TC1 users, some questions for you

spi

Well-known member
I just ordered a TC1 tester--my intent was to get ballpark measurements for some Ge transistors.

I'm pretty frustrated with it though: I'm finding it doesn't detect JFETs, it doesn't detect Ge transistors, and it can't measure detect several types of high-gain BJTs (I'm getting no readings on some 2n5088s, B549Cs and MPSA18s, although some I get in the 500 Hfe, I'm guessing the ones I can't detect are over 600).

It does ok with lower Hfe transistors (BC549Bs, 2n3404, 2n2222), and it does good with mosfets BS170s and 2n7000s.

It's possible I have bunk Ge and JFET transistors, but I don't think they're all bad... my j201s were in spec via the ROG method.

Am I just expecting too much from the TC1? Did I get a bad one? Is there some trick to it I'm missing?
 
I just ordered a TC1 tester--my intent was to get ballpark measurements for some Ge transistors.

I'm pretty frustrated with it though: I'm finding it doesn't detect JFETs, it doesn't detect Ge transistors, and it can't measure detect several types of high-gain BJTs (I'm getting no readings on some 2n5088s, B549Cs and MPSA18s, although some I get in the 500 Hfe, I'm guessing the ones I can't detect are over 600).

It does ok with lower Hfe transistors (BC549Bs, 2n3404, 2n2222), and it does good with mosfets BS170s and 2n7000s.

It's possible I have bunk Ge and JFET transistors, but I don't think they're all bad... my j201s were in spec via the ROG method.

Am I just expecting too much from the TC1? Did I get a bad one? Is there some trick to it I'm missing?
I got the TCR-7. It looks identical but I think it's based on the Mega GM328 chip. It seems to do ok with anything I've thrown at it. But what I don't know (yet) is what ma it's measuring diodes at.
 
It should test almost anything

Google TC1 tester manual there's a calibration procedure in it if you get incorrect readings
Mcknib is right, it should test most components without having to do anything funky - One exception is JFETs, where it will tell if you if it's N-Ch or P-Ch and the pinout, but won't give you VGSoff or Idss. You'll need something like a Peak DCA75 or the Greatly Improved JFET Matcher II.

If you're new to these types of AVR testers, here are links to manuals & such (they are kinda tricky to find):
  1. TC-1 Multitester TC-V2.12k Manual - Original TC-1 manual
  2. MPJA Quick Guide - Another, shorter guide to the TC-1
  3. TransistorTester with AVR microcontroller Version 1.12k - Detailed description of how the unit works & what kinds measurements it will produce

To start off the troubleshooting, kind of a silly question: Which ZIF test sockets are you using?

When testing a transistor, you'll need to make sure the legs are inserted into three different socket numbers (one each into 1, 2, & 3). If you place the transistor legs into the "2 3 2" sockets to the far right, or the "K A A" zener diode test sockets on the bottom left, it will come up with a "No, Unknown, or Damaged Part" error.
TC-1 Multitester Front ZIF Pinout.jpg
Fortunately, you can use any set of numbered slots, and in any order, as the TC-1 will adjust the measured pinout to match. Make sure you also close the lever completely to lock in the legs before hitting the "Start" button.

Here are some other things you can check:
  1. Check the voltage output of your power source with a multimeter (preferably under load). You shouldn’t be powering it from less than 4.5V or more than 6V DC. If you’re using a microUSB cable, make sure whatever you’re powering it from can provide up to 500mA of current.
  2. Open the case. Carefully inspect the PCB & display for mechanical damage (cracks, chips, damaged/disconnected wires, etc.). Also look for solderless/cold solder joints, flux residues & general grime. These things are cheap for a reason, so look closely & take pictures of any questionable connections.

If you're still having issues, it's probably worth doing the calibration:
Calibration & Self-Test - You'll need the 3 included interconnected metal pins to perform this.
  1. Connect the three test leads to the inputs 1, 2 & 3 of the ZIF-socket and connect the three crocodile clips to these three pins.
  2. Press Start to perform a self-test, in which the device also calibrates itself. This procedure takes about 10 seconds and is accompanied on the display by a thermometer scale on which you can see the progress of the test.
  3. At some point, after 22% of the test procedure, the text 'Pls Isolate Probe' will appear and you need to remove the three test leads.

Going forward, here is some info I've aggregated on using the TC-1 to test Ge transistors. Some of the measured parameters are a little unclear at first glance:

Germanium Transistors:
  1. Hfe - Gain - hFE = parameter measured under DC conditions, hfe = parameter for AC signals.
  2. Vbe - Voltage b/w Base & Emitter - (mV) - 0.65-0.7V for Si, 0.15 to 0.3V for Ge.
  3. Ic - Collector Current used for test - (mA) - Most pedal transistors run Ic <1mA. Some (i.e. Harmonic Percolator) run below 100uA. Some testers measure HFE at 5mA or higher, which is not particularly useful to pedal builders.
  4. Iceo - Leakage Current at the Emitter - (mA) - Iceo = (1+ β)xIcbo where Icbo is the reverse leakage current of Base-Collector junction - Anything <100uA is good - Collector-to-Emitter current w/Base lead not connected to anything (an extreme case as in most circuits, the Base has a DC path to somewhere)
  5. Ices - Collector-to-Emitter current with the Base lead shorted to the Emitter - (uA) - Leakage Current in-circuit is somewhere in between Iceo & Ices.

How do the TC-1 Iceo & Ices measurements compare to R.G. Method’s leakage values? - Iceo is pretty much dead on. Close enough at least to not have to worry about it. +/-20uA is not a deal breaker.
  • Measured Parameters - These are current parameters, so we use “I”. The next two letters, C & E, refer to the Collector & Emitter pins. The last letter is how the remaining pin (B = Base) is connected; “O” for open-circuit (not connected) or “S” for shorted (to the Emitter in this case).
    • Iceo = Collector-Emitter Leakage current with Base not connected to anything (an open circuit)
    • Ices = Collector-Emitter Leakage current with Base shorted to Emitter.
When measuring Ge transistors, you have to let them sit in the tester for a few minutes so they can cool off after being heated by your fingers. Only then will you get a stable reading, or any reading at all. Even better, always handle w/tweezers as your body temp will mess with the readings (especially Leakage)

P.S. It's worth mentioning that you need to discharge any capacitors before testing. Discharging them into the tester can damage the microcontroller or other circuitry.
 
Mcknib is right, it should test most components without having to do anything funky - One exception is JFETs, where it will tell if you if it's N-Ch or P-Ch and the pinout, but won't give you VGSoff or Idss. You'll need something like a Peak DCA75 or the Greatly Improved JFET Matcher II.

If you're new to these types of AVR testers, here are links to manuals & such (they are kinda tricky to find):
  1. TC-1 Multitester TC-V2.12k Manual - Original TC-1 manual
  2. MPJA Quick Guide - Another, shorter guide to the TC-1
  3. TransistorTester with AVR microcontroller Version 1.12k - Detailed description of how the unit works & what kinds measurements it will produce

To start off the troubleshooting, kind of a silly question: Which ZIF test sockets are you using?

When testing a transistor, you'll need to make sure the legs are inserted into three different socket numbers (one each into 1, 2, & 3). If you place the transistor legs into the "2 3 2" sockets to the far right, or the "K A A" zener diode test sockets on the bottom left, it will come up with a "No, Unknown, or Damaged Part" error.
View attachment 33191
Fortunately, you can use any set of numbered slots, and in any order, as the TC-1 will adjust the measured pinout to match. Make sure you also close the lever completely to lock in the legs before hitting the "Start" button.

Here are some other things you can check:
  1. Check the voltage output of your power source with a multimeter (preferably under load). You shouldn’t be powering it from less than 4.5V or more than 6V DC. If you’re using a microUSB cable, make sure whatever you’re powering it from can provide up to 500mA of current.
  2. Open the case. Carefully inspect the PCB & display for mechanical damage (cracks, chips, damaged/disconnected wires, etc.). Also look for solderless/cold solder joints, flux residues & general grime. These things are cheap for a reason, so look closely & take pictures of any questionable connections.

If you're still having issues, it's probably worth doing the calibration:
Calibration & Self-Test - You'll need the 3 included interconnected metal pins to perform this.
  1. Connect the three test leads to the inputs 1, 2 & 3 of the ZIF-socket and connect the three crocodile clips to these three pins.
  2. Press Start to perform a self-test, in which the device also calibrates itself. This procedure takes about 10 seconds and is accompanied on the display by a thermometer scale on which you can see the progress of the test.
  3. At some point, after 22% of the test procedure, the text 'Pls Isolate Probe' will appear and you need to remove the three test leads.

Going forward, here is some info I've aggregated on using the TC-1 to test Ge transistors. Some of the measured parameters are a little unclear at first glance:

Germanium Transistors:
  1. Hfe - Gain - hFE = parameter measured under DC conditions, hfe = parameter for AC signals.
  2. Vbe - Voltage b/w Base & Emitter - (mV) - 0.65-0.7V for Si, 0.15 to 0.3V for Ge.
  3. Ic - Collector Current used for test - (mA) - Most pedal transistors run Ic <1mA. Some (i.e. Harmonic Percolator) run below 100uA. Some testers measure HFE at 5mA or higher, which is not particularly useful to pedal builders.
  4. Iceo - Leakage Current at the Emitter - (mA) - Iceo = (1+ β)xIcbo where Icbo is the reverse leakage current of Base-Collector junction - Anything <100uA is good - Collector-to-Emitter current w/Base lead not connected to anything (an extreme case as in most circuits, the Base has a DC path to somewhere)
  5. Ices - Collector-to-Emitter current with the Base lead shorted to the Emitter - (uA) - Leakage Current in-circuit is somewhere in between Iceo & Ices.

How do the TC-1 Iceo & Ices measurements compare to R.G. Method’s leakage values? - Iceo is pretty much dead on. Close enough at least to not have to worry about it. +/-20uA is not a deal breaker.
  • Measured Parameters- These are current parameters, so we use “I”. The next two letters, C & E, refer to the Collector & Emitter pins. The last letter is how the remaining pin (B = Base) is connected; “O” for open-circuit (not connected) or “S” for shorted (to the Emitter in this case).
    • Iceo = Collector-Emitter Leakage current with Base not connected to anything (an open circuit)
    • Ices = Collector-Emitter Leakage current with Base shorted to Emitter.
When measuring Ge transistors, you have to let them sit in the tester for a few minutes so they can cool off after being heated by your fingers. Only then will you get a stable reading, or any reading at all. Even better, always handle w/tweezers as your body temp will mess with the readings (especially Leakage)

P.S. It's worth mentioning that you need to discharge any capacitors before testing. Discharging them into the tester can damage the microcontroller or other circuitry.
Awesome explanation! Bookmarked this post for future reference!
 
Yes, great write up @bowanderror.

So here's an example of what I'm seeing with a Ge transistor.

IMG_20220930_174838175.jpg

It just sees a resistance.

I popped it open to see if anything looked suspicious. I can't really tell because I don't know what I'm looking for... but I do see some funny business: R18 and R22 seem to be missing, although there's solder blobs there. Not sure what to make of that, could it be intentional or defective?


IMG_20220930_174611192.jpg
 
Yes, great write up @bowanderror.

So here's an example of what I'm seeing with a Ge transistor.

View attachment 33208

It just sees a resistance.

I popped it open to see if anything looked suspicious. I can't really tell because I don't know what I'm looking for... but I do see some funny business: R18 and R22 seem to be missing, although there's solder blobs there. Not sure what to make of that, could it be intentional or defective?


View attachment 33207

Try and adjust the leg in slot #2. It’s only reading 1 and 3. Could the transistor be damaged?…
 
Try and adjust the leg in slot #2. It’s only reading 1 and 3. Could the transistor be damaged?…

That’s a possibility. I’ve had DOA transistors from reputable sources. It happens.

In my experience, the TC1 reads transistors with shorts as diodes so it’s either user error or a dud transistor.
 
Yes, great write up @bowanderror.

So here's an example of what I'm seeing with a Ge transistor.

It just sees a resistance.

I popped it open to see if anything looked suspicious. I can't really tell because I don't know what I'm looking for... but I do see some funny business: R18 and R22 seem to be missing, although there's solder blobs there. Not sure what to make of that, could it be intentional or defective?


View attachment 33207
Try all three legs in the first three slots 1,2,and 3 I know that’s probably obvious advise but it looks like you have 1 of the transistor legs in a slot that’s not connected to the first 3 slots. I have this same tester and it works for me.
 
Thanks everyone. I'm pretty sure I've got the legs in there with a decent connection. Although this was just one picture, I've tried using the different slots and changing positions, over several different transistors, with the same results.

I also tried with a transistor I know is good because I pulled it from a working tonebender, and it has the same issue.

I think I may just have got a bum unit.
 
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Thanks everyone. I'm pretty sure I've got the legs in there with a decent connection. Although this just was one picture I've tried using the different slots and changing positions, over several different transistors, with the same results.

I also tried with a transistor I know is good because I pulled it from a working tonebender, and it has the same issue.

I think I may just have got a bum unit.
Did you see my post ☝️
 
Have you tried using the probes instead? Sometimes mine reads Ge transistors as diodes, sometimes as capacitors if I stick them in directly but with the probes it usually works.
 
I have a socket thingy like that in a similar device and sometimes it just does not want to make good contact with the components and I have to wiggle them to get it going. I'm not sure if it's a wear thing or oxidation thing. If your connector on that pops off really easy like mine, I'd try it without the socket and just putting the leads into the connector under to eliminate that, that's how I deal with it when it doesn't want to cooperate.
 
I have 3-4 germaniums that my TC1 reads as JFETS or diodes and that's it. Funny thing is, they work. I put them in a tone bender and it sounds great. I wish I knew what they measure :)
 
Have you tried using the probes instead? Sometimes mine reads Ge transistors as diodes, sometimes as capacitors if I stick them in directly but with the probes it usually works.
thanks for suggesting, but I tried and got the same results.


Thanks all for your inputs, I've tried all the things. I used known good transistors, and while I can't 100% rule out boneheaded user error, I'm pretty sure it's not. It worked fine for low gain BJTs but just couldn't get any reading on high gain ones, jfets, or germaniums, which is counter to others' experience.

I decided to return this TC1 as defective, and I hope they don't try to resell it to another unlucky person.
 
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