Troublemaster

cspar · Post by **cspar** » 31 Mar 2021, 03:05

I got this today off a dusty second hand shelf. I can't find any reference to it on the internet and am not sure who made it or what the intended usage was. It seems that if the input was low it could be some kind of germanium sniffer unit. It's got a good germanium fuzz thing going on when I plug into it.

Each channel is the same. It came with 3 of these japan stamped microphones with magnets on the bottoms of the holders. It probably originally had 5.

They're noisy but it it was fun sticking one to the tailpiece of a banjo for awhile

Here's a gut shot.

And another closer one.

There's 3x 2n320's and a 2n188a.

I'm just gonna enjoy the fuzzy goodness for a few days before I pull the board and look at the backside.

Has anybody seen one of these before?

cspar · Post by **cspar** » 31 Mar 2021, 03:10

Oh, I forgot to mention that the on/off is a pot with a switch that starts as fuzz and cleans up clockwise.

cspar · Post by **cspar** » 31 Mar 2021, 12:43

Having thought about it a bit more it really seems to me that it was designed as a troubleshooting sniffing tool of some sorts.

The lack of output other than the earphone jack really suggests that.

Proper placements and selection of mics would pretty much make it a pickup selector for a piano or a pedal steel.

The thing is pretty cool.

I bought it thinking that I was most likely going to gut it and put an excessively variable Rangermaster in the enclosure.

Not gonna happen. I've thought about replacing the caps and resistors to clean up the noise level and decided that it's best left as is since it's an odd vintage unit.

So next step is to lift the board so I can trace it and then clone it.

I don't want to desolder anything unnecessarily and am not going to pull the transistors to check hFE or leakage or anything. The schematic with the cap/inductor values are the what's important. When I clone it I'll probably be more of a workalike with Russian transistors in it since that's what I have.

I've never used transformers before and am not sure if I can test them without lifting the wires.

Instead of rabbit hole Googling can somebody with a bunch of experience tell me how you'd go about it?

cspar · Post by **cspar** » 31 Mar 2021, 14:30

*edit*
Line in goes to lug 2 of the pot. Lug 1 goes to +9 as well as to the sleeve of A-E, my guess is to phantom power the mics.
I alligator clipped in off my Madbeans RoadRage tester and didn't use the sleeve when I went direct. Lug 3 goes to the board.

The pot measures at 8.88k but I don't know the taper of course.

cspar · Post by **cspar** » 31 Mar 2021, 17:31

Here it is without the switching or phantom power to the input. Actually the out sleeve is connected to T2 on the unit not ground. The +9 from the pot goes to the input sleeve of A-E. The transformers are an unknown type and value right now.

It's interesting how it crosses through the transistors between the transformers.

I'm not sure what's going on with it and have no idea what to compare it to. Anybody know of something similar?

ppluis0 · Post by **ppluis0** » 31 Mar 2021, 17:55

cspar wrote: ↑31 Mar 2021, 17:31 Anybody know of something similar?

Looks like the output audio stage of an old transistor radio IMHO

Cheers,
Jose

cspar · Post by **cspar** » 31 Mar 2021, 18:31

Ok, I totally see the similarity. The Troublemaster is basically a PNP version without the capacitor bridging the collectors on q3 and q4 and an extra gain stage up front.

It sure does sound good

Seems like a good foundation for a piezo pickup selecting practice amp head for a cigar box lap steel with a midi plug output... hmm...

fuzzbunny · Post by **fuzzbunny** » 02 Apr 2021, 02:20

Cool unit.
Super cool name too ... "Troublemaster"

kujoalt · Post by **kujoalt** » 08 May 2021, 01:09

I recently obtained some transformers that at have no center tap (just 2 wire a side), is there anyway to make an artificial center tap? Or modify the one ones I have? They're 1:1 filament transformers.

cspar · Post by **cspar** » 08 May 2021, 12:41

I'm in no way an expert on transformers but I don't recall ever hearing of someone just adding more taps.

I have seen some references to people striping them down to the core and rebuilding them.

There's a bunch of math invoved and it seems more likely to be accurate starting afresh and definitely easier to just buy one with the specs your looking for.

kujoalt · Post by **kujoalt** » 08 May 2021, 13:10

cspar wrote: ↑08 May 2021, 12:41 I'm in no way an expert on transformers but I don't recall ever hearing of someone just adding more taps.

I have seen some references to people striping them down to the core and rebuilding them.

There's a bunch of math invoved and it seems more likely to be accurate starting afresh and definitely easier to just buy one with the specs your looking for.

Just the kind of help I was looking for, thanks!

Troublemaster [schematic]