Hello, I need some help please - this thing is driving me crazy. I have a brand new input selector that will not output any audio just loud static and hum even when turned off at the wall.
It's powered by a 12v torroid which isn't connected to anything other than a bulb tester.
On the board there is a 2x12v AC power connection, a bridge rectifier, a voltage regulator with 5V output, diodes and caps. Everything tests ok. The voltage regulator on the board is a L7805 and not the same as in the picture which I took from the sellers website. Sorry everyone for the confusion.
Input is 3.5mm jack from my phone output is via selector switch to a 3.5mm jack connected to a small Class D amp module. I am using the copper cable shield as ground.
There is no ground on the selector, just 12v and 0V and the amp module has a floating ground. Any help very appreciated.
It's powered by a 12v torroid which isn't connected to anything other than a bulb tester.
On the board there is a 2x12v AC power connection, a bridge rectifier, a voltage regulator with 5V output, diodes and caps. Everything tests ok. The voltage regulator on the board is a L7805 and not the same as in the picture which I took from the sellers website. Sorry everyone for the confusion.
Input is 3.5mm jack from my phone output is via selector switch to a 3.5mm jack connected to a small Class D amp module. I am using the copper cable shield as ground.
There is no ground on the selector, just 12v and 0V and the amp module has a floating ground. Any help very appreciated.
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If everything tests ok, it should work. Obviously not.
Do you hear click when you are switching between four inputs?
Do you hear click when you are switching between four inputs?
If you have 2x12V how do you 'feed' the supply input? Because you'd need two diodes, not the 4 diodes of the 'bridge'.
Probably you have an over voltage problem, probably the regulator Is burnt
Probably you have an over voltage problem, probably the regulator Is burnt
Post photos and complete schematics. Also any specific test measurements.
A bulb tester is NOT for use during testing. It is only for the initial turn-on to prevent destruction due to severe faults.
Remove it before any further testing.
A bulb tester is NOT for use during testing. It is only for the initial turn-on to prevent destruction due to severe faults.
Remove it before any further testing.
It all sounds more like a problem with wiring of the audio path, the audio inputs and outputs should be 100% isolated from anything to do with the power supply and relay switching side of things.
Power the board up and check continuity from any selected input to the output. Should read zero ohms.
Maybe your amp objects if it sees a floating input.
Power the board up and check continuity from any selected input to the output. Should read zero ohms.
Maybe your amp objects if it sees a floating input.
It's a 7805 on the board. It has 17V in and 5 out. My (amateur) logic is that 12V rectified is around 17V so it's testing ok.
It's an l7805 on the board. The picture is from the shop website and I think they have changed it. Do you know how I can edit the post? I can't see how to update it with this info
The supplier of the boards specifies 12V AC. The regulator on the board is a L7805 testing 17V in and 5V out which I think is ok as 12V rectified is 17V. I am a complete amateur so likely wrong. I don't really understand what you said about the diodes
I think it is ok as I used the same setup to test a Bluetooth module a few days ago and there was no hum. I have tried quite long cables separating power supply and relay and it didn't make a difference. I have been trying everything I can think of for hours
So the relays are now 5V coils also?
Is there hum with power supply unplugged from the wall?
Just checked and the relays are 12V. The voltage regulator is 5V for some reason. I have tested and there is no continuity between input and output on the board so I suspect that the relays are not been triggered. I don't know how to test them so going to find out how on Google.
If the regulator is 5V, and the relays are 12V, it cannot work properly.
Change the regulator back to 12V.
Also complain to the seller as this is a defective product.
Change the regulator back to 12V.
Also complain to the seller as this is a defective product.
You are working very hard to confuse everybody.
Are the relays clicking?
Clicking sound indicates relays are engaging. You said so.
On the other hand, one out of four inputs must have continuity to the output.
If none of the inputs shown any continuity to output, no relay is engaged. No click! Got it?
Begin again.
Disconnect the output of the board (the green terminals) and power up your amp. If it hums etc you need to first of all address the issue of why and that is most likely because the termination is floating.
So first question. Does it hum in that condition or is it silent?
Sorry, It got late in UK. I checked and the coils are 12V so I don't understand why they changed the voltage regulator. It hums even when unplugged and the selector switch turned to a different output. I tested this morning and there is no continuity between input and output on the board so I think that means that the relay is faulty or not been triggered. I am going to switch out the regulator for a 12V one that I have and if that doesn't work will replace the relay with a known working one that I have. If that fails then I am out of ideas.
Thank you. I have some 12V regulators so will try switching them and see if it helps. It's a Chinese board but made by a respected company so I expected more. I have lost a day of my life trying to figure this out as my first thought is that I am doing something wrong and not that a brand new board is faulty. My bad for not checking the voltage on the relays as I tested everything else on the board. Lesson learned
@Mooly I can't see how to reply directly to your post so hope this works.
I have done what you suggested and used exactly the same setup including the cables and there is no hum or noise so it is definitely the input selector that is the cause. The relays are 12V so that might be the problem. I am going to switch the regulator for a 12V one that I have and if that fails then will replace the relay with a known working one. If that fails then I am out of ideas.
I have done what you suggested and used exactly the same setup including the cables and there is no hum or noise so it is definitely the input selector that is the cause. The relays are 12V so that might be the problem. I am going to switch the regulator for a 12V one that I have and if that fails then will replace the relay with a known working one. If that fails then I am out of ideas.