Shure wireless mic syncs with receiver but won't connect

[OldRock]

I'm not sure if this is the appropriate forum for help with this, but if not I'd appreciate any suggestions as to where to turn.

I'm responsible for our church sound and video systems, but I'm not a pro. We have four Shure SLX wireless mics and receivers. Until two weeks ago, three of them had been working well for many years, and the fourth had been working for over a year. The SLX product line has been discontinued, but there is still a lot of information about it on the Shure website.

Two weeks ago, the two systems that operate n the 530 to 542 MHz range suddenly stopped working. The other two are in the 600 MHz range and they still work fine. According to the Shure Wireless Frequency Finder the 530 to 542 band should still be available at our location (southern NH), and there are no TV stations operating on the frequencies we use. When we set a new frequency and then sync a mic to its receiver, it indicates that it has successfully synced, but then it won't connect.

What is most perplexing is that sometimes when we try a different frequency in that range it will work at first, but then won't connect the next time.

I've followed every suggestion for troubleshooting that I can find, including trying one at my home 10 miles from the church. When I first powered it up at home it connected immediately. I then changed the frequency and could not get it to connect again, even after switching back to the original frequency.

Anyone have any suggestions? We can't afford to replace them at present.

Thanks in advance
Graeme

[shufflebeat]

Do you have access to any kind of RF scanner? The Tinysa is very useful and not expensive and although the learning curve is quite steep it’s not rocky.

Buy from sources listed on tinysa.org to be sure of quality and support.

The fact that more than one unit is flagging suggests it’s an environmental problem which might be picked up on scans.

Otherwise it could be some shared trauma like some very sweaty performers into multiple belt-packs, for instance.

[OldRock]

Thanks for the suggestion. I'll check out the Tinysa.

[Hugh Robjohns]

Granny sucking moment... but it happens... have you checked the transmitters haven't been muted or the sensitivities turned right down?

Switch the transmitters off and listen to the outputs from the receivers. (You may need temporarily to defeat the squelch mode if they have it.) If there's something else operating on those frequencies you'll probably be able to hear something and see the RF signal strength on the receiver display.

Are the transmitters handheld mics or body packs with lavaliers? If the latter, it's very common to suffer cable failures where the cable goes into the plug, because of people being helpful and wrapping the lavalier lead tightly around the body pack... So try a spare mic if you can.

Have you checked the receiving antennas? Are they attached and pointing in sensible directions well away from any metalwork or sources of interference?

[OldRock]

Thanks Hugh. Some good suggestions. One of the mics is a handheld and the other is a body pack, but it’s not an issue with the mic cable. The receivers have a green LED that lights up when the mic connects, and that’s not happening. I know the infrared sync succeeds because the mic or body pack shows the new group and channel. The antennas were all set to 45 degrees as recommended by the mfr. I will check the sensitivity adjustment.

Thanks,
Graeme

[shufflebeat]

Hugh’s suggestions are much more sensible, methodical and cheaper than mine just to buy more kit but it is fun and informative.

With just a few RF units to consider the scan functions, some common sense and an ability to read and understand the meters is probably enough.

[Hugh Robjohns]

Has anything changed over the period between all four systems working and two no longer working?

Has anything been moved? New equipment installed? Cabling changed or relocated?

Two channels in the same band dieing at the same time is unlikely to be a coincidence...

[illegal colors]

Granny sucking moment... but it happens... have you checked

batteries

[OldRock]

Thanks everyone for all the suggestions. Here's an update in case anyone is still interested.

- Battery level is the first thing we check every week.

- Nothing was changed between the time they were working and when they stopped.

- The Shure SLX receivers don't have a sensitivity adjustment, so no progress there. The only adjustment is for volume out to the mixer, which is set to max.

- I bought a Tinysa and it was very helpful in eliminating some potential causes:
--- There was no background interference anywhere near the frequencies we're using.
--- Each microphone was transmitting on its selected frequency.

- One of the two receivers mysteriously started working yesterday. I have no confidence that it will be working next week. The other is still not connecting.

At this stage we're going to assume that the two receivers are flaky. We'll reconfigure to avoid using the one that's still not working and not be too dependent on the one that worked yesterday.

Again, thanks for all the suggestions. At least I can now feel like I've done everything possible.

Graeme

[Hugh Robjohns]

How frustrating! Analogue radio mics have always been troublesome!

Are all four receivers in a rack together?
Do they each have their own 1/4-wave aerials attached or are you using an RF distribution amp to share two antenna between all four receivers?

[OldRock]

They're not rack-mounted, just stacked up with their individual antenna pairs at 45 deg away from the stack. It just occurred to me that it might be heat related. The one that has stopped completely is on top and the one that's intermittent is second from top.

I'm going to separate the stack and order a replacement receiver on eBay.

Thanks again for all the advice.
Graeme