HBP reads 255.. :(

[ddurant]

Finished soldering up the MBI HBP last night and tried hooking it up
today. Got a MBI relay board in there, too. RepG 0018 set to Cupcake w/
HBP, latest firmwares.

The control panel says the HBP is at 255C. Onboard prefs say 4198/100k/
25 for the HBP thermistor.

If I set my multimeter thing at 200k and measure the far end (the end
into plugs into the extruder controller) of the 3-pin cable, the meter
says about 80 (it's in the low 80's F here today) if I put the probes
between GND and SIG, the two outside pins. If I then put my finger on
the thermistor, the value starts dropping. I pull my finger away and
it goes back up.

This sounds to me like the thermistor is working but RepG insists it's
255C. :(

Any tips on what I should check? I'm pretty lost here..

Also, if I set the HBP target temp to 300C, all the LEDs do light up..
Yay for that anyway.. :)

[Andrew Plumb]

Looking back through previous posts the most often cause is an open/break in the thermistor wires.

Andrew.

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"The future is already here. It's just not very evenly distributed" -- William Gibson

Me: http://clothbot.com/wiki/

[Mark Cohen]

When that happened to me I unwrapped the tape around the 3 pin connector and
noticed that the pins were pushed in too much and coming out the back of the
connector.

--

[ddurant]

Thanks for the replies!

> Looking back through previous posts the most often cause is an open/break in the thermistor wires.

That was what I figured it was - those thermistor solder pads are
really small! - but seeing the resistance appear to react to
temperature made me think it was ok after all.. I could well be wrong,
though - I'm not sure how that middle 5V pin fits into the thermistor
stuff.

> ..the pins were pushed in too much and coming out the back of the connector.

Hm.. I put a piece of wire into the female sides and get connectivity
between there and the solder ends. I didn't measure the length but
eyeballed the lenghts of the pins on the controller and tried to push
the wire in no more than that..

Also, with the bot & repg on, I get 5.1V between the GND and 5V pins.

Any more ideas?

On Aug 14, 6:33 pm, Andrew Plumb <and...@plumb.org> wrote:
> Looking back through previous posts the most often cause is an open/break in the thermistor wires.
>
> Andrew.
>
> On 2010-08-14, at 6:04 PM, ddurant wrote:
>
>
>
>
>
> > Finished soldering up the MBI HBP last night and tried hooking it up
> > today. Got a MBI relay board in there, too. RepG 0018 set to Cupcake w/
> > HBP, latest firmwares.
>
> > The control panel says the HBP is at 255C. Onboard prefs say 4198/100k/
> > 25 for the HBP thermistor.
>
> > If I set my multimeter thing at 200k and measure the far end (the end
> > into plugs into the extruder controller) of the 3-pin cable, the meter
> > says about 80 (it's in the low 80's F here today) if I put the probes
> > between GND and SIG, the two outside pins. If I then put my finger on
> > the thermistor, the value starts dropping. I pull my finger away and
> > it goes back up.
>
> > This sounds to me like the thermistor is working but RepG insists it's
> > 255C. :(
>
> > Any tips on what I should check? I'm pretty lost here..
>
> > Also, if I set the HBP target temp to 300C, all the LEDs do light up..
> > Yay for that anyway.. :)
>
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> --
>
> "The future is already here.  It's just not very evenly distributed" -- William Gibson
>

> Me:http://clothbot.com/wiki/- Hide quoted text -
>
> - Show quoted text -

[ddurant]

...and, since Mark got me thinking about the connector, I measured GND/
SIG at the *back* of the extruder controller and it still seems to
react to temperature. And I reburned the extruder FW.

I'm starting to wonder if my extruder controller has something cooked
on it.

:(

> > Me:http://clothbot.com/wiki/-Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -

[Rob Giseburt]

Hmm. Good mystery.

First, double check that the header pin and the IC pin are connected.
In this photo, you can see clearly that the signal pin of A6 can be
traced to pin 19 (third from top right of the photo):
http://reprap.org/mediawiki/images/2/2f/Cache-3315133998_03cd8d98b9.jpg

Check for continuity ("diode tester" sometimes) between the header pin
and the IC pin. (Getting the sharp point of the meter against just the
right pin might be tedious, but you don't have to hold it for long.)

Also look for little solder balls or bridges between the other pins on
the chip. If it's a solder ball, a plastic toothpick might knock it
out without much fuss. A bridge will be harder to fix, but is
definitely fixable.

Check to make sure the board and trace itself aren't damaged or
malformed. (You'd see either dents/scratches in the board or
non-mechanically-straight lines under the red mask.)

The board is very unlikely "fried" while still otherwise working. :-)

-Rob

[ddurant]

> double check that the header pin and the IC pin are connected

Checked - got a nice, annoying squeal out of my meter.

To check the other things, I think I'll have to drag it into work,
where we have nice setups for fine soldering.. I'm going cross-eyed
with the headband magnifier things and my teeth hurt from holding the
mini-mag light. I did spot what looked like a blob of solder between 2
pins on the other side of the atmega but after removing that, there's
not continuity between those pins and it's still reading 255C.

> The board is very unlikely "fried" while still otherwise working. :-)

Good news!

On Aug 15, 1:05 am, Rob Giseburt <giseb...@gmail.com> wrote:
> Hmm. Good mystery.
>
> First, double check that the header pin and the IC pin are connected.
> In this photo, you can see clearly that the signal pin of A6 can be
> traced to pin 19 (third from top right of the photo):http://reprap.org/mediawiki/images/2/2f/Cache-3315133998_03cd8d98b9.jpg
>
> Check for continuity ("diode tester" sometimes) between the header pin
> and the IC pin. (Getting the sharp point of the meter against just the
> right pin might be tedious, but you don't have to hold it for long.)
>
> Also look for little solder balls or bridges between the other pins on
> the chip. If it's a solder ball, a plastic toothpick might knock it
> out without much fuss. A bridge will be harder to fix, but is
> definitely fixable.
>
> Check to make sure the board and trace itself aren't damaged or
> malformed. (You'd see either dents/scratches in the board or
> non-mechanically-straight lines under the red mask.)
>
> The board is very unlikely "fried" while still otherwise working. :-)
>
>   -Rob
>

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[ddurant]

Just back from staring at the extruder controller under a microscope
for an hour. Still reading 255C.

There were a bunch of solder balls but most were quite tiny and near
one end of a resistor/LED/capacitor - nothing that looked like it
would it would cause a short. I removed all I could find anyway.

I did spot one trace on the back that looked a little cracked but it
just goes to the (unused) 6-pin connector next to the atmega. It
didn't look really bad - wasn't totally (or even 'mostly') broken.

Still stumped here.. Is it time to contact MBI or is there something
else I can try?

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[Rob Giseburt]

Perhaps you could write a short arduino program to toggle that pin,
then connect an led to it to be sure it's working.

I'd do it and post it but I'm on my phone.

There a 4.7K resistor that must be correctly soldered as well. Double
check it. It's "Step 2."

http://wiki.makerbot.com/cchb1

-Rob

[ddurant]

Thanks.

I brought the extruder controller in to work today and asked a board
repair tech to take a look at it. He said that things looked pretty
'grainy' and he'd try to get some reflow action done over lunch
tomorrow. I'm not sure what 'grainy' means but if he can fix it, I
don't really care what it means. :)

> "Step 2."

The 4.7K resistor is needed for the thermistor to register correctly?
I think that's the one surface mount piece I soldered by hand before
breaking down and getting a hot plate. I'll take a look a closer look
at that one again tonight.

On Aug 16, 6:03 pm, Rob Giseburt <giseb...@gmail.com> wrote:
> Perhaps you could write a short arduino program to toggle that pin,
> then connect an led to it to be sure it's working.
>
> I'd do it and post it but I'm on my phone.
>
> There a 4.7K resistor that must be correctly soldered as well. Double
> check it. It's "Step 2."
>
> http://wiki.makerbot.com/cchb1
>
>   -Rob
>

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[ddurant]

> extruder controller ... reflow action

Well, that didn't fix it. The extruder controller is now all nice &
shiny (which is apparently good) but it's still refusing to read
anything by 255C for the HBP. I also just redownloaded/reinstalled
repg 18, which also didn't help.

Does that 4.7K resistor really come into the thermistor side of
things? I had been assuming that the HBP itself was ok since it was
changing resistance based on temperature at the far end of the 3-pin
cable but I guess I could redo that bit. Aside from that, I'm at a
loss for what else to check.

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[Rob Giseburt]

That resistor changes what temperatures read as, so it's vital. At
this point I'd say it's the prime suspect.

-Rob

[ddurant]

> That resistor changes what temperatures read as, so it's vital. At
> this point I'd say it's the prime suspect.

Muhahahah!!! (Dave does the evil mad scientist laugh)

Just redid the 4.7K and now it seems to work!

I don't get it, though - I'm still reading about the same resistance
when I measure between SIG and GND. How would somebody diagnose this
same problem?

On Aug 17, 11:20 pm, Rob Giseburt <giseb...@gmail.com> wrote:
> That resistor changes what temperatures read as, so it's vital. At
> this point I'd say it's the prime suspect.
>
>   -Rob
>

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[Rob Giseburt]

It’s about the voltage it reads. That’s how the EC reads it. :)

I’m glad it’s working!

  -Rob

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