Negative reading on the amp meter

[henk]

I understood, the closer that you weld to the components the more reason to disconnect it.
Best way is to disconnect the battery when welding. Could save you a lot of other problems.

[Emiel]

Hi Henk,

You've made the decision I didn't want to make untill now. My father in laws super major shows some strange behaviour in charging as well as your tractor used to do.

Does this beck unit allow you to use the full 11A capacity of the dynamo? Or does it only go up to 75W?

Rgds

Emiel

[Brian]

Rick, no it is not a myth, I have seen it happen many times, the worst culprit is the MIG welder. If you weld on anything with electronic components it is best to disconnect the component from the circuit. The current surges put Positive down the Negative line and, as you know, that is not good for diodes and they will break down.

More and more electronic systems are being built "hardened" to spikes and surges but do you really want to test them?

As an aside but on the same subject, I have just had to redesign the circuit board of one of our systems that has been working happily for a few years but the combination of John Deere tractors and Grimme planters started to throw up problems with wiping information from the computer chip. Turns out that the electronic reed switch used as a trigger and being powered by the tractor battery was picking up surges from the tractor and putting them down the Negative line into the controller. A redesign of the circuit board sorted the problem but it took a year to actually be able to generate the problem in the workshop and actually stop it.

If you are welding on any tractor or vehicle using electronic components it is best to disconnect both battery and alternator. Doing just one or the other is not the answer, you have to do both.

I can also tell you, from bitter experience, never try to jump start a BMW car, it can be very expensive. Jump starting can also wipe out electronics in an alternator.

To jump start correctly (except BMW cars):

1. Connect jump leads with both engines stopped. Negative lead last connection.
2. Start engine on vehicle with good battery.
3. Start engine on vehicle with discharged battery.
4. Turn all the lights on when engine has been started before disconnecting jump leads.
5. Disconnect jump leads.
6. Switch off lights.

I have seen cases where both alternators on two tractors were damaged when this proceedure was not followed.

Henk's point about putting the earth as near to the point to be welded is good advice but the earth point must be clean and a good connection when you strike the first arc, if it has to "burn in" the damage is done in microseconds.

[oehrick]

Thanks for the confirmation Brian, I started worrying when I swapped alternator for dynamo on my S1 Landy back in the 80's and made sure to isolate if arc welding. Never used a MIG but got quite proficient with TIG on stainless which I think is DC but pulsed at high frequency.

Intermittent faults - yes I've struggled with those over the years, our kit ran on either PLC's or dedicated microprocessors, both tend to be fairly reasonable to monitor and we did a lot of remote PLC diagnoses (if you had a good observer with the machine - this was pre looking at them over the internet!) but some 'left field' jobs remain etched in my memory.

Because they had some sort of 'brain' people tended to assume that any problem must be associated and we had some real doozies that were genuine NFF's such as adjacent plant sucking enough air out of the factory system to trip but not latch our machine, air normal when the inquest starts! Hydraulic reservoirs out of level so on a cold oil start up a local 'hole' in the oil level trips a sensor, which clears moments later. A favourite was the twitching hydraulic return hose carrying slugs of oil at 600lpm which just slid about on a wet fish factory floor but on odd days when the afternoon sun dried the floor, gained enough traction to gently walk up to an estop switch, operate it electrically but not enough to latch physically and when the machine stopped (NVR) and the oil pressure dumped it relaxed and was over a metre away with no indication of what it had done, when the poor bemused German factory engineer came to investigate (several of my service guys, the hydraulics designer, plc programmer and myself had all tried to see it happen, the engineer was jubilant when he called us to say he had found it)

Then of course there are the own goals, we had a machine range which ran under Z80 control and over about 10 years had suffered enough inexplicable but similar faults which the designer dismissed for hadn't he himself written in a routine for this sort of fault which screened a system warning or failure code, the fault must be in the stepper drive software !

I had to dig into the code while he was away ill for some other reason (not normally allowed access, some people can be a bit precious) anyhow not being a programmer I was going very cautiously when I found the system warning subroutine so copied it out to have a look at later. Not being fully conversant I did the numpties thing, compared the lines where we had seen the failure messages with those never seen and found a difference, the ones we had seen were written in yellow on a black background, I then understood why we were not reacting to the ones we had never seen, he was quite right, the machines had displayed each and every one of them, written in black on a black background The design office never let this die and a number of memo's or notices appeared in this format from time to time

While some factories could be pretty grotty, at least my gear had the decency to stand still under a roof, do not envy your sort of fault finding Brian, where field engineer means just that!

[henk]

Hi Emiel,

The unit will be set at max. 11 Amp. and will go no further.
Building in the Super Major is easy because you don't have to put it in the dashboard.
The unit can be build in the old Lucas regulator housing.

I had very good help from Hans Beck. You could ask if he can build in a solution for disconnecting when idling. Would be even better.