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Power Transistor Code Identification help

MrBrian

Dec 31, 2021
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This is a PSU for a Trident 80 Series Mixing Console and the resistors on the underside of these power transistors got fried. Got stopped pretty quickly as I am having trouble identifying these transistors. Any help would be very much appreciated.

Trident PSU Transistor.JPG
 

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Martaine2005

May 12, 2015
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I can tell you they are Motorola.
8152 seems to cover quite a few so I’ll leave it there and hopefully somebody will know or have an equivalent.

Martin
 

MrBrian

Dec 31, 2021
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Is the transistor kaput..??
There are a ton of them actually ( at least 8 in this same configuration, more elsewhere too) and the resistors connected to about half of them have exploded (upon powering up). I'll upload a photo.

Noticed an additional resistor had been added on half of them, which happens to be the half that did NOT explode, which is somewhat telling. Trying to figure out what exactly caused them to blow up, and also to understand what the resistors are doing there in the first place. This is my first time working with power transistors so I still don't quite understand everything. That's why I wanted to find the datasheet.
 

Bluejets

Oct 5, 2014
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Depends on the resistors and where they are placed.
It is normal to have a variety of resistor values around transistors both to limit current and to bias the transistor at the correct level for the incoming signal.
Mostly power transistors will have emitter resistors to stop thermal runawayas well.

Still the question remains, is the transistor faulty or are you just guessing.
Point being, it is possible it is ok.
If not, it is a;so possible to get parameters from a good transistor if there are others the same or in similar configuration by using a $20.00 component tester from Fleebay or where ever.
 

MrBrian

Dec 31, 2021
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Depends on the resistors and where they are placed.
It is normal to have a variety of resistor values around transistors both to limit current and to bias the transistor at the correct level for the incoming signal.
Mostly power transistors will have emitter resistors to stop thermal runawayas well.

Still the question remains, is the transistor faulty or are you just guessing.
Point being, it is possible it is ok.
If not, it is a;so possible to get parameters from a good transistor if there are others the same or in similar configuration by using a $20.00 component tester from Fleebay or where ever.

I'm not sure what caused the resistors to explode. Would it be a faulty transistor? Or would the resistors exploding indicate something else? Can I test the transistor while it is in circuit?
 

AnalogKid

Jun 10, 2015
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The part was made in December of 1982. Back then it was a semi-common practice for manufacturers to have transistors marked with "house numbers", their own company's internal part number rather than the industry standard number such as 2Nxxxx. Theoretically, this made it more difficult for their products to be copied. House-marked parts were all over the surplus components markets. Eventually, but still rarely, some documentation slipped out. For example, I used to have a cross-reference list for Peavey internal part numbers.

You can get a pretty good feel for the operational parameters needed by measuring the operating voltage for the circuit, calculating the current based on whatever the transistor is driving, inferring the frequency response from the signal bandwidth and circuit gain, etc.

ak
 

bertus

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Nov 8, 2019
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Hello,

Using the attached crossreference list, the 6552 leads to a MJ15018.
The trouble with inhouse numbers is that you can never be sure.
I hope it could be of any use.

Bertus
 

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MrBrian

Dec 31, 2021
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The part was made in December of 1982. Back then it was a semi-common practice for manufacturers to have transistors marked with "house numbers", their own company's internal part number rather than the industry standard number such as 2Nxxxx. Theoretically, this made it more difficult for their products to be copied. House-marked parts were all over the surplus components markets. Eventually, but still rarely, some documentation slipped out. For example, I used to have a cross-reference list for Peavey internal part numbers.

You can get a pretty good feel for the operational parameters needed by measuring the operating voltage for the circuit, calculating the current based on whatever the transistor is driving, inferring the frequency response from the signal bandwidth and circuit gain, etc.

ak
I get it, that's good stuff to know. Very much appreciated. I am constantly looking to fill in the gaps in my knowledge. It's hard to find this specific of information when I'm not exactly sure what I'm asking sometimes haha. Thank you for the help.
 

MrBrian

Dec 31, 2021
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Dec 31, 2021
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Hello,

Using the attached crossreference list, the 6552 leads to a MJ15018.
The trouble with inhouse numbers is that you can never be sure.
I hope it could be of any use.

Bertus
Very much so...I really do appreciate it. Thank you
 
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