Need Help Troubleshooting Gen7 1.4 Board

Hey everyone,

I have been having some problems getting my electronics working. Okay, so I have just finished soldering the main board today, everything looks fine but when I connect it to the power supply all that happens is the standby LED faintly flashes. The PSU also makes a very faint clicking sound and the power LED on that also flashes. It seems the problem is not with the PSU because it works fine when I connect it to a computer or just disconnect it from the board. There seems to be no visible damage to any of the components and the soldering looks fine. Anyhow, I proceeded to the 3rd step of the power supply checks and when I shorted the wire bridge with the top right pin of the ATmega socket all that happened was the Standby LED stopped flashing.
Hope someone out there can throw some light on the problem for me.
Thanks in advance.

Leo.

Quote

when I connect it to the power supply all that happens is the standby LED faintly flashes.

Looks like you have a short between 5V Standby and GND or similar and the PSU's overload protection kicks in.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Thanks for your reply.
So I measured the resistance between the stand by LED and ground and I couldn't find any evidence of a short. It just shows 980 ohms which I think right . Everything else also seems to be ok to.
Leo.

The green 5V LED shouldn't light up with the PSU just connected. I'd start with having the ATX20/24 connected only, all jumpers off, then searching why the green LED gets juice. Requires some patience and re-checking all the findings and assumptions. Usually, the problem is quite visible, still hard to find.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

A few people have made the mistake of connecting the green power on signal to the grey power good signal. That causes the PSU to oscillate.

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[www.hydraraptor.blogspot.com]

nophead Wrote:
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> A few people have made the mistake of connecting
> the green power on signal to the grey power good
> signal. That causes the PSU to oscillate.

Yeah I think the PSU is oscillating so I could have made the mistake that your talking about but could elaborate on what you mean by "connecting the green power on signal to the grey power good signal" sorry it's just I'm not super knowledgeable of this kind of stuff.

On Gen7 the connections are on the PCB so what I said probably isn't relevant in this case, sorry.

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[www.hydraraptor.blogspot.com]

Oh okay then, don't worry about it i'm just going to have to do what Traumflug said then. Thanks anyway.

Edited 1 time(s). Last edit at 06/19/2012 10:26AM by Leo94.

I think I may have found the problem! But I could be wrong. From what I can tell some of the pins of the jumper headers are connected to ground. I'm assuming that's the problem. If so how can I go about fixing it? Because I just cant see how they are connected to ground.


The pins in question.

The left pin of the upper jumper header and the right pin of the lower one? These two are both 5V Standby.

To find the problem, take this picture: [reprap.org] , follow the track and watch it very closely. Also the part of the track going through L1. In the worst case, you have to desolder L1, R30, C14 and both wire bridges; then you have the bare track.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

I desoldered L1 and the problem seems to have been fixed So what do I have to do now? Do I juat need to replace L1?

Thanks for your help by the way.

It's unlikely L1 it's self is the culprit. How would a coil manage to short to GND, if defective?

The problem is on the track behind that coil. I'd continue with desoldering the wire bridge below R8. If the problem stays, the short is between L1 and that bridge. If the problem goes away again, the short is behind the bridge.

Make your way along the remaining track, simple strategy. There are a few capacitors on that remaining track which connect to GND. Capacitors can short out if blown, making a wire-bridge equivalent.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Yeah that makes sense now I think about it.
Well I did what you said and followed the track and I removed C19 and the problem was still present so I then removed the wire bridge which is further up the track and the problem is still present. I have checked all my soldering and I cant find any problems especially around the area between C19 and the bridge. So from what I can tell there short is some ware between L1 and the bridge and that is with C19 removed. I can't think of what to do next. Any ideas?

I'd remove the ATmega and use an ohms meter to see wether there is some connetion to somewhere else /surrounding tracks. If not, well, it's time to consider an ATmega replacement.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Do you mean reomve the whole socket for the ATmega??

I mean removing the ATmega it's self. The socket shouldn't add any connections.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Oh good because that would have been a pain. Anyway I have never even put it in because I can't complete the testing, I don't want to break it.

Edited 1 time(s). Last edit at 06/27/2012 06:50AM by Leo94.

Quote

Anyway I have never even put it in

No ATmega, yet? Then you have a short on this track between L1 and the bridge below R8.

I mean, from the electronics view you simply add a piece of wire/copper to one of the pins of the ATX20/24 connector. There's no reason adding a piece of wire would change behaviour of anything.

BTW., do you have a load on the 5V rail? Connecting an old CD drive or a 12V lamp between 5V and GND sometimes makes PS PSUs happier.

You could also put a photo of your work here, perhaps we see more than you.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Traumflug Wrote:
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> I mean, from the electronics view you simply add a
> piece of wire/copper to one of the pins of the
> ATX20/24 connector. There's no reason adding a
> piece of wire would change behaviour of anything.

I'm not sure what you mean. Add it to which pin? and connect it to what? and why? Can you give me a bit more detail please.

Edited 1 time(s). Last edit at 06/29/2012 07:45PM by Leo94.

Hello? Oh by the way someone told me that it could be a board it's self that I cant see. Do you think that may be the case?

If you simply can't get it to work, you can send me the board and I'll fix it. Usually I do this for the price of the postage stamp required to send it back.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY