Steve or ChicagoBill please help [message #23524] |
Wed, 29 July 2015 13:48 ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
Kustom_Bart
Messages: 601 Registered: October 2010 Location: Greenville, MichiGUN
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looking for transistors for K100 they are the ones for q126 rca 38869 and q127 rca 38870 is there another part that will cross for these two parts that you know of off hand? Or is there a supplier for these two pieces that you know of.
Thanks,
Bart
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Re: Steve or ChicagoBill please help [message #23525 is a reply to message #23524] |
Wed, 29 July 2015 16:26 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
chicagobill
Messages: 2005 Registered: April 2003
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Those part numbers are the main driver transistors for the power amp. I've been using a 2N3440 for the NPN (38869) and a 2N5415 for the PNP (38870).
They need to have a small heat sink attached to the cases.
Edit: I just looked up these part numbers and now the 2N5415 is only being made by one company and they want 12.00 apiece for them.
I guess it's time to switch over to a TO-220 case transistor like a TIP41c/TIP42c. Or maybe a plastic cased one like the MJE340/MJE350. Unfortunately the pinouts are different and will be harder to fit in position.
[Updated on: Wed, 29 July 2015 17:10] Report message to a moderator
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Re: Steve or ChicagoBill please help [message #23542 is a reply to message #23524] |
Fri, 31 July 2015 06:45 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) |
stevem
Messages: 4758 Registered: June 2004 Location: NY
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Senior Member |
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What else was replaced other than the transistors?
Is it the driver board that is motorboating ?
If the tech disconnects the signal input to the driver board does the amp still motorboat ?
A bad electrolytic coupling or gain cap could make for the same issue , or maybe one of those two driver transistors are way above spec !
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