Purple Line Enduro Caravan Mover Fault

[CptChronic]

I have replaced lots of parts on this board to try and get it working. It works for a few minutes then shuts off and does a led flash sequence that shows its not getting the correct voltage (10 flashes of the green led) I turn it on and it works fine, something has a slight hum which gers louder over time. The voltage regulator 78L05 gets hotter than anything else on the board (40C). Then the thing shuts off and won't work again for a while, just constantly does the led flash sequence. I'm guessing something is heating up and it shuts down for protection. I have changed the voltage regulator, all diodes, swapped the relays around, changed the op amp chip (LM258), zeners and even bought a new power supply incase it was my old one causing the problem.

I get a nice solid 12V output in P3-6 when using the remote, until it goes into protect mode or whatever it is with the flashing leds.

I made a simulation for the op amp, its in the pictures, the 2 outputs are going to 2 pins on the ATMega, not leds like in the picture.

I'm stuck, can anyone please help?

[CapLeaker]

Re: Purple Line Enduro Caravan Mover Fault

Figure out why the regulator is getting hot. Is it because the circuit is drawing current like crazy, or is the regulator itself faulty and cannot supply the voltage / current anymore. The 78xx and 79xx are notorious for this. Best thing is to swap the regulator out right, or test it (if you can). See what happens and go from there.

Maybe upload some straight shot, high resolution pictures using the attachment function, so we can see something?

[CptChronic]

Re: Purple Line Enduro Caravan Mover Fault

Figure out why the regulator is getting hot. Is it because the circuit is drawing current like crazy, or is the regulator itself faulty and cannot supply the voltage / current anymore. The 78xx and 79xx are notorious for this. Best thing is to swap the regulator out right, or test it (if you can). See what happens and go from there.

Maybe upload some straight shot, high resolution pictures using the attachment function, so we can see something?

Swapping the regulator was one of the first things I did. I've also taken it off and powered both 12V and 5V rails with 2 supplies but get the same result so it's not the regulator that's at fault.

Sorry, I thought I had added pictures when I posted. You can see some here: https://imgur.com/a/65eNvhd

Thanks

[CptChronic]

Re: Purple Line Enduro Caravan Mover Fault

Nevermind, I have now fixed the problem ��

[sam_sam_sam]

Re: Purple Line Enduro Caravan Mover Fault

Nevermind, I have now fixed the problem ��

Please do not let us hang here without telling us what the issue was
Thanks

[CptChronic]

Re: Purple Line Enduro Caravan Mover Fault

Swapping the regulator was one of the first things I did. I've also taken it off and powered both 12V and 5V rails with 2 supplies but get the same result so it's not the regulator that's at fault.

Sorry, I thought I had added pictures when I posted. You can see some here: https://imgur.com/a/65eNvhd

Thanks

Please do not let us hang here without telling us what the issue was
Thanks

The resistor at R15 wasn't working properly so rather than giving a solid 1V at the output of the divider, it fluctuated and eventually crapped out at 0.2V which was why the leds were showing that it was undervolted. Tough one to find as the resistor read fine, wasn't shorted and only showed signs of being faulty once voltage was applied.

[CapLeaker]

Re: Purple Line Enduro Caravan Mover Fault

That resistor issue can happen and would have been on my next suggestion. Dealt with that on a power supply where the PSU clunked out after 30 seconds (the time depended on how hot the resistor was). The resistance value would go higher and thus not letting enough power go through. When the resistor was cold, it just measured normal like it should. Nice repair!

[CptChronic]

Re: Purple Line Enduro Caravan Mover Fault

That resistor issue can happen and would have been on my next suggestion. Dealt with that on a power supply where the PSU clunked out after 30 seconds (the time depended on how hot the resistor was). The resistance value would go higher and thus not letting enough power go through. When the resistor was cold, it just measured normal like it should. Nice repair!

Thanks man, you know when you get something that just seems like it doesn't want to be fixed? This was one of those jobs! It had multiple problems but persistence always pays off.
First time experiencing a resistor like that, will not be forgotten!

[sam_sam_sam]

Re: Purple Line Enduro Caravan Mover Fault

Was this the load resistor so the power supply would stay on or if not what is the resistor for

[redwire]

Re: Purple Line Enduro Caravan Mover Fault

R15 2k on motor at P6 feed from R16 22k, I guess that was the culprit? No idea what made the voltage regulator hot.
I think the LM258 op-amp is doing some current-sense by looking at voltage drops of the PC board traces. To detect a jam or confirm the motor is running probably.

Just a note, I see from other pictures they've had problems with these misbehaving due to EMI from the brushes arcing.
Their fix was to add ferrite-beads on each motor lead, a couple turns each. I would also make sure the motor can (chassis) was grounded as well.