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Member Since 28 Jan 2011
Offline Last Active Yesterday, 06:36 AM

Posts I've Made

In Topic: Loud 'bang' heardible from channel A when turning on XTi4000

12 July 2014 - 07:10 AM

Yesterday (friday) evening i finally had some time to find out what was wrong with the XTi4000 amplifier. First of all i shorted the input to the
power amplifier. At point 1 of the U10-A opamp (the output) i make a connection to the ground of the amplifier and the 'bang' noise was gone.
Offcourse there was also no audio sended to the amplifier.

I measured all the components round this circuit and replace the ones that i had in stock. But still no solution. After this i decided to shorted the
output from the DA converter to ground. When shorted the 'ch1 +' output to ground, the 'BANG' sound was gone. To try furter i remove
R52 and R18 for channel 1 input and R20 plus R17 for channel 2 input, all 6.34k resistors and routed the output for channel 2 from the DA converter
to the input of channel 1, offcourse i used some temporally 6.34K resistors (axial trough hole types) to replace R52 and R18.
Resulting the 'BANG' sound was gone and the power amp from channel 1 passes audio from the input of channel 2.

So it looks like the CS4272 converter has a malfunction, but i'm not shure because i do not have lot of experience with AD/DA digital audio converters.
Can it be something else like a non accuracy clock signal or something like that?

Just to test i shorted the analog inputs from the CS4272 to ground, but this doesn't affect the problem. So it looks like the analog circuitry is ok.

But there is something that i don't understand. The amplifier started with the muted circuits activated. The schematics says that this circuit is located
AFTER the input of the power amplifier. I compared switch times and signals with both channels with my 100MHz oscilloscope and a Fluke DMM. Both channels worked exactly the same, so i think this circuit works fine. But i dont understand how can passed the 'BANG' produced at the input with activated mute.

Thank you all!

In Topic: Loud 'bang' heardible from channel A when turning on XTi4000

11 July 2014 - 11:56 AM

Hello Alain,

Thank you for answerring (again).

The amplifier self works fine. No distortion and lots of power. Only the loud BANG on channel one. after switching on.
The main board is still mounted into the chassis and the BANG is came out of the speaker, connected at channel output A.

The mainboard is a new type, the heat sinks are connected with contact pens to the PCB.

What are the filter caps? The electrolytic caps? These are fine. If they where faulty i assume it has the same issue on both channels?

In Topic: Where to buy Crown audio parts for Holland?

11 July 2014 - 04:37 AM

Hello every one,

at this time some parts are delivered, some still not. So its waiting for this parts.

In Topic: Where to buy Crown audio parts for Holland?

02 July 2014 - 06:42 PM

Hello Alain (and others ofcourse),

After a nice conversation with the distributor it looks like they have speed up
the ordering process. The promised that the parts wil be deliverd in this or next week.

I also found a second source for parts (in the UK) so if i need some parts in the future
i can ordered it over there!

When i recieve the parts i let you know!

In Topic: Where to buy Crown audio parts for Holland?

21 June 2014 - 04:56 PM

Hello Alain,

The K2 transformer that you mentioned is the one i mean. It has a short between 2 windings.

For the XTi and CDi amps i need parts that are been lost during a movement. The amplifiers
where listed on the 'to do' list for a long time.

I need the following parts:
2 Complete CDi4000 mainboard Assys (I have 2 of this amplifiers that looks like new, but the PCB's have been damaged due to a fire)
12 screws for the top cover (for 4 amplifiers)
1 push rod for the on/off switch for a CDi4000 amplifier
5 screws for the AC inlet
3 foam sheets (the sheets with adhensive tape on the aluminium heat sinks)
1 XTi4000 front panel

Does anybody know if its possible to order a seperate LCD display (not the complete PWA)?
One of the XTi LCD displays has a damage (spots that has the same color as the letters/symbols of the display)

Thank you!