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Old 30th May 2004, 05:24 PM   #11
JonPike is offline JonPike  United States
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Join Date: Feb 2004
Location: Irvine
Yep, sounds similar to what I found out and did to this model. My friend only with great worry allowed me to look around inside.. then it was a battle to gain the confidence of changing things.. He still only has let me make a few changes, though.

Without any documentation, I did reverse engineer the DAC section even to the point of creating schematics in Orcad, which I'd be willing to share.. especially for that service manual!

I did upgrade the I/V resistors, and on the two boards that were cooked, put in sockets and quality bypassing. I also "socketized" the 4 DAC boards, so we could pull them out at will, and do things like compare a single stock board with the board using different I/V op amps, or better power bypassing caps. Made a believer out of him on modding.

I agree with you on the many things that could be improved a LOT in this unit.. the power supply is noisy, the clocks and digital signals are horrible... long long cables from the main board, and NO DECOUPLING at all on the "secret" board (actually a bunch of 74LS166's time shifiting the wc and data lines for the 4 DAC's) which floored me. For a "high end" unit, the build quality was surprizingly cheap.. Of course this means you can make a lot of worthy improvements.

I still would like to try: local low noise regulated power to the DAC's or even each one with it's own set, redistribute the data and clock so it gets there undistorted, reclock the data/clock lines to the DAC section, and or add a good low jitter master clock.

A note on the heat.. on this model, there were little aluminum plates glued to the 1541A'a, not much bigger than the chips, as simple heatsinks.. they need better than that! I found some finned heatsinks at Digikey (meant for 14 pin IC's) that have more area than that flat plate.. a small, quiet fan like for PC uP cooling blowing across the 4 boards, even just stirring the air inside would go a long way to cool them. But, my buddy is still thinking about that one..

When I get back to fixing things up, I'll attack the display. Should be easy to fix once the problem is understood.. Displays are simple.

It's a good design, done extremely cheaply.. Guess they had a genius design engineer, and a compulsive-obsessed cost reduction engineer and the latter won the fist fight...
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Old 10th June 2004, 09:05 AM   #12
skippy is offline skippy  United Kingdom
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I used to have a CD2 as well. Picked it up from the factory new, as many got damaged in the post.

It had a number of design flaws. I had to uprate the transistor driving the muting relay as it was a 0.3W device running at 0.5W. The LED displays failed as the drive current was set too high. I got new modules and increased the current setting resistor. The layout of the digital circuitry was appauling and the EMI was so bad I had to unplug the player to listen to the FM radio.

If yours has spasms, try pressing the bottom right button and the one above it at the same time. If I remember that's the reset.

I did have all the schematics for it plus my own notes, but I think I binned them. I'll have a look.

It sounded great for its time, but most CD players over 200 from the past five years sound better!

They're really not worth keeping running, unlike a MG-B.
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Old 4th August 2006, 03:03 PM   #13
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Can anyone supply the service manual (or any other info)? Would be really helpful!
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Old 26th August 2008, 02:38 PM   #14
wmincy is offline wmincy  Malaysia
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hi all,

just got a Cambridge Audio CD2, however defected, no reading, spinning just for a couple of seconds, display out.

After removing the upper panel and giving a PCB inspection, i found some components burnt, may be replacing them the player would function again.
I took a picture of the burnt area, can someone be so kind to help me providing the value of those burnt components? what's the voltage drop of the resistor? many thanks
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Old 26th August 2008, 03:19 PM   #15
pilli is offline pilli  France
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If that's the "lower left" corner of the main PCB when looking facing the front, I think it is the "delay" circuit that controls the output-muting relay.

By memory I think this is a 100ohm resistor that controls the current charging one of those caps, that then through some transistor switches the relay. See post #12 above: it dissipates much more than the 1/4W it is apparently rated for.
You can (to start with) just feed the relay directly from 5V (or 9V or 12V, see what rating it has), you'll just have some initial noises.


I don't think that this is related to the other problems you have.

The display, just forget it. All machines in this family are known to behave strangely in the display.

The not-reading is probably from the CD transport. These machines are old, and laser may be ageing.
Look at the threads about Philips CDM2 and CDM4 mechanics.
The replacement of a certain electrolytic capacitor in the mech sometimes make them work.

Another strange thing is the "on-off-standby", which is based on some TTL flip-flops (in the rear right area of the PCB, about in front of the regulators). Make sure it is "on" - do like me: short circuit it and turn it on-off from a normal switch on the AC.


The strong point is the DAC card.
You did read this whole thread above, didn't you?


If you want to get rid of the player, I'll take it
Are you really in Italy?




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Old 27th August 2008, 09:03 AM   #16
pilli is offline pilli  France
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Two more things came to my mind (maybe to yours too already).

One: check the voltages given by the transformer and the regulators. I remember in my CD2 one secondary was half of what it should have, and one of the 78/79xx regulators was fried. Everything runs hot in this player.

Two: Since the 4xTDA1541 DAC is about the only thing worth saving of this player, you can also hook it into another Philips player. All that the DAC needs is a 4x oversampled I2S (Philips flavour). This you can easily get out of the SAA7220 of any cheap Philips machine from eBay.


I confirm my interest in the player in case you lost yours.

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Old 7th September 2008, 09:23 AM   #17
wmincy is offline wmincy  Malaysia
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hi pilli,

thanks for your help. I have found a faulty capacitor in power supply, the -10v, the voltage float with an ampiltude of +/-2v.
However replacing it still didn't solve the non reading issue.

Then i tested the signal output from TDA5708 pin27, the oscilloscope showed the wave form (eye pattern) that didn't seem like the one we used to see it on a working machine.

Besides, the L292 was hot, is it normal?

Anyway, i'm not in Italy anymore, just move into Taiwan few months ago.

4x TDA1541 are definately more useful than the entire machine, haha, well a TDA1541 NOS is in progress.
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Old 11th May 2009, 06:01 AM   #18
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Default CDM 2 Schematic

Hello

I also have a Cambridge CD2 that is fully functioning and have a schematic for the CDM2 Mechanism (not the actual CD2 schematic) driver board if you require it.

I have just replaced the Op-amp on the CDM2 mechanism driver board
with LM4562 also all electrolytics with Sanyo Os-Cons (soon to replace all polypropylene caps as well) and it was a decent sound improvement I am currently trying to get the schematic off the designer Stan Curtis but it is taking a while to do so.

Maybe if we all request it from him he will be more persuasive in his response but I do realise he is busy so it might still take a while , if you want his E-mail give me a reply and we can hopefully get this thread moving again.
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Old 11th May 2009, 04:25 PM   #19
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Default Re: CDM2 mechanism - are you sure?

Quote:
Originally posted by Lenin
Just to reiterate Jean Paul's point - are you absolutely sure yours has a CDM2 mechanism?

My dead-'ish' CD2 has a CDM4 and I happen to know that the player was specifically designed around it. Maybe it was replaced - If it was, hunt around for a CDM4 - It will read just about anything.

I managed to get a complete service manual from Cambridge, as a result of a connection I used to have with the company. Its like no other, with a long, rambling explanation (from the unit's designer, Stan Curtis) of the rationale behind the design, etc, etc. It (along with my CD2) is at the other end of the country, where a friend has been playing around with it. I'll get hold of it and post it here.

The service manual also explains what the various fault codes that appear on the display from time mean (and how to clear them).

Jean Paul, you sound like you know my girlfriend...

Hello Lenin

Is your CD2 service manual are a hard copy or a file ?

Thank

Bye

Gaetan
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Old 14th July 2009, 05:50 PM   #20
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Default Cambridge Audio CD2

Hello Lenin
Could I please have a copy of the Cambridge Audio CD2 service manual.
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