I have an OC44 transistor that I am putting into a Rangemaster. I have the socket in place but am having a hard time identifying the leads so I know how to orient it in the socket. There are no printed marks or markings molded into the transistor. Two leads are slightly closer to each other but it is just slight. Help?
Here you go.
(http://www.radiomuseum.org/images/tubesockel_klein/allglas_trans_6.gif)
Taken from here
http://www.radiomuseum.org/tubes/tube_oc44.html (http://www.radiomuseum.org/tubes/tube_oc44.html)
Cody
Quote from: selfdestroyer on February 03, 2015, 11:54:54 PM
Here you go.
(http://www.radiomuseum.org/images/tubesockel_klein/allglas_trans_6.gif)
Taken from here
http://www.radiomuseum.org/tubes/tube_oc44.html (http://www.radiomuseum.org/tubes/tube_oc44.html)
Cody
Thanks for that info. Using a magnifying glass I found the faintest circle molded into the side. So now that I have identified the collector (c) can you tell me how to load this into the socket?
(http://i839.photobucket.com/albums/zz320/FenderBuilder/3%20Pin%20To-5%20Transistor%20Socket_1.jpg) (http://s839.photobucket.com/user/FenderBuilder/media/3%20Pin%20To-5%20Transistor%20Socket_1.jpg.html)
I assume that C goes into the hole near the bump in the socket casing (3 o'clock position)? Then does 'B' go into the next hole that is counterclockwise from the 'C' hole (12 o'clock position)? And then the 'E' into the hole in the 9 o'clock position?
That will be entirely determined by what you have each of those sockets connected to in the rest of the circuit.
dave
Dave is correct when he says it depends how the socket is arranged in the circuit. This would be a good time to look a little bit at the schematic.
If we look at Madbean's Rangemaster schematic we will find the PNP transistor where the OC44 transistor goes. The thing to remember is that the little arrow is on the emitter leg. Here's a picture:
(http://i1033.photobucket.com/albums/a420/TGP39/imagejpg1_zpsad954663.jpg) (http://s1033.photobucket.com/user/TGP39/media/imagejpg1_zpsad954663.jpg.html)
Now that you know which leg is the collector.....let's look at the schematic. On the schematic is the OC44 PNP symbol. Going upwards towards the boost pot is the collector. Going downwards towards the R2 resistor (3k9) is the emitter leg. The third leg is obviously the base leg. So now you know the orientation of the OC44 pins (thanks to Cody) and you know the proper orientation of those pins in the schematic. I hope this helps you a little. Don't be afraid to ask any more questions if you need help.
Steve
Thanks guys, this was a big help. My only problem was going from the schematic to the actual PCB. But I think I have it figured out. I'll find out when I fire it up this weekend!
Well,I fired it up and it's not working. No signal passes in the on or off mode. It's quite noisy in the on mode, in fact I am receiving AM radio through it >:( I left the leads on the transistor a little long- about 1/2 inch. Could that be the reason for the radio reception? Also, what would the symptoms of an incorrectly placed transistor be? Like I said earlier the mark on the transistor casing was very faint, so there is a small chance that I misread it.
on the rangemaster board (and most others that use the TO5 style socket you've pictured above) the bump or tag indicates the Emitter. always good to confirm this by comparing the schematic and the board though.
on your transistor, you should have the middle leg (base) closer to one outer leg than the other (as per Cody's picture above). That should help you figure out which leg is the emitter ;)
If you are not getting any signal in the off(bypass) mode, then your transistor is not your starting spot for fixing this build. We need to figure out why you are not even getting a bypass signal. Post some pictures of your build and we can go from there.
Steve.
Quote from: TGP39 on February 08, 2015, 08:27:17 AM
If you are not getting any signal in the off(bypass) mode, then your transistor is not your starting spot for fixing this build. We need to figure out why you are not even getting a bypass signal. Post some pictures of your build and we can go from there.
Steve.
Thank you for the offer to help. I think I will start a new thread for that. I'll try to do that tomorrow with some photos.