Hello,
After years of faultless service my A22 has recently started to shut itself down after 15-20 minutes of use at normal volumes. The display also seems to be a bit unreliable occasionally not coming on at all on power up and occasionally going off while the amp is running. Is there any chance that this is related to the protection circuit kicking in?
I've taken the lid off and can't see anything that looks particularly suspicious - no bloated caps, no signs of overheating etc. Is this something that I could debug by probing the Z9 device or is it likely to be a lost cause?
Also, Arcam's website now says that they are "unable to engage with Arcam owners directly when it comes to servicing equipment" which is a shame as they are just up the road and I previously found them very helpful. Has anyone tried to deal directly with Arcam recently? I'd contact my dealer for help but sadly they closed a couple of years ago...
Thanks for any advice!
After years of faultless service my A22 has recently started to shut itself down after 15-20 minutes of use at normal volumes. The display also seems to be a bit unreliable occasionally not coming on at all on power up and occasionally going off while the amp is running. Is there any chance that this is related to the protection circuit kicking in?
I've taken the lid off and can't see anything that looks particularly suspicious - no bloated caps, no signs of overheating etc. Is this something that I could debug by probing the Z9 device or is it likely to be a lost cause?
Also, Arcam's website now says that they are "unable to engage with Arcam owners directly when it comes to servicing equipment" which is a shame as they are just up the road and I previously found them very helpful. Has anyone tried to deal directly with Arcam recently? I'd contact my dealer for help but sadly they closed a couple of years ago...
Thanks for any advice!
According to this thread, the FMJ A22 is apparently a reworking of the Alpha 10. This should help as there is no service manual available on the web for this model, unless perhaps you are a service agent for Arcam.
Without a manual, it's not smart to try to fault-find or even offer specific help or advice on a complex model like this.
Arcam Alpha 10 Manual - Stereo Integrated Amplifier - HiFi Engine
Without a manual, it's not smart to try to fault-find or even offer specific help or advice on a complex model like this.
Arcam Alpha 10 Manual - Stereo Integrated Amplifier - HiFi Engine
My A22 has a similar fault. Flashing red power light after a few seconds of turning on.
Its the second time this has happened and I’m not going to send it to Arcam again.
With the lid removed, there is a main circuit board and it has “Alpha 10” printed on it. I found the circuit for an Aplha 10 and compared some parts to those on my board and they match up. Good.
There are 4 black metal lumps on the circuit board each with a component clipped to them, these are the power transistors that are the final stage in generating the audio signal - and that’s what often fails in an amp. Specially when you overload it by wiring the red and black speaker posts together. Oops.
I measured the resistance between the 3 pins of the transistors and found that on 2 of them some pins were short circuit so they’re no good anymore. It looks like one channel is dead causing the protection circuit to cut in. One can now go measuring the resistance of other components in that area of the circuit to see if there is any other damage. Resistance measurements can be compared with the equivalent component on the supposed working channel and should be about the same.
Ive ordered new ones , part no IRFP360LC from ebay. They are Mosfets. CPC Mouser and Amaxon sell them too.
Can’t see any other damage, ie no puffed up capacitors, burnt stuff, fuses, other big shorted transistors (check them too) so I’ll replace the Mosfets and see what happens.
Please take safety precautions if you are thinking of doing this. In particular when turning on for the first time, fit the lid for protection incase something goes bang inside, put the box somewhere safe like outdoors and switch it on from the plug socket using an extension lead keeping back.
Stay safe, and good luck
Its the second time this has happened and I’m not going to send it to Arcam again.
With the lid removed, there is a main circuit board and it has “Alpha 10” printed on it. I found the circuit for an Aplha 10 and compared some parts to those on my board and they match up. Good.
There are 4 black metal lumps on the circuit board each with a component clipped to them, these are the power transistors that are the final stage in generating the audio signal - and that’s what often fails in an amp. Specially when you overload it by wiring the red and black speaker posts together. Oops.
I measured the resistance between the 3 pins of the transistors and found that on 2 of them some pins were short circuit so they’re no good anymore. It looks like one channel is dead causing the protection circuit to cut in. One can now go measuring the resistance of other components in that area of the circuit to see if there is any other damage. Resistance measurements can be compared with the equivalent component on the supposed working channel and should be about the same.
Ive ordered new ones , part no IRFP360LC from ebay. They are Mosfets. CPC Mouser and Amaxon sell them too.
Can’t see any other damage, ie no puffed up capacitors, burnt stuff, fuses, other big shorted transistors (check them too) so I’ll replace the Mosfets and see what happens.
Please take safety precautions if you are thinking of doing this. In particular when turning on for the first time, fit the lid for protection incase something goes bang inside, put the box somewhere safe like outdoors and switch it on from the plug socket using an extension lead keeping back.
Stay safe, and good luck
Arcam A22 flashing red light
An update on my attempt to fix this fault..
Replacing the power mosfets didn’t repair the amp so I took a closer look to see if any other parts were damaged. I replaced the following parts because they were faulty or I wasn’t sure.
Q13,14,15,16 new set of mosfets
Q23,24,17,30. not sure if damaged. Nb SMT parts are glued to the PCB
R138,141,143,146 all had overheated and changed value
D5,6,7,8 10v zeners. not sure if damaged
All working now, sounds fantastic.
I wouldn’t advise messing with this amp unless you are experienced in this sort of thing, there are exposed mains voltages on the circuit board plus +/-30v DC driving the output stage.
An update on my attempt to fix this fault..
Replacing the power mosfets didn’t repair the amp so I took a closer look to see if any other parts were damaged. I replaced the following parts because they were faulty or I wasn’t sure.
Q13,14,15,16 new set of mosfets
Q23,24,17,30. not sure if damaged. Nb SMT parts are glued to the PCB
R138,141,143,146 all had overheated and changed value
D5,6,7,8 10v zeners. not sure if damaged
All working now, sounds fantastic.
I wouldn’t advise messing with this amp unless you are experienced in this sort of thing, there are exposed mains voltages on the circuit board plus +/-30v DC driving the output stage.
Congratulations on getting this model to work again. It seems the problem was confined to the output transistors where both channels appear to have at least one mosfet failed short, causing the drivers and their emitter resistors some grief too. Those are hefty mosfets and with both channels failed, there must be something strange going on elsewhere for that to happen.
Frankly, I would not trust Ebay traders for genuine parts. The majority are selling local copies and fakes based on sanded, relabelled parts which could be anything that works and has the appropriate style package. Sure, there are some honest traders supplying genuine semis with bonafide trademarks and batch numbers but they won't be so cheap.
Many semis will work fine in a range of applications but not for long at their maximum ratings. May I suggest you keep an eye as well as your ears on this amp. and don't leave it on and unattended until satisfied that it's stable and puts out the same power level in both channels consistently.
Frankly, I would not trust Ebay traders for genuine parts. The majority are selling local copies and fakes based on sanded, relabelled parts which could be anything that works and has the appropriate style package. Sure, there are some honest traders supplying genuine semis with bonafide trademarks and batch numbers but they won't be so cheap.
Many semis will work fine in a range of applications but not for long at their maximum ratings. May I suggest you keep an eye as well as your ears on this amp. and don't leave it on and unattended until satisfied that it's stable and puts out the same power level in both channels consistently.