SHP3 Part 2.5: Why the "equivalent" replacement transistor.... isn't.

Описание: *WARNING* Working with electricity is dangerous!!! If you do not understand the basics of electricity, please do not attempt the following project. Failure to use care around electrical devices may result in injury or death. If you choose to attempt this project, you do so at your own risk! Please be careful. This concludes the death disclaimer...

**Special thanks to xraytonyb for pointing out something that I forgot and should have caught. A lot of of older amplifiers used germanium transistors. Well, that might explain those gain characteristics, huh?
While I have said it before, my lack of experience with these will show up and guys like xraytonyb have forgotten more about them then I may ever learn. If you like learning about audio repair and restoration, he is one of the best, despite his modesty. Be sure to check out his channel. Here is a link to one his repair videos.

   • Marantz 2500 Receiver Part 1 - Restoration...  

Plus, he has amazing audio on his channel.**

I should start by saying, I should have caught this when I was looking at the data sheets before ordering the 2N2222A transistors. I was looking at numerous windows with datasheets and while comparing the gain characteristics, I believe I was actually looking at the chart for the 2N5088/89. Much better gain, inadequate threshold voltages. I apologize if anyone got their hopes up thinking we had found the unicorn. Alas, we have not.

As I hope to demonstrate in this video, the “equivalent replacement transistors” recommended by the few websites on the net pertaining to jukebox repair, aren't all that “equivalent”. They might however, be the best you can get. Most transistors that have adequate threshold voltages to replace the original Seeburg pre-amp transistors lack the gain characteristics found in the originals. If you find yourself in need of replacing one of these transistors, you will most likely need to replace them all in order to properly “match” them. This video shows how the this difference in gain actually looks in waveform. We also discuss why replacements for this type of amplifier are not made any longer. Just remember, if you are trying to make a Seeburg sound “original”, then you will more than likely need to open your pocket book and hope for a technical miracle. Of course, miracles happen every day. Maybe we just need to modify our circuit? That's for another video.

I hope you find this video helpful and entertaining. If so, feel free to hit the “Like” button and subscribe for future videos. Thanks for watching and have a great day!