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Problemen with CDi4000 / service manual


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#1 Patlover1983

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Posted 12 May 2013 - 02:36 PM

Hello everybody on this forum,
I've got a question about my Crown CDi4000 power amplifier.
I used it for a long time without any problems (also applies to my
CTs and XTi amplifiers) i found a (small?) problem during last gig.
When i switched on the CDi4000 amplifier, channel B produces a
"thick/bang" sound. It looks like the same sound at the moment the
"Ready" leds lights up. I found out when i used a longer speaker
cable this sound will go louder.
Also when i started the amplifier in mute status (so the ready LEDS
will not light up) this sound is present, but still only at channel B.
Does anybody have an idea where to look out for? It looks like a BIAS
problem for channel B? Normally the BIAS current switched on the power
amplifier after a couple of seconds (when the Ready LED lights up) but
i thinks its starts immidiatly after powering on the amplifier.
Can i get a service manual of this amplifier?
Thank you!

#2 joust

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Posted 13 May 2013 - 10:21 AM

Welcome and hello Patlover!

The amp should be muted until the Ready indicators light up.
* Have you the latest firmware updated?
* As for the service manual, you can enquire with the Crown Technical department. Just send them a request via email.
It is not a BIAS issue; But may be related to a MUTE issue.
I've also seen defective rail switching issues causing similar symptoms (normally, the amp would shut down before completing bootup).
What is the serial number or date code of the amp?

Alain

#3 Patlover1983

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Posted 13 May 2013 - 01:43 PM

Hello Alain,
Thank you for your answer. I think the muting circuitry works fine,
the amplifier passed sound at the moment the ready lights are on and not
before.
I allready have installed the latest firmware, but for sure i reinstalled it.
I shall contact the service department.
The serialnumber of the amplifier is 8001494729.
Thank you!

#4 joust

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Posted 13 May 2013 - 03:52 PM

Take a look at the Amplifier Discussion forum, most specifcally, 'XTi / Band Manager strangeness' and report back if the 'strangeness' resembles a bit what you art experiencing.

A.

#5 Patlover1983

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Posted 13 May 2013 - 04:45 PM

Hello Alain,
I read the topic you mentioned, but i have none of this problems.
The only problem with this CDi4000 is that channel B produces a
"thick/bang/pop" sound immidiatly when the amplifier is switched
on. For the rest the amplifier works fine (as far as i have been tested).
At this time my workbench (its my daily job to repair professional
audio equipment) has been "wasted" to repairing a Chinese OEM amplifier
with blown output devices. When this one is fixed, i going to try
to repair the amplifier, because i'm pretty sure its a hardware problem.
In the past i repaired four Crown XTi amplifiers (one with blown output
devices, one was needed to replace the LC2412 DSP, one with a BIAS problem
and one with a blown power supply) so i'm little familiar with the XTi
amplifiers.
I just recieved the service manual from Kip (thank you very very much!)
for the CDi4000 and at first sight i looks very close to an XTi, so
i hope i'm been able to repair it.
Do you have any idea where to look for? I still have the idea that it
could be a BIAS problem. At the same time the "Ready" LEDs are lit,
the power amplifiers itself are been activated because the BIAS starts
at the same time. Normally until this time the amplifier cannot produce
any sound because there is simply no BIAS to turn on the output devices.
So i think it could be a BIAS problem.
Just my toughts. Do you have any other toughts about this?

#6 joust

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Posted 14 May 2013 - 09:28 AM

This is a first for me! Have been repairing these units for years and I've not seen this behavior before. A lot of SMPS issues, some output and tracker faults, easy to fix once you know the symptom. Have you verified the tracker components?