Help! Revox PR99 MKII trouble

[cwkim]

Gentlemen,

I bought PR99 a year ago and didn't like some of functions but it still sound great. These day I reconized this PR99 has lot of problem since begining. I was stupid. Please advise what should I do to this beautiful up and running correctly?

Problems are:
1. Automatically starts play when I turn power switch on. Is this normal?
2. Reel is continuously spinning when FF or REW and can playing this unit without tape on it. Is this normal?
3. Locator problem: When finding zero, it slowing down speed at near zero point and rewinding to the end of tape. It doesn't stop.
4. Sometimes when I use monitor speaker, I can hear Boo~ hum from monitoring speaker and it disappear by cycling power few times.

Please someone advise me.

 

[westgate]

Gentlemen,

I bought PR99 a year ago and didn't like some of functions but it still sound great. These day I reconized this PR99 has lot of problem since begining. I was stupid. Please advise what should I do to this beautiful up and running correctly?

Problems are:
1. Automatically starts play when I turn power switch on. Is this normal?
2. Reel is continuously spinning when FF or REW and can playing this unit without tape on it. Is this normal?
3. Locator problem: When finding zero, it slowing down speed at near zero point and rewinding to the end of tape. It doesn't stop.
4. Sometimes when I use monitor speaker, I can hear Boo~ hum from monitoring speaker and it disappear by cycling power few times.

Please someone advise me.

don't have a pr99, i do have 4 akai and 1 teac r2r decks. and seeing no one else has answered, i'll take a shot.
1-if by 'play' you mean the capstan starts spinning on power up, on my akais that is normal.
2-again, that is normal on my akai decks.
3-not sure what you mean.
4-no idea.

wish i knew more about a '99'. hopefully a 99 owner/user will show up and help you.

good luck!

 

[cwkim]

Appreciation

don't have a pr99, i do have 4 akai and 1 teac r2r decks. and seeing no one else has answered, i'll take a shot.
1-if by 'play' you mean the capstan starts spinning on power up, on my akais that is normal.
2-again, that is normal on my akai decks.
3-not sure what you mean.
4-no idea.

wish i knew more about a '99'. hopefully a 99 owner/user will show up and help you.

good luck!

Hello, westgate

Your AKAI r2r probably has different function and also has no tape locator but not sure.

I really appreciate for your reply anyway.

 

[david winter]

Those Revox often have dry electrolytic capacitors. If you hear a hum in the speaker, it is likely that the main power supply no longer provides accurately rectified current. This may hang the zero locator as this function is run by a microprocessor board (6502 cpu + 4K ROM) which will obviously never like any unstable power. If you have an oscilloscope, check the power supply to see what it delivers.

Also, make sure that all the keys of the keyboard will physically work fine without be stuck pressed.

Another thing to check is the motor capacitors (there are three of them and they are all screwed to the chassis) and those 0.47uF caps. On the A77 series they often short and fry a 47 ohm resistor put in series.

Finally, always replace those white electrolytics. I can't remember their brand (might be Frako or something similar) but they looks like a small cube with a round side. The value and voltage are written on the top. Once this is done, also replace the yellow electrolytics which may be from that brand. I found several in short-circuit or with insufficient ESR.
If you still have the same problem after checking all that, let us know.


David