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Comtech 410 cooling problem


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#1 bako

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Posted 03 May 2011 - 03:15 PM

During use the fan in my comtech is not running. Also at higher output powers the fan does not start, and after a long time the amplifier mutes, I think because overheating of a component. Only when I turn on the amplifier the fan starts at high speed and the spins down in about 10 seconds. On the control board the resistor (R944, between the rectifier and the inductor) gets really, really hot.
If I disconnect the transformer switch the fan start running in full speed and out mutes, as expected.
I couldn't find any schematic of this type (only the comtech 400, which has a different control board). Is there someone who has an idea for this problem? Since the amplifier is quite old, I don't think it's cost efficient to bring him to a repair centre. But i'd like to repair him since the ampifier sounds just to fine on my sub biggrin.gif

I appreciate your help.

PS. sorry for my bad English, I'm using the international 220V model wink.gif

#2 Kevin Heber

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Posted 03 May 2011 - 03:30 PM

If you can email me, I'll send you a schematic for the 410 - kevin.heber@harman.com.  thanks.

#3 bako

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Posted 09 May 2011 - 12:42 PM

@Kevin, thanks for your fast respons!

I think the problem is not in the control board. Can I do some of the test out of the CT-810 / CT-1610 Service Manual? For instance, the output bias adjustment, and ODEP voltage? (with the same values?)

Thank you