[SOLVED]Cambridge audio Azure 640C V2 repair. - Page 1
Forum section: electronics / repair

author: djsb
author_rank: Super Contributor
timestamp: June 07, 2024, 04:49:37 pm
content: 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 thoughts1/ 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.

author: Haenk
author_rank: Super Contributor
timestamp: June 07, 2024, 05:17:21 pm
content: 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.

author: Smith
author_rank: Frequent Contributor
timestamp: June 08, 2024, 08:19:24 am
content: +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.

author: rkabz
author_rank: Contributor
timestamp: June 11, 2024, 03:17:14 pm
content: 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.

author: djsb
author_rank: Super Contributor
timestamp: June 11, 2024, 04:56:33 pm
content: 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.

author: rkabz
author_rank: Contributor
timestamp: June 12, 2024, 05:59:19 am
content: 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.

author: FIXITNOW2003
author_rank: Regular Contributor
timestamp: June 12, 2024, 06:27:36 am
content: 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

author: rkabz
author_rank: Contributor
timestamp: June 13, 2024, 05:35:14 am
content: 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.

author: djsb
author_rank: Super Contributor
timestamp: October 06, 2024, 06:14:23 am
content: R11 (2.2K 0.25W 1% original 0.125W) replaced. Problem solved.

author: Gyro
author_rank: Super Contributor
timestamp: October 06, 2024, 12:49:16 pm
content: Quote from: FIXITNOW2003 on June 12, 2024, 06:27:36 amExcellent catch!