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Help diagnosing poweramp fault (Parasound Halo A21)

T

therixonator

pfm Member
Hi All,

My Parasound Halo A21 poweramp has developed a fault. When I switch on the power button I hear the usual immediate click and the led behind the power button changes colour. After a couple of seconds it would then make a loud clunk and the 2 blue LEDs in the middle would light up. This second stage no longer happens and so no signal is getting passed through to the speakers anymore.

I've opened up the lid and moved some dust around but I can't see any leaky capacitors or anything that looks burnt out. It all looks in good nick. I did take a couple of videos if this might help?

I just wondered if this was the sort of problem that happens to many power amps and is easily diagnosable from the symptoms above? If so I could maybe just get a part shipped like a new transformer and fit it myself. But if not I will carry on with trying to find someone to fix it professionally. I think it weighs 30kgs plus so getting it delivered will be interesting.

I bought the amp 2nd hand a few years ago so it is out of warranty. This is the first thing to go wrong on it. Parasound don't seem to be a big presence in the UK so I've been hunting round for someone to fix it. The Parasound UK website has the service link greyed out! I've emailed a few people yesterday including Parasound in the US and UK plus a few distributors so hopefully somebody will know where I can go. Obviously if anyone in the UK has got something Parasound fixed before, please let me know what you did.

I love the amp so am very keen to get it fixed rather than find something else.

Many thanks,
James
 
It would seem from what you say that the internal protection circuit has been triggered. Have you tried powering the amp standalone i.e. without any inputs connected and the speaker cables disconnected? If its still not working then the amp is faulty and you could try Jez over at AoS as he is likely to have a go at repairing anything.

If the amp does power up correctly then its a process of elimination as to what it doesn't like.

BTW the amp weighs just over 27Kg (or 34Kg with original box) and thats easy to ship by courier. My own amps were delivered in this way and they weigh in at 42Kg and over 50Kg boxed!

Cheers,

DV
 
therixonator where are you located? If you are within a reasonable distance of Southampton I might be able to help.
 
Darth Vader said:
It would seem from what you say that the internal protection circuit has been triggered. Have you tried powering the amp standalone i.e. without any inputs connected and the speaker cables disconnected? If its still not working then the amp is faulty and you could try Jez over at AoS as he is likely to have a go at repairing anything.

If the amp does power up correctly then its a process of elimination as to what it doesn't like.

BTW the amp weighs just over 27Kg (or 34Kg with original box) and thats easy to ship by courier. My own amps were delivered in this way and they weigh in at 42Kg and over 50Kg boxed!

Cheers,

DV
Click to expand...

Thanks DV, it certainly does feel like some protection circuit has been triggered. But yes I have tried switching it on with only the power cable in and it didn't make a difference.

Incidentally, I did change something about a week ago. In my stepped attenuator style preamp (Tissbury Audio Mini Passive Preamplifier) i changed the switches on the bottom to -10db as my system is so gainy, my wife moaned about the volume even when it was on level 1! Not sure if this could have caused the issue?

Thanks for the Jez recco, I'll contact him if I don't get anywhere with Parasound.
 
awkwardbydesign said:
Have you checked the position of the switch on the back, that toggles between 12V trigger on, normal on and music signal on?
And mine came from here - http://www.connecteddistribution.com/index.php/online-store/parasound
Failing that, talk to Richard Schram, [email protected] He owns Parasound and is really helpful.
Click to expand...

Thanks ABD, I've got it in the middle position at the moment and have been trying the other positions. With nothing plugged in and the amp on, flicking it up or down switches the amp off. And it won't switch back on whilst in the up or down positions.

I've emailed the general Parasound contact us email address. If they don't reply in a couple of days I'll give Richard a try.
 
mickhick1 said:
therixonator where are you located? If you are within a reasonable distance of Southampton I might be able to help.
Click to expand...

Hi Mick,

I'm in North London. But I could drive down to Southampton on a weekend if need be, that's not a problem. Are you familiar with Parasound gear? Got spares etc?
 
therixonator said:
Thanks DV, it certainly does feel like some protection circuit has been triggered. But yes I have tried switching it on with only the power cable in and it didn't make a difference.

Incidentally, I did change something about a week ago. In my stepped attenuator style preamp (Tissbury Audio Mini Passive Preamplifier) i changed the switches on the bottom to -10db as my system is so gainy, my wife moaned about the volume even when it was on level 1! Not sure if this could have caused the issue?

Thanks for the Jez recco, I'll contact him if I don't get anywhere with Parasound.
Click to expand...

You haven't tuned the gain control on the rear panel to minimum have you?

Cheers,

DV
 
Hi Eekeroth,

Yes i was, I forgot to post a reply on here. Bad form, sorry.

The instructions manual doesn't quite tell the truth. There is a fuse located on the back of the amp. It's there to protect the output channels on the amp from surges. The amp will still power up if this blown but the channel circuits won't clunk into action. This isn't what the instructions say. The instructions say it won't come on at all. That's only true if the fuse in the plug is blown.

Take the fuse out and try turning it on again, when I got the same result I knew it had to be that fuse. You'll see it's the US variety, a bit longer than the UK ones. Read the tiny numbers on the end and order some spares. I used eBay. Cost about £2! Thought it was going to cost hundreds so I was very happy!!
 
Thanks for the update! I know of 5 fuses (the one on the back, and 4 located by the capacitors). Is it the one on the outside, or another (#6) that I am not aware of?
 
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