|
Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
|
Thread Tools |
6th Mar 2021, 6:48 pm | #1 |
Hexode
Join Date: Jun 2014
Location: Chelmsford, Essex, UK
Posts: 386
|
Revox PR99 display problems
Hi all. I'm in the process of refurbishing my PR99 MkII. It's not a shotgun project, I'm only doing one board at a time and then testing. My knowledge is limited but growing (hopefully) but I've hit a problem.
I started by completely overhauling the transport system. Brakes, motor run caps, and transport control board. All fine. Yesterday I recapped the power supply, it made sense while I had the transport control board out. Put it all back together and tested. All good except I've lost the locator display. All the buttors work ok (well they seem to, I can't guarantee as I can't see the display). Everything else works fine also so, I'm a bit flummuxed. I haven't touched the locator board, other than to take the front panel off which only involves taking out a multipin plug. Is it just a coincidence or am I missing something blindingly obvious? Either way any suggestions would be most welcome.
__________________
Small Scotch, New Aids and Happy Ears |
6th Mar 2021, 9:03 pm | #2 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,603
|
Re: Revox PR99 display problems
Not familiar with this at all, it looks a great and complex machine.
Nothing blindingly obvious to me but may not be co-incidence, maybe the act of removing the front panel has disturbed a bad connection at the Locator board. I assume the Locator board is the "Locator Command" which houses the 7 segment LED displays for the tape counter displays. If all 6 displays are off then would suggest something common. First thing I would do (if practical to access and monitor) is check the +5V (pin 18), 0V (pin 9) and clock signal (pin 13) at the MC14499 (IC1 & IC2) Decoder/Driver chips for the 7 segment displays. Looks like these connections are derived from the Locator MPU board. David |
9th Mar 2021, 5:28 am | #3 |
Hexode
Join Date: Jun 2014
Location: Chelmsford, Essex, UK
Posts: 386
|
Re: Revox PR99 display problems
[QUOTE
Nothing blindingly obvious to me but may not be co-incidence, maybe the act of removing the front panel has disturbed a bad connection at the Locator board. Looks like these connections are derived from the Locator MPU board. David[/QUOTE] Right in one David. The locator board is connected via a multipin plug/socket. The 5V+ pin was loose in the plug and was not making contact.
__________________
Small Scotch, New Aids and Happy Ears |
9th Mar 2021, 2:39 pm | #4 |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,603
|
Re: Revox PR99 display problems
That is good, well done.
David |