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C-Audio Pulse 2x1100 - identifying mods
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Haschatan View Drop Down
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Joined: 06 May 2021
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Points: 3 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Haschatan Quote  Post ReplyReply Direct Link To This Post Posted: 05 August 2021 at 11:08pm
Hello All,

Sorry for hijacking the post.
I recently bought a C-Audio 4x300.
It did have already the inductor mod done.
I have changed the resistors on the four amps from 75ohm to 100ohm, i have ordered the 0.0047µF capacitors, and it already had the proper IGBTs and driver transistors for the IGBT.
The only mod who will be left is the pulse transformer. I am wondering if it is difficult to wind it up or if i should not hesitate to make it? i have never wound a transformer.
What are the risks if i leave the old pulse transformer?

And while i am here, the IGBT are the old NGTG50N60. How long do the IGBT last? While the board is off, i could change the IGBTs if needed.

Thanks a lot for your help.
Regards.
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ceharden View Drop Down
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Points: 11851 		Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 05 August 2021 at 11:43pm
Speak to SimonP (see previous posts) for a ready wound transformer.  Otherwise I think I have a few of his transformers around.  I used to wind them myself, then Simon got a batch done and saved me the effort.
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Points: 1150 		Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2021 at 4:25am
enclosed link for Pulse Transformer.


Clap
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kedwardsleisure View Drop Down
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Points: 5157 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2021 at 10:08am
Quote How long do the IGBT last?


They aren't a wearing part, just leave them be.
Kevin

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Haschatan View Drop Down
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Points: 3 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Haschatan Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2021 at 5:08pm
Thanks a lot for your answers guys.

My C-audio 4x300 is going to be ready for many years now Smile
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ceharden View Drop Down
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You're not after any more Pulses are you? 😉
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Speaking of which,

@ceharden,

What are the values of those two bodged yellow caps ? 0,0047uF/100V ? Nothing 'bout them in service bulletins. Ermm
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ceharden View Drop Down
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Points: 11851 		Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 07 August 2021 at 12:01pm
It's a good question.  To be honest due to the lack of full information it's not a mod I've ever done.  They appear to be Miller caps across the transistors doing the Vbe clamping (current limit) so I'm assuming they are there to reduce the sensitivity of the current limit to high frequency signals.
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simonp1100 View Drop Down
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Originally posted by ceharden ceharden wrote:

It's a good question.  To be honest due to the lack of full information it's not a mod I've ever done.  They appear to be Miller caps across the transistors doing the Vbe clamping (current limit) so I'm assuming they are there to reduce the sensitivity of the current limit to high frequency signals.

Thumbs Up Yes i think this is correct & this mod came out just after Crown took over the C-Audio brand & used it in the XS series etc. I also do this mod on any C-Audio Pulses i get in for service / upgrade. Clap


Edited by simonp1100 - 07 August 2021 at 12:19pm
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the later crown-badged pulses (silver face) have the caps built into the pcb
Kevin

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M4trix View Drop Down
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Points: 465 		Post Options Post Options   Thanks (0) Thanks(0)   Quote M4trix Quote  Post ReplyReply Direct Link To This Post Posted: 08 August 2021 at 10:08pm
Guys, your conclusions about the caps were right. I've found the Crown's XS schematics with all mods included.

 
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Danypi View Drop Down
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Points: 1 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Danypi Quote  Post ReplyReply Direct Link To This Post Posted: 06 August 2024 at 4:54pm
hello, I just got 2 C-audio pulse 2x1100, both have protection problems. could you help him repair them! I am in France where the translation) a big thank you to you
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