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September 30, 2020, 10:30:40 PM

Author Topic: Kaiju mishap: first troubleshooting steps?  (Read 436 times)

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Offline joepiecuch

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Kaiju mishap: first troubleshooting steps?
« on: June 25, 2019, 04:52:37 PM »
I was enjoying a problem fee build until the stage of driver testing.  IA and OA voltages were within spec on both C4S boards, and I adjusted the voltage with the pot to spec at both off-board locations. I was rechecking the IA and OA voltages on the D board to see if anything had changed when the cell phone in my shirt pocket rang, which startled me and resulted in me, judging from appearances, shorting one of those points to the middle leg of the adjacent transistor; this is, however, speculation. The 2 A side LEDs and the 90.9 ohm resistor exploded, and the fuse blew. I replaced the obviously damaged components and went to test again, but the fuse blew at power up. So...wondering about where to start on sorting this out.

Offline Doc B.

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Re: Kaiju mishap: first troubleshooting steps?
« Reply #1 on: June 25, 2019, 06:03:16 PM »
Start by testing the transistors to see if they are shorted. Most likely that the big transistor is shorted if the fuse is blowing. Measure the resistance between each of the three possible pairs you can make out of the three legs - left to center, right to center, left to right. If you see a very low resistance on any of these pairs, like under 100 ohms, the transistor is shorted out and needs to be replaced. You can check the small transistors the same way.
Dan "Doc B." Schmalle
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Bottlehead Corp.

Offline joepiecuch

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Re: Kaiju mishap: first troubleshooting steps?
« Reply #2 on: June 26, 2019, 03:06:02 AM »
Yeah...low resistances on that transistor, all right; and certainly as compared with the other board. Given the difficulty I experienced desoldering and replacing the other components, I wonder if it is possible to, without it being a pain in the neck for you guys, buy a board(s) kit and replace the whole thing?

Offline Doc B.

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Re: Kaiju mishap: first troubleshooting steps?
« Reply #3 on: June 26, 2019, 05:13:17 AM »
Yup, Eileen can pull together what you need. She's out this morning but will be around this afternoon.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline joepiecuch

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Re: Kaiju mishap: first troubleshooting steps?
« Reply #4 on: June 27, 2019, 11:37:21 AM »
And I have parts in hand in less than 24 hours after making the call; thanks again for the always extraordinary customer service.