re: Revox PR99 MkIII no output
Morning Michael,
I’m not sure I can be a lot of help but I had a MkIII exactly the same. They are ex bbc and we’re modified by a company in Croydon. From memory it was a bit of a ****** to calibrate as they do not work in the conventional way. They are not stand alone tape decks and are modded to work remotely off of a mixing deck. That’s why the output control only works on headphones. During the day I’ll have a look back through my notes and see if I can add a bit more information. I will say that once I’d got my head around the procedure it did sound great! Mike
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Small Scotch, New Aids and Happy Ears |
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