Aiwa AD-WX929 Double Cassette Deck Repair

I recently detailed the service of an Aiwa AD-WX727. I wasn’t complementary about that machine and I stand by the fact that you could do a lot better for your money. Its new owner sent me the top of the range AD-WX929 for a similar service, and I thought this would be a good opportunity to see what it had to offer.


First appearances are a lot more positive. The construction is still cheap and flimsy, but you do at least get an aluminium fascia over the plastic front panel. The flimsy sheet steel casework is identical, and curious electronic anomalies remain. But that’s where the similarities end.

Inside are two identical mechanisms, both offering recording and full autoreverse. They’re a vast improvement with metal flywheels, one of which even has a thrust plate. There are obvious similarities in their construction and design, but the uplift in quality can’t be overstated.

Back Of Deck A

They are not without fault though. The primary flywheel drives the reels via a secondary belt. Yet the motor and thrust plate is positioned to support the secondary flywheel, not the primary. The flywheel that is under the greatest pressure, with the tension of two belts, is still supported only by the front capstan bearing.

The mechanisms are controlled by two solenoids and a pair of cam gears which are driven by the flywheels. They’re quite slick in operation though with a lot of unnecessary flipping of the autoreverse heads. Nevertheless winding speeds are good, wow & flutter do at least meet the specification, and the mechanisms don’t grind and clatter to the extent that the cheaper units do.

Back Of Deck B

The days of grinding and clattering were behind this deck, as storage and a lack of use had seen its belts degrade to the sticky, tar-like substance I love so much. The stuff is a nightmare to clean out, and it gets everywhere. There are a couple of ways to clean it. If the mechanism is mostly comprised of metal components, you can stick it in the freezer for a couple of hours and the stuff will harden enough to flake off. In this case almost the entirety of the mechanism is comprised of plastic components which are known to become brittle at temperature extremes. So it’s down to isopropyl alcohol, a pile of cotton buds, a roll of tissue paper, and time.

Dirty Side View 2

The stuff was everywhere. All over and behind the flywheels, in the pulley grooves, on the reel tables and on every moving part possible in both mechanisms. I ground the end of a steel nail to an extended 15-degree point to scrape the grooves of the pulleys. The flywheels are held in by tiny e clips at the front but they’re a pain to get off, so it’s easier to clean them in place.

Dirty Wheels 2

You’ll have an easier time if you remove the switch and speed board. It is held in by the two solenoids on either end which have to be de-soldered. Do so carefully as the pads on these boards are fragile, a good de-soldering pump is strongly recommended. There’s a small plastic clip additionally securing the board, which is melted in manufacture to bond it to the board. Lifting the board isn’t necessary, but it gives you better access to the reel drive pulley. You can slip a belt over top of the pulley with the board in place but it makes an easy job a great deal harder.

Back Of Switch Board 2

The reels are driven by the central pulley mounted to a swinging arm which is shifted by the primary cam to engage either of the reels, with additional gears engaged for the two playback speeds. That pulley is held in by a central pivot. Carefully prise up on the top of the pivot and lift the pulley out if you need to remove it, though it is possible to clean the pulley without taking it out. The challenge is getting to the belt residue trapped between the pulley and the pivoting arm.

Take care to remove all of the belt residue. If residue contaminates your replacement belts, it will degrade the rubber and they will fail prematurely. You’ll find that parts you cleaned become sticky again once the alcohol dries, so go over the mechanism a few times to make sure. Few of the parts are greased from the factory, so don’t be concerned about the alcohol getting into the mechanism. The reel tables are oiled, but from the top.

Dirty Wheels Side View

Don’t forget the motor pulleys. I remove them by prying up evenly with a flat screwdriver, and soak them in a zip lock bag with a generous splash of alcohol. They then needed scraping clean once the stuff was sufficiently loosened. You’ll find the residue has probably crept into the top motor bearing too. I decided to strip the motors in this deck and clean them thoroughly as the mess was bad, but you can usually get away with a drop of alcohol into the top bearing using a pipette or syringe, and rotating the shaft by hand. Flip the motor up-side-down to drain excess and let it dry thoroughly. Repeat until the shaft spins freely and the up and down movement is unhindered, and then oil the bearing with a drop of lightweight motor oil. 3 in 1 oil works, or a lightweight 100% synthetic gear oil.

New Belts On Cleaned Up No Board

I used belts from DeckTech, naturally. The best belts on the market by far, after years of trying belts from every supplier I could find. Most give dreadful speed stability, some fail within a few months, and some of these belt kits you buy are compiled based on inaccurate data. DeckTech actually research the correct belts for every machine by obtaining samples of the machines and checking the belts for suitability, manufacturing the correct sizes if required. They have everything from Minidisc belts (including custom belts sized specifically to correctly fit Sony mechanisms) to CD player belts (including a manufactured replacement for the unobtainable belts for first generation Panasonic models) , and belts for hi-fi cassette players to Walkmans (Walkmen?) and everything in-between. I’m not being paid to say this. I use their product and can’t recommend them enough.

Side View New Belt No Board

The reel belt goes over the reel drive pulley and beneath the primary flywheel. The flat capstan belts thread around the motor pulley, over the top of the secondary flywheel and around the larger primary flywheel. Correctly sizing both belts is important as applying an excessive load to the primary flywheel will cause the mechanism to throw the capstan belt during mode cycling operations.

The speed is adjusted exactly as per the WX727. Hold the left-most detection switch of deck B during power up, and continue to hold until the deck enters service mode. You can then press the high-speed dubbing button to switch playback speeds. The speed adjustments are on the mechanism switch boards. Adjust normal speed first, using a 3kHz test tape, and then repeat for high speed. Rinse and repeat until you have them balanced. You should be able to get within 20Hz of 3kHz (0.67% deviation) using a good test tape and decent belts, though these mechanisms do wonder a bit. You’ll certainly have an easier time than you will with a WX727. You’re doing well if you can get the 727 within 50Hz (1.67% deviation).

Overall Inside 1 2

I proceeded to test both mechanisms with a few pre-recorded test tapes and was pleasantly surprised by the performance. Noise levels are relatively low and speed stability acceptable, though I could hear some flutter on sustained notes. Fast winding operations are painfully slow and cueing isn’t much better, and running both motors simultaneously even when only one deck is in use seems a waste of power and mechanism wear. Operation is also inefficient, with lots of unnecessary flipping of the playback head which will eventually knock the azimuth out of alignment. .

All things considered, I still wouldn’t buy one. The AD-WX929 is loaded with features, but none of that matters when the quality of the bits that actually matter has suffered to such an extent. It’s miles better than the WX727, but the mechanical improvements don’t count for much. The mechanisms are badly flawed, the electronics are average and the build quality is so-so at best. A good low-end single tape deck (even from Aiwa themselves) or a better twin unit from another manufacturer would easily blow the WX929 out of the water.

Main Board

The WX929 is better than the WX727 in some areas, and it does an acceptable job playing back pre-recorded tapes. But it’s unreliable and not very well made, and there are a plethora of better cassette machines out there. The best thing the WX929 has going for it is a few extra metal components which add to its scrap value.

Guide prices on the used market – £0 to £15 for a broken one depending on condition. £30-50 for an untouched working unit, and by some miracle £70-90 for a good to mint one that has been serviced. Way too expensive in this author’s opinion, 

By Ashley

I founded Audio Appraisal a few years ago and continue to regularly update it with fresh content. An avid vinyl collector and coffee addict, I can often be found at a workbench tinkering with a faulty electronic device, tweaking a turntable to extract the last bit of detail from those tiny grooves in the plastic stuff, or relaxing in front of the hi-fi with a good album. A musician, occasional producer and sound engineer, other hobbies include software programming, web development, long walks and occasional DIY. Follow @ashleycox2

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