Have had this happen two times now, need to debug more. 69 Series 2a NAS Petrol. Truck is running and goes off, also no electrical power (no headlights), wont start. After a few minutes, she is back to life will start now and runs great. Did replace the ignition switch, but has happened again with the new Lucas switch. Thinking Fuse box (contact) or the Voltage Reg under the hood? (it does have an alternator)..... not sure what would kill the engine and also shut off the head light power too and reset by itself. After that it seems great as it will restart and run. Any ideas? Will have the DMM in the truck now to debug if it happens again.

That is a strange one. A dud coil can overheat and start working again when cooled, have a feel next time it shuts down. [careful] the headlamps going off as well is odd.
Not much in the way of fuses in a series 2a, a brit one anyway. Check just the same.
It may also be worth checking battery connections.

I'm going to say check both ends of the earth lead.. better still, bypass it when the issue presents and see if the headlights come back on

I replaced my fuse box last year as the spade terminals were loose due to rivets gone slack losing voltage so that’s a good call

steve2286w said:

I replaced my fuse box last year as the spade terminals were loose due to rivets gone slack losing voltage so that’s a good call

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Thanks all for the comments - I inspected the battery ground to chassis and yes it is due for some clean up - will also likely swap out the fuse box as its ready for a refresh as well. On next occurrence, will check coil and debug further. One time was after 5-10min driving, the last time was a min after start up. Both times no start or electrics, wait 2-3 min then shes back perfect. Have had for the last 10 years and electricals have been good other than the occasional toggle switch change out needed.

To me its odd that there is no electrics when it occurs to sort out. I know the 10V stabilizer is behind the gauges, what is in the black box "Voltage Regulator" box on the firewall? Is that some sort of relay function for the generator? Truck has had an alternator upgrade many years aqo by PO. Inside the box it appears to be some coil wraps..... Just not sure of that device's function yet. Thanks again - will update as we solve it.

As you have an alternator the voltage regulator for the dynamo is not required. Alternator has built in regulator.
I seam to recall that when an alternator is replacing a dynamo some connections to the regulator changed but forget what.

tottot said:

As you have an alternator the voltage regulator for the dynamo is not required. Alternator has built in regulator.
I seam to recall that when an alternator is replacing a dynamo some connections to the regulator changed but forget what.

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You bypass the regulator, just connect the necessary wires together, if i recall