Shure vintage wireless guitar, died ?

[ricci]

For about 20 years I have had this Shure wireless system that I kept in a bag with cables, placed between the sofa and the radiator.

https://images.reverb.com/image/uplo...x6bvrtpang.jpg

After about 5 years of not using it, it suddenly stops working, both the transmitter and the receiver are switched on normally but the guitar signal does not reach the receiver and perhaps it does not even start from the transmitter. I disassembled both but found no loose wires and no burn marks.

With this little oscilloscope (i am not an expert)

http://english.instrustar.com/produc...l.asp?nid=1556

i just tried to put the probe on the transmitter antenna solder but playing the guitar i don't see any variation in the oscilloscope graph. How do I know if the transmitter or receiver is faulty ?

I don't know, could the heat of the radiators in recent years have created some problems ?

Thanks for all !

[Marshtech]

With the transmitter turned on, look for a high frequency carrier waveform from the antenna. Don't overlook the basics either - faulty on-off switch (if it has one). Be absolutely sure that the cable from the guitar jack to the belt pack is 100% connected and in good condition. Use that as a starting point.

[Enzo]

Transmitter works at what 180MHz? 400MHz? And your scope has how much bandwidth? Likely even if the scope would react it would be tiny. loop a few feet of wire and wrap around the transmitter, then connect your scope probe to that wire. It is an antenna now. Turn your scope up to the highest sensitivity and speed up the trace. Now flip the transmitter off and on. DO you see any corresponding growth in the scope trace? That is about all you can expect. Also these work on FM, so I doubt you'd be able to see the audio on it on a scope.

[ricci]

With the transmitter turned on, look for a high frequency carrier waveform from the antenna. Don't overlook the basics either - faulty on-off switch (if it has one). Be absolutely sure that the cable from the guitar jack to the belt pack is 100% connected and in good condition. Use that as a starting point.

I had checked the input connector and it is fine and the signal is 100% connected to pcb but curious thing, on the antenna i see 50 Hz about Vpp=700 mV

[ricci]

Transmitter works at what 180MHz? 400MHz? And your scope has how much bandwidth? Likely even if the scope would react it would be tiny. loop a few feet of wire and wrap around the transmitter, then connect your scope probe to that wire. It is an antenna now. Turn your scope up to the highest sensitivity and speed up the trace. Now flip the transmitter off and on. DO you see any corresponding growth in the scope trace? That is about all you can expect. Also these work on FM, so I doubt you'd be able to see the audio on it on a scope.

The transmitter works at 169445 Mhz. The bandwidth is around 20Mhz. I understand what you mean, so i would not be able to perceive the frequency of the transmitted wave, right? I see 50 Hz both when turned on and off.

[Enzo]

I had a B&K 35MHz scope for years, and with the setup I described, I could just barely see a response. It was good enough to tell me the Xmtr was sending, but not to see the signal.

[Helmholtz]

The transmitter works at 169445 Mhz..

Wow, 169 Gigahertz. Not very likely.

I see 50 Hz both when turned on and off.

Isn't the transmitter battery powered?

[Enzo]

Yes battery Xmtr, but his shop will be surrounded by 50Hz fields to pick up with a scope,

[The Dude]

Do the diversity lights light up when the transmitter is switched on? If either does, it indicates that the receiver is receiving RF.

[Helmholtz]

Yes battery Xmtr, but his shop will be surrounded by 50Hz fields to pick up with a scope,

Properly connecting the probe's ground clip should help.

[Enzo]

Sure. Just want him to realize he is just picking up the environment, not the transmitter.

[Helmholtz]

Sure. Just want him to realize he is just picking up the environment, not the transmitter.

Yes, I figured but wanted to hint at the battery (might be dead) and the proper use of scope probes.

[ricci]

Wow, 169 Gigahertz. Not very likely.




Isn't the transmitter battery powered?

sorry, the decimal point 169.445 Mhz is missing. Yes battery.

[ricci]

Properly connecting the probe's ground clip should help.

I connected it to the ground of the connector

[ricci]

I had a B&K 35MHz scope for years, and with the setup I described, I could just barely see a response. It was good enough to tell me the Xmtr was sending, but not to see the signal.

in fact it would be enough to understand if it is sending to be able to focus on where the problem is