Help identify component

[imaddicted2u]

Trying to identify the component in the pic. It's in an old car battery charger.

[R_J]

Re: Help identify component

Looks like it is a UJT 2N2646 should work
I found the information here: https://forum.nutsvolts.com/viewtopi...0809b&start=15
Is it bad or does it just check strange?

[imaddicted2u]

Re: Help identify component

Hey, thanks for that. I turned the internet upside down looking for that and nothing fell out...lol. I dig around and see if I have one. Thanks again.
Haven't tested it yet. Didn't know what it was.

[imaddicted2u]

Re: Help identify component

Looks like it is a UJT 2N2646 should work
I found the information here: https://forum.nutsvolts.com/viewtopi...0809b&start=15
Is it bad or does it just check strange?

Tests bad, thanks again.

[R_J]

Re: Help identify component

It won't check like a normal transistor. But if it checks shorted, it will be bad. http://www.circuitstoday.com/testing-a-ujt

[imaddicted2u]

Re: Help identify component

Right, it checks like 2 diodes. It measures open every which way.

[imaddicted2u]

Re: Help identify component

That last post reads kind of funny...
The UJT should check like 2 diodes but this one measures open every which way. The only other semiconductors in the battery charger, 2 SCRs and 1 zener diode test ok.
Thanks R_J for being ever helpful. It's much appreciated.

[redwire]

Re: Help identify component

I have some 2N4871 UJT. The only readings I get on diode-test is between E-B1, and E-B2 around 0.98V, +ve to emitter.

There should be an RC phase-delay and the zener must be to back off when battery voltage gets up there.

[imaddicted2u]

Re: Help identify component

Here are some pics in case you are interested. It's a Motomaster model 11-1519 battery charger, 12 volt at 6 Amps. The circuit board has Tenatronics Ltd. 50-114 etched on it. They seem to be from Newmarket, Ontario.

The transformer that feeds the board is a 27 volt center tap.

[redwire]

Re: Help identify component

It looks not bad, anything beats selenium rectifiers lol. Not hard to sketch a schematic. In the late 1970's lots of GE circuits for SCR chargers.
The blue Philips electrolytic caps, I find they don't last.
It probably eats SCR's if you short the output.

It looks more like a "programmable unijunction transistor" circuit?
Like this but drives two SCR's.

[imaddicted2u]

Re: Help identify component

It looks not bad, anything beats selenium rectifiers lol. Not hard to sketch a schematic. In the late 1970's lots of GE circuits for SCR chargers.
The blue Philips electrolytic caps, I find they don't last.
It probably eats SCR's if you short the output.

LOL, I thought I was the only one that remembered selenium rectifiers...When my neighbor dropped it off yesterday, I said, I hope that thing doesn't have a selenium rectifier...lol.
The SCRs were soldered before I got it so they may have been replaced. I think whoever soldered it before used acid core solder.
The only protection is a little glass self resetting breaker in the output, I doubt it's much help for reverse polarity.

[stj]

Re: Help identify component

i see them still, in old jukeboxes.

[imaddicted2u]

Re: Help identify component

I already ordered a couple of 2N2646 UJTs based on the link provided at the start of this thread since I can't cross the original part directly. If it turns out to be a Programmable I'll get one of those. I think I'll sketch it out when I get some time.

[imaddicted2u]

Re: Help identify component

i see them still, in old jukeboxes.

Funny you mention jukeboxes. When I was in school taking electronics in the mid 70s our class project was to refurbish a 50s jukebox.

[redwire]

Re: Help identify component

Motorola SU316 unijunction transistor. No NTE cross (like a SU112), not in my 1980 Motorola datasbooks. MPU131, 2N6027 are.
Also in this thread about Sears 10A battery charger: https://forum.nutsvolts.com/viewtopic.php?f=45&t=8342
But images gone due to third party aholes
The guy did not get the 2N6028 PUT to work, but 2N2646 UJT did ok.

[R_J]

Re: Help identify component

I found another circuit that uses a 2N2608 (SU316), with the SU316 listed in brackets in its parts list, so it might just be a fet?

[R_J]

Re: Help identify component

But the circuit does look closer to this, using ujt
The parts list I refered to was this one, the (su316) might have different meaning in this case

[redwire]

Re: Help identify component

I drew a schematic and it looks like a voltage-controlled oscillator that pulses the SCRs (trigger transformer). I'd guess it's a UJT or PUT.

I think the circuit has some issues... The snubbers are sort of terrible to have AC on electrolytic caps, and the zener should get supplied not from the trimpot. Unless I have drawn it wrong.
Why are the SCR's on an insulator but not the mounting screws? I think that would short the power transformer?

[imaddicted2u]

Re: Help identify component

I drew a schematic and it looks like a voltage-controlled oscillator that pulses the SCRs (trigger transformer). I'd guess it's a UJT or PUT.

I think the circuit has some issues... The snubbers are sort of terrible to have AC on electrolytic caps, and the zener should get supplied not from the trimpot. Unless I have drawn it wrong.
Why are the SCR's on an insulator but not the mounting screws? I think that would short the power transformer?

Thanks everyone for your efforts...
I didn't get notifications for these updates for some reason.
I drew this over coffee this morning.
This is a little more rudimentary than yours but here is my rendition...
edit...made corrections to original drawing

edit: adding pic of back of PCB lit up to see traces better.

The SCRs are isolated but from the back side.

[Willybb]

Orientation of 2N2646 Component.

Hi Guys

I am trying to fix one of these Canadian Tire Battery Chargers. Found your article and I'm taking a chance that my Battery Charger has the same issue as yours did. Ordered a replacement 2N2646 Transistor. Having issues figuring out the correct pin layout for the 2N2646 I seem to get conflicting Case/Pin layout for this component.

Questions
(1) Is the attached picture the correct pin layout?
(2) What is the correct Case for this part?

Thanks for your help
Willy