Need some help troubleshooting

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Need some help troubleshooting

Postby leonc » Fri Sep 26, 2014 2:52 pm

I've completed assembly, I think, but I've hit a snag when going through the low power testing cycle. The interruptor is in "on" and "fixed". I see that it generates a steady light, and when I turn the power knob, the light gets brighter or dimmer appropriately.

When I plug in the main board, the blue and red LEDs come on. However, when I plug the fiberoptic cable in to the main board and the interrupter, the green LED on the main board doesn't come on or flash as the testing instructions indicate that it should.

Other than "everything", any tips on what to check?

Thanks in advance for any help.

- leon
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Re: Need some help troubleshooting

Postby E.TexasTesla » Fri Sep 26, 2014 9:51 pm

The green LED may be very dim because it's PWM at a high frequency.
Can you hear any noise from the gate transformer? Faint buzzing?
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Re: Need some help troubleshooting

Postby Frost273 » Sat Sep 27, 2014 7:57 am

Check the soldering.
Try using a flashlight instead of interrupter and fiberoptic cable - the green LED should be steadily bright.

If it's not..
Could you have pulled three pin optic receiver out of it's plastic box while soldering?
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Re: Need some help troubleshooting

Postby Alex » Sat Sep 27, 2014 3:54 pm

remove all 4 of your IC's and see if the problems persists.
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Re: Need some help troubleshooting

Postby leonc » Tue Oct 07, 2014 6:42 am

E.TexasTesla wrote:The green LED may be very dim because it's PWM at a high frequency.
Can you hear any noise from the gate transformer? Faint buzzing?


Thanks for the idea. There is no buzzing that I can hear.
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Re: Need some help troubleshooting

Postby leonc » Tue Oct 07, 2014 6:44 am

Frost273 wrote:Check the soldering.
Try using a flashlight instead of interrupter and fiberoptic cable - the green LED should be steadily bright.

If it's not..
Could you have pulled three pin optic receiver out of it's plastic box while soldering?


I tried a flashlight and the green LED didn't light. I might have screwed up the receiver but I was trying to be careful with it when I was building it out. Maybe I just didn't solder it in well?
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Re: Need some help troubleshooting

Postby leonc » Tue Oct 07, 2014 6:46 am

Alex wrote:remove all 4 of your IC's and see if the problems persists.


After removing all four ICs I still had the same behavior. When I took one of the smaller, 8 pin ICs out I noticed that one of its legs had folder under. I thought I'd try to put them back in (with _all_ the legs in this time) to see if it helped, but I broke one of the pins off one of the big ICs.

So I'll need to get another one.

Any ideas what else to check while I'm waiting?
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Re: Need some help troubleshooting

Postby Alex » Mon Oct 13, 2014 12:41 pm

if all of your IC's are still out and your LED isn't lighting, and your LED isn't backwards, your receiver may have died.
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Re: Need some help troubleshooting

Postby dale » Tue Oct 14, 2014 7:39 pm

OK I see arcing between silicon pads on driver heat sink ! and popping noise also. :shock:
not sure why yet......

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Re: Need some help troubleshooting

Postby Alex » Wed Oct 15, 2014 8:33 pm

is the silicon pad covering the entire back of the IGBT?

are you using thermal paste? (you don't need it and it may also cause arcing.)
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