HL2 - Accidental negative voltage on RCA (TX GND)

Jiri Culak

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Aug 3, 2024, 10:52:37 PMAug 3

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Hello all

since I am finishing my remote build up and finished R140 moded amplifier (military, ceramic/glass tube GU43b equvalent) an fully semi automatic PA, requiring only 200mW to get full legal power with ease, I forgot that it uses -27 for TX signal and without a relay accidentaly wired -27V to RCA socket behind N2ADR filter board.

Since then no TX OUT, no relay clicking and all of the SW is saying TX is 222W....

I guess the smell of burned omponent is obvious. Visual inspection showed that likely one transistor looks popped.Q5 on the mainboard, not sure why I missed that I would need P channel to use negative voltage...aaaaah.. I guess negative voltage pulled the GND to even lower potential, so since direct path from N2ADR board to ping TX GND, schematics so I hope Q5 will be only victim, if not, FPGA will be gone I guess. ??

Am I correctly thinking?

73 Jiri OK2IT

Steve Haynal

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Aug 5, 2024, 12:27:55 AMAug 5

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It is possible you blew an entire FPGA bank. Are temperature readings still working?

73,

Steve

kf7o

Dean Davidson

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Aug 16, 2024, 11:02:10 PMAug 16

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I repaired 1 couple weeks ago that w4klf did same thing! You blew a diode 2 resistors and a transistor all surface mount tiny tiny

Jiri Culak

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Sep 3, 2024, 3:31:50 AMSep 3

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Any chance of sharing what resistors and other components need to be replaced or checked before I go for FPGA??

Thx

Jiri

Dne sobota 17. srpna 2024 v 5:02:10 UTC+2 uživatel Dean Davidson napsal:

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