Ge Transistors

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FuzzMitch

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Can anyone identify (manufacturer etc) these spare Ge Transistors i was given for my 1970's Dunlop JH-2 FuzzFace?
The two that were in the FzFc are a NKT275, and a B175; so the two spares are what im wondering about and they both look the same tho different engraving on top, see hand written note in pics.
Thanks.
 

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The pic of top of can, when zoomed out of focus so cannot read its
alpha numeric stamped value....

I think the hand written number device measured parameters, like beta
for example.

Regards, Dana.
 
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Agree with Dana that the numbers listed are most likely Hfe values.

With respect to the part numbers, those must be “house” numbers. Essentially a common transistor (for those days) which has been selected with correct characteristics (I like to call them selected defects) to provide the required non-linear distortion which produces the warm, fuzzy sound.

Those vintage transistors are worth a lot of money. They are also *very fragile.* An error and they would be damaged.
I would not install them in the circuit unless you have positively identified the BCE terminals.
 
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To Dana: Thanks, i dont know what alpha or beta parameters is/are. Ill try to google.
To (Hulk): Thanks but by original Newmarket or the company Dunlop got to fake NKT's? I think it depends on when this NKT was made as theres no colour dots on it either, would you agree?
To SchmittTrigger: Thanks, when you mention 'those vintage trannies...' are you referring to the spares or the ones (NKT/B175) in the FzFce? Because its the two spares im wondering where/when they were made.
And what are 'BCE terminals'? - the three prongs/pins coming from each transistor?
A quick background: I bought the JH-2 FzFc 13 yrs ago, it was already modified with three extra dials by the bloke who gave me the spare Ge's - one dial im sure is a bias dial (an excellent dial for Ge FzFcs), BUT a month ago i dropped it so doesnt work (dont hassle me, im traumatised!) , but i think its the soldered wires not the Resitrs or Transtrs. The values written on back plate are what he wrote for the Ge's that are in it ie NKT and B175.
 
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FuzzMitch said:
Cant seem to add more pics.
Click to expand...
Possibly due to the large size of the pictures.
The pics in the first post are 1.1 and 1.7 Mbyte size.
I know that there are size limits for picture (can't remember what it is), I am surprised that the system accepted those sizes already.

FuzzMitch said:
And what are 'BCE terminals'? - the three prongs/pins coming from each transistor?
Click to expand...
Yes, the three "electrodes" of a transistor are Base, Collector and Emitter.

JimB
 
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JimB: BseColEmt thanks.
One of the Ge's electrodes 'slides' slightly (by 1mm) in and out from where it enters the can i noticed a year ago but still worked till i dropped it recently, so i think that Ge is on its way out. Yes wont take any detailed pics only this one (below), Nope took more,Thanks.
 

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The problem with germanium transistors is that none have been manufactured for decades many of even the "New old stock" ones on the surplus market have degraded so their characteristics are nothing like the datasheet, if they even function at all.

[I had a batch of a dozen AC128 a while ago to repair an old soviet machine tool board that needed a couple - the only similarity between any in that batch was the four or five dead ones. The remainder all had wildly varying characteristics].


I'd suggest you get a few from ebay - eg. AC176 is available on there - and try different examples until you find some that work and give a sound you like.

One of the articles on the JH-2 says to just put a pair of BC109 transistors in it.. They are a common silicon type from a few years ago.

Schematic, for reference:

 
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Then fixing the sliding solder joint that is the first priority. If that doesn't help, next step is to check all connecting points on the circuit board to make sure the board didn't crack when you dropped it.
 
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ZipZapOuch said:
Then fixing the sliding solder joint that is the first priority. If that doesn't help, next step is to check all connecting points on the circuit board to make sure the board didn't crack when you dropped it.
Click to expand...
Im not sure its soldered there where it enters the can underneath. Yes checking points ill need to get done - ive never used/owned a multimeter. A friend has one, im in a very rural community. Thanks ZZO.
 
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Thanks. I have the two spare Ge's and wondering where these were made (see original pic). I wouldnt go Si after having this JH-2 with its excellent Ge's. I also have an original Fender Blender with Si trannies and i much prefer the JH-2 w Ge's. Thanks for the schem, and interesting about the AC128's you had.
 

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FuzzMitch said:
Im not sure its soldered there where it enters the can underneath. Yes checking points I'll need to get done - ive never used/owned a multimeter. A friend has one, im in a very rural community. Thanks ZZO.
Click to expand...
If it is not connected to a circuitboard it has to be connected to a wire or another component (like a potentiometer) or you'll have intermittent or no connection. Get a meter, get a soldering iron and, since you're using germanium transistors, I'd get some tin/lead solder and a little alligator clip (crocodile clip in your parts?) to act as a heat sink as you solder (reflow) each lead.
 
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No it slides 1mm in and out from under the Ge canister not the pcboard, these areas are sealed not by solder but plastic sealant or similar. The Ge's BCE electrodes soldered to the pcb are fine, its underside of the canister where one of the electrodes slides slightly in and out. Thanks.
 
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That's not good.
 
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That JH-2 in your picture is not original - has been modified with extra controls and the pcb is from something else (possibly another model) - it's using 2SB175's which are still Germanium and were used for a short while (I think it was possibly in the 90's) before reverting back to BC109's.

Also that schematic further back is not correct for the JH-2.

Note that you can't just drop BC109's in, the original JH-2 used the germanium PNP transistors and the BC109's are NPN type.
 
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