Need some help with Tab Funkenwork T13 in a WA87

[JMc]

I just picked up a 2019 Warm Audio WA87 mic that had a Tab T13 transformer mod by Zen Pro Audio. The original Cinemag transformer was included with the purchase. Right out of the gate, I noticed that the output level was much lower than expected. My mind immediately flashed to something I read here about a large batch of the Tab Funkenwork transformers that went out with wrong wiring instructions. I also noticed that this mic has a static pop that occurs periodically. It's intermittent. Sometimes 30 seconds apart. Other times 8 minutes or more apart. I don't know if these issues are related or not, but I'm beginning to think so. Before I return this mic for a refund (I'd rather not because it was a good deal and in all other respects, I'm liking it), can you tell me by looking at this photo which wires need to be switched to correct the output issue that I'm having?

 

[Bonnie1]

T13 data sheet attached

 

[doqmemory]

can you tell me by looking at this photo which wires need to be switched to correct the output issue that I'm having?

This looks similar to my Zen Pro mod version, with black primary and yellow secondary wires. As long as the colors are correct, it does not really matter what order the pairs are wired (except for the phase of the output).

Note that the WA87, like the U87i, does not have particularly strong output signal, so it does need quite a bit of gain on the preamp.

The static pop is the more worrying issue. With a regular timing like that, I would suspect a faulty capacitor. I suggest visually inspecting the rest of the board to see if any of the capacitors look like they have been damaged. On my WA87, many of the tantalum capacitors were bent all of the way over, as if someone had been man-handling the PCB when they swapped the transformers.

 

[dmp]

I don't think a low output level would be caused by either the primary and secondary being reversed, or the wires being flipped across primary secondary. You would have much more noticeable problems with either of these. What was the previous transformer ratio? If it was a lower ratio, you will have less volume with the 10:1

For the pop, check that the solder joints are good. Tap the mic and see if it happens reliably with a mechanical shock.

 

[JMc]

The static pop is the more worrying issue. With a regular timing like that, I would suspect a faulty capacitor. I suggest visually inspecting the rest of the board to see if any of the capacitors look like they have been damaged. On my WA87, many of the tantalum capacitors were bent all of the way over, as if someone had been man-handling the PCB when they swapped the transformers.

Thanks for the all the replies. Upon further inspection yesterday, I discovered that C1 capacitor was in fact damaged, most likely by a Zen Pro tech's soldering iron when they were swapping in the new transformer. So you're probably right about that. I decided to just send the mic back to the seller for a refund rather than mess with it.