Do i have a dead AC128?

[347sixtyseven]

I recently bought a matched pair of AC128 transistors and have just tried to check the leakage and gain using the instructions in the FAQ at Smallbear.

http://www.smallbearelec.com/HowTos/FuzzFaceFAQ/FFFAQ.htm

When i hook the collector and emitter to + and - 9v as shown my multimeter (in lowest current setting) is reading 180 to 190 for one of them, when all connected as in the diagram.

When i do the same for the other one the display flashes some numbers for an instant but then shows the .1 that the meter shows when checking resistance but have no continuity. 

Why would it do this? I have swapped the transistors numerous times and got the same result (one shows 180 to 190 other shows .1 or whtever the symbol is)

I then took the one that seemed to be testing ok and brought the 1M resistor in to the circuit to measure the gain. As soon as i connect the resistor to the base i get the same .1 thing.

Can anyone help me out with whats going on here? 

Gary

[347sixtyseven]

Just wanted to clarify that i didn't buy these from smallbear. Thought people may assume that as i mentioned smallbear in the post. Bought them privately.

Gary

[smallbearelec]

Hi--

What is the maximum reading of the low-current scale on your meter? My guess is that the device that shows ".1" on the low-current scale is either open or excessively leaky. Try moving to the next highest current scale...if you then get a reading in the milliampere range, the device is definitely too leaky.

[any]

yep, gain is probably over 200. go to "next up" current scale.

[347sixtyseven]

can't believe i didn't think of that   

Will give it a go now, thanks guys

[347sixtyseven]

Turns out the suspect trans has a lekage reading of approx 326.

The one that seemed good at 181 last night is now showing 230ish, i am assuming a temperature related rise.

I have read that 300 is the cutoff point for leakage. Has anyone had success using 300+ leakage germanuiums in fuzz circuits?

Or have i just got and expensive diode now?

[smallbearelec]

Turns out the suspect trans has a lekage reading of approx 326.
I have read that 300 is the cutoff point for leakage. Has anyone had success using 300+ leakage germanuiums in fuzz circuits?

That figure is not hard-and-fast, and it is temp-related, as you note. At worst, the long-term reliability of the device might be questionable. Unless the room in which you are testing is so chilly that you need an overcoat, a device that shows leakage in the Low 300s is useable.