NAD 5425 - disc read issue (not the laser!)

[MattP79]

Hi all,

I have a faulty NAD 5425 CD player I'm repairing. The fault is sometimes it wont detect discs, may not be able to play to the end of the disc or change tracks. Occasionally it works perfectly - all with the same pristine CD. I think I've traced the fault to IC Q102 (a Sony CXA1082BQ) which controls the pick up assembly. That's because if I deploy my chopstick-of much-probing and flex the PCB directly above Q102 (the chip is on the bottom side of the board) any reading fault is instantly resolved. I have already retouched the solder joints on Q102 and any other visibly cracked solder joints with minor improvement. I'm thinking of desoldering the chip to get a better look at the PCB / traces but before I expose the chip or the pcb to a lot more heat I thought I'd ask if anyone has found / resolved this issue or has a less invasive suggestion? The IC looks to be available if I need to replace it.

Any thoughts welcome

 

[percival007]

Could it be the Flexible Cables to/from the Laser/Motors?
Not necessaily on NAD equipment, but I have had some problems caused by intermittencies on those kinds of Cables.Connectors.

P

 

[MAAC0]

I presume You have already cleaned the lens and checked the mechanism gears, smooth movement, lubrication etc..

You could try to cut 1mm of the flex cable and connect it again. Easy whit a scissor.
Don't use an X-acto knife, since it probably bends the fine contacts.

 

[JonSnell Electronic]

I doubt Q102 is at fault. Check heavy items first; regulator on heat sink/Q507 for dry joints. re solder the edge connectors and if still an issue, re flow the solder on the PCB with flux and hot air or suitable PCB heater.

 

[MattP79]

I doubt Q102 is at fault. Check heavy items first; regulator on heat sink/Q507 for dry joints. re solder the edge connectors and if still an issue, re flow the solder on the PCB with flux and hot air or suitable PCB heater.

Thanks to all who responded

You were correct Jon. I had already paid attention to the most visibly cracked solder joints around the voltage regulators but some were obscured by a coating of the original flux... After a good clean and close inspection I found pin 79 on Q103 was loose (WDCK). It's close enough to Q102 to be affected when I was flexing the PCB. All re-soldered and no playback issues now Now I know the player is working I just need to replace the board fuses (someone installed the wrong value) and replace the burnt out incandescent bulb with an LED and R515 with an appropriate current limiting resistor...