Posts Tagged ‘GatesAir’

Fixin’ Things: Week’s Update

Figured I would try and and get back into the swing of things and update a bit more often.  Mostly boring stuff, but, hey, someone has to do it! This week I have a bit of F.O.R.D. action to mention along with plans to  repair a Nautel NV20.  Also a little fun with NexGen and Sage communications.  A little bit of everything.

F.O.R.D. = Fix Or Repair Daily.  Harris Z10.  This box just sits there and is used on occasion when I do a Nautel update.  As it sits, it fails.  No, it doesn’t need to be turned on, it just fails.  I should clarify, it shows Faults.  Currently 4 when I look at the logs, used to be 5.  Let me remind you, it gets these just sitting idle.  Apparently 2 of the 4, was 3 of 5, are PA modules showing the PS#_OT, or over temperature fault.  Again, it isn’t running.  A little research and some interaction with tech support a couple months ago, I finally ordered the parts through Mouser and did a test repair.  This repair entails the replacement of a capacitor and thermistor.  Easy enough except they are surface mount, so I finally got a chance to experience this type of repair first hand.  All I can say is it takes patience.  Needless to say, the test PA module installed and fault is cleared.  I have 2 more to do.  The other faults I will act on when I get these obvious ones out of the way.  Unfortunately it looks like one of these pending faults corresponds to a dead PA.

But, wait, did I say a Nautel repair is imminent?  Yeah, I guess I pushed the old beast a bit too hard as I prepare for an HD carrier increase.  I began to adjust the HD PA voltage to accommodate the new power increase and two PA modules said they did not like that, and Poof!  I just finished doing some research and I have all the parts to replace them.  I even have the tools!  What did I find out today?  I have version A of the modules and all the latest documents show they are up to C, and they look more modular!  The old ones require de-soldering and then replacement.  At least it doesn’t look to bad.  I also get to perform the modifications that the modules required a few years back to improve efficiency.  All in all, I call this fun.

We us IP to control most everything these days, and this includes how the RCS NexGen communicates with the Sage Endec.  Sure enough, this week I noticed that the RWT did not fire properly.  This is normally caused by the old architecture of NexGen where it just decides to not talk.  After a couple of tests I had to do the old CTRL+Alt+Shift+F4 on the A-server so it would load a fresh database.  Why it decided to start doing this is beyond me.  The other two stations do not have this issue.  I know we will be moving off this system some day, so whatever we use better be IP savvy in running all tests and alerts.

Interspersed among all this fun is Microsoft and Windows 10.  Thanks.  Apparently there is an issue with Win 10 and USB 3.0.  At least with some of our stuff, more specifically Digigram and the UAX-220v2.  Thought he device uses generic Windows drivers, the system will throw a fault and reboot spontaneously.  When trying to track it down, the Event Logs show nothing except the “previous shutdown was unexpected” error.  I finally caught a memory dump and analysed it.  A reference to a USB device was there.  As a test I removed the UAX and that machine has settled down.  I think I will need to experiment with a couple of other USB sound devices and see if it is isolated to Digigram or it is more universal issue.  Sad if it is the UAX as the beauty of it was plug and play with no special drivers.

If you get a long weekend, enjoy!  If not, take advantage of the time you have!




Step Forward, Then Back

Another week has gone by and wouldn’t you know it, that exciter of last week made me take a step back.  That Superciter was working just dandy on the bench when I shut down on Friday of last.  I had it up to 30 watts running happy as a clam (wherever that phrase came from) into a load.  All afternoon it ran until I pulled the plug for the weekend.  Come Monday of this week, Mr. Murphy struck.

As usual with these things, I felt I should run another bench test before calling this exciter good.  Plugged it in and let it run.  It started out just fine at 30 watts.  I’m happy that nothing changed while it sat doing nothing for a weekend.  We all need time off.  I wander through the shop while doing other things.  I walk right by the bench late morning and stop.  Take a couple steps back and look at the forward power.  16 watts!  Huh?  Fan is working and I pop the top open.  Not heat.  Shoot, it’s even sitting under an air conditioning vent.  Time to pull it apart and take the test point readings.  I start to see a couple of anomalies, though for the most part all readings were good.

I sit down with the schematic and refresh my brains on the previous week pointers on what drives what and who and where.  Take a couple more readings as I watch the power drop down below 10 watts.  Something is failing and failing slowly.  No faults, just no power.  OK, if those don’t get enough drive what happens?  I’m starting to get the feeling there is a drive issue.  Why it didn’t show last week is interesting.  I have a brief email exchange with GatesAir.  I describe the situation and how it changed from last week.  The same conclusion that something is not giving enough drive.  We are going t concentrate on the RF drive produced by the FM Synthesizer board.  I have a couple of parts ordered, so we wait until they arrive.  Let’s see if this takes care of it.

In the meantime, we had our annual fire inspection.  Meetings.  A last minute invite to Al Salci’s (of SAS fame) presentation of AVB (Audio Video Bridging) was a highlight.  Great presentation if you get a chance to witness it.  At least I had time off from wrestling with that exciter!  Every week is a learning experience, so take advantage when you can.  Next week more meets and greets.  Let’s see what I learn and maybe even get an exciter repaired.


Categories: Equipment, Management Tags: , , ,

Engineering Week Successes

Motivation has been lacking.  Been waiting a while for the sale to go through, so now we are a new company.  Very cool and it looks to be quite fruitful with the resources that appear to be had.  Many little/minor repairs have been done since my last post.  If you read the trades much in terms of streaming and connected media.  While all that goes on there is still radio and still needs to be met.  As a broadcast engineer the main deed is to keep our stations on the air!

Granted I had no off air time this week, I did have to deal with a couple of issues.  One is an auxiliary exciter that decided not to produce power.  This bad boy is an old Harris Superciter.  I believe it to be a post-Digit exciter and dates back to 2006.  As I had a spare Digit I was able to bring the Superciter to the shop for work.  Acquiring the schematics and manual was fun, and I dug up a schematic set, but no manual.  GatesAir was able to forward me a manual and another set of schematics.  After poking around I got frustrated as I did not know what readings I needed to see as certain points to determine what direction to go.  A few more emails and a better understanding led me to testing each stage.  Eventually I got really curious, so when I got to the Power Amp (PA), I began static testing the transistors which began to look good.  As this exciter is an Aux and just sits there with a quarterly turn on and run I figure it was time to really look for dirty contacts everywhere.  Anything I saw I cleaned.  I reconnected everything and had forward power!  Crossing my fingers, I put the box back together thinking it won’t turn on when I do.  Luck on my side, it came on again.  Ran it for over an hour into a load without issue.  I’ll fire it up again Monday to verify and plan on taking it back to the site.

As if this exciter thing was a pain, one of my main transmitters started doing something odd: It began having power fluctuations.  This is an “old” Nautel NV20.  Yeah, remember, I have the oldest ones out there at 6 1/2 years old now, so I get to experience the aging process.  No faults were showing except for PA module foldbacks and, sitting down, “Module # not responding.”  If a PA module is not responding there must be some fault somewhere.  I looked at everything.  I ran it into the load and watched it.  It didn’t matter which module it just randomly picked on as not responding, or two, three….  What else can I do?

I did what anyone would do.  Shut it down.  Remove each PA module and reset it.  While I did that I also checked the fans on each, though not showing failures, I’ve had a couple fail from old age already.  Found 2 that showed signs of failing and replaced them.  I check the connections to the exciter.  All good and tight.  Flipped the disconnect back on and let the AUI boot up.  I took it slow and selected a low power preset.  I stepped to to a low power with HD preset.  I went for the gold to full TPO of 10 kW.  I watched it with eagle eyes.  I dared it to do something.  Rock solid.  Heated that room up good running it into the load for 20+ minutes.  Time to put it back on the air, and it came right up.  Again I eyed it.  Both via front monitor AUI and via remote web browser, one on the main screen and the other on the status screen just waiting for it to mess up.  Rock solid.  Absolutely no power wavering.  I watched that thing for an hour, and then called it good.  The conclusion:  Even 20 kW Linux computers need to be rebooted, from a cold boot, on occasion.

Hope all your repairs turn out to be as simple and successful as mine have.  Look for the signposts while troubleshooting and take the proper path.  The repair becomes easy.  (Oooh, a Zen moment there.)


Categories: Equipment Tags: , , , ,

A Little Harris (GatesAir) HTHD+ Repair

February 13, 2015 1 comment

Not to focus on anything like this, but, damn, I have not posted in a while.  Let’s start flooding you with some real boring stuff!  A few weeks back I had the un-welcomed 12:30am phone call from the remote control.  How we love those calls.  The basics were there:  No forward power, off air alarm, etc.  I do the normal, let’s try and turn it back on.  Nothing.  I tried to switch to the Auxiliary transmitter, but that did not happen.  My first thought was “great there goes a UPS” which would explain lack of control, but my remote control was working.  Up on the Aux site I went.  Mind you all this took place quick enough the person in building was never aware of the condition.

Off to the site I go ready to find some melted metal.  First lesson of the evening: Make sure all connections are tight and good even on the remote control!  A wire backed out of the Phoenix connector on my command for the coax switch.  Doh, no wonder it didn’t switch.  Fixed that and put the Aux transmitter on the air and turned off the Aux site.  (Nice to have an actual auxiliary site.)  Crazy how that switch ALWAYS remotely switched until this night.  Now on to the main transmitter.

The HTHD+, as all HT series transmitters, has the mimic panel. I see red LEDs for the Plate and a Fault indicators.  Well, isn’t that nice.  I did just replace the tube a month prior.  Let’s see what happens if I shut everything down and start it up again.  This usually clears a strange fault or situation especially with a power fluctuation.  Wham and Bam.  Nope.  Immediate slam, in your face, time to troubleshoot sound.  I checked the obvious PA cavity and tube.  Always check that plate blocker.  No obvious signs and no arcing.  Jeez, it was clean.  Give the tube a shake.  Not rattle.  Good.  Let’s give it another chance, so I turn on the filament, then plate.  Same result.  Nothing.  At this time I take a step back and glance at the big picture.  Plate and Fault indicators on the mimic panel.  I glance at the High Voltage Power Supply (HVPS) cabinet and there I see it, a MAG OVLD indicator.

How I didn’t notice it when I first walked in I cannot say.  Tired or just fixated on the mimic panel.  Time to focus on the HVPS.  First step is I verified the fault through the multimeter overload faults.  Code 21.  A cross check corresponded with the MAG OVLD which indicates either relays being open or control voltage was not there.  I did all the basic checks:  Input line volage, cabinet connections, and interlocks.  All good.  So, I either had a bad relay or, worst case, a shorted transformer, though I did not smell any magic smoke.  I messaged GatesAir via the customer portal, and then studied the schematic.  As all line voltages were good I was beginning to suspect a set of relays, and after a nice chat with GatesAir, we determined to focus on magnetic relays 3K1 & 3K2.  I set out to do just that.  There happens to be contacts on those relays that are exposed.  I gave them a little burnshing.  I did a quick test into the load.  Everything came up flawless.  As I had the aux transmitter on the air, I decided to proceed with a cleaning of the HVPS cabinet.

After cleaning up I placed the HTHD+ back on the air.  I still find it odd that this failure occurred in the middle of the night.  I also find it all that something got in between the contacts on either or both relay contacts while they are normally closed.  I did go through a cleaning while I did the tube replacement earlier, but it never occurred to me to burnish these contacts.  In addition all was running fine up to that point.  As power at the site can be somewhat inconsistent, I wonder if a phase dropped briefly and upon an automatic restart an arc or some dust affected the relay contacts.  I have an HT-25, I’ve installed and maintained an HT-30 in the past.  I have never had this situation, and they were in environments worse that this.

I love this job as there is always something to learn even if it is a minor, and somewhat obvious item.  We do not “know it all” and I love to learn.  Pack it in your data bank of a brain so next time the repair is a no-brainer.


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