Keeping CD players going, Part 27

[rdenney]

I have said here that I bought a Naim Audio CD player because it has a manual swing-out drawer, with the thinking that troublesome drawer mechanics can be avoided, without being a top-loader that doesn’t work in my stack. This was a matter of sustainability for me. It also has a simple linear power supply and circuitry that is relatively easy to troubleshoot. So far so good, up until several weeks ago.

So, I started hearing bad crackling distortion in my right ear, listening through K371’s wired to the headphone amp of my Adcom preamp. A series of diagnostic steps led me to conclude, after much moving of wires, that the CD player was the source of the crackling. (I was mistaken, and I’m paying the price for that mistake, but that’s not the point of the thread.)

So, I removed the covers so I could start tracing audio signal. Naim cases are made from cast alloy panels—very heavy and fancy, but also fiddly. Once I had the covers off, I applied power to start testing. And two of the four 1N4007 bridge rectifier diodes immediately released their magic smoke. I can only conclude that I had allowed the shorting jumpers (that I’d improvised because I lacked the shorting plug needed to use the internal power supply for the audio section) to get shorted out against a loosened case panel.

I set it aside for some weeks while messing with a new (to me) preamp and signal router, repairing my PEQ, and re-EQing my room. During that time, I discovered the problem with the right-channel crackling.

I figured the short, if that’s what happened, would have killed the regulator, too, but I see no signs of it. I replaced the diodes, and once I realized I had unplugged a ribbon cable and reattached it, the unit powered up just fine. The power supply seems fine—solid DC output, no AC output.

When I insert a CD, it spins a turn and stops. Pressing play then tries another brief spin and then reports “Err”. That’s usually a laser unit problem in my experience—the control system isn’t getting confirmation of focus. I watched the startup sequence. The laser position motor, which on this Philips VAM1205 is a separate motor with a worm drive that turns a stacked gear that engages a rack on the laser sled, seems to work fine—it repositions properly when I manually position it away from the inner track. I see a red dot in the laser diode. But I do not see the laser unit moving the diode/lens up and down to seek focus. Aha! think I.

Given that the proximate problem was a shorted power supply, I measured the voltage being delivered to the transport—solidly five volts, and CMOS-level voltages at the pins going into the ribbon cable to the sled that powers the focus motor.

Well, while fiddling with the unit to remove the case, I had clumsily allowed the swing-out tray to slam shut with a considerable head of steam and a loud THWACK! that could well have caused some trauma to the laser sled, despite that it is shock-protected. That’s my current theory, anyway.

I even checked every line in that ribbon cable I dislodged to make sure continuity is good.

Of course, I can’t get service info, nor can I get any response from Naim, its US service provider, or the local Naim dealer. So I’m having to make it up as I go. The CD player is two decades old and Naim reportedly can’t get Philips parts any more anyway, but the rhetoric on their website about being able to service everything they’ve ever made is just hot air to me right now.

I just bought a knockoff VAM1205 from an eBay seller, recognizing that it’s probably crap. It’s a $30 experiment to see if the behavior changes. It’s very easy to install—that aspect of the simple mechanics has proved itself. If that doesn’t fix it, I’m back to some unresolved symptom of the power short.

More installments as the saga continues.

At this point, I’m predicting no better than a 50% probability of success.

Rick “comments and advice welcome” Denney

 

[sq225917]

Rick, speak to mikep on pinkfishmedia forum in the UK, he's a bit of a swing arm guru.

 

[rdenney]

Rick, speak to mikep on pinkfishmedia forum in the UK, he's a bit of a swing arm guru.

I do need to join that forum--a little bit Naimophile but the only place where unapproved hacks can be discussed, apparently. Much of what I know about the CD5 that I didn't learn myself by inspection came from there.

But my choice of words was misleading--the Naim CD5 uses a swing-out drawer, but the Philips VAM1205 is not a swing-arm transport--the laser moves on a sled, motivated by a motor with a worm-gear drive. It's not a terrible design by any means, though not in the same league as, say, a Sony KSS151, which uses a linear-drive motor for the laser sled with no plastic gears. Of course anything can break.

Apparently, Philips was producing the VAM1205 in a Chinese factory before they discontinued it, and the supposition is that the factory just kept making them, particularly after Philips's patents ran out. But quality control is reportedly getting worse and worse.

Rick "should be here next week" Denney

 

[sq225917]

He's still worth asking. A genuinely knowledgeable hobby repairist dedicated to golden age players and transports.

 

[Vini darko]

If magic smoke has been released it may have got onto the lazer lense. Have you tried cleaning it?

 

[rdenney]

If magic smoke has been released it may have got onto the lazer lense. Have you tried cleaning it?

There wasn't that much magic smoke, and the lid was off. But I did try cleaning it, even though with a strong magnifier it looks spotless (like everything else inside this unit).

But thanks for suggesting something that links the dumbassery on my part with the current symptoms. I am not a believer in coincidence, but I just can't figure out what shorting the low-voltage power supply would do to the laser unit. Of course, it might have taken something else out upstream from the laser, but I would think if so it would keep the laser unit from getting its voltage, and it's getting its voltage.

Rick "could be a control issue, I suppose" Denney

 

[rdenney]

The last sentence I wrote in the post above sparks some thoughts: The ribbon cable to the VAM1205 includes "Focus+" and "Focus-", both of which are carrying -3.8 volts relative to the ground pin on that same connector when the unit is powered up. Apparently, the focus control is performed on the Naim board and is driven by their software. That makes me wonder if my power supply problem damaged their chip. It shouldn't--the usual reset mechanism is shorting the power supply to the chip (but in a current-controlled way, unlike what I did). I need to check the board and see where those shorting plugs apply--whether it is upstream or downstream of the regulators. There are lots of taps off the toroid, but there is only one bridge rectifier that I saw.

Rick "more to figure out" Denney

 

[rdenney]

Well, no luck. Installing the new laser unit had no effect. I didn’t really believe it would.

I studied the main board on both sides closely, and traced to the voltage regulators downstream from where the external supply would be connected, and found one with solder joints that were a bit crusty. I resoldered it, not really expecting that to help, and it didn’t. Voltages at regulators looked reasonable—some were at 24 volts, some were at 15 volts, and a couple were at 5 volts. The board has lots of those LM317’s. Without a schematic I can’t really know what the voltages are supposed to be, but they all looked reasonable.

The spindle motor spins a bit, and the laser sled motor positions the sled at the inner limit switch. I can’t really tell if it’s attempting focus.

But it won’t spin up after the initialization, so it’s not getting the confirmation of focus.

Without service information, I’m stuck for now.

I heard back from Naim in the UK and they referred me to the service company in North America, and that channel remains silent.

Rick “sigh” Denney

 

[sq225917]

Ask on pfm, Martin, Mike or Richard will know the answer.

 

[JayGilb]

Well, no luck. Installing the new laser unit had no effect. I didn’t really believe it would.

I studied the main board on both sides closely, and traced to the voltage regulators downstream from where the external supply would be connected, and found one with solder joints that were a bit crusty. I resoldered it, not really expecting that to help, and it didn’t. Voltages at regulators looked reasonable—some were at 24 volts, some were at 15 volts, and a couple were at 5 volts. The board has lots of those LM317’s. Without a schematic I can’t really know what the voltages are supposed to be, but they all looked reasonable.

The spindle motor spins a bit, and the laser sled motor positions the sled at the inner limit switch. I can’t really tell if it’s attempting focus.

But it won’t spin up after the initialization, so it’s not getting the confirmation of focus.

Without service information, I’m stuck for now.

I heard back from Naim in the UK and they referred me to the service company in North America, and that channel remains silent.

Rick “sigh” Denney

You could check the vin on the 317s and make sure it's least 3 volts above the vout. Tracing back the adjust resistor would allow you to calculate the vout based on the vin.

 

[mhardy6647]

Ask on pfm, Martin, Mike or Richard will know the answer.

Just out of -- academic -- curiosity: what's a "pfm"?

 

[sq225917]

Pinkfishmedia

 

[rdenney]

You could check the vin on the 317s and make sure it's least 3 volts above the vout. Tracing back the adjust resistor would allow you to calculate the vout based on the vin.

Yes, all that I tested had reasonable values.

I’m going to have to button it up until the new year—life crowding in. But u think I have to eventually figure it out.

Maybe somebody on Pink Fish will have a schematic—that would go a long way.

Rick “remembering when owner’s manuals had schematics” Denney

 

[JSmith]

I did try cleaning it

Then the laser lens may be out of alignment.

That’s usually a laser unit problem in my experience

I agree... can be quite fiddly to rectify.


JSmith

 

[Vini darko]

Hi shame nothings worked so far. You probably need to scope the eye pattern to get it aligned ( assuming naim even provides adjustment points). Here's a good video from 12volt vids dealing with a very similar issue recently.

 

[EJ3]

Well, no luck. Installing the new laser unit had no effect. I didn’t really believe it would.

I studied the main board on both sides closely, and traced to the voltage regulators downstream from where the external supply would be connected, and found one with solder joints that were a bit crusty. I resoldered it, not really expecting that to help, and it didn’t. Voltages at regulators looked reasonable—some were at 24 volts, some were at 15 volts, and a couple were at 5 volts. The board has lots of those LM317’s. Without a schematic I can’t really know what the voltages are supposed to be, but they all looked reasonable.

The spindle motor spins a bit, and the laser sled motor positions the sled at the inner limit switch. I can’t really tell if it’s attempting focus.

But it won’t spin up after the initialization, so it’s not getting the confirmation of focus.

Without service information, I’m stuck for now.

I heard back from Naim in the UK and they referred me to the service company in North America, and that channel remains silent.

Rick “sigh” Denney

You might try these folks, I've had good luck with them being able to repair things:

Audio Proz Service and Sales​

SHIPPING ADDRESS: 779 Mt. Auburn St., Watertown MA 02472
PHONE: (617)926-8020
EMAIL: [email protected]
M(12-7), W-F(12-7), SAT(11-3)
Closed Tuesday and Sunday​

Audio Proz has been in the Hi-Fi and Pro Audio business for over 40 years. The owner, Vince Naeve has worked for companies such as Apt, H.H. Scott, and KLH. We are a different kind of shop. We assist our customers by helping them choose the correct equipment for their application, with special attention to the serviceability, longevity and manufacturer support. We try to be competitive on prices for new products and all of our used items are fully serviced, calibrated and Warranteed. We do not stock cheap throw away electronics that are actually more expensive to own and needlessly pollute the environment.

We have a huge inventory of parts required for our service (tubes, transistors, caps, controls, etc). We take a comprehensive approach to repairs and specialize in restoring vintage Pioneer, Marantz, Harmon Kardon, and many others. Every repair is thoroughly cleaned, maintenanced and calibrated so your unit leaves with all functions working properly. We also do custom modifications to equipment such as Electrix Repeater, Apt Holman Pre Amp, Art Pro Channel, B2-Pro Mic and Speakers of all kinds.

 

[rdenney]

I’ll have to send it to someone eventually. Naim provides no information at all and my ability to trace stuff in circuit is not nearly good enough. No, I would not know how to find the adjustment points for the eye pattern, and my learning time, especially of late, is nonexistent. My idea that it was a serviceable unit because of its mechanical simplicity has shot craps. I’d be a little more sanguine about had I not paid a stupid price it.

But in the meantime, I did manage to snag a Marantz commercial CD player in good working condition, so that’s there in place of the Naim. Because it’s a pro-sound model, it lacks the Marantz fairy dust, apparently, and therefore did not fetch the usual Marantz price. Philips transport, of course, with a conventional drawer. But lots of nice playback controls not found on my other players. Balanced outputs, too, for when I can take advantage of it.

Rick “bench now a bit deeper” Denney

 

[restorer-john]

Here's a good video from 12volt vids dealing with a very similar issue recently.

The guy in that video has absolutely no idea what he is doing. Adjusting laser power can only be done with a laser power meter. He's just a clown with a screwdriver turning pots with no concept of how a player works or the correct service procedures. The Pioneer was reading the TOC lightning fast, which means the laser, focus and associated servos were fine.

It's just another fake youtube 'repair'. Just turned a few pots until the player muted and then 'repaired' it in the video. We know he'd already completely dismantled the mechanism and put it back together because there's the classic Pioneer trap for people with no idea, sitting on his bench- a single ball bearing he missed when re-assembling the mechanism the first time around. LOL.