Well, I just got back and asked all sellers if they had the Heath tester, but no joy,,, I had told my hamfest buddy that I found another bad transistor in the Sansui, if he had any more Ge, and this is what he brought me,,,
Another guy there found this tester and grabbed it for me,, He checked it out, and said he uses one also, and I think its better than any that I have now, so still trying to move fwd!!!, So I got some transistors and a tester,,, just need to DL a manual,,,
If I can find any that aren't shorted or open, with reasonable values to sub for 2SA49, I can try it in the ckt...
We'll see...
Another guy there found this tester and grabbed it for me,, He checked it out, and said he uses one also, and I think its better than any that I have now, so still trying to move fwd!!!, So I got some transistors and a tester,,, just need to DL a manual,,,
If I can find any that aren't shorted or open, with reasonable values to sub for 2SA49, I can try it in the ckt...
We'll see...
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Found 18 transistors so far that could sub for the 2SA49, just need to them... Just talked to my buddy with the alignment gear, he said he's going to align the Scott 299 he just rebuilt,, and then we'll give teh Sansui a try,,, Guess I better get that FMX board sorted by then!!!!
Good luck John!!
You need a PNP Ge transistor, signal. Doesn't need to be high frequency.
Look up the IT-18. That one isn't that useful by comparison. Heathkit made more complicated testers (I have them) and so dod B&K, but the IT-18 hits all the important things dead on. See if you can find one in the HAM network, or even Eeek-bay.
A search in the US site yields this ...
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p4432023.m570.l1313&_nkw=heatkit+IT-18&_sacat=0
The first couple look like new.
You need a PNP Ge transistor, signal. Doesn't need to be high frequency.
Look up the IT-18. That one isn't that useful by comparison. Heathkit made more complicated testers (I have them) and so dod B&K, but the IT-18 hits all the important things dead on. See if you can find one in the HAM network, or even Eeek-bay.
A search in the US site yields this ...
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p4432023.m570.l1313&_nkw=heatkit+IT-18&_sacat=0
The first couple look like new.
Thanks,, going to try to make sure these aren't open or shorted and give one a try,,, one should be better than the original, as it was reading the same V on all the pins,,, I'm beat, tomorrows another day!!!!
Hi John,
Agreed! Tomorrow is another day.
Please order one of those IT-18 transistor testers. I have a manual I can email to you if you can't find it. You will understand why you should be using one once you try it out. Ask me questions, these are so useful and great at getting an insight to how a transistor is.
I have almost every transistor tester you can imagine, and curve tracers. Some have specific things I need, but the IT-18 covers all service use to find bad parts and even rudimentary matching if you're very careful. It operates on basic principles and therefore tells you a lot about a transistor. It also allows you to understand that transistor. The tester you have isn't very good - sorry.
Agreed! Tomorrow is another day.
Please order one of those IT-18 transistor testers. I have a manual I can email to you if you can't find it. You will understand why you should be using one once you try it out. Ask me questions, these are so useful and great at getting an insight to how a transistor is.
I have almost every transistor tester you can imagine, and curve tracers. Some have specific things I need, but the IT-18 covers all service use to find bad parts and even rudimentary matching if you're very careful. It operates on basic principles and therefore tells you a lot about a transistor. It also allows you to understand that transistor. The tester you have isn't very good - sorry.
OK well we're makin progress because I'm finding more that wont work,,, I chose a NOS TI 2n404 from the stash I got yesterday, it tests strong on the little tester I picked up, and its values are a bit higher across the board, but not outrageous...
I get the same V reading as I did with the original 2SA49, E 19.8 B 19.6 C 19.8 VDC... I have a few more different number transistors that test good and meet the parameters, but doesn't sound like its the trans...
You mentioned the Tx could be bad,, shorted or open? Is there a way to test that?
Thanks...
I get the same V reading as I did with the original 2SA49, E 19.8 B 19.6 C 19.8 VDC... I have a few more different number transistors that test good and meet the parameters, but doesn't sound like its the trans...
You mentioned the Tx could be bad,, shorted or open? Is there a way to test that?
Thanks...
Yes, measure the continuity of the coils with your ohmmeter.
I'm sorry, but you actually do need both a good DVM. You also really need a Heathkit IT-18 because the leakage readings are what you need. Remember I did say that modern digital transistor checkers are normally not sensitive enough to read leakage in a meaningful way. The IT-18 is the least expensive and most useful instrument to get for this. I simply am not confident with the measurements you have made except for voltage readings.
One good technique is to measure right on the transistor terminals because the junction drop is small in comparison to the voltage wrt ground. Use th emitter as your reference (black lead).
Hint: I bought more than one (I had three, wore out one). No way would I do that unless they really were not replaceable and really useful. I paid over $100 for mine new in the 1970's.
I'm sorry, but you actually do need both a good DVM. You also really need a Heathkit IT-18 because the leakage readings are what you need. Remember I did say that modern digital transistor checkers are normally not sensitive enough to read leakage in a meaningful way. The IT-18 is the least expensive and most useful instrument to get for this. I simply am not confident with the measurements you have made except for voltage readings.
One good technique is to measure right on the transistor terminals because the junction drop is small in comparison to the voltage wrt ground. Use th emitter as your reference (black lead).
Hint: I bought more than one (I had three, wore out one). No way would I do that unless they really were not replaceable and really useful. I paid over $100 for mine new in the 1970's.
Thanks,,, yes you did,,, ebay ain't an option here,,, past experience and I dont see any positive changes, are my reasons,,, I asked about the IT-18 at the last show,,, so guys know I'm looking for one,,,, Next show isn't til mid Sept tho....
The tester I got yesterday is from the Ge era,,, first out in 1967 I believe, and seems to be popular with those that use it,, I can sort the transistors I tested,,, but it may be missing something too....
I still have other transistors I can try in TR403 spot ,,,
Not giving up!!!!
Regards,
John
The tester I got yesterday is from the Ge era,,, first out in 1967 I believe, and seems to be popular with those that use it,, I can sort the transistors I tested,,, but it may be missing something too....
I still have other transistors I can try in TR403 spot ,,,
Not giving up!!!!
Regards,
John
Hi John,
Great! I'm glad you aren't giving up. I bought four IT-18 off Ebay without any problems, two for friends.
Anyway, if you can't measure leakage in uA, the tester isn't really useful.
Great! I'm glad you aren't giving up. I bought four IT-18 off Ebay without any problems, two for friends.
Anyway, if you can't measure leakage in uA, the tester isn't really useful.
And here's Tx resistance readings, in ckt... I also noticed that the MPX indicator lamp will briefly light if the selector is in the FM or FM stereo position...
There are jacks to connect VTVM and a scope to this meter for more readings,,, I have just used it to sort transistors, and check short/open,,, NPN/PNP so far... IT-18 is in my sights,,, just need to find one... Remember you said be patient, take your time!!!!
Seems I need help from others on their time frames to move on!!! I'll find a tester,,, and a better DMM, and recalibrate the Triplett 850 I rebuilt a while ago,,,, also get my buddy's help aligning it!!! Just may not happen today!!!!
The txs look OK...
Thanks again for the support!
There are jacks to connect VTVM and a scope to this meter for more readings,,, I have just used it to sort transistors, and check short/open,,, NPN/PNP so far... IT-18 is in my sights,,, just need to find one... Remember you said be patient, take your time!!!!
Seems I need help from others on their time frames to move on!!! I'll find a tester,,, and a better DMM, and recalibrate the Triplett 850 I rebuilt a while ago,,,, also get my buddy's help aligning it!!! Just may not happen today!!!!
The txs look OK...
Thanks again for the support!
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Hi John,
No problem at all. I'm glad you are considering these things. They will greatly help in troubleshooting. That makes things more easily understandable and makes everything more enjoyable.
Resistance readings make little to no sense and vary widely between meters.
Try this in the short term. Take a 9V battery (or 1.5V) Stick an 8K2 (1K3 for 1.5V) resistor in series with the positive (doesn't matter, I just picked one). That will generate approximately 1 mA of current. Use your voltmeter to measure the drop across the junction and report those readings. These will make sense to you. It's a PN junction, so the positive lead goes on the "P" junction, the negative on the "N" junction. Reverse would be open with the 1.5V battery, emitter - base junctions tend to break down 6 ~ 7 VDC with silicon transistors. So 1.5 V is safer but may not conduct with a darlington transistor (3V would be nice, use a 2K7 resistor in series).
-Chris
No problem at all. I'm glad you are considering these things. They will greatly help in troubleshooting. That makes things more easily understandable and makes everything more enjoyable.
Resistance readings make little to no sense and vary widely between meters.
Try this in the short term. Take a 9V battery (or 1.5V) Stick an 8K2 (1K3 for 1.5V) resistor in series with the positive (doesn't matter, I just picked one). That will generate approximately 1 mA of current. Use your voltmeter to measure the drop across the junction and report those readings. These will make sense to you. It's a PN junction, so the positive lead goes on the "P" junction, the negative on the "N" junction. Reverse would be open with the 1.5V battery, emitter - base junctions tend to break down 6 ~ 7 VDC with silicon transistors. So 1.5 V is safer but may not conduct with a darlington transistor (3V would be nice, use a 2K7 resistor in series).
-Chris
Yep,,, I'm still working on it,,, I want find or build a AC/DC probe for the Triplett 850 to use with the transistor tester I got...
Sorry, I dont understand the test with resistor and battery,,,
Sorry, I dont understand the test with resistor and battery,,,
Hi John,
All you're doing is generating a current using a battery and resistor. You want about 1mA, so just figure out your voltage drops. Include 0.2 ~ 0.3 V for Ge and 0.55 V for Si parts. It isn't critical, but you would like it to remain in the ballpark over some time. Then all you're doing is measuring the voltage drop across the junction. Now you can see how things really work.
A reverse biased junction should not draw any current at all. So you should then read the open circuit battery voltage. Keep in mind most silicon junction will break down 6 ~ 7 VDC for the emitter - base junction.
This does not measure leakage really. For that the IT-18 places a very sensitive meter in series with the reverse biased junction and reads in uA. That is extremely useful especially with Ge transistors. Heat the part and you will see this current increase. With what you are doing, you do need to assess leakage as well as gain (beta). Silicon transistors need to measure ZERO leakage with that meter. Any at all and the part is in fact bad.
-Chris
All you're doing is generating a current using a battery and resistor. You want about 1mA, so just figure out your voltage drops. Include 0.2 ~ 0.3 V for Ge and 0.55 V for Si parts. It isn't critical, but you would like it to remain in the ballpark over some time. Then all you're doing is measuring the voltage drop across the junction. Now you can see how things really work.
A reverse biased junction should not draw any current at all. So you should then read the open circuit battery voltage. Keep in mind most silicon junction will break down 6 ~ 7 VDC for the emitter - base junction.
This does not measure leakage really. For that the IT-18 places a very sensitive meter in series with the reverse biased junction and reads in uA. That is extremely useful especially with Ge transistors. Heat the part and you will see this current increase. With what you are doing, you do need to assess leakage as well as gain (beta). Silicon transistors need to measure ZERO leakage with that meter. Any at all and the part is in fact bad.
-Chris
Hi Chris... I need a schem to see how to wire in the transistor being tested,,, someone else offered a "simple" test mule like this earlier and I asked for a schem to include the trans and measure it, but never heard back...
Its OK for now, if my voltage readings from the receiver are not accurate enough, I'll need a better meter to measure the transistor test it seems,,,
I am trying to solve that problem also!
PS,, I did notice that the readings on Ge transistors change dramatically if you touch them !!!
Its OK for now, if my voltage readings from the receiver are not accurate enough, I'll need a better meter to measure the transistor test it seems,,,
I am trying to solve that problem also!
PS,, I did notice that the readings on Ge transistors change dramatically if you touch them !!!
Hi John,
I'd need to draw it and scan it for you. At the moment I don't have time for that. All it is, is a resistor in series with a battery or pair of batteries. The common end (-) (negative to make it easy) we'll call negative. The "outside" end of the resistor we'll call positive (going to battery +). Connect your meter to those two points. From there, the common goes to the cathode of a diode, the positive to the anode. You should measure 0.5 ~ 0.7 VDC with a silicon diode. You're measuring the voltage drop of the junction at approximately 1 mA. A transistor has two diode junctions. Emitter to base and collector to base. The drops will be close - but different due to differing doping levels in the silicon. There should be no current between emitter to collector. Some transistors have a reverse diode between collector and base (horizontal output transistors and Mosfets).
All you are doing is generating a current close to 1 mA and measuring the voltage drop across the junction. If the connection is open you will measure the battery voltage. The meter is always connected across the leads going to the junction under test. It is in parallel.
-Chris
I'd need to draw it and scan it for you. At the moment I don't have time for that. All it is, is a resistor in series with a battery or pair of batteries. The common end (-) (negative to make it easy) we'll call negative. The "outside" end of the resistor we'll call positive (going to battery +). Connect your meter to those two points. From there, the common goes to the cathode of a diode, the positive to the anode. You should measure 0.5 ~ 0.7 VDC with a silicon diode. You're measuring the voltage drop of the junction at approximately 1 mA. A transistor has two diode junctions. Emitter to base and collector to base. The drops will be close - but different due to differing doping levels in the silicon. There should be no current between emitter to collector. Some transistors have a reverse diode between collector and base (horizontal output transistors and Mosfets).
All you are doing is generating a current close to 1 mA and measuring the voltage drop across the junction. If the connection is open you will measure the battery voltage. The meter is always connected across the leads going to the junction under test. It is in parallel.
-Chris