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 Post subject: Need pass transistor test jig
PostPosted: May Fri 26, 2017 4:10 pm 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
I am trying to find a schematic and parts list for a test jig for testing some 2N5886 and MJ15003 pass transistors I bought. They will be used in a piece of commercial gear running at a regulated 29 votls. I don't want to put these things in as replacements and find that they are floor sweepings but so far I have not found any test setups to actually test them. Short of building a 28v at 20 amp power supply and placing them in it, what can be used for testing these transistors to make sure they are not going to prematurely fail under load?

Thank you.


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 Post subject: Re: Need pass transistor test jig
PostPosted: May Fri 26, 2017 5:16 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 9107
Location: Santa Rosa, CA
The short answer is: if this commercial gear has to work reliably, buy some new transistors from an authorized distributor like Mouser or Digi-Key.

Before power transistors get shipped by the manufacturer, they would get voltage tested (25 C and 150C) to 100% of Vceo and Vcbo. They would get a pulsed gain test to measure Hfe (without heating the part). Good suppliers would also do a one second SOA (Safe Operating Area) test to confirm stability and good attachment of the chip to the case. You would need 40 V @ 3 amps and some way to time out one second.

http://www.onsemi.com/pub/Collateral/2N5883-D.PDF

It's difficult to do home testing as even with the correct power supplies, measuring gain requires a series of short pulses. If you measure gain with DC, the chip heats and you won't get the correct reading.

Do you know anyone with a Tektronix 576 that has the high power attachment? That's what we used in the lab to verify production test results.

Rich


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 Post subject: Re: Need pass transistor test jig
PostPosted: May Fri 26, 2017 5:37 pm 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
Rich, W3HWJ wrote:

Do you know anyone with a Tektronix 576 that has the high power attachment? That's what we used in the lab to verify production test results.

Rich

No, I don't know anyone with a Tek 576 or similar so I am limited to what I have on hand. Even finding a transformer that can be used in a 28v at 10 plus amps will be a trick (and expensive). When I got into the hobby I would have just found an old TV and robbed the transformer and rewound it but that is no longer an option.

These transistors came straight from China and Chinese suppliers and also from a surplus outfit in Baton Rouge so they are of unknown origin although the MJ15003's say Motorola on them with a 1999 date code but I thought that was about the time that Motorola became something else.


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 Post subject: Re: Need pass transistor test jig
PostPosted: Jun Mon 05, 2017 9:15 pm 
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Joined: May Sun 28, 2017 9:08 pm
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Location: Whiteville, TN
Reliability is important especially in a commercial application. Why, pray tell, is your comany buying stuff from china suppliers that YOU have to test? I suspect there is an answer that may even make real sense. However, being the eternal cynic, I suspect some suit that counts beans is saving a buck at your expense. Please set me straight. Put a big dent in my cynacism!

Karl
KI4ZUQ

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 Post subject: Re: Need pass transistor test jig
PostPosted: Jun Mon 05, 2017 9:46 pm 
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Joined: Sep Tue 30, 2014 6:08 am
Posts: 2123
Location: The Old Dominion VA 23518
Southerner wrote:

These transistors came straight from China and Chinese suppliers and also from a surplus outfit in Baton Rouge so they are of unknown origin although the MJ15003's say Motorola on them with a 1999 date code but I thought that was about the time that Motorola became something else.


Check the ONSemi Product Change Notice for Motorola/OnSemi changeover:

http://www.onsemi.com/PowerSolutions/pcn.do?id=10143

More gouge, straight from OnSemi:

Any date code >2000 with a Motorola "M" logo is fake. 01##, 02##, 03##, 04##, etc.
Any OnSemi device with a date code of Sub-1999 is fake. 98##, 97##....etc.
Date codes in 1999-2000, some wiggle room, but nothing after 2000 week 30 (0030) should bear the Motorola logo, and all Mexican Fab (mostly power!) stuff was changed over in early 2000, so more "wiggle room".

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"Capacitor Cosmetologist since 1979"
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 Post subject: Re: Need pass transistor test jig
PostPosted: Jun Sat 10, 2017 4:23 am 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
Southerner wrote:
they are of unknown origin although the MJ15003's say Motorola on them with a 1999 date code.

As I said, these have a 1999 date code with the Motorola M emblem. Short of throwing them in the circuit and hoping they are not floor sweepings I don't know of any other way to test them.


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 Post subject: Re: Need pass transistor test jig
PostPosted: Nov Sat 25, 2017 4:06 am 
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Posts: 2002
Location: 08033 Cherry Hill Jersey
I am doing the same thing oddly; building a 27v 10a supply to run the filament string of my ART13.

If found the right transformer, and a huge heatsink with a bank of old Westinghouse NPNs that cross reference to 2n3005. They test out with an ohmmeter, but for the real test I'm just going to put them in circuit, add several tubes at a time, taking measurements.

Building a test power supply wouldn't be bad if you had the right transformer - I modified one that was close with a few additional 12 gauge turns. Then there's the load - how to simulate that.

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 Post subject: Re: Need pass transistor test jig
PostPosted: Nov Sat 25, 2017 7:09 am 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
SmoothOscillator wrote:
I am doing the same thing oddly; building a 27v 10a supply to run the filament string of my ART13.

Then there's the load - how to simulate that.


Simulating the load would just take a fixed power resistor. 27v at 10A would be 270 watt resistor. With R=E/I that would be 27v/10A or 2.7 ohms. Correct me if I am wrong. I wonder if the heating element from an electric heater might work too as a good load?


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 Post subject: Re: Need pass transistor test jig
PostPosted: Nov Sun 26, 2017 12:31 am 
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Location: 08033 Cherry Hill Jersey
You're correct - I thought about this, and don't have any resistors of that big wattage. I have a dummy load, and no other resistance to pair it up with to get close to the real load. In my case I just elected to test on the real load. - Did not think of a toaster element! That would be an interesting experiment.

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 Post subject: Re: Need pass transistor test jig
PostPosted: Nov Sun 26, 2017 12:39 am 
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Location: 08033 Cherry Hill Jersey
Can you test these at 24v? Here's a 24v 10a transformer:

http://r.ebay.com/sVFI65

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 Post subject: Re: Need pass transistor test jig
PostPosted: Nov Sun 26, 2017 12:45 am 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
SmoothOscillator wrote:
Can you test these at 24v? Here's a 24v 10a transformer:

http://r.ebay.com/sVFI65

$46 shipping? I think I will stick with just finding a transformer and making my own.


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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Tue 12, 2017 9:07 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9431
Location: Powell River BC Canada
Find a Heathkit IT38. This bridge is easy to use, and with external power supply,
you can use the calibrated 15 amp Ic range. External voltage max is 50. (750 watts)
Leakage testing, maximum, external 150 Volts.


Attachment:
Heathkit  IT 38.jpg
Heathkit IT 38.jpg [ 74.3 KiB | Viewed 182 times ]

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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Tue 12, 2017 5:22 pm 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
radiotechnician wrote:
Find a Heathkit IT38. This bridge is easy to use, and with external power supply,
you can use the calibrated 15 amp Ic range. External voltage max is 50. (750 watts)
Leakage testing, maximum, external 150 Volts.


Attachment:
Heathkit IT 38.jpg

I am not seeing any information on a Heathkit IT38. Does it come with an external power supply that hefty? If I can build a 28v 10 amp supply or actually 40v at 15 amps then I can just use the transistors and see if they smoke. When I search for IT38 I get a lot of hits for IM38 vtvm hits but no IT38 transistor testers.
Thank you.


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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Tue 12, 2017 5:26 pm 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
CROSSBOLT wrote:
Reliability is important especially in a commercial application. Why, pray tell, is your comany buying stuff from china suppliers that YOU have to test? I suspect there is an answer that may even make real sense. However, being the eternal cynic, I suspect some suit that counts beans is saving a buck at your expense. Please set me straight. Put a big dent in my cynacism!

I am not a company! I am that bean counter you refer to and because I am not a company I do not have unlimited funds and that is why I can't afford a big transformer like a 40v 10 amp transformer to make a big power supply and regulate it to 28v to simulate the power supply in the commercial product I am trying to repair and hoping not to have to repair more than just the pass transistors!


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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Tue 12, 2017 6:05 pm 
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Joined: Aug Sat 31, 2013 5:57 pm
Posts: 13
Yeah, this is kind of a strange situation. Mouser(and others I'm sure) still sells the OnSemi MJ15003, brand new, for $4/each. I don't see any reason to be buying old stock of these components, with questionable origins, when it's easy to get verified authentic ones.

As for testing them, I'd say isolate the piece of gear they go in, install them, and test the piece of gear for whatever period of time you feel is sufficient to say they are good to go. Testing high power transistors with DIY solutions can be fairly difficult.


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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Tue 12, 2017 6:37 pm 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
blasphemy000 wrote:
As for testing them, I'd say isolate the piece of gear they go in, install them, and test the piece of gear for whatever period of time you feel is sufficient to say they are good to go. Testing high power transistors with DIY solutions can be fairly difficult.

Or I could just buy K6IOK's replacement power supply for the TS940...when it comes out later this month...but that goes back to not having unlimited funds. It also goes against my grain to pay $350 for a replacement power supply (because the real manufacturer of the TS940 cut too many corners) for a rig that only cost me $350 (the second one, not the first one that cost me $2500)! That is what prompted the question in the first place.

Yes, I know I can throw the transistors into the rig and hope that these 2N5886's are not floor sweepings or 2N3055's in disguise.


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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Tue 12, 2017 10:33 pm 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9431
Location: Powell River BC Canada
Southerner wrote:
radiotechnician wrote:
Find a Heathkit IT38. This bridge is easy to use, and with external power supply,
you can use the calibrated 15 amp Ic range. External voltage max is 50. (750 watts)
Leakage testing, maximum, external 150 Volts.


Attachment:
Heathkit IT 38.jpg

I am not seeing any information on a Heathkit IT38. Does it come with an external power supply that hefty? If I can build a 28v 10 amp supply or actually 40v at 15 amps then I can just use the transistors and see if they smoke. When I search for IT38 I get a lot of hits for IM38 vtvm hits but no IT38 transistor testers.
Thank you.


Sorry, I just looked at Heath bridge. This time with glasses.. It is an IM 30.

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
Steve Dow
ve7aso@rac.ca


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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Fri 15, 2017 5:58 am 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
radiotechnician wrote:
Find a Heathkit IT38. This bridge is easy to use, and with external power supply,
you can use the calibrated 15 amp Ic range. External voltage max is 50. (750 watts)
Leakage testing, maximum, external 150 Volts.

radiotechnician wrote:
It is an IM 30.

I am not familiar with the IM30 and see none listed on ebay right now. I do see 2 manuals but no IM30 in the flesh. I will look for one though. Thank you.
Jim


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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Fri 15, 2017 6:54 am 
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Joined: Sep Thu 23, 2010 6:37 am
Posts: 9431
Location: Powell River BC Canada
As a matter of fact, I took it out yesterday and ran some tests, and cleaned the top cover.
It works perfectly. Without the batteries it needs external power supplies, three of them.

It has a very sensitive meter, and I checked the collector current readings against what the
power supply meter was showing. The beta/alpha is read off the bridge dial.

My unit was bought from a school, and was used when Electronics was a
credit course at the local high school.

I remember that the school used the electronics lab to teach pottery when electronics
was dropped in favor of computer classes in the eighties.

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de
VE7ASO VE7ZSO
Amateur Radio Literacy Club. May we help you read better.
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 Post subject: Re: Need pass transistor test jig
PostPosted: Dec Fri 15, 2017 4:16 pm 
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Joined: Sep Sat 06, 2008 3:04 am
Posts: 191
Location: Benton City, WA
radiotechnician wrote:
Without the batteries it needs external power supplies, three of them.

Are those 3 external power supplies part of the IM30? Or is that an item you have to provide from other sources? If I have to provide the external power supply then why get the IM30? Why not just use the power supply as the tester? That is my problem anyway as finding a 40v at 10 amp transformer (or 80v 5 amp if using a full wave rectifier) is tough and no longer any crt tv's to steel the power transformer and rewind one with the voltage I want.

Thank you.


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