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Help with Crown ma1201 amplifier


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#1 vk3kbr

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Posted 12 April 2006 - 05:21 AM

G'day all,
I have a Crown MA1201 amplifier.  It has started an intermittent fault on Ch1.
The sound output varies considerably after using it for a short time (15 mins).
I have just opened the case, connected a friends Sig-Gen, and connected a CRO across a dummy load (4 Ohms).  Naturally, it will not fault in this condition.

I hope that someone may have come across this problem, or if not, might direct me to somewhere to obtain a circuit for this amp.

Await your reply,
Rod,  vk3kbr

#2 vk3kbr

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Posted 12 April 2006 - 10:59 PM

QUOTE(vk3kbr @ Apr 12 2006, 09:21 PM)
G'day all,
I have a Crown MA1201 amplifier.  It has started an intermittent fault on Ch1.
The sound output varies considerably after using it for a short time (15 mins).
I have just opened the case, connected a friends Sig-Gen, and connected a CRO across a dummy load (4 Ohms).  Naturally, it will not fault in this condition.

I hope that someone may have come across this problem, or if not, might direct me to somewhere to obtain a circuit for this amp.

Await your reply,
Rod,  vk3kbr
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G'day again blokes,
no answers !!.  I found the fault today, it was a dry joint in the plug end of the multi-cable, connecting the small signal board to the power amp stage.  The joint was not visible to either the naked eye, nor under a magnifying glass, resoldering them all cured the problem.

I would still like "someone" to point me in the right direction to purchase the circuit for this machine.  An old Ozzie bushie like me doesn't really have much access to "big city things", so an answer would be much appreciated.

Rod,  vk3kbr

#3 DGlass

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Posted 13 April 2006 - 01:12 PM

QUOTE(vk3kbr @ Apr 12 2006, 10:59 PM)
QUOTE(vk3kbr @ Apr 12 2006, 09:21 PM)
G'day all,
I have a Crown MA1201 amplifier.  It has started an intermittent fault on Ch1.
The sound output varies considerably after using it for a short time (15 mins).
I have just opened the case, connected a friends Sig-Gen, and connected a CRO across a dummy load (4 Ohms).  Naturally, it will not fault in this condition.

I hope that someone may have come across this problem, or if not, might direct me to somewhere to obtain a circuit for this amp.

Await your reply,
Rod,  vk3kbr
View Post



G'day again blokes,
no answers !!.  I found the fault today, it was a dry joint in the plug end of the multi-cable, connecting the small signal board to the power amp stage.  The joint was not visible to either the naked eye, nor under a magnifying glass, resoldering them all cured the problem.

I would still like "someone" to point me in the right direction to purchase the circuit for this machine.  An old Ozzie bushie like me doesn't really have much access to "big city things", so an answer would be much appreciated.

Rod,  vk3kbr
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If you will email me directly at dglass@crownintl.com with the serial number I will send you whatever schematic we have for it.

#4 vk3kbr

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Posted 23 April 2006 - 02:08 AM

G'day David,
I have sent you the detail to the address given, did you receive it ??

regards,
Rod  vk3kbr

#5 vk3kbr

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Posted 14 May 2006 - 07:50 AM

G'day David, and all.

Thanks for nothing..!!!

#6 DGlass

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Posted 15 May 2006 - 03:13 PM

QUOTE(vk3kbr @ May 14 2006, 07:50 AM)
G'day David, and all.

Thanks for nothing..!!!
View Post

I have not received your information as of this date and as none of here sit on the forum all day and I try to answer as many as I can, when I can in between phone calls, emails and other things I am sorry I missed your second request. If you will please try and email me again I will gladly send you the information.

#7 DGlass

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Posted 16 May 2006 - 08:18 AM

I got your posting and have removed it to keep your email off the open posting. I will be sending you the schematics.

#8 vk3kbr

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Posted 17 May 2006 - 03:56 AM

Thank you David, I will certainly look forward to receiving the circuit diagram.  I hope to never need it, but electronics being what they are, Murphy's law Etc.
Regards,
Rod  vk3kbr