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Amcron MT1201 stuck.

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ceharden View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2018 at 11:32pm
It's not really a fan, it's more just a device for collecting dust and depositing it on everything inside the amp.  One of the biggest issues is that the bearings dry out and they seize up.
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M4trix View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 29 October 2018 at 11:57pm
We should ask Gerald Stanley why he placed this hair dryer/blower on a weird spot. LOL
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2018 at 11:39am
Like chris says. Dry bearings. Broken fan blades (how....?). Had 1 with a burnt out winding. Had to replace a couple because the bearings were so worn there was a deep groove in the motor shaft.

The fan motors are no longer available.

Kevin

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2018 at 1:12pm
You were right Kevin, tiny little ceramic capacitor burnt near the LV regs....will order one and fit.


Be seeing you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2018 at 2:45pm
So C4 exploded ? LOL

Anyways, it should work even without that cap. Do you have +/- 15V output on those U1/U2 regulators Question

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 30 October 2018 at 3:39pm
Yes...but..i just checked that row of 1N diodes above them...D3 is dead, so that cant be helping at all Mario!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 31 October 2018 at 9:40pm
@Ian, any updates ?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote odc04r Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2018 at 9:37am
Given that D3 is a pretty chuncky diode of the 1n4007 type (or thereabouts), it would take a fair bit to kills that. As Mario says I'd move on to check the entire LV regulator circuits. Recap the lot too. The row of diodes are almost certainly protection diodes for the 2 regulators in case of Vout exceeding Vin, that type of thing. As I recall there are typically 2-3 per regulator. If one those has died, something bad has probably happened to the regulators too. You can kill such a device instantly from an incorrect reverse bias, I speak from experience in that regard Smile
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2018 at 2:02pm
Just waiting for correct value parts to arrive, will update shortly.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2018 at 2:39pm
Ok, new diode and correct ceramic cap fitted on the LV + side output of the positive regulator, now showing the correct 0.00v DC on both channel outputs, and we now have audio again,so all is well. Also gave it a thorough clean inside,and lightly lubricated both ends of the fan bearings.

Thanks to Kevin, Mario and odc for your advice on this one. Thumbs Up



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Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2018 at 3:39pm
Good to see you've sorted out the problem. Thumbs Up
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