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My old Aleph 4 clone
My old Aleph 4 clone
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Old 6th May 2018, 06:04 PM   #1
KatieandDad is online now KatieandDad  United Kingdom
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Default My old Aleph 4 clone

The other day I turned on the faithful Aleph 4 that my brother's Dad built and it instantly popped it's internal fuse.

There is no soft start on this amp and it has 1000VA of transformers (2 x 500VA) in it. It's got 4 x CLCC supplies, 12 x 33000uF caps in total.

It is about 8 years old now.

Could this just be a lazy fuse that has failed or might it be something more sinister ?

Last edited by KatieandDad; 6th May 2018 at 06:56 PM.
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Old 6th May 2018, 06:25 PM   #2
nigelwright7557 is offline nigelwright7557  United Kingdom
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I would check the value of the mains fuse, it should probably be around 13 amps for that amount of storage.
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Old 6th May 2018, 06:52 PM   #3
KatieandDad is online now KatieandDad  United Kingdom
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The 5A mains fuse is intact, the internal fuse might have been smaller than that. The beast weighs over 50Kg so I haven't been able to drag it out and open it up yet. I'll try to drag it out on Wednesday and just change the internal fuse.

Last edited by KatieandDad; 6th May 2018 at 06:59 PM.
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Old 8th May 2018, 01:04 AM   #4
Eric is offline Eric  United States
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My old Aleph 4 clone
If it's not a fuse, check your PSU caps for short. I had one of my PSU caps short a while ago, it drove rail voltage onto the ground and blew the fuse.
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Old 10th May 2018, 09:56 AM   #5
KatieandDad is online now KatieandDad  United Kingdom
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I finally got around to digging the beast out to have a look. Sadly I replaced the 10A internal fuse and it failed immediately.

I'll need to dig deeper to find out what has failed.

It's a dual mono-block in one chassis so at least I can separate the two amp's easily enough.

I might just try a soft-start to see if that works.

Last edited by KatieandDad; 10th May 2018 at 10:00 AM.
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Old 10th May 2018, 11:39 AM   #6
KatieandDad is online now KatieandDad  United Kingdom
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I might take this opportunity to split the beast into two mono-blocks.
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Old 10th May 2018, 11:53 AM   #7
qwertyl is offline qwertyl  United Kingdom
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Quote:
Originally Posted by KatieandDad View Post
I finally got around to digging the beast out to have a look. Sadly I replaced the 10A internal fuse and it failed immediately.
Are you using slow blow fuses?
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Old 10th May 2018, 11:55 AM   #8
Eric is offline Eric  United States
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My old Aleph 4 clone
A variac or dim bulb tester will work as an adequate soft start before you dig into changing internal wiring.

I would suggest checking caps for short and then checking your output mosfets for short. Use your DMM and test each leg of each mosfet for continuity with the sink. Any non "open loop" reading is a problem for output devices. My money is on a bad power supply cap...
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Old 10th May 2018, 12:29 PM   #9
KatieandDad is online now KatieandDad  United Kingdom
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The mains fuses are slow blow type. It's been working fine for over 5 years. I'll check the caps. Nothing has happened to stress the output MOS-FETs.
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Old 11th May 2018, 03:10 PM   #10
KatieandDad is online now KatieandDad  United Kingdom
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RS are selling capacitors by KEMET, has anyone any experience with these.
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