[TechAssist] Re: CROWN AMCRON MICROTECH-1000
- From: "Rafael Gallegos" <gallegra@xxxxxxxxxxxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Wed, 03 Oct 2001 19:51:20 -0700
somehow seems like the protection circuit it's on and as long as you have =
the protection circuit on you won't have any output. What's causes the =
protection to be on?. Shorted output most of the time, leaky transistor =
prior to the power otput transistors, or maybe the the circuit itself is =
defective.try to bypass the protection circuit and measure voltage in all =
the current sensing resistors to see wich transistor is drawing more =
current but before you bypass the protection put a 100w bulb in series =
with the a.c.
good luck.
Rafael Gallegos
Lead electronics technician
Rockford corp.
>>> t8872695@xxxxxxxxxxxxx 10/03/01 08:03PM >>>
Hello.
I wonder this one has relay that turn on the output transistors. Check =
this
relay close or not.Also remove the colectors of all transistor output. =
then
turn on unit with input max.
check what happen.Check signal at the colectors with scope.
good luck .
----- Original Message -----
From: Hans <nettaberfrech@xxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Wednesday, October 03, 2001 4:23 PM
Subject: [TechAssist] CROWN AMCRON MICROTECH-1000
> Hi there.
> A bit unusual question in here, I know.
>
> I recently got a CROWN AMCRON MICROTECH-1000 Power-Amplifier in my
workshop.
>
> Customer says before it was permanently clipping it sometimes went into
clippping just out of nowhere.
>
> Transformer delivers 90 Volt +/-, all transistors seem to be ok =
(measuring
says so), powersupply for pcb works, too.
>
> But nothing s happening- stays in clipping-mode - LED s show disabled.
> No output, not even a minor signal ... it s standing on my desk - I have
no idea anymore ... has anyone of you??? Who knows something about these
amps ?
>
> I soldered out ALL power-transistors and checked them - they all look
good.
>
> I can t order the circuits here (in germany) - they told me via phone I
need to get them in the states.
>
> That s too much cost-effort for us and the customer.
>
> I d be grateful for every repair tip !!!
>
> Thanx to u all and keep up the good work - I got two TV s repaired by =
just
reading the newest emails every morning ... !
>
> NILZ (from germany) :o)
>
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