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PostPosted: Thu Nov 15, 2007 1:03 pm 
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Hen
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Joined: Thu Nov 15, 2007 10:30 am
Posts: 4
Location: Sweden
Greets everyone!

I have a HiiH Electronics M900 mos-fet 400W/channel at 4ohm, amplifier.

When i turn it on (not connected in any way to any device) plugged into a 230V grounded outlet, my 10A fuse pops.
Can it really be possible that this amp needs more than 10A to just warm up? the fuse is of the slow kind.
this is the first time i work with PA equipment...but it should'nt be that different from hifi right?


sorry for my wierd english =)

Martin
Sweden


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PostPosted: Sat Nov 17, 2007 8:46 am 
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Goat

Joined: Thu Aug 10, 2006 5:53 pm
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Location: Scottish Borders
Hi,
has it got a power thermistor in the transformer primary feed that may have gone short circuit?

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Andrew T.


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PostPosted: Sat Mar 01, 2008 3:36 am 
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Hen

Joined: Sun Dec 30, 2007 7:33 pm
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Location: Ratae Coritanorum
hi Martin,
are you talking about the HH company M900 amplifier? now defunk English brand
if so i can help you

kind regards
bob


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PostPosted: Sat Mar 01, 2008 10:16 am 
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Hen
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Joined: Thu Nov 15, 2007 10:30 am
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hi Bob!

Aha.. the logo looks like H||H... guess the lines dont count :D

So yes, that is the one!


All help greatly appreciated!!
martin


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PostPosted: Sun Mar 02, 2008 1:55 am 
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Hen

Joined: Sun Dec 30, 2007 7:33 pm
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Location: Ratae Coritanorum
hi Martin,
the lines between the HH was a company logo thing.

there is a mains voltage selector switch on the back panel has this been set correctly for your mains supply?

very early models did not have a soft start, later models had a crude power resistor in series with the mains supply which was shorted out with a pair of contacts of a relay. maby you have an old one without the soft start circuit?

they had a high inrush current and were known to blow plug fuses (13 Amp here in the UK)

or you could have a fault with the amp of course, causing excessive current to flow.

i have some service data and schematics for the amp.

regards
bob


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 Post subject: HH M900 power amplifier
PostPosted: Wed Apr 09, 2008 6:04 pm 
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Sheep

Joined: Mon Apr 07, 2008 7:11 pm
Posts: 11
Hello
I really need the circuit diagram of the mosfet M900 (with value of the components).
best regards-Thu


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PostPosted: Thu Apr 10, 2008 11:32 pm 
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Hen

Joined: Sun Dec 30, 2007 7:33 pm
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Location: Ratae Coritanorum
hi Thu,
i will see if i can find the info for you, give me a day or so

regards
bob


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PostPosted: Mon Apr 14, 2008 2:57 pm 
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Hen

Joined: Sun Dec 30, 2007 7:33 pm
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Location: Ratae Coritanorum
hi Thu,
sorry about quality, hope it helps


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PostPosted: Mon Apr 14, 2008 2:58 pm 
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Hen

Joined: Sun Dec 30, 2007 7:33 pm
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Location: Ratae Coritanorum
and this one


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PostPosted: Mon Apr 14, 2008 6:27 pm 
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Sheep

Joined: Mon Apr 07, 2008 7:11 pm
Posts: 11
thanks Bob. it is very fine. (also vx600)


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PostPosted: Tue Mar 10, 2009 8:11 pm 
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Sheep

Joined: Mon Apr 07, 2008 7:11 pm
Posts: 11
thudao wrote:
thanks Bob. it is very fine. (also vx600)

I ´d like to know how to adjust the bias of the HH M900.
somesone helps. Thanks


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PostPosted: Mon Mar 23, 2009 12:43 am 
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Hen

Joined: Sun Dec 30, 2007 7:33 pm
Posts: 8
Location: Ratae Coritanorum
the M900 has a bias trim pot (see drawing)
i like to bias these amps at 100mA per mosfet pair so thats 400mA total.

measure this by breaking + supply connections and inserting an ammeter.
bring the Iq up to 400mA then check after 15 minuites.


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PostPosted: Tue Mar 29, 2011 11:55 pm 
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Hen

Joined: Sun Dec 30, 2007 7:33 pm
Posts: 8
Location: Ratae Coritanorum
hi Thu
this site may be of interest to you regarding HH amps

http://www.hhamplification.co.uk/index.asp
regards
bob


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