Revox b77

[mikeVan25]

1982 revox b77 (mark I), original owner, heavy use for the first 4 years, then it was mostly parked. Acquisition of a new fine tube amp and klipschorns made it too obvious that the B77 had to come out of retirement...

Audio signal drops off after maybe 4 seconds to 20% of original...

Recap? audio amp or power supply? Or all?

Thanks for your opinion
Mike

 

[tapetech]

If the volume always starts out good and then fades out, I would say it's a tape skew issue. Not a problem with the electronics. Skew is a mechanical problem where the tape wanders up and down when traveling across the head face. Causes could be a polished capstan shaft or defective pinch roller (or both). Also, be sure the heads and capstan are spotlessly clean. Use a magnifier and strong light to check.

 

[jan_stevns]

If the volume always starts out good and then fades out, I would say it's a tape skew issue. Not a problem with the electronics. Skew is a mechanical problem where the tape wanders up and down when traveling across the head face. Causes could be a polished capstan shaft or defective pinch roller (or both). Also, be sure the heads and capstan are spotlessly clean. Use a magnifier and strong light to check.

Applying extra "backtension" can normally reveal skewing problems

 

[tapetech]

While observing the play head closely, put the deck in play and check for any lateral/side to side movement of the tape where it contacts the head. Also, check the tape within the guide (just to the right of the head) to see if any tape curling or buckling occurs.

As Jan mentioned, applying extra back tension (by dragging your hand on the supply reel) can reveal skew problems. It will reduce or stop skewing.