ICE TUBE:low voltage w boost controller chip

[mattkpetersen]

I'm having trouble getting my ice tube kit working. Without the VFD boost chip in, I'm measuring 56.5V at D3. But with the chip in it's very low. About a half a volt. Attached are pics of the assembled board.

[adafruit_support_bill]

There is usually a substantial drop with the VFD chip installed, but 1/2 volt is way too low. Can you post a more detailed shot of the solder side of the VFD-half of the board?

Also, on the smaller board there is an AC logo and then a 4 digit number, what does yours say?

[mattkpetersen]

The number is AC-03 3511. Attached is a close up of that half of the board. Let me know if the image is too poor and I'll scare up a better camera. Thanks.

[adafruit_support_bill]

A better image would be helpful. I see what looks like some cold joints to the right (frosty appearance). But I think what we are looking for is a short somewhere in the vicinity of the VFD chip and tube-header.

[mattkpetersen]

Here is a better image. I've already gone through and checked for shorts and resoldered any suspicious or frosted looking joints. But I don't really have enough experience to know exactly what a bad solder looks like.

[adafruit_support_bill]

That's better. I don't see any obvious shorts, but there are some solder spatters that should be cleaned up before they work loose and cause a short.

Are you still getting the 'beep' on power up?

[mattkpetersen]

I do get a beep on power up. Do I just brush off the spatter with a firm bristled brush? Also, I didn't take out the controller chip before I reworked the soldering on the socket. Could the heat have damaged it? Thanks.

[adafruit_support_bill]

If a firm-bristled brush doesn't do it, the tip of a knife should work. Too-long with a hot-iron can damage a chip. But I don't see an excessive amount of burnt flux, so that may not be case here.

[mattkpetersen]

How do I verify that the chip is good? Or is there some standard procedure to go about troubleshooting the kit? I'm a bit over my head here. My only experience with this sort of thing was a college physics lab several years ago.

[adafruit_support_bill]

About the only practical way to verify it is to test it in a known good clock - or swap a known good chip into your clock.

Let's start by carefully removing the chip and seeing if your boost voltage goes back to normal. Work slowly with a thin-bladed screwdriver and be careful not to bend any of the spring-contacts in the socket.

[mattkpetersen]

Without the chip the voltage is 56.6V at D3.

[adafruit_support_bill]

OK, so your boost circuit is still good.

With the VFD chip in place, is there any drop in the 5v supply voltage?

[mattkpetersen]

There is a drop. Without the chip I measure 8.9V and 4.9V on the first and third pin of the 7805 respectively. With the chip in I measure 1.0V and 0.0V on the first and third pin.

[adafruit_support_bill]

OK. does either the fuse or the voltage regulator get warm when that happens?

[mattkpetersen]

The voltage regulator does not, the fuse becomes too hot to touch.