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Post by mdmitch2 on Nov 28, 2016 23:00:05 GMT -6
I'm trying to find some transistors for my Neotek Elite, but the part is obsolete and so are all of the substitutes I've found. The part I'm looking for is a 2N5638 transistor. Any tips on locating obsolete parts or their substitutes? I've seen some on eBay, but most appear to be Chinese knockoffs and I don't want to gamble on those.
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Post by johneppstein on Nov 29, 2016 6:12:24 GMT -6
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Post by kcatthedog on Nov 29, 2016 15:48:22 GMT -6
Have you posted on the blackmarket at group diy ?
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Post by svart on Nov 30, 2016 7:32:03 GMT -6
It's an N-channel Jfet. Is it used for the mutes or signal switching?
Looks like the J111 will work just fine. Check your pinouts though.
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Post by mdmitch2 on Nov 30, 2016 12:38:09 GMT -6
It's an N-channel Jfet. Is it used for the mutes or signal switching? Looks like the J111 will work just fine. Check your pinouts though. It's part of the master solo bus.... the left side went out, so I only hear solo'd tracks on the right. Schematic below. As for the J111, the pinouts are the same, but some of the on/off characteristics seem quite different.... maybe it's close enough? 2N5638 Spec SheetJ111 Spec Sheet |
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Post by svart on Nov 30, 2016 14:41:05 GMT -6
It's an N-channel Jfet. Is it used for the mutes or signal switching? Looks like the J111 will work just fine. Check your pinouts though. It's part of the master solo bus.... the left side went out, so I only hear solo'd tracks on the right. Schematic below. As for the J111, the pinouts are the same, but some of the on/off characteristics seem quite different.... maybe it's close enough? 2N5638 Spec SheetJ111 Spec SheetI think it's probably close enough. They're cheap, so give it a shot! |
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Post by mdmitch2 on Nov 30, 2016 15:24:48 GMT -6
I think it's probably close enough. They're cheap, so give it a shot! Thanks for the advice -- I ended up fixing the problem.... there was a pretty sketchy looking solder joint at C125, so I fixed that. And I did go ahead and swap the 2N5638's with some that I pulled from the Talkback and Oscillator circuits, but those sections still seem to be working fine, so I think the transistors were probably fine to begin with. I'll go ahead and order some J111's with the next mouser order since this console apparently used the 2N5638 quite a bit. |
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Post by Deleted on Dec 3, 2016 3:48:03 GMT -6
If, for whatever reason, you need or want to have rare original parts, there are some specialized distributors that specialized in stocking rare and obsolete parts.
Often, you don't find them on google with the part name, because they sometimes don't have a public parts database that could be indexed. I bought at one place of this kind once, it was UK based, but i really can't remember their name.
Anyway, they were easy to deal with, i made an e-mail inquiry of the parts and the sales woman came back to me with prices and availability of their NOS parts timely. Prices were significantly higher, but still acceptable so i ordered and got flawless service.
I would recommend going this route for historic units, where "original" parts *can* make a better resale value. Otherwise i recommend using modern replacement. Often they are less noisy, cheaper and more reliable. I had packages of NOS diodes and transistors, where half of them did not reach specs anymore or were actually totally non-usable/non-functional. I would not blame distributors on this really, you have to expect high failure rates on really old parts....
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