Looking for info on this transistor
Its part of a public address system
The logo says it’s a Motorola semiconductor.
If it has two leads and the reference designator prefix is “D”, then it’s a diode.
If it has three leads and the reference designator prefix is “Q”, then it’s a transistor.
If it has more leads it’s an integrated circuit and it’s reference designator prefix should be “U”.
It also has slip on heat sink attached, package appears to be TO-5 package.
yes it’s a 3 lead with a Q designator. one of the leads is pulled out of the package. Is there an equivalent transistor that would work?
So far I am not seeing specifications for that Motorola item.
The below link shows the items we currently have.
These are TO-5 and transistors. We would need the type, voltage, and current to really narrow further.
Single Bipolar Transistors | Bipolar (BJT) | Transistors | Electronic Components Distributor DigiKey
My memory was that Motorola used the 2Nxxxx designators for regular transistors and longer numbers for private labeled and custom parts. A quick search seems to indicate that my memory is correct. Unfortunately that makes it extremely difficult to choose a replacement.
If, and only if, you don’t mind completely destroying the device, then:
Buy the highest power NPN and PNP TO-5 Transistors you can find and try out each one. Only one will do anything good, the other could fry the rest of the circuits.
With one doing something, see if the device works fully. If it does not work fully try other TO-5 package transistors of working type of transistor that have different specs.
1 Like
Hello @andrewrobicheau23,
You mentioned this was part of a PA system. Judging by the picture, this amplifier appears to be from the late 1960s to mid 1970s.
Please share the manufacturer and model number as there is a small chance that someone may be able to location the schematic. This would significantly reduce the risk of an improper substitution.
Best wishes,
APDahlen
2 Likes
circuit board is manufactured by Gai-tronics corporation. It has a number on it 17051-101. Manufactured date 04-80. Thank you for your help.
Unfortunately I couldn’t find much of a way to narrow down our options on replacement transistors any further, it looks like that Gai-Tronics board is still out there and some people do carry boards that could be used for either a wholesale replacement or for spare parts, but I wasn’t able to confirm any further details on the transistor n question, or really any of the parts on the component level on this board.
The only documentation I could find is an old Gai-Tronics manual that recommends against field-replacing any individual components. Obviously someone who works in repair would have a different view on the matter, but it still leaves me with no new leads to get an ID or specifications for this transistor.
Try this.
Remove the transistor from the board. Using a meter set to resistance (or diode) get one probe on even the smallest part of the broken lead and see if you can get forward bias between the leads. You may be able to at least determine if it’s an NPN or PNP.
There’s nothing to grab on to. It looks like part of the leg was vaporized, the only remaining thing is a ball of overheated resin
I found it! It’s a 2N3439 NPN
Fantastic. I was wondering if that had happened. That board has some burnouts on it for sure. That had to be very catastrophic to vaporize the transistor lead.
I’m curious how did you figure out it was a custom labeled 2N3439?
2 Likes