Arcam Alpha 10 Intergrated Output Transistors Location?? - diyAudio
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Old 1st February 2014, 09:20 AM   #1
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Default Arcam Alpha 10 Intergrated Output Transistors Location??

Hi anyone know the location of the output transistors in the alpha 10.
Amp going into protect mode flashing red led after about 15 seconds from being powered up.
Did some digging around the net and best guesses are output transistors shorted out.
Downloaded Arcam service manual the transistors I'm suspecting are the ones to check are refferred to as Trans Power Mosfet(Part IRFP360LC)
I could be wrong with this assumption as I'm a complete novice.
Another possible culprit , although again I could be wrong are transistors reffered in service manual as Trans Audio Driver.
Have done a little reading up on testing FET@s with multimeter although a little confusing I have worked out Gate, Drain, Source with the FET's in question just looking for a little guidance on best way forward,with correct Fet's to measure and hopefully diagnose as defunked.
I have put what I think are the possible Output transistors in the red square box on the attatched picture, and as my second choice the red circles.
Hopefully someone can get back to me with opinions and help.
Thanks in advance.
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File Type: jpg Arcam Fet Positions.jpg (524.9 KB, 78 views)
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Old 1st February 2014, 10:19 AM   #2
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Red square boxes... definitely. But be careful. With those kinds of outputs, standard multimeter readings can give strange results (specially if you charge up the gate capacitance with the measuring voltage, they can "stay" open for long time.....) Your best bet is someone knowledgeable enough with that kind of stuff.

Last edited by dragonweed; 1st February 2014 at 10:23 AM.
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Old 1st February 2014, 10:49 AM   #3
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Which Arcam Alpha 10 is it. There are three models.
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Old 1st February 2014, 11:09 AM   #4
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Standard Integrated without DAVE module.
Not really clued up on the model as I was given it.
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Old 1st February 2014, 11:14 AM   #5
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Many thanks Dragon Weed!
I was given the amp and was thinking of just replacing the four FET's as a start- to be honest the process of determining which ones are defective looks a little confusing.
Maybe you could give me a little help.
I know to put multimeter on diode test, I know which is G,D,S but I not sure what results I should be obtaining from the measurements.
Also can they be measured in situ or will they need to be liberated from the board first.
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Old 1st February 2014, 11:34 AM   #6
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Arcam Alpha 10 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
This covers 2 of them.

I just hope I never have to work on one of these - what a complex beast, and for what net benefit? Savings on heatsinks?
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Old 1st February 2014, 12:17 PM   #7
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Well, my best advice is: leave the repair to someone who has good experience with amplifier repairs. This stuff is not for newbies -regardless of your enthusiasm- there are lots of other thigs that can go awry besides the FET-s.
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Old 1st February 2014, 12:28 PM   #8
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I would agree with dragonweed. In inexperienced hands it is all too easy to lift PCB tracks and then you are in a whole world of hurt.

If you are very careful you could just try the outputs but be aware that other components could have caused them to fail.
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Old 1st February 2014, 04:57 PM   #9
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Again all great info and thanks very much for your input.
I'm still tempted to replace all four Output FET's,
If only to try and isolate the problem or move onto something else.
Besides how will I learn otherwise.
Can anyone explain what kind of readings, or procedure I should use when testing the FET.
Again would it be better to isolate the components from the board or measure in situ?
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Old 1st February 2014, 05:00 PM   #10
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[QUOTE=
If you are very careful you could just try the outputs but be aware that other components could have caused them to fail.[/QUOTE]

Yeah my sentiments too, although I would look to be learning something about diagnosing potential problems by using the multimeter approach.
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