Tascam, Fostex and Yamaha sold cassette multitrack recorders in the golden days of home recording in the 1980′s and 90′s. The 4 track format was especially popular but an 8 track format was also developed that squeezed even more out of the small tape width of the cassette.

We love these cassette formats and their accessibility helped start many musicians’ careers. Unfortunately one of the best 8 track machines, the Tascam 238 Syncaset also suffers from a common and frustrating problem that renders most of these machines useless over time, the dreaded direct drive capstan motor failure…

The 238 and other 8 track and high quality stereo tape decks, the 688 and 122 MkII and III, used a direct drive capstan motor for precise speed control and reduced speed variation or wow and flutter (w/f). The circuit that controls this motor fails in certain ways causing lack of speed control and in our case the capstan motor wizzing away at a crazy speed, not the 9.5 cm/sec that it should do.

This here is the culprit  – you can see the attempted repairs which didn’t ultimately work.

One common failure is that the surface mount electrolytic capacitors fail or their capacitance changes to such an extent to cause speed problems. These can be changed for standard through hole caps but you do need to be very careful as the tracks are damaged very easily – good tools are essential.

The other point of failure in the circuit is the BA6304F SO16 IC – we even changed this but the motor still didn’t turn!

There was some suggestion from previous repairers that the grease at the end of the capstan flywheel hardens over time. increasing the friction and causing problems with the circuit.

This can become frustrating quickly, especially when you have a large archive of cassettes to digitise.

When we can’t repair we reluctantly do the next best thing and buy the whole replacement part but this is another exercise in frustration. Teac parts and Teac UK don’t have any european supply of this capstan motor (part no. 53700075-01) anymore as of November 2011. Interestingly about 6 months ago they did at around £60 GBP, then about 3 months ago they had one left at £160 GBP!

Lots of emails later to Teac US, Teac Canada and Teac Japan there seem to be a nice stock still on shelves somewhere and at reasonable prices UNTIL you ask them to ship to the UK when you discover they can’t do this and I’d need to go through Teac UK!!! I’m pretty persistent but I gave up finally even though some of the support staff tried to be pretty helpful.

We find support for older machines from the original manufacturers is not good generally and unreasonably expensive when you can find it. This is similar across audio and video, semi-pro and professional products. Some companies are easier to deal with and have better parts situation than other but stockpiling machines, parts, manuals and obsolete knowledge is the best course of action.

What we finally did that worked and was a good solution was purchase 3 Tascam 122 Mk III stereo cassette decks which use the same but a later revision of the capstan motor, (part no. 53700121-00).One machine was donated for the cause and the capstan motor removed, modified and refitted in the 238. The 122 motor has a few factory extras, such as these resistors, shown here:

You also need to solder / desolder the speed pads, to change the motor speed from 4.8 cm/s to 9.6 cm/s that the 238 needs to run at.

It’s also a good idea once you’ve got the capstan motor apart to clean the old grease from the seat, check the end float which can be adjusted using the screw shown on the left and apply new grease to the capstan end.

Put it all back together – be careful to solder the wires to the motor to the correct pads – they’re different on the 122 and test… Ours worked almost perfectly.

As the transport hadn’t been used for a while the reel motor would intermittently stop as if sensing the tape end. This can sometimes be loose counter belts but on the 238 it’s a digitial counter. We cleaned up the leaf switches on the transport top and also sprayed a small amount of deoxit into the inside of the reel motor. A bit more use and it finally worked to spec…

For 4 track and 8 track multitrack cassette transfer please contact us for more information.

Cassette decks when they left the factory or a service centre should have been aligned to a standard reference for the position of the record and play heads. Unfortunately they often weren’t all the same and over time the alignment can get drift, get knocked out or manual ‘fiddled with’ by an owner.

What this means is that unless you’re playing back your tape on the machine it was originally recorded on you may be getting the maximum quality as the angle of the head to the recording or azimuth will not be optimal.

Without calibration tones recorded at the start of the tape which is very unlikely on most domestic cassette tape recordings you must set the playback azimuth manually. A few high end tape decks, namely those made by Nakamichi, either had a easily accessed Azimuth adjust or could even automatically adjust this throughout the tape. The Nakamichi Dragon was one such tape deck and could be the best, if working well, for high quality playback.

If you want to transfer or convert a cassette to CD and adjust the azimuth yourself this is the an easy way to do it:

1. Look at the tape path (everything the tape will move across) and if it looks brown and dirty get some isopropyl alcohol and give it a good clean with a cotton bud.
2. If you haven’t demagnetised your deck for a while now would be a good time to do it..
3. Power up your cassette deck, which hopefully works correctly and doesn’t have too much speed instability!
4. Pop your tape in the cassette well and start to play.
5. Turn your amplifier’s volume up and if you can put it in Mono.
6. Now, look under the tape machine’s playback or combined record and playback heads you should see a small screw or nut possibly with anti tamper paint on it.
7. Using an appropriate tool, turn this nut or screw a little left or right while listening to the audio.
8. You should hear the recording, especially if it has a lot of high frequency content such as cymbals etc get bright and dull sounding or more technically get more in or out of phase.
9. Your aim is to get the most in phase or bright sounding playback.
10. Sounds better now?? Great, start to record using you favourite computer audio software. We like SoX for the control but there’s a huge range out there.

While some of our machines are serviced by others we like to regularly check them and have gradually bought our regular servicing in house. Of course this needs specialised tools, test tapes and gauges, often totally unavailable new now.

On a lucky eBay day I happened to win one of these beauties, an Information Terminals M-300 gauge. This enables you to accurately set the tape guide height and also the head stroke. It is a universal gauge and can be used across many decks.

Nakamichi tape deck owners have had a hard time doing this part of their servicing as the original Nakamichi gauges are very very rare now as is this.

A member of the naktalk mailing list though recently borrowed our gauge and has had it measured and will soon have a small batch CNC machined and made available. These remanufactured gauges will have a few small modifications to improve the design.

Thanks to Willy at www.willyhermansnervices.com many more tape deck transports will be able to be aligned correctly.

www.mowbraywoodwards.co.uk

We’ve recently been happy to be involved, with Mobray Woodwards Solicitors,  in the audio transfer of important evidence in a  local Crown Court case.

Even given the poor quality or the recordings, made on the slowest tape speed of 1.2 cm/s we were able to make transfers to CD which were clear and understandable with CD track markings for easy access to specific sections of the audio.

Microcassettes, until recently, were used regularly for voice recording in small, portable dictaphone type of machines. Their fidelity is not high but when used for voice it is usually acceptable.

Greatbear are able to transfer all formats and speed of microcassette in addition to 1/2 speed standard cassettes that were common for voice recording of interviews and meetings in the police service, inquests, etc.

For more information on high quality audio tape transfer and restoration please visit our transfer pages.