[SBE] Harris HT40 TV transmitter question

[Jon Frank]

No difference.  From what I can see on my schematic the short takes place between pins 10 and 11 on the module connector. Yes the connector you pointed out is the correct one.


On 6/22/10 11:02 PM, "Curt Yengst" <cyengst at star991fm.com> wrote:

You're definitely on to something here.

One question:  What's the difference between opening the DC power connections inside the module versus simply disconnecting the power wires from the supply buss bars in the back of the PA cabinet?  I figure no power is no power.  6 or a half-dozen.

We would like to keep the unused aural modules in place for airflow reasons.

It almost sounds like it would be possible to simply mod the mating plug to fool the transmitter into thinking the dead modules were OK.  Then the control cabinet would stop sending false module fault alarms.

By "module mating plug" I assume you mean the connector on the back of the module that has a sort of oddball dog-leg shape to it and has about seven pins of about three different sizes in there.  Am I right?



-----Original Message-----
From: sbe-bounces at sbe.org on behalf of Jon Frank
Sent: Tue 6/22/2010 10:33 PM
To: sbe member discussion mail list
Subject: Re: [SBE] Harris HT40 TV transmitter question

We had a 33Kw low band Harris Platinum and we did run in to that problem if we had to take a module out for service.   The PA fault light is turned on due to the lack of a jumper that connects two pins through the module mating plug. When a module is plugged in to a transmitter chassis slot, the jumper completes a circuit that tells the logic that the module is properly seated.

In our case we had talked to Mike Finley (The Platinum guru) and suggested an idea for a dummy module that we could install in the place of a module we had removed.  He had it built and sold it to us for very low money.  The module had a jumper on the mating plug and also served the purpose of filling the hole so that the proper air flow was maintained around the other modules. I believe Mike may have retired at the end of NTSC and I'm not sure Harris makes these available, but you could ask.  You could try just buying the mating plugs and soldering a jumper wire on.

Another idea would be to modify the old aural modules by simply opening the dc power connections inside of the modules,  then installing those modules back in to their old slots.

Jon Frank
WGBH
Boston
________________________________
From: sbe-bounces at sbe.org [sbe-bounces at sbe.org] On Behalf Of Curt Yengst [cyengst at star991fm.com]
Sent: Tuesday, June 22, 2010 4:20 PM
To: sbe at sbe.org
Subject: [SBE] Harris HT40 TV transmitter question


I'm not a TV engineer, nor do I play one on TV; but I'm currently assisting at a local TV station.  We've installed a Harris HT40 which was purchased second-hand.  Everything works great except for one thing.....

We're not using the stock exciters, nor are we using the aural modules in the PA cabinets.  Since the station is digital, we're using an after-market digital exciter and using the visual PA's to amplify that signal.  We've disconnected the aural modules from the power supplies, and the stock exciters are completely removed.

We now get, as can be expected, module fault alarms and exciter alarms on the display in the control cabinet.  The exciter alarms are not the big issue here, but the module alarms are.  We know the alarms are caused by the fact that the aural modules are disconnected.  The problem comes if and when we have a legitimate visual module fault.  There's no way to tell.  This prevents us from connecting the module fault alarm to our Burk remote system.

Has anyone else been through this configuration already, and could you suggest a way to "fool" the transmitter into seeing good aural modules, or even getting it to just ignore the disconnected modules?

Curt


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