It first materialised as not accepting commands then servos starting to twitch erratically…
Before anyone says power supply, thats the first thing I checked and its good, in fact the same thing happens on 2 different battery packs (10.8V) and a power supply.
I checked the output of the regulator with a meter and at power on, the voltage is 5.5V (not right), it then over the next 30 to 40 seconds slowly rises to over 6V at which point everything starts to fail. If I switch off it goes down again and repeats the cycle when I switch on again.
BTW this is with the EEPROM, servos and CPU removed. Also, all links to the servo banks and RS232 are removed as well.
Any idea what the breakdown voltage of capacitors C12 to C20 are (from SSC32 schematic)?
At a quick glance they are labeled as 22/10V. If 10 volts is the breakdown and you are using 10.8v you may be having dielectric breakdown.
If you’ve lost a capacitor or two from parallel bank (C12-C20 , minus C13) you are no longer meeting the conditions for equivalent series resistance. This will result in regulator instability. Like you, I speculate your capacitors are the problem. Which one is anyone’s guess. See if any are hotter than the next when charging.
I dont own an SSC32 but it does say to use 9 volt Vin in the manual.
Just reviewed the circuit, the only cap that is subject to 10.8V is C13 which is right across the voltage input. All the others are after the voltage regulator are are only seeing the output of the regulator which at present hasnt seen more than 6.0V
I checked the 10.8V input and that has a similar effect as well. the voltage is slowly rising. But that doesnt make sense as if C13 were faulty the voltage may rise on the input side but the regulator should hold the voltage stable on the output side…
I removed the links so that only VLogic was powered and the effect was still there so C8-C11 arent the cause. I removed C13 from the board but that didnt fix it.
The effect, if it is capactive must be feeding back through the regulator somehow which is about the limit of my knowledge on this aspect of electronics.
Without regard for the “fun” of trying to figure out a weird problem like this, please allow me to replace the board. I have not heard any other users have this problem, and I have no reason to think it was caused by misuse or abuse, so have fun tinkering if you want, but let me send you a new one. Please email me your shipping address and real name. I have been chastised for searching our database with forum email addresses before, so I don’t do it anymore. Even though I was merely trying to help.
