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 AUY21K transistor
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 Return to top of page · Post #: 1 · Written at 10:38:51 PM on 19 March 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 656

Would anyone have an AUY21K Germanium power transistor .I require it to attempt a repair on an ECU belonging to a 1974 Mercedes.
Regards Jimb.


 
 Return to top of page · Post #: 2 · Written at 11:32:12 PM on 19 March 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6010

A few listed on eBay and other overseas sites. Not cheap!


 
 Return to top of page · Post #: 3 · Written at 10:50:21 AM on 20 March 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1904

I can see data for this part. NPN, 10A 45 volts but I can't confirm the outline.

If it's a TO3 package then an ordinary 2N3055 should replace it with ratings to spare.


 
 Return to top of page · Post #: 4 · Written at 11:34:29 AM on 21 March 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 656

Hello Ian .
Not sure where you got that data from it is a germanium PNP transistor the package is TO3.
Regards Jim


 
 Return to top of page · Post #: 5 · Written at 11:41:10 AM on 21 March 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 656

Hello GTC.
Yes I had a look not keen to spend that amount at the moment.
Testing it with an ohm meter it tests ok however I have a Peak component analyser some time it tests ok other times not.
The tester may not like Germaniumm transistors for this reason I am left with some uncertainty .
I would love a circuit diagram of it however Mercedes never released it .
Regards Jim.


 
 Return to top of page · Post #: 6 · Written at 12:37:48 PM on 21 March 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6010

I would love a circuit diagram of it however Mercedes never released it

Getting such schematics is often Mission Impossible. Same with Alpine car radios.


 
 Return to top of page · Post #: 7 · Written at 2:37:32 PM on 21 March 2020.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 409

MJ2955 Jaycar.
PnP, 100V, 15 Amps. TO3.
JJ


 
 Return to top of page · Post #: 8 · Written at 2:40:12 PM on 21 March 2020.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 409

Another comment,
Have repaired several ECU’s but not 3 pointers.
All fixed, ———-dry joints.
JJ


 
 Return to top of page · Post #: 9 · Written at 6:22:54 PM on 21 March 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6010

My workshop neighbour has brought a few modern ECUs back to life on a best try but no guarantee basis. Prying them open is half the job and removing the silicone jelly which covers the PCB is another chore. After that he usually finds corroded wires (which are hair like) or bad SMT caps.


 
 Return to top of page · Post #: 10 · Written at 7:37:42 PM on 21 March 2020.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6348

I would love a circuit diagram of it however Mercedes never released it

MB is still coy about releasing its service data. I was talking to my mechanic a couple of years ago about how he gets on with servicing German cars and it costs him a lot to get even the basics off German companies. Unlike Japanese and former local companies which by comparison, virtually hand it over on a plate, mechanics pay through the nose, beg and plead for service manuals from the Germans.

By the way, to retract pistons on brake callipers on a Merc, you don't use a $10 G-clamp and a scrap of flat steel like you do on a Commodore, you apparently have to use a laptop and a OEM service manual worth thousands of dollars. It's good owning a Commodore, I have to say, especially if you don't like being torn a new arsehole just when renewing brake pads.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 11 · Written at 8:35:31 PM on 21 March 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6010

Most car manufacturers nowadays licence the software that allows access to ECUs to 'approved' service people on a per year model basis, and it's not cheap. Guy I know pays a small fortune to GM for the licences he needs to performance-tune GM engines. Given that he does that on a dynamometer, he needs the code to stop the ECU from detecting 'race mode' and putting the engine into crawl home mode.


 
 Return to top of page · Post #: 12 · Written at 12:42:02 AM on 22 March 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4339

That's why you have to love the old cars & tractors, there's not a lot of complicated stuff & it stuffs the young ones as there's no plug for the computer. You actually have to know how it works. The genuine Zephyr radio & early Holden ones had there respective radio circuits in their genuine factory manual.


 
 Return to top of page · Post #: 13 · Written at 10:38:46 AM on 22 March 2020.
Ian Robertson's Gravatar
 Location: Belrose, NSW
 Member since 31 December 2015
 Member #: 1844
 Postcount: 1904

Yes I was expecting it to be a PNP transistor like an AU103 but the data says otherwise.

However when I look again, the datasheet is confusing in that it also covers its complement.

Testing it, just look for valid diodes using an ohm-meter


 
 Return to top of page · Post #: 14 · Written at 6:02:31 PM on 25 March 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 656

Thank you all for your input.
Ian my normal testing method is the ohm meter and in this case it was also. However I also have a Peak component analyser there are two of these transistors it initially tested one OK the other it ignored the base connection. I have since tested the good transistor several times at occasionally it gave the same inconsistent result. So yes I believe the multimeter is correct and they are OK. Fortunately the ECU on my Mercedes is OK this one belongs to a friends Mercedes. My car was used as a test bed. I have proceeded with extreme caution it it was mine and I had no alternative I would get stuck in. The rear heat sink has some components with 6 legs with high temperature leads hanging out of them which would require some serious effort to remove so I can identify them. I have very bad shakes which makes me very cautious I do not want to go where Angel's fear to tread. His best bet will be to source another from a wrecker then I will have another go. I was an electronic tech by trade Broadcast TV Industrial and commercial electronics however those days are no longer with me and radio repairs are now difficult due to the dry paste joints I am guilty of from my hands oscillating.
Kind Regards Jimbr


 
 Return to top of page · Post #: 15 · Written at 4:08:16 PM on 26 March 2020.
Labrat's avatar
 Location: Penrith, NSW
 Member since 7 April 2012
 Member #: 1128
 Postcount: 291

Jimb.

I have a good ASZ18, which is listed a replacement for the AUY21. It has a higher voltage rating, and a lower base current to make it turn on.

I could not find any reference to the letter K at the end of the designation. My feeling is that it a grading as to gain, probably requested by the purchaser.

Yours if you need it.

You have my details.

Regards

Wayne.


 
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