Anyone have an estimated emissivity for the IVAC 9000 radiators?

[_Wim_]

Thanks for the fast reply Wim.
I followed in fact your post, put the bridge and powered it even at the same points.
I tested the peltiers and the temperature probes. The uP works since the display works and the ADC also shows activity. The ANDs driving the MFETs seem to work but I didn't yet re-engineer the logic, which I assume ensures the right combination of MFETs of the H bridge to be driven or switch between cooling and heating?

Hmmm, maybe try and put 5V on pin 1&2 of the DIN connector, and wire pin 3&4&5 to ground? Maybe I forgot to document something when I made that post? 

It really does seem like the same issue I had when powering this up.

As to the heating and cooling, I also presume it can do cooling as it has a full H-bridge, but because the regulation does not overschoot I have never seen it do any cooling?

[_Wim_]

Just a question, how much power does it draw when hooked up like above? It could be that this message is displayed as long as it is heating up and not stable in temperature, and it does take quite a while unit is it stable.

The micro and control logic only draw about 50mA, so it your seeing currents in excess of 500mA it is working correctly and heating up the elements.

[_Wim_]

If I remember correctly, the unmodified unit took well over 10 mins to heat up and stabilize...

[_Wim_]

I found the original display in my parts bin and connected it again to my unit, "R0.03 not ready" is indeed displayed while heating up, so that is normal behavior.

[Userli]

Thanks for testing! It's good to know that the controller part is happy and I don't need to worry about this part.

The current is always around 50mA and I indeed left it for quite some time but looking at it with the IR camera, it's clear that the peltiers don't heat at all.

I'll do some more testing on the power part...

[_Wim_]

Hmmm, maybe try and put 5V on pin 1&2 of the DIN connector, and wire pin 3&4&5 to ground? Maybe I forgot to document something when I made that post? 

I checked my unit again, and powering it up with the single solder bridge as shown in the previous post should be ok. So it really seems something is not correct with the H-bridge. Just ask if you need me to measure any voltages on my unit to compare.

[_Wim_]

Maybe another question, how much amps can your power supply deliver? When the H-bridge triggers it draws quite a bit of current (+-5A), and if the power supply sags this will reset the controller causing it to never really heat-up due to the constantly resetting.

[Userli]

Following your explanation, I was indeed wondering about the ground bridge and finally added it.
It makes sense to have the uP and the power circuit somehow separate. However, since the power input is the reference for the MOSFET gates, they have to be related.

My PS is 25V 5A. When powering the peltiers directly they draw less than 2A each, so 5A should be fine to power the whole unit.

I'll do a bit more measuring....

[Userli]

Wim, would you mind to check pins 9,10,11 and 19 on the micro controller (those drive the H bridge as far as I can see)? I only see activity on pin 19.

[_Wim_]

Wim, would you mind to check pins 9,10,11 and 19 on the micro controller (those drive the H bridge as far as I can see)? I only see activity on pin 19.

From top to bottom: 9, 10,11 and 19. Measured just after power up the unit.

[Userli]

Thank you very much Wim!

This is the same for my unit. I re engineered now the path from uP to MOSFETS. (I'll try to draw the schematics and post it here.)
This leaves in principle only the logic gates and the MOSFETS as culprits.
I'll continue measuring tonight...