Teac A3300SX-2T
Overhaul

Ever since I first encountered "high-end" audio in the early 1970s I was always impressed by the VERY expensive reel-to-reel tape recorders that dominated the-best-of-the-best. The quality of the sound recording and playback exceeded any other media at the time and would continue to do so until the rise of digital "high resolution audio" around 2010.



In 1974 while working as a technician in a high-end audio shop, the cost of such magnificent machines was equivalent to about 6 months wages so it  was not until the late 1980's that I acquired a second hand machine from a coworker. but I had the chance to work on a few of these gems on the service bench and to borrow one for field recordings.

In December of 2018 I happened to be window shopping on eBay and ran across a Teac A3300SX-2T up for auction. This model was among the  best and a "master recorder" (used for making the final copy of studio recordings to go to music production companies). The unit had spent most of  its life in an FM radio station in Virginia (USA) and was obviously significantly worn. It had also been in cold storage for years and showed some environment damage but the current bid price reflected its condition. In the last minute of  the auction I threw in a very modest bid and won the unit at a very reasonable price. I thought restoring the Teac would be a good winter's project.

Two weeks later the Teac arrived and an initial assessment showed a number of problems
(headphone jack broken - input channel strong  in but output extremely low - too much wow & flutter)

Initial work included lubricating the mechanical components, replacing the headphone jack, and cleaning the switches.
I decided to tackle the "wow and flutter" (tape speed instability) first and get all the mechanical parts of the deck working properly. Considering its age, amount of use, and poor storage, this turned out to be a major rebuild!
The motor was in  descent condition and just in need of cleaning and fresh lubrication.

By the time I got to the mechanical linkages, I had most of the machine apart!



I had to straighten the capstan shaft, rejuvenate all rubber parts, and clean and lube all moving parts.
With so many hundreds of little parts laying around I was quite relieved when it went back together with no missing parts and none left over! LOL!

With a few new parts arriving, I replaced the headphone jack.


Then took a bunch apart  to get at the tiny VU meter lamps, one in each meter.


Looks better now!


The heads (erase, record, and play) were badly worn (as I knew before I purchased the unit) and I wasn't about to pay nearly $300US to have them professionally lapped (resurfaced) so I ordered an assortment of emery paper from 400 grit to 3,000 grit to have at it myself.



When the abrasive sheets came in I decided to have a go at the heads and get rid of the trapezoid shaped flat spots on each head.

I stated with 400 grit to bring the face of the head even using a glass plate under the abrasive and a slight rolling motion of the wrist to keep the face perpendicular to the base and keep some curve.

I went to progressively finer grits while each time extending the parabolic face and finally finishing up with 3000 grit and oil the full width of the face. It took less than an hour per head but I did have to rest my eyes between heads LOL! (Having an illuminated magnifying glass and a jeweller's loupe helps to assess the condition of the head in each step.)

The end result is better than I expected!



Well 2 steps forward and one step back!

After lapping the heads and doing the preliminary head alignment, and after replacing the pressure roller, playing back a tape recorded on another machine the VU levels are right up where they should be and the sound quality is great. The wow & flutter is greatly reduced - haven't measured it yet but it is not noticeable now.

Before tackling the record problem(s) I was setting up the transport mechanics - brakes, back tension, etc. The brakes set up fine but when I got to tensions I noticed the left reel brake doesn't release in PLAY so the back tension is the full braking force (1200g) rather than tension set by the back-tension resistor! So the capstan is pulling against the brake. Unfortunately the schematic I have is a P.O.S. that's almost impossible to read and very incomplete.
(Downloadable manuals, even if "free", aren't worth what you pay for them!)

(I wonder if the left brake has not been working for years and may be why the heads were so badly worn!)

While trying to set the tensions, something else has gone awry - either a sticky relay contact or a bad connection. After PLAY and then STOP, it will not play again unless I give the machine a solid bump. In this state, if I press the REC button, the PAUSE light comes on. After the bump, this doesn't happen and the PLAY works again.

I have a better service manual coming from the UK and I am kind of stuck until it comes in.

While waiting for the service manual I  noticed one of the mic jacks was broken - I already replaced the headphone jack. It looked like it had been broken before and somebody glued it back together.

I ordered two new jacks and installed them so ALL the jacks are new.


After replacing the jacks, I was able to complete the mechanical setup, solved the brake not releasing on the  left spool in play mode and the problem with not going into PLAY a second time - the two were related.

With a factory service manual and a calibration  tape having arrived from overseas it was back to work on the tape deck only to find that the  high frequency response was non-existent :(
After chasing the problem for a week I finally induced a strong magnetic signal into the playback head that confirmed the electronics were working and that the  problem must be with the worn-out head.

So the project is suspended unless or until I can find replacement heads.


*** to be continued (I hope) ***