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Need help with part

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cidium

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I have no specs for the diode in the trggering circuit. I need to replace the diode and the ref # KV619 printed on the diode isn't matching up anywhere. I was wondering if someone could lend some information on what the specs should be for this diode. The diode is labeled with ( ? ) on the schematic. Here are the values for the rest of the strobe circuit.
R1.........10 ohm
R2........ 2200k
R3.........1500k
R4.........1800k
R5.........1100k
C1.........7u 250v
C2.........9u 250v
C3.........(.047uf 250v)
No value for R or L

**broken link removed**[/img]
 
cidium said:
I have no specs for the diode in the trggering circuit.

The way it is used suggests it highly likely to be a DIAC that is common in triggering SCRs. Try your local component store for suitable diac.
 
I tried that

I have tried local stores they can't cross ref the number KV619 to anything. I have no idea on the secs for this doide - so what do I do?
 
Re: I tried that

cidium said:
I have tried local stores they can't cross ref the number KV619 to anything. I have no idea on the secs for this doide - so what do I do?

Did they have any diac's at all?. Most of the ones I've ever seen are pretty similar, a slightly different spec would probably only alter the speed.

Where did you get the circuit from anyway?.
 
I went back to the store

They had 4 diacs total and the top diac was 70v max I think my circuit is 230v so I'm not sure if this is going to work. I have asked everyone and even some electronic suppliers on the net about the KV619 and no one has a clue - how can this happen? The circuit came as a strobe light, from an interent supplier, the brand is visual effects inc. I have done a search for this company and can't find anything on them either. The reason why this diode blew is because, I'm stupid. I have 3 units and I was trying to chain all three together so they would fire at the same time. I took 2 and wired them, this is where I become stupid, and fried the a trace and diac on both boards. The trace is easy to fix, but the diode is proving harder to fix. So now I have 2 units with no triggering and one that does. I might forget trying to fix the fired 2 and continue to work a solution for the triggering. Since I only really need one for triggering maybe I should stay focused on the original idea. What really hurts is these strobes retailed for 8.99$ and I have spent more than in time and buying replacement parts. If you think a diac rated at 70v max would work I'll try that.
 
Re: I went back to the store

cidium said:
They had 4 diacs total and the top diac was 70v max I think my circuit is 230v so I'm not sure if this is going to work. I have asked everyone and even some electronic suppliers on the net about the KV619 and no one has a clue - how can this happen? The circuit came as a strobe light, from an interent supplier, the brand is visual effects inc. I have done a search for this company and can't find anything on them either. The reason why this diode blew is because, I'm stupid. I have 3 units and I was trying to chain all three together so they would fire at the same time. I took 2 and wired them, this is where I become stupid, and fried the a trace and diac on both boards. The trace is easy to fix, but the diode is proving harder to fix. So now I have 2 units with no triggering and one that does. I might forget trying to fix the fired 2 and continue to work a solution for the triggering. Since I only really need one for triggering maybe I should stay focused on the original idea. What really hurts is these strobes retailed for 8.99$ and I have spent more than in time and buying replacement parts. If you think a diac rated at 70v max would work I'll try that.

That seems a pretty high voltage for a diac, the common one I've used in the past was the BR100 rated at 32V (and it's not max, it's the trigger point - similar to a zener diode), it certainly shouldn't be anywhere near 230V - it's used as a crude relaxation oscillator, with the pot altering the charging current/voltage.
 
side by side

here are the two diodes side by side. As you can see the newer one is smaller - not sure if that means much. If you look at the blown one you can see the KV on the outside. This is becoming a labor of love trying to figure out what this is.....

Sorry for losing the specs on the diac, I'll post them

Part # NTE6412

I pulse - 1.5a max
I(bo) - 50 ua max
V(bo) - 56v min to 70v max
^V(b0) - 4v max
Pd - 250 mw <--------- this concerns doesn't seem high enough
 

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The 'KV' looks very crudely applied, I wonder if that's why you can't find anything about it?, it could well be an 'in house' number - used purely by the manufacturer of the strobe.

I should try the diac you can get, and see if it works?.
 
Looks more like a power zener (or tranzorb) to me. Diac's don't (look like this) and have a band on the one side. If they have one it is normally in the middle. Also looking at the circuit with the diode at the top will make current flow only in one direction, so it is possible that they are using a power zener (or tranzorb) here.

It can easily be verified if you remove one of the other working boards. You need a series resistor (a few k-Ohms) to limit the current and a power supply to provide about 50V. Using a voltmeter across the device will indicate at which voltage it clamps and by reversing the device will prove if it is a zener diode or a bi-directional device. Or make the measurement over the device of the working PCB with a scope if you have one. You will need an isolation transformer or float the scope's GND for this measurement, so be careful!
 
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