Cyrus dAD3Q CD player repair – part 1

I’ve had my Cyrus dAD3 (later updated with Q module) since 1997. It’s still a very decent player even by today’s standards and it’s been fault-free for many years. Recently, though, CDs started to periodically mute and, before long, failed to play or even be recognised. Realising there was something seriously wrong, I was not a jovial rabbit. I remembered having a warranty repair soon after I’d first bought it, since it failed to recognise a handful of my CDs, yet was fine with all others. It came back unchanged so I sent a couple of the affected CDs off to Cyrus, together with the player again, and this time it came back totally fixed. I remember being vaguely aware at the time that the dAD3 was built around a Philips CD transport/laser mechanism that others – many with different players using the same mechanism – had mentioned they were having trouble with. I assumed the mechanism had been replaced and I soon forgot about it, until the other day. So what to do? Send it to Cyrus to repair (about £300), upgrade to something new (equivalent player now is about £1200) or attempt to fix it myself. I’ve been on a bit of a make-do-and-mend roll lately so I decided on the latter option, based on the assumption that the Philips mechanism (possibly the laser diode) was failing. So the Philips unit in question is the CDM12.4 – this I found out quickly from t’internet. This small unit houses the spinning motor, laser and laser drive motor. It sits within the larger Cyrus tray drive assembly and it is a little fiddly to get out but, with a little coaxing and a few expletives, out it came. There’s a certain order in which things need to be taken out and there are some very small wires and fragile flex cables which need some care, but patience paid off in the end. Firstly, the entire tray drive assembly needs to be taken out and it’s not going to be possible to do that without first pushing the tray out and unclipping the Cyrus tray front piece, then pushing the door closed again. Careful removal of cables and two boards will then allow the drive to be removed. It’s then a case of unhooking wires, carefully pushing out the rubber mounts, opening the drive again and sliding out the Philips unit. This will still have the Cyrus spiring-loaded clamp attached; this is detached from the back, leaving the bare CDM12.4.

Tray drive seen from underneath; boards and cables removed

Replacement CDM12.4 units can be had for £15 on eBay, which all seem to be advertised as being new even though they clearly are not. I didn’t like the sound of some of the feedback comments so I decided to try a reputable electronic spares company instead. OK, twice the price, but no misleading descriptions and I’d like to think that a company such as this would test such things before selling with guarantee. Still, at a tenth of the likely repair cost, had I decided to send the dAD3 away, it had to be worth a shot.

CDM12.4 is lower middle, still with Cyrus clamp attached

So, this morning I began the reverse surgery. After a careful couple of hours the result was… nothing. To cut a long story short, I had mounted the tray drive assembly slightly too far back, so whereas the door closed, it hadn’t properly engaged at the front. Naturally I assumed the Philips unit was another duff one, but by process of elimination I found it simply wasn’t being allowed to engage fully. Once I’d fixed that I powered up, loaded a CD and… the display looked good and I could see tracks playing through. Finally it was done – or so I thought. Hooked back up to the system, I waited for the first CD to play. Nothing. Not a sausage. Although the display was running through properly there was no audio output. Two possibilities: the CDM12.4 was duff after all, or it was fine but something had gone wrong in the analogue stage. A quick check showed that the digital optical out was fine going into an external DAC, so that ruled out the CDM12.4. Oh dear. Had I screwed up the DAC or analogue stage in the player? My unjovial rabbit status had been resumed. I took the Q module out and flipped the connectors to STD from UPG. This meant that the original DAC, which the Q replaces, was put back into service. I had audio! Phew. So, at worst, I’d damaged the Q module but after flipping back to UPG and re-installing the Q, it worked! I guess I must have nudged it somehow, during surgery. So, for £30, a few hours of my time and a little bit of grumpiness, I have my player back. Not long ago I’d have seen this as an excuse to upgrade, but I actually feel much better having fixed what I consider to be all the CD player I’ll ever need. I have, therefore, saved £1170 on the cost of the current model. What shall I buy?

DAK Novo pt. 3

There are optional tweaks mentioned for the Novo and I decided to try a couple of them out. The first, fitting optional twin capacitors, fell at the first hurdle (buying the capacitors – only one in stock!) and so it was time to thermally couple some transistors (oh yes).

I shan’t pretend I really understand why, but it’s theoretically beneficial to have a consistent temperature across each of two pairs of closely facing transistors on the board. In each pair, though, one transistor is likely to get a bit warmer than the other. Having them as closely facing as they are is probably enough but my obsessive nature meant that I was always wondering whether I could/should tie them together somehow. It’s been mentioned that an elastic sleeve should do the trick but I decided to go further: heat-transfer grease and heat-shrink tubing.

With a cocktail stick I applied the special grease to the facing surfaces of the transistors (quite a bit of prodding was necessary as they were close together) until I was satisfied that there was enough between them. This grease is the same stuff as is used between CPUs / GPUs and their heatsinks so the idea is that the warmer transistor transfers heat more efficiently to the cooler transistor in much the same way that a CPU dissipates heat through its heatsink.

I cut some heat-shrink tubing to give two sleeves which were placed over and around each facing pair. The hard part was moving the tip of a hot soldering iron around the sleeve several times, so that it shrank, but without touching anything. Not a job to do with a hangover! I then put a little more grease on top, around the join.

That’s it. It’s questionable whether this will make an audible difference – it’s supposed to but I guess it’s clouded by the fact that my Novo is still burning-in, having been powered for a little over two weeks.

DAK Novo pt. 2

Next in were the rest of the capacitors, followed by the input and output jacks. The potentiometer supplied to take care of volume control needed to be hacked about a bit: first to remove a lug and then to cut the shaft down to size – this was probably the one time I was worried I’d trash something. Thankfully, I didn’t. I started off with a hacksaw and then decided a Dremel with rotary cutter would do the job better. With that finally soldered into place, there were a few odds and ends to connect to the board, including all earths, and the LED.

Almost done...

I powered it up. The green LED lit. Get in!

Nothing blew up or started smoking, so I measured the voltages across several components as described in the booklet. All seemed well. Once mounted in the case (quite straightforward) it was time for the ultimate test: sound.

Case earths connected

It works! And not only that, it sounds good! With a source unit (CD, MD, whatever) set to line-out instead of headphone-out and a decent set of cans, such as the AKG 702 which I happen to have, the sound is noticeably better in every respect compared with the built-in headphone stage of the source unit. The Novo is used in this way instead of the source unit’s own headphone amp or it may be used to provide a headphone out for a system that doesn’t have one. Especially in kit form, this is a bargain for what it does; yes, it was a few hours’ work but there’s the satisfaction of building it thrown in for free. Good stuff!

Listening test

DAK Novo headphone amplifier kit

So I decided to get a dedicated headphone amplifier for the AKGs even though they sound pretty amazing with my portable units. It’s fairly well known that the amplifier stages of most portable units – and also those built in to most full-size separates – are compromises in terms of cost and available size and so I went looking for dedicated amps. They naturally varied in cost from a few tens of pounds to literally thousands and I had to set a limit as to how much I was prepared to spend. One name kept cropping up in the more affordable range: Graham Slee Projects. Graham and his team are U.K.-based audio engineers whose products – mainly headphone amps and phono stages – have been getting rave reviews for some time. Their Novo Discrete Solid State Headphone Amplifier has won awards from What Hi-Fi and can be bought direct for a very reasonable price, but it’s also possible to save a bit of money and buy this amp in kit form. The saving is around £80 and so it’s worth it, but only for those who are confident with electronics and soldering. I’ve messed around with electrics/electronics and soldering on and off since I was fairly young but I’ve never built anything like this from discrete components, from scratch. This was a challenge I had to take.

When bought in complete kit form you get exactly the same components, exactly the same case (except for a couple of cosmetic differences) and exactly the same power supply as for the retail version. The cosmetic differences are visible on the front of the case: the name and font are different (to reflect that this is a DAK – DIY Audio Kits – amplifier) and the front screws are different. That’s it – otherwise exactly the same.

The first thing I needed to do was identify the components, particularly all the resistors. The supplied booklet helps a great deal here, reminding me how to read the colour codes (although I don’t think I’d ever come across a six-band one before so I looked it up just to double check that the bands meant what I thought they did) and a multimeter helps to verify if necessary. I suppose I could have just used the multimeter to read them all off in the first place, but where would be the fun in that? A cross-reference with kit numbers enabled me to identify each one in relation to the board.

Resistors identified and marked
Component kit
Component kit with my adjustable grip holding the PCB

The next step was to insert the resistors and solder them into place. I’d bought some 60/40 tin/lead 0.7mm solder especially for this and it does the job nicely. I’d say my soldering skills are fairly basic but there’s nothing difficult here, given some care and attention.

After snipping off the excess pins underneath, the diodes went in next, followed by ceramic capacitors and transistors. With the bottom of the board becoming more and more busy with soldered joints, some concentration was needed for the transistors – especially as the pins should be soldered in a certain order.

Resistors and diodes in place
Transistors are in
Underneath

To be continued…

AKG K702 headphones

My old Sennheiser HD495 cans were starting to show their age – mainly through the earpads’ and head pad’s disintegration – so I decided it was time to semi-retire them and get something new. I also wanted to take the opportunity to replace them with some higher class headphones and so my search began, albeit without the opportunity to actually hear any.

Before long I had shortlisted a few and kept coming back to the K702, being described as revealing, flat-response reference class headphones. Basically, the descriptions of the sound appealed to me even though some said that the sound was a bit uninvolving (I ignored any comments from obvious “bassheads” who raved about their cans and put these down as I’ve heard the type of overly warm, overblown bass that they like and it’s not what I want). Although the K702 is aimed at studio recording/mixing use, its sibling, the K701, is aimed more at audiophiles and the sound is, apparently, practically the same.

It’s said that the K702 needs around 1000 hours’ running-in time before they really shine. Some say that the sound has settled nicely by about 200 hours. My initial impression was disappointment as the sound seemed distant and light.

Approximately one hour later my opinion had reversed totally and I could hardly believe  what I was hearing. What I hadn’t taken into account, clearly, was that I needed a little time to get used to this sound; all of my music sounded – sounds – different, hence the initial disappointment. It’s night and day. My 595s sound as though they are being pushed into my ears via a pile of old socks, in comparison. There’s just no real detail there but the K702, by contrast, reveals everything – both the good and the bad of any source. On balance this is undoubtedly good since I want to hear what’s there, rather than some veiled “best effort”. Having listened mainly to compressed music – usually no lower than 256 kbps ATRAC or AAC –  I can say that these ‘phones are a definite improvement at every level compared with anything I’ve used before and I’ll say the same for the few 132 kbps ATRAC tracks that I have.

I’m hearing things I never knew were there and everything has opened up considerably. If they are this good virtually out of the box, then I am very happy indeed as I’m having trouble imagining how they could improve with running-in. But that’s what everyone who owns these seems to say, so we’ll see what happens. Incidentally, it’s often said that a decent, dedicated headphone amplifier is pretty much a requirement for these in order to get the best out of them. That I can understand, especially since their sensitivity is lower than all my other ear/head phones, but so far I’ve only used the K702 with portable music systems (iPod, minidisc, etc.).

If there’s one niggle then it’s this: when I first put them on and for a few minutes afterwards, the pads seem to put a little too much pressure on the areas directly below my ears. It starts to feel uncomfortable so I need to pull them away a few times until I get used to them. No big deal, and it doesn’t seem as bad after a few wears as it did at first.

Other than that, I am extremely happy with them and, if they improve with running-in and/or a headphone amp, then happy days.