I found a local store. They cross referenced the BD139 to a NTE184. Their specs are similar.
BD139
http://www.futurlec.com/Transistors/BD139.shtml
NTE184
VCBO 80V
VCEO 80V
VEBO 5V
Lc 4A
Pd 40W
hFE 7Min
fT 2MHZ Min
Any idea about if it will be all right in the Project 27?
BD139
http://www.futurlec.com/Transistors/BD139.shtml
NTE184
VCBO 80V
VCEO 80V
VEBO 5V
Lc 4A
Pd 40W
hFE 7Min
fT 2MHZ Min
Any idea about if it will be all right in the Project 27?
...you may find inspiration here, for example:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=97030&highlight=
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http://www.diyaudio.com/forums/showthread.php?s=&threadid=97030&highlight=
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NTE parts are usually adequate for general purpose repairs, and usually exceed the specs of the original part with Vce and Ic and Pd, but if you're using it in a diff amp, current mirror, driver or output stage, theyre not really very good for that, because they will be mismatched (unless you replace these devices as pairs with matching NTE parts, which gets very expensive very quickly). NTE parts are usually twice the cost of original parts, and NTE parts dont neccesarily match or exceed other parameters for the devices they replace, such as Ft and beta. thats why they are "Replacement Parts". theyre used for repairs where "close is good enough", but not where you must have an exact replacement.
Hi unclejed613,
Hmmmm, old post. Sorry, but I want to clear something up.
I'm sorry to have had to disagree with you on this unclejed613. There are no good service technicians that will use these things. people who use them only think they are good, or they are forced to use them from management.
-Chris
Hmmmm, old post. Sorry, but I want to clear something up.
Nope, they aren't. The problem is that you have no idea what the original part is, or it's exact characteristics. Their subs are sometimes in error as well.
I only wish this were the case. There is no such thing as NTE matched parts in reality. Often, those parts are mixed from different run numbers at the OEM. They may also be mixed form different manufacturers on top of that. You have no realistic hopes of obtaining a matched pair with NTE or ECG.
Since they may not even be the same part, not much can be counted on being the same. I've also had higher failure rates when I was forced to use ECG parts, and I see a high failure rate in equipment that comes in for service. If I see an ECG or NTE replacement part, they need to be replaced. Period.
Actually, there is no excuse for using these darn things. There is no repair that "close is good enough". No such thing. If you don't have the exact part, a good technician is capable of making a more intelligent substitution with real parts. I don't classify ECG or NTE as real parts. They are "remarks" or fakes. Just imagine if fake parts got into that supply chain. If they haven't already.
I'm sorry to have had to disagree with you on this unclejed613. There are no good service technicians that will use these things. people who use them only think they are good, or they are forced to use them from management.
-Chris
Hi Chris,
It's true that I haven't dealt with NTE replacements much, but I used to work a bit with ECG replacements (before learning how to better sub in Motorola parts and such - this was mostly for monitor and switching power supply repair). I just checked my old ECG, and they had a series of MCP numbers that were for matched pairs of bipolar transistors. Numbering was ECG(PNP Number)MCP, which would get you one each of the NPN and PNP part, supposedly matched.
It's been my general (perhaps unfounded?) impression that NTE was a big step down from ECG. Is this one of the services they did away with?
Cheers,
Paul
It's true that I haven't dealt with NTE replacements much, but I used to work a bit with ECG replacements (before learning how to better sub in Motorola parts and such - this was mostly for monitor and switching power supply repair). I just checked my old ECG, and they had a series of MCP numbers that were for matched pairs of bipolar transistors. Numbering was ECG(PNP Number)MCP, which would get you one each of the NPN and PNP part, supposedly matched.
It's been my general (perhaps unfounded?) impression that NTE was a big step down from ECG. Is this one of the services they did away with?
Cheers,
Paul
Hi Paul,
ECG was terrible stuff. I used to work at a parts distributor where I also did service. I had a very high return rate and after getting berated once too often, I put my foot down and began using real parts. Honestly, I was poking the transistor leads out through the plastic to test them first. Many rejects went back on the hook for the TV guys to use. That helped my return rate.
Once I began using th real parts, my return rate went down to practically zero.
NTE parts are about the same as ECG parts. They tested the same.
About the only thing I didn't have a problem with in ECG were the MPX and IF chips. I guess those had to come from the original factory. Probably rejects on measured performance.
-Chris
ECG was terrible stuff. I used to work at a parts distributor where I also did service. I had a very high return rate and after getting berated once too often, I put my foot down and began using real parts. Honestly, I was poking the transistor leads out through the plastic to test them first. Many rejects went back on the hook for the TV guys to use. That helped my return rate.
Once I began using th real parts, my return rate went down to practically zero.
NTE parts are about the same as ECG parts. They tested the same.
About the only thing I didn't have a problem with in ECG were the MPX and IF chips. I guess those had to come from the original factory. Probably rejects on measured performance.
-Chris
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