I have come across an old split system air-conditioner with a failed A105 Germanium transistor on the remote control input by the looks? It belongs to a neighbor who asked me if I can fix it, he had a quote of $1,200 for just the board? He said that he found a dead Gekko on the board and I noticed burn marks around the A105 transistor which I then gave a diode test and found it had gone to transistor heaven. We will now respectively observe 1 minute of silence.................sniff, sniff! lol, I see there are substitutes for the A105 that may be easier to get but are they suitable for this circuit? I'm out of my depth here, this is foreign territory, can someone help me with this, please. 
WHICH looks?
Show a picture.
This hints at a modernish circuit which would NEVER use a Germanium transistor, which fell out of favour around 1965/70 never to return.
You are probably misreading the code, post a picture.
Ouch!!!! Ugh!!!!
Sadly I´d expect more damage than just a dead transistor, but let´s start with a ....
Please state AC brand and model , a picture of the ID/serial number plate, maybe somebody here working with AC can be more specific.
Thanks for all the info fellas. The transistor is marked with A105, underneath that it says M.704. I've tried photographing it with my phone but the lettering is too small? My good camera won't upload photos to my computer? The transistor is on the right-hand side of the photo next to the white connector. So I should be right if I order a 2SA105 transistor from someone like Digikey then?
Attachments
I have never seen a germanium transistor in a plastic case. Nor have I seen one made after the commercial introduction of integrated circuits.
Why do you think it is a germanium transistor?
The 2SA105 is in a metal TO5 case.
The important issue is to trace enough of the circuit to identify the emitter, base and collector. Then most likely any common NPN silicon transistor can replace it. By the case size it is a very low power transistor. So anything rated above 50 volts should work.
Why do you think it is a germanium transistor?
The 2SA105 is in a metal TO5 case.
The important issue is to trace enough of the circuit to identify the emitter, base and collector. Then most likely any common NPN silicon transistor can replace it. By the case size it is a very low power transistor. So anything rated above 50 volts should work.
Last edited:
Why does it look like somebody barfed all over the legs? I know, geeko, but why just there? Even a New Jersey cockroach is bigger than those legs. (Yes, I have shoveled roaches (not pot-butts) out of tape players.)
There's no way that is Germanium in that package.
> I'm out of my depth here, this is foreign territory, can someone help me
Not until you say WHAT "territory" you are in. Panasonic? Swampcooler? Carrier? 1990s? 1940s?
There's no way that is Germanium in that package.
> I'm out of my depth here, this is foreign territory, can someone help me
Not until you say WHAT "territory" you are in. Panasonic? Swampcooler? Carrier? 1990s? 1940s?
THIS is a Germanium 2SA105
Early 60´s vintage, GLASS case (everybody still made tubes way back then), painted or sleeved body (or transistor would work as a phototransistor).
Model ID is SO old that it can be recycled with no damage or confusion, I had to pull data from RadioMuseum, go figure:
2SA105, Tube 2SA105; Rohre 2SA105 ID60876, Transistor
This is what you have, modern plastic body SILICON 2SA105, cheap Korean Made general purpose transistor.
or:
same thing.
Early 60´s vintage, GLASS case (everybody still made tubes way back then), painted or sleeved body (or transistor would work as a phototransistor).
Model ID is SO old that it can be recycled with no damage or confusion, I had to pull data from RadioMuseum, go figure:
2SA105, Tube 2SA105; Rohre 2SA105 ID60876, Transistor
This is what you have, modern plastic body SILICON 2SA105, cheap Korean Made general purpose transistor.
or:
same thing.
The Superimposed transistor in the photo is Germanium according to my VRT Asia Pacific Transistor book. The A106 is the same as the A105 except that the former is 30mhz and the latter is 75mhz. But then again it is for a 2SA105 and not an A105? That is where the confusion comes in! Anyway, the white connector is labeled Central, it goes to the A105 transistor then to an eeprom (the eeprom had a sticker on it but the ID underneath was sanded off) and then to a microprocessor looking thing underneath?
Attachments
Sorry if I was not clear.
"A105" IS 2SA105
"2S" is a given so it´s not printed if there is little space available, but of course you need it for a search..
The one your transistor manual mentions is a 60´s Germanium transistor, meant for Radio Frequencies in early transistor radios.
Its case was:
clearly not yours.
I *guess* any General Purpose Silicon transistor will do, but be aware it´s "Japanese" (even if made in China or Korea) which have a different pinout from "American" and "European" ones so get the datasheet nd check pinout.
Not to be evil, but maybe you have more damaged components than just that transistor.
Of course, you might get lucky
EDIT: this page clarifies it ... sort of.
"A" / "2SA" series Japanese datasheets?
Maddeningly, it shows transistors from (2S)A106 and higher
IF somebody recognizes this manual ......
The page also mentions the confusion caused by name recycling.
"A105" IS 2SA105
"2S" is a given so it´s not printed if there is little space available, but of course you need it for a search..
The one your transistor manual mentions is a 60´s Germanium transistor, meant for Radio Frequencies in early transistor radios.
Its case was:
clearly not yours.
I *guess* any General Purpose Silicon transistor will do, but be aware it´s "Japanese" (even if made in China or Korea) which have a different pinout from "American" and "European" ones so get the datasheet nd check pinout.
Not to be evil, but maybe you have more damaged components than just that transistor.
Of course, you might get lucky
EDIT: this page clarifies it ... sort of.
"A" / "2SA" series Japanese datasheets?
Maddeningly, it shows transistors from (2S)A106 and higher
IF somebody recognizes this manual ......
The page also mentions the confusion caused by name recycling.
Last edited:
That's not 'A105' but 'M05' or 'M06' where the M is the Motorola logo!
The next line is a smudge and 'TBG' (To Be Good ???).
I would say a general silicon, solder it out and determine pnp/npn, the basis and the beta (in that order). The highest beta determines which of the other legs are the c and e.
edit: post #11
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.