Help needed with Brauduino

[Ramps]

Firstly Thanks guys (especially Matho) for the development and all the work on the Brauduino and all the support from the forumites
I have have been slowly building my Braumiser over the last 6 months or so (pics will come soon to display some of the novel approaches I took to utilising stuff I had)

I'm at the testing stage after fixing all the leaks

The problem: the heater is permanently on

The scenario:
power on ... all good
Brauduino displays correctly
Can move to manual mode ... all ok with correct prompts
Can turn pump on/off ... with green LED lighting appropriately
Can't switch heat on or off and no red LED lighting to indicate "heat on"

Noticed
a) heat was rising and displaying correctly on screen
b) heat would go on as soon as power was switched on regardless of mode
c) led built into the SSR was also always on
d) in Manual mode cannot use button to turn heat off/on (pump works and the actual heat button is functional ... in order to get it this far)

History
when first install I couldn't get the heater to turn on at all (and in manual mode button wasn't turning heat on/off)
power at Arduino pin 9 when it was meant to be
traced power up to transistor continuity resistor to transistor etc
figured it might be faulty transistor (or soldering :unsure: ) so changed it over ... now it turns on ... but won't turn off!!!
re-loaded Braudino2.ino ... no change

ideas please as I'm itching to try my first all grain (this w/e ... with some good advice and a bit of luck!)
Am I missing the obvious??

Cheers
Ramps

 

[mr_wibble]

Have you checked whether pin 9 is actually always on now ?

At least knowing that separates the problem space into circuit and arduino.

If it was me who did the job, this is what I'd check (note: these are guesses):
- A micro solder bridge or suchlike
- The new transistor is stuffed
- The new transistor is not quite installed correctly (my usual trick is backwards)
- Maybe there could be enough leakage current on pin 9 to switch the transistor?

I'm not familiar with the braudino circuit.

I drive my SSRs straight from the arduino. Can your SSR switch on low voltage? Maybe you could temporarily wire the transistor out of the circuit to test.

Hope some of this helps.
Usually it doesn't, but it pushes your thinking around to where the problem is.

cheers,
-kt

 

[MastersBrewery]

agree with above, insure all your solder joints are good and not crossing adjacent pins. To help those in the know a close pic up both sides of your board, also which version is it? Did you build your own arduino? what brand and what amperage are your SSRs?

ED you will find quicker responses if you post in the controller thread as those that can help have that thread on notifyhttp://aussiehomebrewer.com/topic/59563-mathos-controller/page-48

 

[Ramps]

thanks MB I'll pursue the Matho's controller thread but thought it might be lost in the 48 pages!
Thanks also to you Mr Wibble, yeah the pin 9 on the Arduino is turning on/off correctly according to the program (4.99 and 0v respectively)
will further asses the transistor (and then removing it as the SSR is 3-24V (but does the arduino pump out enough current?)
quite confident the transistor is installed the correct direction
while I thought it might be that the first transistor might be faulty, what's the chance that two in a row would be?

Will now do some more digging and if the prob exists will transfer this thread to the Matho's controller thread with some pics
Thanks guys

 

[MastersBrewery]

note the reason I asked about the SSRs was some of the cheaper brands can fault out at or close to rated amps, so if your pulling 10 amps on the heater you should really be using a 25 or40amp SSR.

It may be worth while isolating the SSR from dc to see if it has failed as SSRs fail in the closed position when they fail

 

[Ramps]

Thanks again... good call ... yep pulling close to about 9-10 Amps (2200W element)

SSR: Fotek SSR 25DA (25 Amp)

removed transistor:

12v across emitter/collector on the PCB (with transistor removed)

-2v at base when "off"

does that sound right as the other transistors showed zero across E/C ???
Ramps

 

[booargy]

if it is showing 12v it means the component is high resistance

 

[Ramps]

thanks boo
in this case ... with the trans removed I'd expect there to a a fairly high resistance
I also found that if I touched the emitter and collector pins (no base pin in contact) to the "right holes" the power went on to the SSR immediately, is this right? I would have thought that there would need no be power on the the base in order for power to flow from E to C?? ...too many years since I played around with very basic electronics.
Cheers
Ramps

 

[mr_wibble]

The arduino can sink 20mA ok through an I/O pin, 40mA is the the absolute maximum rating.
There are limits for the combined steady-state current too depending on the pin grouping ~ http://playground.arduino.cc/Main/ArduinoPinCurrentLimitations

 

[mr_wibble]

I also found that if I touched the emitter and collector pins (no base pin in contact) to the "right holes" the power went on to the SSR immediately, is this right? I would have thought that there would need no be power on the the base in order for power to flow from E to C?? ...too many years since I played around with very basic electronics.

Have you double-checked it's the right flavour of transistor for the one replaced? NPN / PNP etc.

 

[Ramps]

.. will look into the current draw of the SSR...looks good at 4-20mA and just saw a youtube vid of someone running the SSR straight from an Arduino
So Arduino direct to SSR is a viable proposition then

transistors:

Old one
"P2N2
222A
A08"

New one
"2N 2222
-108"


both plastic

 

[mr_wibble]

Hmm, those two transistors they seem to be much the same thing, so it's not that.
(they probably only differ by manufacturer)

 

[Ramps]

I'll have another go at it tonight ... or tomorrow
I found post number 562 (page 29) on "Matho's controller" thread as I've been slowly making my way thru it
Looks like someone with a similar issue ... and some good tests to try (which I may not get to tonight
Thanks guys
Ramps

 

[Ramps]

I may have a solution ... checking out Matho's instructions to a similar prob

 

[Ramps]

I'll have another go at it tonight ... or tomorrow
I found post number 562 (page 29) on "Matho's controller" thread as I've been slowly making my way thru it
Looks like someone with a similar issue ... and some good tests to try (which I may not get to tonight
Thanks guys
Ramps

Sorry about that way trying to add the link but stuffed up ... so have it twice :lol:

 

[booargy]

Have you tested the SSR? I had one from Auberins that was DOA.

 

[Ramps]

SSR seems to be OK
no power from the controller board (ie no transistor) ... no LED light on the SSR ... no heating of the element
good suggestion though

 

[Edak]

So let me get this straight, your first post indicated that the LED (between the arduino and the SSR) was off but the SSR was on? This would indicate a bad transistor.
You have since replaced the transistor (beware that not all transistors have the same pinout), so check yours from datasheet.

Post #6 doesn't make sense to me, the fact that you measured a -2 at the base of the transistor is completely wrong, you should have no negative voltages in this circuit unless you were measuring wrong or something is faulty.

To me, everything points to the transistor being blown or wired incorrectly.

Remember, if that LED (on the board, not SSR) isn't conducting (lighting up) then the transistor is not going to turn on, if the SSR is on when the transistor is off, you have a wiring problem or a transistor problem.

 

[Ramps]

Thanks Edak for coming to the rescue
I have never seen any light from the installed LED whether there is power at pin 9 or not (and pin 9 seems to be doing the correct thing ... manual mode,lower temp than setting and "heat" button pushed, power at pin 9 ... when heat button pushed a second time pin 9 goes to zero volts).

Yes a the moment, when the transistor is installed ("new" one removed at the moment) the ssr led is on as soon as the power is on (might be the opposite E/C pinout as you pointed out ... and Matho discovered ... will look int that tonight)

as far as the -ve voltage at the base pin ... prob my stuff up will look into tat again tonight

checked LED and is wired up the correct way according to the +/- on the PCB

Initially no light, no heat figured it was a dicky transistor so changed it over, now no light but non-stop heat as soon as power is on to unit ...even if base pin of transistor not connected

Tonight
check pin on transistor (brand unknown so difficult to check data sheet ... all 2n2222 sheets I've seen have the same pin configuration)
check power to LED
Check LED functionality
Then check the voltages at the transistor

Sound about right??

 

[Ramps]

Success

After running thru Mathos's troubleshooting for someone who had a similar issue, it has been solved

Firstly the LED was faulty ... no LED, no current of the base of transistor

Secondly the transistor that I replaced the first one with was one of those odd ones with the emitter/collector pins the wrong way around :huh:

All good now so after a test with water on Saturday and then (if all ok) grain on Sunday ... lookout AG club here I come!


Thanks for you feedback/ideas

especially Thanks to Matho, Edak, and Lael (for organising the pcb and electronics) for all their efforts


Cheers guys :super:

Ramps