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Advice for fixing a faulty Neumann M149a power supply

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Re: Advice for fixing a faulty Neumann M149a power supply

Postby yannlu » Tue Jan 29, 2019 11:08 am

I had the same problem with mine. A pad of the mains connector in the Ault SPSU has broken and started to burn. Probably due to the mechanical traction. After fix it I got 12VDC again on its output. I checked all the voltages but probably something else failed in the main board. Is someone has the schematics of it ? Thanx

ef37a wrote:Pin 1: –70 V
Pin 2: +5 V
Pin 3: audio signal (+phase)
Pin 4: +70 V
Pin 5: sensor line
Pin 6: ground
Pin 7: +32 V
Pin 8: audio signal (–phase)

Those ^ are the voltages that should come from the supply. THAT supply does not look like anything mssrs Neumann would produce!

If I have the right model we are looking at a £3000 microphone? I suspect that getting the PSU or its connections wrong could damage the mic and I would urge you to find the correct supply from a Neumann agent. Expensive? Probably but it could get much worse IMHO.

Last but CERTAINLY not least. Are you qualified to safely poke about in mains powered devices and are you certain you can leave them in a safe state for other people? Anytime you have mains kit apart and work on the '230V' side said kit should then be PAT tested.

Dave. http://www.studiocare.com/neumann-n149- ... gLKDfD_BwE
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby gdowling » Mon Feb 18, 2019 11:19 am

Just wanted to say thanks for the info here.

My 2 box style power supply failed last night before a session today, after reading the advice here I was able to use a spare 12V switched mode power supply to get it working again.

Will do a proper job at some point - but would never have attempted it without the thoughts here.

Thanks guys!
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby crescentmoon66 » Sat Feb 23, 2019 10:02 pm

Here is a link to the actual model and part..... https://en.globtek.com/search/?q=TR9KE1 ... &x=11&y=13
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby yannlu » Mon Feb 25, 2019 8:16 am

I fixed the 12V power supply but there is a problem on the main board (not the correct voltages). I need to replace/fix this board but it is not possible to get a new board or the schematics from a Neumann distributor or retailer....
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby avalonvt » Wed May 01, 2019 9:55 pm

jondo wrote:Just an update on this, the replacement power pack arrived from the US, I've soldered it in, and fortunately there's no sparks, smoke and tears, just a green power light that is now on :D

Left it on for an hour to make sure it didn't subsequently explode, then turned off and sheepishly connected the M149 mic to it and........... happy days fully working again, been on for 10 hours now and no problems.

The cost, £4 + postage, but i did also buy an extra 2 spares, just in case.

Thanks for everyone for their advice who helped me get it working again.


HI!
My n149 stopped working, the led wont turn on. this mic should be at least 15 years old, probably even more! the n149 looks very different than the one i have seen on sale now, it has two boxes one with the plug and one with the xlrs. Sennheiser is asking for those £300 which it is quite a lot... did you say you have a couple of spares ? would i be able to buy one from you ? are you in london by any chance ? thanks!!!
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby gdowling » Thu May 02, 2019 12:21 am

With luck what has failed is the 12V switched mode power supply (the bit that plugs into the mains).

If so you can easily replace it with another. I had a couple of 1A ones floating around (my Neumann supplied one was 12V 640ma), I tried both and they both worked and sounded identical. I think the serious work is done by the second power supply box with the XLR connector.

My new supply is a fraction of the weight of the old one!

So check if you’re getting 12V from the initial supply, and if not replace it. I think the cable between the supplies is colour coded red / black, so it’s easy to get the polarity right.

I added a trailing 12V power socket to the Neuman cable - so can now use any supply with the standard laptop style plug.
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby avalonvt » Thu May 02, 2019 2:47 am

gdowling wrote:With luck what has failed is the 12V switched mode power supply (the bit that plugs into the mains).

If so you can easily replace it with another. I had a couple of 1A ones floating around (my Neumann supplied one was 12V 640ma), I tried both and they both worked and sounded identical. I think the serious work is done by the second power supply box with the XLR connector.

My new supply is a fraction of the weight of the old one!

So check if you’re getting 12V from the initial supply, and if not replace it. I think the cable between the supplies is colour coded red / black, so it’s easy to get the polarity right.

I added a trailing 12V power socket to the Neuman cable - so can now use any supply with the standard laptop style plug.

Mine looks exactly like this one, any idea on where i could find the parts?
Thx
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby gdowling » Thu May 02, 2019 7:02 am

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Re: Advice for fixing a faulty Neumann M149a power supply

Postby avalonvt » Thu May 02, 2019 3:42 pm

gdowling wrote:This one worked fine.

https://uk.farnell.com/xp-power/vet18us ... dp/2708280

i still think mine is a different model of the n149
here are some pics
ive opened it and there is no such a power supply.
any idea if this could be something i could fix myself ? or shall i just send it to sennheiser and pay the £300 ?
thanks a lot!!!
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby gdowling » Thu May 02, 2019 4:05 pm

Sounds like you have the later version (1 power supply box rather than 2). Seems like it’s basically the same in a better box.

Same trick will work, but a little harder to do because the switched mode supply needs to fit in the box.

Pictures and details here https://www.gearslutz.com/board/geekslu ... aulty.html
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby avalonvt » Fri May 03, 2019 2:19 am

avalonvt wrote:
gdowling wrote:This one worked fine.

https://uk.farnell.com/xp-power/vet18us ... dp/2708280

i still think mine is a different model of the n149
here are some pics
ive opened it and there is no such a power supply.
any idea if this could be something i could fix myself ? or shall i just send it to sennheiser and pay the £300 ?
thanks a lot!!!

https://www.dropbox.com/sh/1cgaadnlx9l7 ... nEBpa?dl=0
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby avalonvt » Fri May 03, 2019 2:20 am

avalonvt wrote:
avalonvt wrote:
gdowling wrote:This one worked fine.

https://uk.farnell.com/xp-power/vet18us ... dp/2708280

i still think mine is a different model of the n149
here are some pics
ive opened it and there is no such a power supply.
any idea if this could be something i could fix myself ? or shall i just send it to sennheiser and pay the £300 ?
thanks a lot!!!

https://www.dropbox.com/sh/1cgaadnlx9l7 ... nEBpa?dl=0
please have a good look at these photos
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Re: Advice for fixing a faulty Neumann M149a power supply

Postby gdowling » Fri May 03, 2019 7:55 am

So yours is exactly the same as mine.

If you’re lucky the “wall wart” box that plugs into the wall socket has broken, and you can replace it with the power supply I linked above.
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