Tuning / Adjusting a VRM (600/650/850)

[fireradio]

I'm checking out some VRMs that have been pulled from deadlined vehicles, and using WinRSS and my service monitor, I've found a few that are off frequency, need power adjustment, etc.

Is there a tuner application (or some option in WinRSS that I'm missing) to adjust the transmitter reference oscillator? Power output? The only thing it looks like I can do with WinRSS is adjust the signal deviation.

Thanks!

[GlennD]

We use the dos MCS2000 tuner program through the db25 to set frequency. This really does need to be done on a PM schedule. I have seen them off by over 7Hkz in our system.

[fireradio]

Ah, I didn't think about that. So far the worst I've found is +/- 1 KHz off frequency, but that's still plenty to bug me.

I know the 650s and 850s are based off MCS2000s, but the 600 is Spectra-based. Does anyone know if the Spectra tuner would work with a VRM600?

Thanks.

[jackhackett]

I've never seen one that far off either, I'd think anything very much over 1kHz off would indicate a possible hardware problem.

I believe the spectra software should work on the 600, but you can't use the normal spectra programming cable, you need one with the ignition sense lead moved from pin 5 to pin 4. This is because there is no power switch circuit in the vrm600, so the ignition sense lead is connected directly to the SW B+ pin on the accessory connector.

[fireradio]

Awesome. I'll have to give it a try if I get some spare time at work!

[GlennD]

We do not have the people to have a mobile PM schedule. We check all equipment when it is removed or comes in for service. I think the -7Khz VRM was from a detective removal. They rarely, if ever use the MDT. It is a RDLAP 19200 system but that is more than enough offset to not work at all.

[fireradio]

I am trying to use MCS2000 Tuner R2.01.00 and a "belly" DB25 cable to read/tune a VRM650 and I'm not having any luck. I'm not 100% sure the cable I dug up is the correct one, but it I think it is. Should I be going through a RIB or straight to the serial port via a DB25 to DB9 adapter?

The Tuner app tells me that communication with radio failed, unsupported model through a RIB.

The cable has two speaker connectors (one male, one female) and two red molex-style connectors (also one male, one female) in addition to the RIB DB25 end and radio DB25 end.

Any tips?

Thanks!

[jackhackett]

Cable should be RKN4063A, through a RIB.

I'm not sure what the cable you described is, the programming cable I have has the connector for the radio with two cables coming out, one to a male DB25, the other to a female DB25.

R02.01.00 is what I've been using, it can be a bit quirky with the VRMs though. I've had them get stuck in TX even when the software says TX is off, sometimes it's hard to get them to key up on the right frequency, and I've had problems with the power settings. I haven't tried the DOS software, maybe I'll give that a go next time I do one and see if it works any better.

[GlennD]

I am using a cable built from Batlabs info through a rib. I am using DOS ver 5.05. This has worked for every 650 and 850 we have including a batch of 70 VRM850s we received earlier this year.