Arcam Alpha 5 prob

gman70 · 1st April 2007, 03:32 AM

hello all. First post here. So al get an appology in just incase am in the wrong place.
I ahve a problem with my Arcam Alpha 5 Amp. out of the blue, it has ceased working

.
I had a look inside and noticed that the 1 amp Timed/slow blow fuse had blown. I got replacement fuses and have since blown another 5. I have removed the circut board and there is no OBVIOUS sign of damage.
I cant afford to send it to arcam to be fixed. Has anyone got any ideas what the problem maybe and how to fix it? Any help welcomed as I miss my music.

Thanx

big jim · 1st April 2007, 06:53 AM

Hi its probaly the o/p transistors [fets]
i have the manual if you need it PM me

all the best jim

gman70 · 1st April 2007, 12:01 PM

Hi Jim. Thanx for replying. Is the prob you suggested easily solved? Is it likely to be a pricey thing do you know?

jaycee · 1st April 2007, 01:16 PM

I have an Arcam Alpha 7R here for repair at the moment

It is likely that the output MOSFETS on one or both channels (IRF540) have blown short circuit, causing a short across the power supply. IMO the heatsinks in the Alpha amps are far too small, so it's not really a surprise. There is also no TVS/MOV across the mains supply, so this amp seems to be suspect to power surges.

I would suggest that you just obtain new MOSFETS (IRF540N works, as should IRF540NPBF) and they are only about £2.50 each, BUT because you have tried so many fuses, it is likely that you have caused further damage to the circuit.

I also suggest obtaining the service manual from Arcam - they should send you this as a PDF file.

gman70 · 1st April 2007, 02:39 PM

Thanks jaycee. I have contacted Arcam like you sed and will look to get these components you mentioned.
Are they readily available from the likes of Maplin or do I need a more speacialised supplier?
Cheers!!

jaycee · 1st April 2007, 03:01 PM

Rapid stock them, as do bigger suppliers like Farnell or RS. I would go with Rapid as they will cater for small orders - order code 47-0317. These days, I wouldn't touch Maplin with a barge pole.

If you want to confirm that the outputs are blown, unsolder them and use a continuity check or resistance check to measure between source and drain (pins 2 and 3). They are blown if they read short - you will probably find continuity between the gate and source/drain also.

1st April 2007, 03:32 AM	#1
gman70 diyAudio Member Join Date: Mar 2007	Arcam Alpha 5 prob hello all. First post here. So al get an appology in just incase am in the wrong place. I ahve a problem with my Arcam Alpha 5 Amp. out of the blue, it has ceased working. I had a look inside and noticed that the 1 amp Timed/slow blow fuse had blown. I got replacement fuses and have since blown another 5. I have removed the circut board and there is no OBVIOUS sign of damage. I cant afford to send it to arcam to be fixed. Has anyone got any ideas what the problem maybe and how to fix it? Any help welcomed as I miss my music. Thanx

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
ARCAM Alpha One	weissi	Digital Source	21	2nd October 2009 07:09 AM
Best arcam alpha 5 plus mod	jutter	Digital Source	2	25th January 2009 11:42 AM
Arcam Alpha Plus	amc184	Digital Source	6	17th January 2008 06:01 PM
Arcam alpha 9	pumpkin	Solid State	0	5th October 2005 06:31 PM
Arcam Alpha 5 +	j baldam	Digital Source	1	9th July 2003 10:20 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

1st April 2007, 06:53 AM	#2
big jim diyAudio Member Join Date: Feb 2006 Location: london	Hi its probaly the o/p transistors [fets] i have the manual if you need it PM me all the best jim

1st April 2007, 12:01 PM	#3
gman70 diyAudio Member Join Date: Mar 2007	Hi Jim. Thanx for replying. Is the prob you suggested easily solved? Is it likely to be a pricey thing do you know?

1st April 2007, 01:16 PM	#4
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	I have an Arcam Alpha 7R here for repair at the moment It is likely that the output MOSFETS on one or both channels (IRF540) have blown short circuit, causing a short across the power supply. IMO the heatsinks in the Alpha amps are far too small, so it's not really a surprise. There is also no TVS/MOV across the mains supply, so this amp seems to be suspect to power surges. I would suggest that you just obtain new MOSFETS (IRF540N works, as should IRF540NPBF) and they are only about £2.50 each, BUT because you have tried so many fuses, it is likely that you have caused further damage to the circuit. I also suggest obtaining the service manual from Arcam - they should send you this as a PDF file.

1st April 2007, 02:39 PM	#5
gman70 diyAudio Member Join Date: Mar 2007	Thanks jaycee. I have contacted Arcam like you sed and will look to get these components you mentioned. Are they readily available from the likes of Maplin or do I need a more speacialised supplier? Cheers!!

1st April 2007, 03:01 PM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Rapid stock them, as do bigger suppliers like Farnell or RS. I would go with Rapid as they will cater for small orders - order code 47-0317. These days, I wouldn't touch Maplin with a barge pole. If you want to confirm that the outputs are blown, unsolder them and use a continuity check or resistance check to measure between source and drain (pins 2 and 3). They are blown if they read short - you will probably find continuity between the gate and source/drain also.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)