My new A77 just went crazy. Help?

[Deleted member 255135]

First off, I'm very new here, so I apologize if this is not the correct subforum to post in. It was the most appropriate I could find.

I recently bought a Revox A77 and about a dozen tapes. The deck recorded and sounded great, but I just now ran into a problem.

The deck had played a tape through, and I had stopped the machine, but not turned it off as I planned to play another tape shortly after. I didn't get around to it, and suddenly the reels started to spin in different directions. Like when you push play without tape, but I think they spun at winding speeds. I ran from my chair to turn off the machine. Pushing stop didn't do anything, but I turned it off on the speed knob after 5-10 seconds, then pulled the power chord shortly after. There was a burnt smell, and now I'm afraid to turn the deck back on. And sad, I'm sad too!

I had previously noticed that the deck became warm on the top during operation, but assumed it was not an issue.

I've opened up the deck, and I did notice the reel motors and power supply transformer was warm. The smell seems to be coming from the relay board, but it's difficult to say here five minutes after the incident. I had the machine apart after bringing it home, and found it clean and good looking, and thus didn't touch anything.

Visually, I don't see any obvious defects, but I'm not that electrically educated.

Was I an absolute idiot letting it sit around turned on but not playing? What could be wrong, and does this seem like an expensive repair?

I've linked pictures below:
http://imgur.com/a/oa7U4

 

[dhnash]

Here's a thread that may be helpful: http://audiokarma.org/forums/index.php?threads/bringing-back-my-revox-a77.283601/

The Frako capacitors in these units are a well known source of "burnt smell" problems.

 

[markpilk]

I was relieved to find the frakos are a common issue when mine went up in smoke. Once replaced I've not had any issues. This was my first Revox and it's a OK deck, but I've invested more than I should have for the A77! I'm not sure where you are located, but you might want to check out tapeheads.net. There's lots of info about these decks and many repair techs that visit the site. Shipping for repair can be a pain and I felt fortunate to find the one US authorized Revox repair tech was local for me. AK and Tapeheads are both a great source for info.

Good luck

 

[Deleted member 255135]

Thank you dhnash and markpilk. With the help of some fine folks over at the Danish forum vintagehifi.dk, I've found the likely culprit to be the Rifa capacitor C113 on the Tape Drive Control board. As I understand, that type of capacitor is well known to blow and cheap to replace. It may not be the end of the world.

 

[tuttebenne]

One of the most reliable aspects of an A77 is that one that is 40 years old or older and that has not had the three Frakos replaced is that it WILL end up with smoke and a horrible smell. So if you are replacing C113, there are two more on that board that should be replaced too. The cost is silly (as an example $6.00 vs $2.00). These are great decks so it would be advisable to get familiar with their minor weak points. One other especially is the speed control potentiometer. These older pots fail and cause problems. Again, really cheap to replace.