Troubleshooting

Troubleshooting

Nothing is happening

·         Is the battery connected the correct way round?

·         Are the batteries fully charged?

The large 10 ohm resistor is heating up.

·         You have a short.          Check for solder bridges.

The 12v bulb illuminates

·         Check for solder bridges round the MOSFET pins

·         Allow time for any static charge on the MOSFET gate pins to leak away

With the PIC IC inserted the Red or Green LED is not showing the correct indications.

·         Check for bad soldered joints and solder bridges.

·         Check the control board is configured as a Master.

·         Check component Values and orientation.

·         Are resistance values correct?

·         Are the diodes inserted the correct way round?

·         Are radio leads in the correct way round?

·         Are the 5v and 12v voltage regulators inserted in the right place and the correct way round?

·         Are electrolytic capacitors values correct and are they in the correct way round?

·         Are the ICs inserted the correct way round?

·         Is the dual colour LED in the correct way round?

Symptoms:

Are12v and 5v indicated at the correct places on the board?

·         Does the control board LED shine red when the battery is connected?

·         Does the control board LED go out when the Transmitter is turned on?

·         Does the control board LED light GREEN when either control stick is moved?

·         Is the brightness of the GREEN LED proportional to the speed demanded?

NB: Do not insert the Driver IC if the LED is not giving the correct indications as you could cause consequential damage to the expensive MOSFETS and Driver IC.

Ask for advice. You can email us technical@rampagingchariots.org.uk for help.

IF YOU HAVE PROBLEMS TESTING THE BOARD AND ARE NOT GETTING THE CORRECT INDICATIONS, STOP AND REEXAMINE THE BOARD WITH A MAGNIFING GLASS.

            RESIST THE TEMPTATION TO TRY THE NEXT STAGE OF TESTING.

            DO NOT SUBSTITUTE COMPONENTS FROM YOUR OTHER BOARD.

            DO NOT REMOVE THE TEST BULB.

SOME TEAMS HAVE IGNORED THIS ADVICE, DESTROYED EXPENSIVE COMPONENTS AND MADE OUR TROUBLESHOOTING TASK MUCH MORE DIFFICULT.

Advice

Don’t panic!

Try re-reading the instructions.

No, really – it might help, and you may have missed something

Seriously; do not be shy about contacting the Rampaging Chariots Guild for help. We are very keen to see you build a successful Chariot and like hearing about your engineering exploits and ideas.

For advice, contact us technical@rampagingchariots.org.uk.

Please describe your problem and supply as much detail as possible about the symptoms.

State whether you have checked the board for solder bridges, components in correct place and correct component orientation.

State which numbered steps you have completed with the voltage values obtained.

State which steps gave unexpected or confusing results with the voltage values if applicable.

The circuit boards are sophisticated, but 90% of the problems we have experienced are due to solder bridges, poor solder joints and wrong or misplaced components. You should be able to identify and correct these faults yourselves with minimal help. Remember, the fault could be in an area of the board well away from where you are testing. We have learnt from experience to take nothing for granted.

If you are unlucky, a fault may have caused consequential damage to a component. We could easily send you spare parts, but unless you have seen smoke coming from a particular component, it is physically broken or it has changed colour, it is very difficult to confirm which one is at fault.

The circuit is quite high tech and not easy, even for an experienced electrical engineer, to trouble-shoot. If you have checked everything, and it still refuses to work, e-mail us the symptoms and the results of your testing to technical@rampagingchariots.org.uk. If this communication fails to solve the problem you will arrange further help to get them working for you ASAP.

We do expect pupils to have practised soldering on scraps of veroboard and to have reached a reasonable standard before being let loose on the circuit boards, but we do not expect them to be soldering experts. The Guild therefore only charge for this repair/troubleshooting service in exceptional circumstances.

Check list for e-mail communication

• Circuit voltage/power problems with both the main ICs NOT inserted in their sockets.
• What is the battery voltage when the battery is not connected?
• Does the red wire and red battery connector go to the battery positive?
• Does the halogen test bulb light up when you connect the battery to the board?
• What is the battery voltage when connected to the board?
• Is the big 10 ohm resistor heating up at all?
• What is the voltage on output from the 12v regulator?
• What is the voltage on output from the 5v regulator?
• What is the voltage (destined for the receiver) on output from the left diode?
• Check component values and orientation.
• Are resistance values correct?
• Are diodes the correct type and are they inserted the correct way round?
• Are electrolytic capacitors values correct and are they in the correct way round?
• Get a magnifying glass and check EVERY solder joint and track.
• Are there any solder bridges between the tracks anywhere over the board?
• Are ALL the joints shiny and nice looking?
• Is there a tiny piece of wire shorting the radio leads together on TOP of the board where they enter the board?
• What indications is the Red/Green LED giving and under what conditions?

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