Warm Audio - TB12 Tone Beast ORANGE - No Signal

[amplexus]

That is a bog standard linear power supply. 3 x 3 terminal regulators some caps and basic 400* diodes in a full wave bridge configuration- which is why you got diode readings in both directions when you probed them in circuit. Probably also a basic voltage doubler to get the dc for the phantom supply (an issue there could be bringing all the rails down…)

You are certainly not getting correct voltages out of that psu based on your readings- but even at +/-13VDC i would expect SOME signal. At any rate you’ve got a 317 and 337 for audio rails, and probably a TL738 for phantom.

First step- check the ac output of the adaptor where it comes into the psu board. Is it where it should be? Second step, look at the DC voltage on the input pins of each of the regulators (check the datasheets when you confirm which regs are on the board). That DC input voltage should be at least 2-3 V higher than the desired rail voltages, so i’d say you’re likely going to want to see a minimum of +/-18V on the 317/337 and minimally 51-52VDC on whatever the phantom reg is.

If those voltages all check out then the issue is the regulator or forward (output caps), if not its in front. These are very simple linear reg circuits, basically right off the datasheet application notes, so there aren’t a lot of places they can go wrong. If your input voltages to the regs is bad then I might suspect the voltage doubler circuit, if you can trace where the 48V rail is sourcing from and disconnect it by lifting a component leg, then check the audio rails and see if they snap back.

Verifying those voltages at those locations will narrow things down considerably.

 

[TLK]

I would agree with the observation that the power input connector is NOT a mains AC power input. Likely that it requires an external power pack that outputs either an AC or DC voltage source and rest of DC power needs are created on the power supply board. I don't see anywhere in your posts that describe what you been powering this unit up with when testing ??? Do you not have the proper AC mains power adapter it came with ?

 

[pucho812]

Rear shot of a tb12 v1. Note the 24v ac plug…

If your using a dc wall wart, it won’t work.

 

[Nele]

Although this looks like a faulty psu also check the switches. I had one unit in for repair which turned on but passed no audio. After checking everything the owner called WARM and they said to check the switches. They are self-cleaning so clicking them 20 times should clean them.

 

[NoisyIndividual]

It is not uncommon for customers to bring me gear with the wrong DC power supply instead of the correct AC one.
Quite often the DC supply will be able to supply the 5v or whatever for the computing side of things, and often +15v, but not the -15v.

So the unit will power up, lights on and everything, but there is no audio.