MTR3000 Fan Control

[escomm]

I swear, either the MTR3000 line is the biggest piece of garbage to come out of Motorola since the CP200's audio jack or I have the worst luck in the world.

I am burning in a customer's warranty replacement MTR3000 and I've had it keyed since about 0830. The power supply fan has not come on once. My meat thermometer is reporting temps on the PS heatsink at anywhere from 125 to 135 degrees. I suspect it's actually 10-15 degrees hotter and the thermometer is garbage, just like the station it's measuring.

So uh, at what temperature should I be expecting these fans to come on at? The basic and detailed service manuals report nothing on the threshold, only that they will come on automatically when the software says they need to come on.

Something is bad order here, I suspect, as the fan does not turn on at all when the station is freshly power cycled. The manual states pretty clearly both fans should come on for 5 seconds when power is applied to the station to confirm operation. Unsurprisingly, no alarms in present in RDAC, and evidently fan operation is not one of the QC criteria Motorola puts the station through. Certainly no pass/fail condition is present on the test results printout.

Alternatively, does anyone know the thresholds for the MTR2000? I'd think them to be the same across both stations.

Then again, I'd also think Motorola QCs these $5,000 repeaters before shipping...

[kcbooboo]

I have a 100w UHF MTR2000 with a PS problem (won't power up with AC), so I run mine on 28VDC. I did take the PS apart and since I put it back together again, the PS fan has never turned on. On 28VDC power, my PS runs ice-cold. The PA runs on 28VDC that just passes through the PS, so only the 14V and 5V regulators are creating any heat, and I'm guessing the power draw is fairly low. I suspect the PS fan is just there to cool the AC->DC portion of the supply. The PS, like all the other modules, aren't designed to be repaired or even opened in the field, so specs like fan turn-on/turn-off temp aren't necessary.

The PA fan does turn on and off when the unit is transmitting at 75 watts into a dummy load. It does not always run when initially powered up. I have no idea what the thresholds are. There is a screen in the MTR2000 software that lets you run diagnostic tests and those report both fans operating properly, even when it causes the PA fan to run. I'm not sure what sort of failure would be detected. The fans only use two wires, so the best they can do is measure the load current. You could unplug the fan and see if any errors are detected.

QC? Remember who you're talking about! This isn't Zenith, where "the quality goes in before the name goes on."

Bob M.

[escomm]

Well that's unfortunate.

After letting the station sit overnight but with no transmitting my thermometer says the PS heatsink was at 105.1 degrees this morning.

I jumped the PTT about an hour ago. I suspect it'll be at 120+ here shortly.

Connected with RDAC and unsurprisingly no alarms were present.

Looks like a call to "tech support" is in order. I've already sharpened my knives so I can stab myself in the eye. That will be more productive than talking to those clowns. Can't wait for the suggested resolutions of a firmware upgrade and codeplug recovery.

[escomm]

Woo hoo, we have an update.

So, the problem with my fan was that it was not properly connected at the factory. I decided to disconnect it and test voltage on the pins. Bam, 13 volts on power up. Hooked up the fan to my bench power supply, bam it runs. Reconnect it to the station, power cycle, bam I have 3 seconds of the PS fan running as part of the self test.

What's fun here is.... the PS fan apparently does not throw an alarm on the status panel. Nor does it throw an alarm in RDAC.

It's entirely ostensible that a user has their station installed and would never know there was a problem with the PS fan until the PS blows up, or suffers some other fault that does end up causing it to throw an alarm.

With regard to my OP... I am now inclined towards the former and not the latter...

[d119]

Plastic fantastic throw it together and get it out the door piece of :o.

It's NOWHERE near as advanced as it's counterpart, and it's counterpart was pretty horrid in my opinion. Just look at all these folks having to DC power the things.

Maybe someday we'll see this thing really shine, but for now, it's 100lbs of :o in a 10lb box with 1lb of functionality.

[kcbooboo]

That's useful to know that the fan it not measured for presence. Does the same hold true for the PA fan?

Can you easily power the station via external 28VDC and see if the PS fan comes on at turn-on? I know mine doesn't but I may have broken something when I (unsuccessfully) tried to take my PS apart to fix it.

Bob M.

[escomm]

The PA fan should definitely throw an alarm. At least the manual says it should. In hindsight, I probably should have disconnected that one, too, and observed what happened.

My only 28V power supply tops out at 3 amps. Good for working on Technisonic radios. Not so much for MTR3000s hehe

[kcbooboo]

3A is fine for power-up/receive. If you can easily test it, I'd be interested.

Also, a couple of 12V 7AH gel-cells in series will do the job. You only need power for several seconds, until it finishes the self-tests.

Bob M.