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A-1 RCA Transistors [message #19964] Thu, 09 January 2014 01:40 Go to next message
kustomhead is currently offline  kustomhead
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Registered: April 2012
Location: Redding, Ca
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Question: does a NTE 128 transistor cross reference with the RCA 40406's on the power board of a K200 A? I read that a 2N5087 through Mouser will match. If not, what will? Any thoughts on this?
[Updated on: Wed, 08 January 2014 12:53]

[Updated on: Thu, 09 January 2014 01:42]

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Re: A-1 RCA Transistors [message #19966 is a reply to message #19964] Thu, 09 January 2014 08:34 Go to previous messageGo to next message
stevem is currently offline  stevem
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Registered: June 2004
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No, the 40406 is a pnp type equal to a nte129, a npn version is nte 128.
When replacing these a slip on star type heat sink should be added ( for a TO-39 type transistor) if they do not already have one on them.

[Updated on: Thu, 09 January 2014 08:39]

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Re: A-1 RCA Transistors [message #19971 is a reply to message #19966] Thu, 09 January 2014 11:51 Go to previous messageGo to next message
kustomhead is currently offline  kustomhead
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Registered: April 2012
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The amp doesn't buzz with nothing plugged in but if you touch the far left RCA 40406 on the 702 board or the input jack with the tip of a screwdriver it buzzes until you touch it again. That's why I'm suspecting the transistor is bad. Also that's in the circuit section where a previous owner bridged a broken trace and did some messy soldering. I've cleaned that up though and am pretty positive that that's not the problem and the transistor is.

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Re: A-1 RCA Transistors [message #19972 is a reply to message #19966] Thu, 09 January 2014 12:01 Go to previous messageGo to next message
kustomhead is currently offline  kustomhead
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Does the NTE129 have the heat sink or are you talking about adding that to a 128? There's plenty of NTE129's on ebay.

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Re: A-1 RCA Transistors [message #19973 is a reply to message #19966] Thu, 09 January 2014 12:30 Go to previous messageGo to next message
kustomhead is currently offline  kustomhead
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Location: Redding, Ca
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I see both 128 and 129 are TO39 types.

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Re: A-1 RCA Transistors [message #19974 is a reply to message #19964] Thu, 09 January 2014 12:35 Go to previous messageGo to next message
stevem is currently offline  stevem
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They do not come fitted with heat sinks.

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Re: A-1 RCA Transistors [message #19975 is a reply to message #19974] Thu, 09 January 2014 12:38 Go to previous messageGo to next message
kustomhead is currently offline  kustomhead
Messages: 121
Registered: April 2012
Location: Redding, Ca
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The local antique radio shop has the transistors and probably has the heat sinks too. I'll check it out. Thanks so much for the info Steven-Jim

[Updated on: Thu, 09 January 2014 12:39]

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Re: A-1 RCA Transistors [message #19977 is a reply to message #19966] Thu, 09 January 2014 13:50 Go to previous messageGo to next message
kustomhead is currently offline  kustomhead
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Will a T03-B heat sink work?

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Re: A-1 RCA Transistors [message #19978 is a reply to message #19964] Thu, 09 January 2014 14:13 Go to previous messageGo to next message
stevem is currently offline  stevem
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No, but since they just slip on you can always add the right ones latter, it's not a life or death thing for a new transistor, but every 20 degree drop in running temp will double a semiconductors life span!

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Re: A-1 RCA Transistors [message #19979 is a reply to message #19978] Thu, 09 January 2014 14:32 Go to previous messageGo to next message
kustomhead is currently offline  kustomhead
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the legs go through the T03-B but the right ones slip on the case?

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Re: A-1 RCA Transistors [message #19987 is a reply to message #19964] Fri, 10 January 2014 08:35 Go to previous messageGo to next message
stevem is currently offline  stevem
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A TO3-B is a transistor with a case like the to3 outputs on the bottom of the amp in the heat sink bracket, the transistors you are asking about are a TO-39 type case, so I do not understand what you are asking about there?

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Re: A-1 RCA Transistors [message #19988 is a reply to message #19987] Fri, 10 January 2014 10:24 Go to previous messageGo to next message
kustomhead is currently offline  kustomhead
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I get it, the heat sink fits around the case of the NTE129. I've got some 129's coming and my friend at the Antique Radio Store is getting the heat sinks ordered. I'll replace the suspect one and go from there.

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Re: A-1 RCA Transistors [message #19990 is a reply to message #19964] Fri, 10 January 2014 11:51 Go to previous message
stevem is currently offline  stevem
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Cool!

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