Sanity Check for RG Keen PNP Transistor Test

[Phend]

From Small Bear GT404b Russian which I tested today.
Looking at the drawing posted above you might see an offset on the center lead

[antonis]

Now we have all three options and is getting silly enough..

[Rob Strand]

Yes, the GT308V has the red dot above the emitter and the collector in the center. That one I can figure out!

It's not uncommon for transistors for have different pinouts.

Presumed "bottom view" based on conclusions in this thread.
Pic fix: (GT308)

Blocked pic: (GT308)

I did measure with correct orientation, got 0.118V with the switch open AND closed. Does that mean complete leakage on these suckers

If I saw that my first thought would be the pin out is wrong.  If you connect the transistor's base lead to the test jig's collector terminal you can get a situation where it will read 0.1V to 0.2V for germanium (0.6 to 0.7 for silicon) *regardless* of the transistor's state, hFE, leakage.  What the jig is actually showing in this case is the transistor's base to emitter or base to collector voltage  - which is a "fixed"  germanium diode drop of 0.1V to 0.2V.

It would be very worthwhile to check pinout using the DMM's diode test as per the link Antonis posted earlier.    It's a very easy test.  The more things you check the more you know and that makes it easier to go forward.  You can't trust a lot of parts you buy these days, sometimes you need to decipher what you have from scratch.  Of course if you have real parts they are going to match the datasheet (overlooking the fact datasheet isn't 100% clear).

[FWIW:  One thing most people add to the pin identification test is to check the diode voltage between E and C in both directions - it should be open circuit.  If you get a dead short of 0V then the transistor is usually fried (C to E short).  That's a very common test done by  repair technicians when hunting for bad transistors.]
EDIT: blocked pic fixed.

[bluelagoon]

Get yourself one of these over at Aliexpress, Dirt Cheap and saves the conundrum of not knowing the correct transistor pinouts.

Transistor Tester

Lots of them available

[duck_arse]

the B1M pot is to drop the power supply from 9.16V down to 9V to the 2M2 and 2k4 resistors. Not in the spec, but I saw in other forum posts that getting as close to 9V on the nose is important to the test.

measure your 9.000V. then insert a transistor, it will draw a leakage current thru the pot, the 9.000V MUST then droop. now push the test button, the transistor draws test current thru the pot resistance, and the already dropped 9.000V drops even further. you can't have accurate 9V with the pot.

forget about accurate and exact, think in relative terms. measure all your transistors, write down the numbers. then you can say this part is higher gain, that part is lowest leak, etc. the measures will change with temperature anyway, so exact numbers become meaningless.

R.G. himself says don't get hung up on the numbers. technology of the fuzz face.

The ones I have currently are straight from Russia so who knows.

this is a strange statement. they are Soviet type numbers, where would you want them to come from, if not _ussia? most of the parts were manufactured in soviet satellite countries anyway - I don't think we've had reports of counterfeits, yet.

I am testing a BC183C, and luckily for TO92 package, it's easy to tell which leg is the collector!

.....

 I'm switching to a 2N2222A that I got from Tayda. I get 0.103V with switch closed and 0V with switch open. This is in range based on the datasheet here: https://www.onsemi.com/pdf/datasheet/p2n2222a-d.pdf

you need to have a very close look at those parts. the BC183 is one of the types that often turn up in the L suffix, which moves the base from centre to the package end. and the PN2222(A) / 2N2222(A) are different pinout to the p2n2222a - the "p2n" makes the pinout [CASE 29–04, STYLE 17 -- TO–92 (TO–226AA)] match the standard BC5xx pinout, instead of the standard PNxxxx pinout.

at the manufacturor's whim, of course.

[wimacfee55]

Hello all,

Great discussion and I've learned a ton through the experience. Want to note my findings here for posterity and those who Google after me:

antonis is correct on the pinout orientation! If the pins on the MP39B make an isosceles triangle with the "point" going to one's left, the emitter is on the top, the base in the middle and the collector down the bottom:

      E
B
      C

A transistor tester is indeed worth the investment. I used a cheap one I forgot about. Here is a picture of it:



Measuring the correct orientation in the jig did have the same voltage with the switch open and closed. I did not perform the DMM diode check mentioned by Rob Strand but for those in the future I recommend it if you do not miraculously find your transistor tester in a drawer.

Lo and behold, my Fuzz Face roared to life with the correct orientation of the transistor. For those in the future, quadruple check those orientations via a transistor tester.

Thank you again to all who responded!

[mozz]

CBE.
I don't know how you are getting it backwards.

[Rob Strand]

ntonis is correct on the pinout orientation! If the pins on the MP39B make an isosceles triangle with the "point" going to one's left, the emitter is on the top, the base in the middle and the collector down the bottom:

You haven't said if that is viewed from the top or bottom.

CBE.
I don't know how you are getting it backwards

That one isn't 100% clear about top/bottom view either.

[Rob Strand]

These two sources are at least consistent, and they say viewed from the bottom,

https://www.cpearson.me.uk/2019/03/06/MP38A-transistor-pinout/
https://smallbear-electronics.mybigcommerce.com/germanium-transistor-russian-mp42b/

Which agrees with the corrected pic I posted earlier,

https://postlmg.cc/tsggcfqJ

[PRR]

It's always viewed from the Technician's side.

Look at Octal tube pinouts.

As said, from "far side" the pins and seals would be dotted, not solid.

Yes, there ARE (were) national differences in drawing conventions. Packard in the US actually re-drew many thousand UK Rolls-Royce engine blueprints (from third-angle projection to first-angle projection, cite) so American workers wouldn't screw-up American Merlin engines. (Post-war, UK moved to US drawing conventions.) But "dotty" for "far side" seems pretty universal.

[mozz]

I do have some MP39 and found some MP39B. I will run both on the Peak DCA55 and a few of my other transistor tester to make sure but I'm gonna stand by CBE for now.
Edit: bored, turkey day is over, work tomorrow, tested them. Don't make me have to relearn the Hickoks.