Author Topic: [SOLVED]Cambridge audio Azure 640C V2 repair.  (Read 1356 times)

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Online djsbTopic starter

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[SOLVED]Cambridge audio Azure 640C V2 repair.
« on: June 07, 2024, 04:49:37 pm »
Was just playing RUSH by RUSH (their debut album) on my Cambridge Audio Azure 640C V2 CD player last night and the audio suddenly stopped. I can't afford a new CD player, so it looks like I'll have to fix it. I've made the following observations.
1/ Drawer works fine, although it could maybe benefit from a new belt, as I'll have the lid off.
2/ The ON/OFF is a bit erratic sometimes.
3/ All the tracks can be skipped through one at a time, and the counter and track indicator works on the display.

There is just no sound. I've checked my amps etc with another source and they are working fine.

My initial thoughts
1/ The unit has been plugged into the mains for a while, so something in the power supply may have failed.
2/ After doing a visual inspection and taking photo's and cross-referencing with the service manual (which I have already downloaded and attached here) I will check some voltages.

Questions.
1/ How do I know if the laser has failed?
2/ Are there any stock/common areas to check on these models?

The laser assembly is fairly inexpensive, so not too bad if it needs replacing.
I've also bought an audio test CD just in case.

Thanks.
« Last Edit: October 06, 2024, 06:15:03 am by djsb »
David
Hertfordshire, UK
University Electronics Technician, London, PIC16/18, CCS PCM C, Arduino UNO, NANO,ESP32, KiCad V8+, Altium Designer 21.4.1, Alibre Design Expert 28 & FreeCAD beginner. LPKF S103,S62 PCB router Operator, Electronics instructor. Credited KiCad French to English translator
 

Offline Haenk

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #1 on: June 07, 2024, 05:17:21 pm »
Put in a disc, press Play. Does the time displayed increase and can you skip to the next track? If the answer is "yes", the laser and CPU are OK - you need to trace, make sure, all voltages are present. If the answer is "No", a failed laser is possible, but check voltages first before buying a replacement.
 
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Offline Smith

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #2 on: June 08, 2024, 08:19:24 am »
+1 for the laser. I had the exact same version, it used up 2 lasers in about 2 years. Then I tossed it out. Also check for bad solder joints. Mine had a lot of them.
Trying is the first step towards failure
 
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Offline rkabz

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #3 on: June 11, 2024, 03:17:14 pm »
Check the power supply filter caps, after years of being on even in standby, they tend to dry out. Cambridge did not use the best caps. The mute relay (RL1:A) circuit has a DC 15V (VAI) and AC (ACI) sense input, there may be an issue with the supplies, C25, or some other component in that. The schematic shows the relay contacts in the mute position. If you had a DSO you could check for audio on R43/48, since it sounds like the transport is working by giving TOC and track/time info on the display.
 
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Online djsbTopic starter

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #4 on: June 11, 2024, 04:56:33 pm »
Thanks for your replies so far. I've checked the following so far.
1/ +/-15v supplies to the Opamps. All check out OK.
2/ Mains input fuses. All OK.
I will be checking the Mute relay RL1 next. I'm going to insert an audio test CD into the tray and try to trace the signal from the output of the DAC's.
There is no visible bulging to any of the capacitors, so they are way down on my list.
For anyone following along, you will need a TX6 TORX screwdriver to remove the lid. I treated myself to a Wera 2067 HF TX6 x 40 mm 05118182001 screwdriver as I want to build my collection of decent tools. More later.
« Last Edit: June 11, 2024, 04:58:10 pm by djsb »
David
Hertfordshire, UK
University Electronics Technician, London, PIC16/18, CCS PCM C, Arduino UNO, NANO,ESP32, KiCad V8+, Altium Designer 21.4.1, Alibre Design Expert 28 & FreeCAD beginner. LPKF S103,S62 PCB router Operator, Electronics instructor. Credited KiCad French to English translator
 

Offline rkabz

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #5 on: June 12, 2024, 05:59:19 am »
Be aware that dry caps often do not bulge or show any physical signs of stress. I have two of these and have replaced caps in both.
 
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Offline FIXITNOW2003

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #6 on: June 12, 2024, 06:27:36 am »
Plays but no Audio -check/replace R11 2.2K ohms , this is part of the audio mute relay circuit and the failure of this resistor is almost certainly down to the hydroscopic glue around it , resistor will found to be open circuit. or drifted  very high ,hidden under glue near the cap C20 and voltage regulator U3
 
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Offline rkabz

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #7 on: June 13, 2024, 05:35:14 am »
Good tip. That damn glue causes lots of failures due to corrosion. It also becomes conductive as it ages and darkens, creating leakage paths where you don't want them. Really sh*t stuff.
 
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Online djsbTopic starter

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #8 on: October 06, 2024, 06:14:23 am »
R11 (2.2K 0.25W 1% original 0.125W) replaced. Problem solved.
David
Hertfordshire, UK
University Electronics Technician, London, PIC16/18, CCS PCM C, Arduino UNO, NANO,ESP32, KiCad V8+, Altium Designer 21.4.1, Alibre Design Expert 28 & FreeCAD beginner. LPKF S103,S62 PCB router Operator, Electronics instructor. Credited KiCad French to English translator
 

Online Gyro

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Re: Cambridge audio Azure 640C V2 repair.
« Reply #9 on: October 06, 2024, 12:49:16 pm »
Plays but no Audio -check/replace R11 2.2K ohms , this is part of the audio mute relay circuit and the failure of this resistor is almost certainly down to the hydroscopic glue around it , resistor will found to be open circuit. or drifted  very high ,hidden under glue near the cap C20 and voltage regulator U3

Excellent catch! :clap:
Best Regards, Chris
 
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