SX 2.5 Won't Power on No Lights

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engnewbie
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SX 2.5 Won't Power on No Lights

Post by engnewbie » Wed Jun 05, 2019 9:22 pm

My SX 2.5 did not wake up this morning. in fact, it was stone cold when I arrived. I had no +5 or +/- 15 volts. I found 120 volts on one AC leg feeding the step-start contactor but not on the other leg. I traced the problem to a chard terminal on the AC terminal strip located under the transmitter floor on the left wall.

Fortunately, there was an unused set of terminals so I moved the defunct 120 branch there and all is well. I attribute the problem to loosened screws that caused overheating, as the previous chief did not perform PM.

You guys have probably seen this, but it was a first for me so I thought I'd pass it on.

I have attached a photo that i took, after I had already moved one of the wires to the spare terminal.
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ChuckG
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Re: SX 2.5 Won't Power on No Lights

Post by ChuckG » Wed Jun 05, 2019 10:07 pm

Nice save! Good reminder to check that stuff.
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Deep Thought
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Re: SX 2.5 Won't Power on No Lights

Post by Deep Thought » Wed Jun 05, 2019 10:46 pm

Always a good idea to check for loose connections on the regular. It'll also save your ATU components and avoid downtime...
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Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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RGORJANCE
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Re: SX 2.5 Won't Power on No Lights

Post by RGORJANCE » Thu Jun 06, 2019 6:56 am

"War story time"............

Back in the day when I was selling xmttrs, I always insisted that a complete check of all nuts and bolts be done during installation.

Quite frequently, I assisted in installations and we always checked hardware. We always found a few that could be tightened more.

The original concern was for things that could have been loosened during shipment. I liked Chicks comment on the follow-up PM idea.....will definitely do that in the future. Hmmmmm, reminds me of a huge power panel fire at an Air Force Comm center, but that's for another post.

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KPJL FM
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Re: SX 2.5 Won't Power on No Lights

Post by KPJL FM » Thu Jun 06, 2019 7:05 am

Loose bolts are one thing, but a guy should never have loose nuts.
Trim to fit, paint to match, tune for minimum smoke.

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Re: SX 2.5 Won't Power on No Lights

Post by grich » Fri Jun 07, 2019 12:03 am

KPJL FM wrote:
Thu Jun 06, 2019 7:05 am
Loose bolts are one thing, but a guy should never have loose nuts.
Ouch!

That's part of our routine with our Harris Platinum SS TV transmitter...check all of the DC bus connections for tightness. Lotta current to arc-weld with if it got loose. That, and cleaning, are about all we do for maintenance. It just keeps running.

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Re: SX 2.5 Won't Power on No Lights

Post by grich » Fri Jun 07, 2019 12:08 am

Deep Thought wrote:
Wed Jun 05, 2019 10:46 pm
Always a good idea to check for loose connections on the regular. It'll also save your ATU components and avoid downtime...
The input and output connections on the SX PA boards are also good places to check for tightness. The output side of the SX1 I care for burned off at the lug and I had to do some creative repairs to the leads coming from the toroids.

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Re: SX 2.5 Won't Power on No Lights

Post by rfn » Fri Jun 07, 2019 9:10 am

Don't overlook incoming AC connections to the entire site. Station I have worked with from time to time had two fires over the years at times when they had no technician on staff. Both originated in the "meter trim" - where the city's Aluminum drop connected to copper terminals. Even though they had been liberally coated with one of those (I want to avoid brand names) AL/CU compounds. Fortunately both only scorched siding. Since I've been back there I've made it mandatory that all AC connections (including those involved in the backup generator/transfer switch) be snugged down at least annually AND that the city power crew does the same at the transformers up on the pole outside. Yeah it costs a little but that's instead of costing it all.

engnewbie
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Re: SX 2.5 Won't Power on No Lights

Post by engnewbie » Sat Jun 08, 2019 8:00 pm

KPJL FM wrote:
Thu Jun 06, 2019 7:05 am
Loose bolts are one thing, but a guy should never have loose nuts.
:lol:

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Re: SX 2.5 Won't Power on No Lights

Post by RodeoJack » Sat Jun 08, 2019 9:43 pm

That picture exemplifies one of the things I appreciate about having entered this business in the '70s as a teen, when everything was made from discrete components, the rigs were full of tubes, the fans were big, the exhaust was hot and the voltages were respectably high.

Back then, a lot of troubleshooting depended less on technical knowledge and more on the common-sense approach of looking for where the smoke was coming from.

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davek
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Re: SX 2.5 Won't Power on No Lights

Post by davek » Sun Jun 09, 2019 11:24 pm

RodeoJack wrote:
Sat Jun 08, 2019 9:43 pm
a lot of troubleshooting depended less on technical knowledge and more on the common-sense approach
Nothing has changed in that regard..

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