Yamaha KX-580SE Cassette Deck Service & Repair

Herein a tail of Yamaha’s penultimate flagship cassette deck, the KX-580SE. Purchased in mint condition in the original box because the price was too good not to. Subsequently shipped with Hermes, so some reassembly and repair was required on late receipt. The prevalence of drop shops make Hermes all too convenient for eBay sellers. I do wish UPS and DPD would increase their spread in this area, so as to rule out convenience as a factor in a seller’s choice of courier and put an end to Hermes rein of destruction and package loss. But I digress.

The KX-580SE was a special edition tuned for the UK market. This ‘tuning’ extends only to electronic tweaks including Nichicon Muse capacitors, copper bus bars in the power supply and a few op-amp substitutions. There are no mechanical or mechatronic alterations; a dual-capstan mechanism would have been nice, as would 3 heads, but alas. This was a last gasp for the cassette format after all.

And as last gasps go it’s a good one. Based around a chassis more solid than most with plenty of features including automatic tape calibration, music scan, a mechanical tape stabiliser and play trim treble adjustment. And of course the crowning feature was Dolby S, along with B, C and HX Pro. Its features and their operations were covered by Mark Pearce in his 2017 review of his KX-580, which you can read Here. Mark has the original model but as far as I know the two are functionally identical. In this article we’ll delve into the internals of the machine.

Lifting the lid reveals mostly a box of air, with a couple of circuit boards, a power transformer and a mechanism that leaves one in no doubt of its production era. The simplicity of this mechanism however is its greatest strength. It is solenoid-driven via the large gear beneath the primary flywheel. There are two motors, one driving the reels via a reduction gear and the other driving the capstan flywheel via the single belt.

This has to be the simplest cassette deck in which to change belts. The flywheel has no thrust plate, so the belt can be simply unhooked and a new one threaded into place without even removing the mechanism from the chassis. The mechanism requires a 63 mm x 4 mm belt. Mine was kindly supplied by DeckTech, from whom you can purchase quality belts that unlike many of the cheap belt kits you find online are actually manufactured to meet or exceed original specifications for wow and flutter. They’re also well-priced and quickly delivered.

Now for a small confession. I actually rebuilt this mechanism before any of the pictures were taken. Thanks to its handling by Hermes there were bits of the mechanism strewn about the chassis, including the flywheel and capstan and parts of the door mechanism. Amazingly nothing was broken – and even more amazingly, the tiny E clip that secures the capstan in place was still to be found in the bottom of the deck. Had there been irreparable damage it is likely this particular machine wouldn’t warranted an article, so the fact that you’re reading this is a spoiler for a happy ending.

The mechanism is held in by 4 screws – two at the top and two at the bottom to either side. It lifts up and slides backwards and is removed as a unit including the door. You’ll find it easier to remove the top chassis bar which is secured by plastic rivets on either side. There are 3 cables – one running to the top control board, and two head cables connected to the mainboard.

The door is its biggest weakness. The spring is under extreme tension, which tends to prematurely wear the left-side plastic hinge. If you have a KX-580 and the door doesn’t sit straight, that is likely the cause. You can lessen this wear by removing the spring from its tab and letting it sit on the bottom mounting bracket. It’s perfectly secure, and alleviates most of the tension resulting in a more damped door action and less strain on the plastic hinge.

The door is easily removed to give better access to the heads and reel assembly. There are three primary components – the top latch, left-side door catch and the door itself, which hooks into two angled slots on each side of the mechanism.

The reel tables and gears are hidden behind a metal cover held in place by a screw on the right and a plastic rivet on the left. Removing this gives access to the reel gears, the pivoting gear that engages either reel during winding or playback operations and the screws for both the reel and capstan motors.

I wanted to lubricate both motors. I removed the four respective screws to loosen the motors. Be careful at this point, as the motors are soldered to the control board directly via tiny solid wires and those would be easily broken. Carefully clipping the mechanism over, the board can be released by gently prying back two clips. They aren’t immediately obvious, but if you have the top of the mechanism facing you with the back facing up, and the heads facing away from you, one is in front of the single detection switch on the right, and the other is in the middle of the two right-most of the three detection switches on the left.

With those released the board will lift out and flip over to give access to both motors. I applied a couple of drops of synthetic oil beneath the pulley of each, allowing it to drip down the shaft into the top bearing. You can disassemble them to get to the bottom bearing, but they’re easily broken and replacements aren’t easy to come by. Lubricating the top bearing made them run in near silence so I left the bottom bearings alone.

The same synthetic oil was used to lubricate the capstan. With everything reassembled, I lubricated the reel gears with a plastic-friendly white grease. These come from the factory with a dry lubricant applied which all but disappears over time. Leaving these parts without lubrication leads to premature wear. Eventually the gears will begin to shed teeth and a constant ticking noise during playback will spell the imminent need for replacements which are not available.

Reassembly is the reverse process, being careful to align the motors with their respective mounts. Also note that the switch levers at the top of the mechanism must clear the edge of the board, as they will fall forward without the board in place. You have to hold them in their forward-most position while you slot the board into its plastic channels and press down until the clips engage.

Parts of this mechanism remind me of a Denon DRM-740 that will feature in an upcoming article. There are obvious differences – the Denon is a dual-capstan, 3-head deck with motorised actuation, so in that regard the Yamaha is a simpler design. The overall chassis around which the mechanism is based is very similar however, so I wouldn’t be surprised if the mechanism was outsourced to the same OEM. The Yamaha has no optics for sensing tape movement, nor rotary encoders to detect take-up or tape spill. Given its simplicity it’s a mechanism that with proper maintenance should last a very, very long time without issues. There are no rubber drive tyres. the only rubber parts are the pinchroller and belt and both are simple to replace providing the aftermarket parts remain available.

With everything reassembled, I calibrated the speed with a 3kHz test tape. Speed control on this deck is via the potentiometer on the back of the capstan motor, which should be rotated with a ceramic or plastic screwdriver. Given the relatively lightweight flywheel this mechanism is surprisingly stable and free of wow and flutter. It copes very well with sustained piano which is a particular area where later belt-drive single capstan decks suffer in my experience. The mechanism is quiet, runs smoothly and sounds fine as far as cassettes go.

I checked the calibration of the electronics and found them to be perfect, well within factory spec. I know this deck hadn’t been serviced before as I purchased it from the original owner. So if you’re looking for a simple 2-head cassette machine that is new enough to require only minor maintenance, the KX-580, KX-580SE or the later KX-493 / KX-393 should fit the bill. They are very simple mechanically and electronically, very easy to service and maintain and generally well constructed as far as later cassette decks go. And for now at least second-hand pricing is still relatively sane.