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Old 7th January 2013, 01:29 AM   #1
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Default Arcam Alpha 8 voltage issues

My beloved Alpha 8 has survived a trans-atlantic voyage only to refuse to accept a 110v input.

I have swapped the fuses on the Alpha 8 and its power amp. The power amp is fine but the Alpha 8 is dead. I checked all the fuses and its definitely getting power, I even switched it back to the 240v fuse to try that and it powers up, but obviously wont play.

I would really love to be able to fix this. And it seems like from what I have read on this forum someone here might know a solution. I am up for re-soldering if required.

Thanks for any help.

Simon
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Old 7th January 2013, 02:35 AM   #2
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Let's clarify - You have a 240V amplifier and you are attempting to power it with just 110V?

Is there a voltage supply changeover switch to allow this - or perhaps you have a dual winding transformer that you have already rewired to suit a 110V supply?

Otherwise, you can take product warnings and advice as real and that they do apply to the products on which they are placed. Only switchmode powered appliances are useable across a range of mains voltages and then only if marked accordingly.

Fuses have little to do with this other than that they must be doubled in current rating when you halve the supply voltage. Ohm's law does actually have application to amplifiers! This is something a convertible appliance will have documentation and marking to cover in any case.

If I were you, I wouldn't even attempt to use a UK lightbulb nor continue to try to use 110V power on your amplifier unless you know what needs doing. You will need to obtain a step-up transformer, rated at least for the total current rating of all the equipment.
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Old 7th January 2013, 02:54 AM   #3
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Ian,

Thanks for the reply. To clarify,

The amplifier in question allows 115v or 240v supply. The change over is accomplished by swapping a fuse on the circuit board to a different position on the circuit board.

Click the image to open in full size.

From what you have said this would appear to be a dual winding transformer. The problem seems to be that the 115v 'wind' is dead! I would like to know what would be a sensible fault finding procedure to get this lovely amp running on 115v.

Thanks again.
Simon
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Old 7th January 2013, 05:11 AM   #4
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There is a 403 permissions error with posting that pic, unfortunately. It would help.

To get the dual voltage primary to change over, it's necessary to make 2 winding connection changeovers, unless one winding at least can carry full 115V supply current - then the switching is only a single wire swap between one or both windings in series. It should be simple enough to trace back on what change(s) you actually made and whether it is adequate. Actually, it wouldn't work on 240V unless both windings were fully functional. That shouldn't be the issue.

Unfortunately, to test what is or isn't working, you will need at least a cat.II approved DMM (for safety) and then to test what AC and DC you have at the output of the power supply. Then you know for certain what problems there are, if any.
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Last edited by Ian Finch; 7th January 2013 at 05:21 AM.
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Old 7th January 2013, 07:27 AM   #5
jaycee is offline jaycee  United Kingdom
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That's odd - you should be able to fit a 2.5A fuse in the 115V fuse holder and the amp would run.

Is there a dark grey wire running from the transformer to the mains side of the PCB, in addition to the orange, blue and green wires?
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Old 7th January 2013, 07:31 AM   #6
Mooly is offline Mooly  United Kingdom
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Try attaching your picture directly to the forum,

"To add a photo, files or non standard files.

First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it foward.

Then click "Manage attachements". Maximise the new Window so that you can see all the text.

Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"

The pictures should now be attached and when you submit your post they will appear.

Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.


If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that."
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Old 7th January 2013, 01:17 PM   #7
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Mooley: Thanks I appreciate the help with the pictures.

Ian: I appreciate you explaining that to me, I know understand how a dual winding transformer works, I have reposted the pics for you to look at.

Jayceee: After your comment I had a good look at my other amp (same Alpha 8 but the power amp for the first) and it does appear there is a wire missing from the power supply side but I definitely havent removed anything and have owned it from new.

Picture of problem amp:
image.jpeg

Difference between fuse areas on problem amp and its functioning power amp (it has a different connection but the first appears to be missing a grey wire in the middle of the connectors):
photo (2).JPGphoto (1).JPG

Any ideas? Thanks.
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Old 7th January 2013, 01:34 PM   #8
Mooly is offline Mooly  United Kingdom
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I'm afraid just going off the colours doesn't mean anything to me (but it might to someone else).

I'd have to look at all the primary connections and possibly first measuring the DC resistance of the primary with it set for 240 volts as a guide. Then I'd look and see what the connection options might be. If the tranny really does accept 110 and 240v then is it two separate windings in series ? or is it one winding with tappings ?

If I was still unsure I'd disconnect the secondaries for safety of the unit and then fit a bulb tester in series with the mains and have a try with different connection options to give the required secondary voltage. The bulb tester keeps it all safe.

It's one of those things you either know for sure or else have to have it in front of you
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Old 7th January 2013, 01:37 PM   #9
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Most of the Alpha's were fairly similar.

If the Alpha 8 is the same as the Alpha 9 (in the PSU part anyway), then simply removing the 115V fuse and inserting the 240V fuse changes the voltage.

If this doesn't work you are going to have to investigate the transformer.

A phone call to Matt at Arcam +44 1223 203200 with your Serial Number, he will verify that you have a dual voltage transformer.
Attached Images
File Type: jpg Alpha 9.jpg (359.2 KB, 32 views)

Last edited by KatieandDad; 7th January 2013 at 01:50 PM.
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Old 7th January 2013, 01:42 PM   #10
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Quote:
Originally Posted by Ian Finch View Post
There is a 403 permissions error with posting that pic, unfortunately. It would help.

To get the dual voltage primary to change over, it's necessary to make 2 winding connection changeovers, unless one winding at least can carry full 115V supply current - then the switching is only a single wire swap between one or both windings in series. It should be simple enough to trace back on what change(s) you actually made and whether it is adequate. Actually, it wouldn't work on 240V unless both windings were fully functional. That shouldn't be the issue.

Unfortunately, to test what is or isn't working, you will need at least a cat.II approved DMM (for safety) and then to test what AC and DC you have at the output of the power supply. Then you know for certain what problems there are, if any.
NO, Arcam use a single winding on the Alpha 8,9,10. If you look at the post above you will see how they achieve this.
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