Who makes "Concordia" micro controllers?

Don't know "Concordia".

Years ago, I had a very big, very expensive NEC laser printer that died because the EEPROM failed-- it didn't get past the initialization routines. Popped in a new 2816 or whatever it was, and it fired right up.

They wanted something like $1500 at the time for a new controller board, which was more-or-less what the printer was worth.

Best regards, Spehro Pefhany

You should, there's one in Montreal :-)

Well, long story short, it just repaired itself. I was probing around, checking the vital signs. After the umpteenth power cycle (to move some probes around without risking a bzzzt) I heard the fan come on and the whole thing came to life. This looks like a dirty reset to me so I guess the same problem is bound to happen again some times when the electricity goes on the fritz. If I knew the controller I could roll my own POR/BOR.

that sounds like bad caps in the power supply/power management circuit.

Power management is set up to insure the correct power gets initiated for systems where it's important that things happen in the proper sequence. Bad caps and up set this procedure and make it unpredictable.

That's the first thing I checked. Basically this unit has two rails for the electronics, 5V and 24V. Both have very low ripple. On the uC board

A good system should control the power sequence, not rely on capacitors and other external stuff to handle that. And if something ain't kosher there should be an error message, IMHO that is not too much to expect if the logic rail is functional. OTOH when I recall all the POR/BOR issues I had in the past it's not a perfect machine. Then again, the HP printer here hangs up a lot more often so maybe one hang-up per month is the best one can expect these days.

It's very possible you have a bad crystal (mechanical connection) in side the unit. This would be the one for the Uc.

I've replaced the common 11.xx mhz types in many industrial controllers after a failure due to moving vibration..

Some times on leg becomes unconnected but very close and causes initiation problems.

Also, you could try coolant spray or Heat concentration next time to track down internal fractures.

That's a good idea. Although I did give the uC board a good whacking to see if it would fail again.

That's bad technique--whacking is what fixes things.

Grins, James Arthur

Ah yes! I remember, Archie Bunker in "All in the Family". Whacked his TV to make it work. Then one fine day ... whack ... phoooieeee ... phssssst ... phut ... *BANG*.

:-)

Freeze spray or flexing, pushing, and probing the PCB with fingertips finds most intermittent connections for me.

But if whacking didn't break it, try a bigger hammer.

Grins, James Arthur

Apparently percussive maintenance is effective even on modern electronics:

I suggest wood rather than aluminum/composite for the tool.

Best regards, Spehro Pefhany

No audio back in the new office yet but this was hilarious! Thanks.

"Spehro Pefhany" schreef in bericht news: snipped-for-privacy@4ax.com...

LOL

petrus bitbyter

Sometimes you can glean technical information on a product by downloading the drivers (windows and linux) and firmware for it and searching the files for interesting strings. One time I found an entire changelog in ROM, and things like "8051 C compiler version X.XX" are fairly common.

Also, for working products, you can try holding down all possible two-key combinations while powering it up. Sometimes you can trigger a setup, diagnostic or self-test/burn-in mode that dispays something interesting. Also try the five three and four button combinations that involve only the corner buttons.

Tried that, it's all just compiled stuff. Printer mfgs are very secretive about things.

Tried that, too. Problem was that the keys did not react at all, they produced no discernible reaction on the uC. Because the keypad polling routine wasn't operating, the whole thing was dead as a door knob. The only activity I could detect was all the crystal oscillators humming. No polling, no RAM accessing, nada, zilch. Then after the umpteen power cycle it shook and raised itself out of the ashes.

It all looks like a dirty reset circuit. Like all those cases where the designers think it's enough to hang an R and a C onto the reset line and be done with it. It is not enough because IME most uC designers haven't figured out how do to a really good POR/BOR. So I'd like to hang my own onto the reset line, if I knew which one that was. But I don't want to probe a high-density TQFP because one slip with the probe, phzzzt ... tssst ... pop, and that would be the end of the printer.

On Sat, 21 Feb 2009 13:04:11 -0800, Joerg put finger to keyboard and composed:

Look for a PSU supervisor IC. This may provide the reset output to the uC.

Could you upload a photo of the board to your web space?

- Franc Zabkar

I looked for one but, nada.

To be honest, unless you really need it I'd rather not take it apart again. This thing seems to be very fickle when a very careful transport from one room to the next already rendered it dead for days.

On Tue, 24 Feb 2009 08:19:24 -0800, Joerg put finger to keyboard and composed:

They may be difficult to recognise. For example, my ADSL modem has two such chips, U7 and U12, 6-pin, centre right of the following photo:

Otherwise look for an RC pair near one of the uC pins, R connected to Vcc, and C connected to ground. You could generate a reset by shorting the RC junction to ground.

- Franc Zabkar

On this unit I found only 8-pin versions and most were resistor arrays.

Yeah, I could, but it'll be tedious because they used really, really small SMT for passive parts.

Perhaps a cracked die? I have a similar problem in my good old Tek