|
Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
|
Thread Tools |
15th Aug 2018, 8:37 am | #1 |
Banned
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 605
|
Revox A77 Record relay.
I'm struggling to understand what's happening (and what should happen) with the record relay, it's not engaging / activating .
It started with no audible input on channel B. I did the usual track with the scope and I have audio going in and out of the input board, input going into the channel A record board, nothing going in to the channel B board. I checked the relay and it's not closing . I have checked the voltages on the relay board and I have the following with the record switches pressed:- 4 = 25v 5 = 25v 8 = 0v 9 = 21v 10 = 0v Would be grateful for some advice 'm not really getting what should be happening with the rec buttons pressed . If I'm reading the schematic correctly there should be 0v on pin 5 and 20v on pin 8 ?!? |
16th Aug 2018, 12:15 am | #2 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
|
Re: Revox A77 Record relay.
I take it you are referring to the record boards A & B.
If you've got nothing going into Ch B board then the fault lies between the input board and the channel B board. The record relay grounds the bias oscilator and rec amplifier output when the unit is NOT in Record and supplies 21V to the oscillators soft start power supply when IN record. By record one or both of the channel rec buttons either side of the VU meters must be in and the record and play buttons pressed in to activate record. |
16th Aug 2018, 9:08 am | #3 |
Banned
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 605
|
Re: Revox A77 Record relay.
Many thanks. All sorted now.
|
16th Aug 2018, 7:09 pm | #4 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
|
Re: Revox A77 Record relay.
What was wrong with it?
|
17th Aug 2018, 11:01 am | #5 |
Banned
Join Date: May 2018
Location: Norwich, Norfolk, UK.
Posts: 605
|
Re: Revox A77 Record relay.
I bought this used spares or repair and someone had been in there before me an mis wired the audio connect board . I`ve still got more issues to sort out but I`m getting there with it . Just need to find a VU meter that doesnt cost £40 as they do on ebay . I`m in no rush .lol
|