Jul 8th, 2015
Q) I have a problem with a Technics SV-DA10. It plays well, but is unable to rewind (except when the pinchroller is engaged, like when using the jog/shuttle). Would you have an idea?
A) The problem may be:
1. The brake shoe for either geared tape hub is loose, falling appart and interfering with the tape hub. I have simply replaced these with a proper sized piece of very fine felt or soft cardboard glued on with a tiny bit of epoxy.
2. The friction clutch/gear (under the chassis where the gear to shift back and forth to the tape gear hubs) is worn and exerting no friction to pull the tape. I pull apart the clutch gear, flip the clutch pad over and stretch the tension spring a tiny little amount, just enough so it is slightly more open to account for it's compression of use for 20 years. This is somewhat complex to access and should be done by an experienced tech.
3. The tape guides have debris or too much friction. Even the helical scan head if severely worn can drag the tape due to friction.
4. The cam mode switch located at the upper right of the head is not cycling totally due to debris in the gear or oxide on the rotating switch. A tiny amount of cleaner can be soaked into this switch can help.
5. The "inter" shift gear (black and moves between the tape gear hubs) has a weak tension spring located on the gear axle. It must be replaced or again I just stretch it a litte amount (only about 20%) and reinstall. This gear also must be cleaned and shifted loosely on it's pivot axle. Infact the clutch gear (mentioned in #2) again must have sufficient tension to move this part easily. It shifts during all play, rewind shuttle modes.
6. The back tension arm, located to the left side of transport may be off position not flipping in and out of position with rewind and play functions. Possibly a deformed mechnical assembly or end stop has damaged the plastic around where the arm retracts when in stop mode. This is seldom the problem but it can be the most difficult to recognize unless you compare mechanics with another.
7. The other issue which must be addressed is the most crucial but now rare part which must be checked, the pinch roller spring tensioner located at the pinch roller scissor arm. This spring sets the pinch tension and is critical for proper tape tension during shuttle modes. The spring is now rare to get but the machine (with a weak spring) will work ok except in shuttle rewind mode. A weak spring will often allow the tape to spill off the pinch capstan axle.
8. Finally, if the helical scan head has obvious wear and your tapes play back with high error rate (200+) then maybe the whole transport should be replaced. We are now selling a calibrated good condition transport (#8 or better) for those people overseas who can't get the service done. A complete transport for SV-DA10 and 3700, 3800 are all the same (I'm pretty sure DA10 is the same). Cost $225 to $285 (the head alone is a $200 part). Shipping is extra.