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AC4AQ

Member Since 01 Oct 2012
Offline Last Active May 21 2014 02:45 PM
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Posts I've Made

In Topic: How to troubleshoot efficiently?

07 May 2014 - 03:49 PM

IT-6000 Update: This particular amp was manufactured 12/28/2004 and is serial number 8000492671. It doesn't appear to have had previous service and does not have the BCA drive board with red capacitors for C526 and C527.

After I replaced a bad FET (Q1007) I just attempted to start the amplifier with the Front End modules removed, as in the manual. However, Q1004 exploded after a few seconds and the blast wave was such that my ears were ringing for several minutes afterward. I think it should be recommended that hearing protection be worn when an amplifier is serviced where there is a fair chance that semiconductors may detonate.

I think it is reasonable to substitute 200 ohm 25 watt resistors for the toroids while troubleshooting, as this will prevent excessive current and allow non-destructive testing.

Tnx...Jeff

In Topic: How to troubleshoot efficiently?

07 May 2014 - 10:04 AM

The answer to my question of how to troubleshoot a K-2 efficiently, at least in this case, is seek out the necessary information. It turns out there was adequate data available had I searched beyond the LAN. In the end, this K-2 needed C57, U2, U51, U52 on the output module replaced and U102 on the main module. Also both opto-isolators (U2 and U52) on the other module were damaged.

As the amplifier arrived, it is likely that the only failed components were C57 (leaky, pulling down the Vss-12 source) and possibly U52. All the other components were damaged by attempting to power-up the amplifier without the rear panel in place, which ungrounds part of the main module and isolates the speaker filter network.

So the answer is: In amplifier repair and in other things it is a goodly lesson to looke ere ye leap.

Now on to the IT-6000, which went Pop! and has a leaky FET in the output stage. This one is encouraging as it uses the familiar International Rectifier Class D audio power amplifier scheme. Time to research and not rush in where angels fear to tread...

Jeff/AC4AQ