Update: The transistor with 3D marking is really an NPN, not a PNP.

I found the exact model at https://www.google.com/search?q=pnp+3d+transistor&tbm=isch&source=univ&sa=X&ved=2ahUKEwiYyZ3bhfrfAhUTh7wKHe3MC-wQsAR6BAgEEAE&biw=1046&bih=501#imgrc=rq_3nUYyqfy3_M:

Datasheet here: http://www.secosgmbh.com/datasheet/products/SSMPTransistor/SOT-23/MMBTA44.pdf


Please help identify these parts:

PCB photo

Is that back thing on the upper left an SCR? What kind of SCR? It's so tiny and has 3 D written on it. I assume the terminal left of it is the anode, and the top terminal on right is the cathode, and the bottom terminal the gate? Or is it not an SCR?

In lower colorful diodes. Are these Zener diodes? Where is the cathode of the one in blue? Why is the glass fat and in blue?



closed as unclear what you're asking by Elliot Alderson, RoyC, Dwayne Reid, Finbarr, Edgar Brown Jan 21 at 22:42

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  • \$\begingroup\$ Unfortunately, neither of these questions are really answerable. All you'll be able to get are guesses. The thing on the upper left could be an SCR, or it could be a transistor, or it could be a voltage regulator, or it could be an AM radio for all we know. Those diodes could be zeners or conventional diodes; there's not enough information here to tell. I don't know about the blue. \$\endgroup\$ – Hearth Jan 18 at 23:36

Hard to tell with so little information, and it looks like, for some reason, you are deliberately concealing part of the PCB.

It might be a zener in series with a diode in some sort of transformerless power supply from the mains. There’s a chance it’s a 6.2V Zener and the diode is a LL4148. The cathodes have the band, so they are in inverse series.

The Q1 is probably a BC856 transistor based on the 3D marking.

  • \$\begingroup\$ The part of the pcb is an IC that I badly soldered.. lol Here is the full picture... imageshack.com/a/img923/5626/CyqeOv.jpg Pls zoom.. why is the 3 D written on the possible transistor? recognize it? I'm still drawing the full circuit diagram and will update it later. Thanks. \$\endgroup\$ – Jtl Jan 19 at 0:24
  • 2
    \$\begingroup\$ Fair enough, lol. The 3D is a code that can help identify the part number (please note my correction, sorry it’s 4:30 am..). \$\endgroup\$ – Spehro Pefhany Jan 19 at 0:29
  • \$\begingroup\$ Kindly see this post electronics.stackexchange.com/questions/417761/… I spent 3 hours tracing and drawing the additional circuits. What do you think are the ones in blue that can detect fault condition in the main circuit (missing main diode for example) and make the red led lights up? Hope you can post there too. Many thanks. \$\endgroup\$ – Jtl Jan 19 at 2:49
  • \$\begingroup\$ @SpehroPefhany Why sorry? You were right! Lol. OP: More flux less solder! Check some of Louis Rossman's videos on Youtube =) I don't personally own convenient flux-from a syringe. \$\endgroup\$ – K H Jan 19 at 2:49
  • \$\begingroup\$ Note Q1 is connected directly to 240v (the black thick lines). The BC856 can only handle 65v. Kindly take a look at the whole circuit diagram for what they may be.. updated circuit diagram at electronics.stackexchange.com/questions/417761/… or pls. take a look here: imageshack.com/a/img923/8069/Q4gZyu.jpg Thanks! \$\endgroup\$ – Jtl Jan 19 at 14:19

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