Faulty LED update, probably thermical error?

nilspupils

Hello forum,
i still have the problem of faulty LED update of the step LEDs, i moved the discussion from bug reports to here because i suspect a thermical error now.
Here are the details:
Lets say i push all step buttons right after the first start, only some of the LEDs will light up, but all of the steps will play. If i select the same voice again, the LED pattern will look different every time i push the voice button, but still all steps will play. Very strange.
This only happens during the first 5-10 minutes of playing or so, and persists even if i reboot during that time. After some time the problem disappears, that is why i suspect a thermical error (which only shows when the unit is cold).
Apart from the first couple of minutes, i really really like my LXR and think i it is a great machine, lots of fun!
Can anyone help to point me to the possible source of the error?
Thank you!

loderbast

maybe a problem with the 595 registers.
the problem is only with some leds, right?
you could switch two of the 595 ics (a working one and one that drives the leds with the problem) and check if that moves the problem to other leds.
check the last page of the schematics to find out which 595 drives which leds. 

nilspupils

Thanks loderbast! The problem is with all of the step LEDs. I ill have a look into the schematics later, and probably get some replacement chips, just to check...

julian

I would check the UART connection from the mainboard to the front.
Pin 9 on the mainboard conector P1 <-> Pin15 on the AVR.

If you have a Scope measure the xtal frequency of the AVR.
I have a suspicion i got some faulty xtals with my parts order