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Solid State Amplifiers => Amplifier Discussion => Topic started by: jpcar on July 25, 2017, 05:11:35 PM

Title: Identifying a transistor
Post by: jpcar on July 25, 2017, 05:11:35 PM
Can someone help me identify this transistor?

It's from a Wurlitzer Orbit 3 organ.

It reads 7179 - which in the schematic is 657179, which I have found on a Wurlitzer page, so I'm thinking that's a Wurlitzer part no. It confirms that it's a PNP power transistor.

Next it reads SP8406A. I can't anything to do with transistors when googling this number.

And next it reads 7346. Is this an age code?

I've attached a pic of the transistor and a schematic of where it's from.

Please help!

I would love to find the specs of this transistor so if I can't find one I can get an equivalent.

Thanks!
Title: Re: Identifying a transistor
Post by: DrGonz78 on July 25, 2017, 07:47:26 PM
Well don't hold me to this completely, but this is where my search took me. I found this link here>>>
http://soundelectronic.ch/shop/index.php?main_page=product_info&cPath=4_37&products_id=493&zenid=pq7k3lmfpdchjng85hu8kfv526

At that point it confirmed B79-1 and it showed Model: 657179. It even had that it was made by Wulitzer. Which I think just means that Model: 657179 relates to Wulitzer. At least it shows something that might help you figure this out, good luck.
Title: Re: Identifying a transistor
Post by: Enzo on July 25, 2017, 08:45:20 PM
7346 is a date code, week 46 1973

657179 is the Wurly part number.

It is a TO220 PNP transistor, a common TIP42B or TIP42C ought to work fine.

Title: Re: Identifying a transistor
Post by: jpcar on July 26, 2017, 10:04:08 AM
Thanks for the help!

I'll get a TIP42B from mouser and complementing TIP41B and see how that works.
Title: Re: Identifying a transistor
Post by: Enzo on July 26, 2017, 01:21:32 PM
If you are going to order something, might as well make it a TIP41C and TIP42C.  The B version is 80v the C version is 100v.  Can't hurt.  Not that B is wrong, it wil be OK.
Title: Re: Identifying a transistor
Post by: J M Fahey on August 15, 2017, 08:25:40 PM
Since it´s the so called "Class A driver" and it´s passing some 100mA , I guess original was a TIP30, letter B or higher,rated 1A.
Of course, 3A TIP32 or 6A TIP42 will also work.
Get letter B or higher, although lately letter C is "preferred" so it might be easier to find, I mention this just because maybe you have some B letter ones in a dusty old drawer.

Only precaution is that 22V x 100mA means over 2W dissipation, and transistor will heat up a lot unless prooperly attached to some heatsing, don´t forget insulating mica, grease and plastic nipples if needed.
Unless it´s mounted on a floating own small heatsink on the board itself, not touching ground or chassis.
You´ll still need some grease.