Hi, I own a Azur 540A and I was using a subwoofer with it via the Pre out. My son pulled out the Rca going from the pre to the Sub and I believe it wa sshorting out possibly. All of a sudden there was smoke coming from unit. I opened it up and noticed that u5 chip is totally fried and when turning it on the unit goes into protection mode and it sounds like the volume motor is moving. Anyone know what function that chip has and also what can i do to repair this.now. This is second Cambridge Amp to die on me. Both times from stupid mistakes.
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Hi
The NE5532 is a well known and respected dual low noise opamp chip with the standard pin configuration used by most (if not all) 8 pin dual opamp chips.
It should be available from most decent electronic part shops.
In this amplifier it is used for the Baxandal tone control followed by an inverter stage to return phase to the original from the input.
I am though almost impressed that a simple extraction of an input cable could bring one of these into smoke.
Before exchanging it - I would therefore suggest that you measure the voltage on pins 4 and 8 (should be -15 and +15V reference to ground).
That is - after carefully removing the burnt chip.
I am just guessing now - but the amplifier going into protection mode could be that the power supply (the +/- 15V) are shorted through the burnt chip.
Cheers, Martin
The NE5532 is a well known and respected dual low noise opamp chip with the standard pin configuration used by most (if not all) 8 pin dual opamp chips.
It should be available from most decent electronic part shops.
In this amplifier it is used for the Baxandal tone control followed by an inverter stage to return phase to the original from the input.
I am though almost impressed that a simple extraction of an input cable could bring one of these into smoke.
Before exchanging it - I would therefore suggest that you measure the voltage on pins 4 and 8 (should be -15 and +15V reference to ground).
That is - after carefully removing the burnt chip.
I am just guessing now - but the amplifier going into protection mode could be that the power supply (the +/- 15V) are shorted through the burnt chip.
Cheers, Martin
+1
I repaired some, and almost every time, a cut track on a capacitor of the regulation board (+/- 15v).
you have to scrape the glue to discover the cut track
I repaired some, and almost every time, a cut track on a capacitor of the regulation board (+/- 15v).
you have to scrape the glue to discover the cut track
The only thing that happened was the removal of the rca cable from
The preout. Only one was plugged into the pre out and one into the line on of subwoofer. That’s when my wife noticed smoke smell and I noticed it was coming from the Amp. That chip is fried and the volume pot motor is making noise. The protection light comes on. What are the odds that only that chip is damaged? This is my second Cambridge now to die. I will tomorrow check voltages on that chip per instructions. Now to figure out how to get at the pre amp board from underneath. Unscrewed all the bottom screws and not getting
The preout. Only one was plugged into the pre out and one into the line on of subwoofer. That’s when my wife noticed smoke smell and I noticed it was coming from the Amp. That chip is fried and the volume pot motor is making noise. The protection light comes on. What are the odds that only that chip is damaged? This is my second Cambridge now to die. I will tomorrow check voltages on that chip per instructions. Now to figure out how to get at the pre amp board from underneath. Unscrewed all the bottom screws and not getting
The 5532 is in the tone control circuit
The voltage regulator probably died.
Thus sending high voltage to the volume pot motor and op amps.
There may be more dead chips in there
The voltage regulator probably died.
Thus sending high voltage to the volume pot motor and op amps.
There may be more dead chips in there
Pulling the pre amp wire, it would have been shorted only briefly before being pulled from the socket - caused so much damage?
Peculiar.
Peculiar.
Exactly - peculiar.
I can not find the pre-amp out on the schematics, so unless it is just my sight, we don't even know if the pre-amp out is connected to the burnt chip.
As I recall it the NE5532 should be a rather sturdy chip - making it even more peculiar.
A question for everybody here: When a RCA plug is disconnected - is possible that the center pin disconnects AFTER the ground (shield) disconnects?
Cheers, Martin
I can not find the pre-amp out on the schematics, so unless it is just my sight, we don't even know if the pre-amp out is connected to the burnt chip.
As I recall it the NE5532 should be a rather sturdy chip - making it even more peculiar.
A question for everybody here: When a RCA plug is disconnected - is possible that the center pin disconnects AFTER the ground (shield) disconnects?
Cheers, Martin
I found the full schematics - the pre-amp out connection is not even connected to the U5 chip - there are two amplifier stages between pre-amp out and U5.
Just guessing now - but I think it is very unlikely that only U5 has suffered damage.
Cheers, Martin
Just guessing now - but I think it is very unlikely that only U5 has suffered damage.
Cheers, Martin
I installed new Op amp chip and thought I wa sin the clear however I have a low hum now when no music is playing. Not sure where to go now. I had cut the wires to the volume pot motor and didnt reattach therm but i doubt its that. any ideas? I only have a multimeter.
I installed new Op amp chip and thought I wa sin the clear however I have a low hum now when no music is playing. Not sure where to go now. I had cut the wires to the volume pot motor and didn't reattach therm but i doubt its that. any ideas? I only have a multi meter.
Nice to see you get some progress.
I would suggest you check the power supply - in particular the +/-15V
The low hum might be be caused by another failed chip drawing such much current that the input to the regulator chips (u2 and u4) in the power supply drops below the minimum voltage for the regulators.
Try to find pin 1 on u4 (the 7815 regulator) that should measure at least +18V referenced to ground. Same for pin 2 on U2 (the 7915 -15V regulator) is should carry at least -18V.
Cheers,
Martin
I would suggest you check the power supply - in particular the +/-15V
The low hum might be be caused by another failed chip drawing such much current that the input to the regulator chips (u2 and u4) in the power supply drops below the minimum voltage for the regulators.
Try to find pin 1 on u4 (the 7815 regulator) that should measure at least +18V referenced to ground. Same for pin 2 on U2 (the 7915 -15V regulator) is should carry at least -18V.
Cheers,
Martin
Cambridge Audio amps usually have very crappy capacitors in them as well. The designs themselves arent bad but then they build them too cheaply with crap parts. Shame really.
Good point about the capacitors
And for Gaspar74:
Faulty capacitors can create a lot of difficulties - so let me add some comments on the meaurements on the power supply:
- the expected unregulated voltages (where I previously wrote "at least 18V") - should be around 23V; and the positive and negative sides should be quite close
(like +23V and -23V).
- check the regulated +/-15V
And visually check the electrolytic capacitors in the power supply - do they bulge or are there signs of something has leaked out?
Cheers, Martin
And for Gaspar74:
Faulty capacitors can create a lot of difficulties - so let me add some comments on the meaurements on the power supply:
- the expected unregulated voltages (where I previously wrote "at least 18V") - should be around 23V; and the positive and negative sides should be quite close
(like +23V and -23V).
- check the regulated +/-15V
And visually check the electrolytic capacitors in the power supply - do they bulge or are there signs of something has leaked out?
Cheers, Martin
Not sure where to measure. You said pin one of U4, where do I attach ground. Can i use the ground post in the chassis? I assume so.
Maybe I wasnt doing it correctly but pin one should be the one to the left of the little dot on the chip right? Where is a good ground for me?
https://www.diyaudio.com/forums/attachment.php?attachmentid=998994&stc=1&d=1637397858
the part that interests you is there.
you have to put down the pcb, then unsolder the two blue capacitors to have access to the regulators and to the traces on the pcb
the part that interests you is there.
you have to put down the pcb, then unsolder the two blue capacitors to have access to the regulators and to the traces on the pcb
