all charged out.

[fv1609]

Jim, well done. To every electrical problem there should be a perfectly logical explanation!

 

Well the goody goody answer is to dismantle it & repair the wire join on the resistor. The problem is it is a sort of collar filled with solder that makes contact to the resistance wire. I don't think it is a true soldered joint. If repairing it was a once off repair it would be worth doing. The worry is that it may recur & is a weak point in the construction & I assume that is the fault on this one here at my feet.

 

As a medium term bodge it would be worth getting two 1 ohm wirewound resistors & wiring them in parallel to give you 0.5 ohms at 20 watts. Although I suspect the power rating needs to be higher. An easy source is here:

 

http://www.maplin.co.uk/Module.aspx?ModuleNo=2181

 

Look at 10W W/W 1R HIR

 

There are higher wattage resistors made by RS components that are metal encased & they can be bolted to the box that give not only stability but the box acts as a heat sink. That would be the better long term solution. Then you can see it is ok & keep an eye on it from time to time.

 

Whatever you decide to do perhaps leave the lid off so you can see if it gets excessively hot. But certainly that resistor under the panel gets very hot normally.

 

For the moment try to find some lengths of wire to make up the 0.5 ohms then at least you can use the system. Roll of wire cheaper than £180:-)

[r8516874]

Clive,

Problem solved.

My dad and I took the resistor off and found that there was a break in the wire so we sorted the wire out and all is now good. I've got a steady 28volts getting to the batteries.

All thats left now is to find the rest of the system to put it back as god intended.

Thank you very much for all your help. You've helped me learn alot and I'm very greatful.

 

How is your 'all charged up' part 4 coming on? I hope your having some plain sailing.

 

Jim

[fv1609]

Excellent Jim you must have a warm glow of satisfaction in conquering the problem & along the way you have saved a lot of money & hopefully learnt some things. You will now be a "load compensating resistor expert"!

 

I've just come in from measuring voltages on the one here. This resistor is open circuit. I had a nice a adjustable wirewound rated 20 watts I think, it is 10 ohms so I just reset the clamp to give 0.5 ohms & clipped it in circuit with some small jump leads.

 

Incidentally in its non actively charging state it only got mildly warm & I think from parts catalogues it was only rated at 4 watts.

 

Now we know yours is working I wonder if you could give me some voltage readings so that I can see if it rings true with this one?

 

So with the ignition off, the cable to gen unplugged & the battery relay pressed closed, could you give me the readings on those points I drew on the picture X Y Z K J & both the readings on the terminals by I. Then repeat with the contacts on the voltage regulator pushed open (they are closed at rest) & not forgetting the volts on the main + line ie C or wherever is easiest.

 

The article? Apart from this 'research' I have created only 4,000 words over 37 hours that's only the document itself which is only about one third done. It takes the time because I keep re-writing bits to explain it better, find that I have gone into too much detail & then have to sort out the dyslexia idiosyncrasies. I have been creating the 5 circuit diagrams which has probably taken a similar length of time. But I'm quite pleased with those as all the various panels have diagrams constructed in differing ways making it difficult to see much similarity between them.

[fv1609]

Snap! If that's the right word. A lot of heat for a 4 watt resistor!

 

[r8516874]

Clive,

Sorry I've been away so long. Duty calls and all that.

It looks like that resistor is a definate weak point. Your has well and truly gone. I've no idea about re winding it but a shorting wire definatly gives you a working system.

I got some results for you but I've go to re-do them while pressing the relay closed.

Ignition on, everthing connected:

G=0.35V

M=0.05V

Q=0V

X=0V

Y=0V

Z=0V

J=0V

I=0V

and K=0V

 

With the engine running and the system charging.

G=0.4V

M=0.2V

Q=between 13V and 25V

X=28V

Y=20V

Z=open line

J=open line

K=28V

I=1V

 

I definatly own you a beer or few for all the help you've given my. Thank you very much.

I'll get back to you with the rest of the results,

Jim

[fv1609]

Jim ok thank you for those. I'll study them & digest them. I thought of rewinding it, but the only wire Maplin had was nearly £7 for a roll when I only need less than 6 inches. But it would need about half the turns that were on there originally so I thought that was introducing a weakness in a high risk area.

 

I bought a 0.47 ohm 10 watt resistor (about 70p) & have fixed that it. Given that the original was rated at 4 watts there is a bigger safety margin. In normal usage it should be ok but if there is any shorting in the field winding the current in the resistor current will go shooting up.

 

Anyway I will re-assemble this & take some measurements. I do have the generator & cable so can compare voltages although I can't run the generator. I need to do some wire tracing as there is a choke a some capacitors fitted & listed that do not appear in successive circuit diagrams.

 

I think this is because there is a degree of copying. A typical example of this is some manuals describe the Mk 3 panel when sections of it have been lifted from the Mk 2 description because it talks about the field relay. But this wasn't used in the Mk 3 instead the battery relay had a reverse winding to perform reversed polarity protection.

[r8516874]

Clive,

I've got some more measurements for you.

With the relay pushed in:

G=0.1V

M=0.1V

Q=0V

I high=18.1V

I low= 0.52V

X=25V

Y=18V

Z=24.8V

J=24.8V

K=24.9V

 

I hope these can help you.

My system is still working fine and the relay is clicking away.

I've moved to another problem now. I took it out for a bit of green laning and it was a bit wet and my indicators have given up. More fault finding to be done. Also my heater fan is shorting out somewhere. Its already gone through 2, 35amp fuses.

Its a good job I love the old girl.

 

Jim

[fv1609]

Jim

Thanks for that, I've not been ready yet to do voltage measurements. I've come across a problem on resistance readings here. Most of the manuals & EMERs have an error in circuit diagrams on the HIGH/LOW setting, but there are also some errors in the readings which look wrong by just looking at the circuit diagram even.

 

Anyway I'm not getting very good readings on the main protection diode next to the relay. I get about 7 meg one way & 0.5 meg the other which can't be right. I wonder could you take a reading from the lead 2B & the top of the diode (large spade connector) for me please? and of course the reading with reveresed prods.

[fv1609]

Anyway I'm not getting very good readings on the main protection diode next to the relay. I get about 7 meg one way & 0.5 meg the other which can't be right. I wonder could you take a reading from the lead 2B & the top of the diode (large spade connector) for me please? and of course the reading with reveresed prods.

 

Having got similar results with another panel it seems extraordinary that all 8 diodes should be defective.

 

The penny has just dropped. I should have used my Avo not a stupid digital meter, because on the resistance range they don't provide enough forward bias for the diode to conduct. One digital meter I have does have a diode function & does bias the diode giving forward voltage drop reading in millivolts. But surprisingly my fancy LCR meter does not. So back to Avo & that doesn't jump around displaying gibberish when it has nothing to measure like these digital things!

[fv1609]

Jim I see you got a range of readings on G, M & Q. I have just been powereing up the two panels I have here with similar strange results for those ones when using a digital meter.

 

I don't have a 90A installation, I was just powering them from the main chokes, so I have no voltage coming through the charge warning light supply. Yet that point = G was giving various readings!

 

M is straight through connection, but has no connections to it either end of it after it leaves the box.

 

Q is the supply for the battery relay that comes as an independant output from the generator. That was neither revolving nor plugged in, yet it was giving readings!

 

None of those gave a steady ready of anything even with the prods not touching anything there is this annoying 'hunting' by the meter giving a gibberish display. Connecting it to those points there was a little bit more consistency but still nothing at all stable. I was still getting these readings with no power to the panel!

 

Putting on, what I call a proper meter, an Avo 7 there was no reading at all, which as one would expect. So unless the digital display remains stable it is just gabbling away to itself. I think the reason that it became marginally more stable was that it was charging up a bypass capacitor that is present in the wiring of each of those test points.

 

I would have thought in this day & age it might be conceivable to develop a meter that only displayed a reading when there was something there to read, rather than make meaningless random displays with the meter prods not touching anything. So I have dusted down my Avo 7 & going to do the same to my Avo Multiminor & that isn't quite so heavy to carry in a vehicle.