sx-5a error 8

[dboucher]

about to drive myself nuts with this one, transmitter powers up for a random amouint of time then shuts down. before it even powers on it comes up with error code 8. i have checked all the fuses and transistors a1,a2,a3,a4 checked the voltages for the 23-32 on all the R L points on those boards, and it check out fine. i have my 10, 5, 15 volts. i am begining to think that status board may have issues as it is giving some readings like 2E or error 2A. any ideas would be great thanks so much

[grich]

From the Harris SX troubleshooting sheet:

8 ) RF DRIVE TO POWER AMPLIFIER EXCESSIVE (OVERDRIVE)
a. IPA tuning network improperly tuned
b. Crystal on incorrect frequency

Having spent 29 glorious years with SX-1 s/n 16, I don't remember having a fault 8...I presume you've double-checked drive levels and oscillator frequency. When the transmitter shuts off by itself does it show a new fault? I've had random no-fault trip-offs happen because of dirty aux contacts on the step-start contactor, flaky bypass caps on the remote control inputs, and bad optos on same.

As an aside, have you replaced any of the big blue caps in the power supplies or the PDM boards lately? You're long overdue if you haven't. We started developing output spurs about five years ago and replaced the IPA supply and PDM caps at that time. Harris put out a service bulletin on filter caps (AM-579-JK) a couple of years ago.

[Sam Buca]

about to drive myself nuts with this one, transmitter powers up for a random amouint of time then shuts down. before it even powers on it comes up with error code 8. i have checked all the fuses and transistors a1,a2,a3,a4 checked the voltages for the 23-32 on all the R L points on those boards, and it check out fine. i have my 10, 5, 15 volts. i am begining to think that status board may have issues as it is giving some readings like 2E or error 2A. any ideas would be great thanks so much

Never saw a fault 8 before...wow.

When I had strange readings, I sent the S/MM board back to harris and they replaced some components (corrosion on the connectors and IC legs are problems too). Since it's out of support now, I'd see if you can find another SX5 and swap in their S/MM board (there is a process...you can't just plop one in there). I forget which card it was, but another member on the forum sent me a card from his SX5 and that really helped in tracking down the issues.

[grich]

Dboucher figured it out a few days ago...he's a stud... U46 (P8282) on the S/M board was flaking out causing itself to latch despite the fact that no errors were present. Swapped chips, all is well.