Huntron Tracker 1000 and transistor damage

[FrankyLttrs]

I bought a Huntron Tracker 1000 to use for debugging dead and/or dying amps. I was doing some additional research and came across the attached independent study article. Some on this site have mentioned that blindly testing transistors leads to them being degraded, and I thought "nuh uh, just look at the success of the Huntron!" and then I read the attached study. Basically, if you test across the emitter to the base or emitter to the collector of a BJT, you'll fry the little beastie. And don't even think about using it on a MOSFET out of circuit.

Seems putting transistors into reverse bias at 6 volts or more can have some serious side effects, who knew?!?

The attached article covers a model of Huntron that has an auto-ranging feature and lower test voltage which I don't have. I have 3 voltage settings, 10V, 20V, and 60V. Looking at the circuit schematic for the Huntron 1000, also attached, it looks like I can turn the test voltage down a bit, so I'm going to give that a whirl and see if I can get my lowest setting to 5V. For sure during testing, I'm going to only go across the base and collector and I seriously doubt I will try it on any MOSFETs. At this point I'm kind of bummed I bought it as it doesn't look like it's going to be very helpful. I don't need it to test resistors, capacitors, and diodes, but I do need something to help me test transistors without pulling them from the circuit. It looks like it was never used, and maybe now I see why.

Anyway, I hope this helps someone who might be considering an older Huntron or building their own circuit analyzer, like the Octopus or the one described on the Elliot Sound Products site. The independent study article is a quick read and worth the effort. It also brings up an issue of the newer and much less expensive component testers that you might be considering. As I understand their operation, they apply voltages and different values and polarities across all leads of a device under test in order to tell you what kind of device you have. Some on this site feel such testers might be damaging to devices, and after reading the report, I agree that it is a real possibility. At least with the Huntron, you can make sure you don't get across the emitter, with an auto device tester, you don't have that option.

 

[gslikker]

Your comments are spot on.

It is easy to demonstrate HFE deterioration using a small signal transistor using the Huntron if also having the Peak DCA75 transistor checker capable of displaying graphs.
The HFE in lowest current region is affected most, at least it is obviously present in the figures the DCA75 gives.

As an example, it may give you HFE of around 400 on the left of the graph when measuring Ic versus Ib, and after attaching base and emittor to the Huntron for some seconds it may be 380, while on the right side of the graph (it measures up to some 10mA) is unaffected.

The "safe to use" notes in Huntron documentation are to be taken with a grain of salt.


Myself, I was extremely lucky to find a Huntron Protrack 1 on the internet on the cheap. Some technical school bought one including the X-Y testbed, but the (very expensive) thing was too complex to use and of course only intended in a factory environment.
What they did they demolished the camera and test pins equipped XY device for "something else educational", they took the computer for other purposes and put the huntron device itself on the market.
Accidentally I was checking and put a initial bid right away of around 400 based on the picture I saw, provided my phone number, and to my surprise the school called me within 15 minutes to say it was OK.
I guess the protrack was around $8000 new, but the hardware they demolished probably was way over $10000, it is a shame what happens with tax money..........

The protrack has the possibility of setting the voltage low enough to avoid compromising base to emitter junction.

 

[egellings]

I bought a Huntron Tracker 1000 to use for debugging dead and/or dying amps. I was doing some additional research and came across the attached independent study article. Some on this site have mentioned that blindly testing transistors leads to them being degraded, and I thought "nuh uh, just look at the success of the Huntron!" and then I read the attached study. Basically, if you test across the emitter to the base or emitter to the collector of a BJT, you'll fry the little beastie. And don't even think about using it on a MOSFET out of circuit.

Seems putting transistors into reverse bias at 6 volts or more can have some serious side effects, who knew?!?

The attached article covers a model of Huntron that has an auto-ranging feature and lower test voltage which I don't have. I have 3 voltage settings, 10V, 20V, and 60V. Looking at the circuit schematic for the Huntron 1000, also attached, it looks like I can turn the test voltage down a bit, so I'm going to give that a whirl and see if I can get my lowest setting to 5V. For sure during testing, I'm going to only go across the base and collector and I seriously doubt I will try it on any MOSFETs. At this point I'm kind of bummed I bought it as it doesn't look like it's going to be very helpful. I don't need it to test resistors, capacitors, and diodes, but I do need something to help me test transistors without pulling them from the circuit. It looks like it was never used, and maybe now I see why.

Anyway, I hope this helps someone who might be considering an older Huntron or building their own circuit analyzer, like the Octopus or the one described on the Elliot Sound Products site. The independent study article is a quick read and worth the effort. It also brings up an issue of the newer and much less expensive component testers that you might be considering. As I understand their operation, they apply voltages and different values and polarities across all leads of a device under test in order to tell you what kind of device you have. Some on this site feel such testers might be damaging to devices, and after reading the report, I agree that it is a real possibility. At least with the Huntron, you can make sure you don't get across the emitter, with an auto device tester, you don't have that option.

Bipolar B-E junction zeners over at about 6.8 or so VDC. Doing that to a transistor too long will clobber its hfe.

 

[FrankyLttrs]

Your comments are spot on.

It is easy to demonstrate HFE deterioration using a small signal transistor using the Huntron if also having the Peak DCA75 transistor checker capable of displaying graphs.
The HFE in lowest current region is affected most, at least it is obviously present in the figures the DCA75 gives.

As an example, it may give you HFE of around 400 on the left of the graph when measuring Ic versus Ib, and after attaching base and emittor to the Huntron for some seconds it may be 380, while on the right side of the graph (it measures up to some 10mA) is unaffected.

The "safe to use" notes in Huntron documentation are to be taken with a grain of salt.


Myself, I was extremely lucky to find a Huntron Protrack 1 on the internet on the cheap. Some technical school bought one including the X-Y testbed, but the (very expensive) thing was too complex to use and of course only intended in a factory environment.
What they did they demolished the camera and test pins equipped XY device for "something else educational", they took the computer for other purposes and put the huntron device itself on the market.
Accidentally I was checking and put a initial bid right away of around 400 based on the picture I saw, provided my phone number, and to my surprise the school called me within 15 minutes to say it was OK.
I guess the protrack was around $8000 new, but the hardware they demolished probably was way over $10000, it is a shame what happens with tax money..........

The protrack has the possibility of setting the voltage low enough to avoid compromising base to emitter junction.

Thanks for the information. My current plan is to only test across the base and collector( or the gate and drain) at as low a voltage as I can get out of the system. Is the "grain of salt" you mention for the part where they say it's safe to test across the emitter or source at low voltages?

 

[gslikker]

No it was about some general remark it can be used in generic digital 9TTL and CMOS) etc circuits, I remember stated somewhere in one of the manuals. I do not remeber which one.