Bugger.

Anybody got an adjustable resistor they are not using?

 

Wot, like a potentiometer?

 

platypus wrote

No. A major component in the MZ electrical system.

 

Lots..

What kind of value do you need, and what kind of current/voltage does it
have to handle?

 

One is on it's way. I hope you have a fork lift truck

 

Loz H wrote

hmmm. yes well...

I the book it says it is 4.5 ohms.

An interesting looking beast. I dunno how they make it variable as it
appears to be a coil of wire, now missing a few turns, wrapped around a
cylinder which is the third terminal?? Burnt and charred it is.

Of course this may only be a symptom of a duff regulator or worse.

 

Is this what you're looking at?

http://www.mztech.fsnet.co.uk/electrics/dyn_wrdia.html

Looking at the circuit, I don't see any reason why it couldn't be replaced
with a plain ordinary 4.5 Ohm resistor. Sweller or sombody like Burwins
might be able to give an authoritarian opinion.

 

platypus wrote

That's the Badger. I agree. I hope so.

 

You don't want to use terms like that round here - you'll have Blaney
and Launchbury on your case in two shakes, bonny lad.

 

It certainly looks that way. If that is the case, bear in mind it will have
to be quite a hefty resistor. Looking at that diagram. Field coil 1.7-2.1
ohms @ 6volt appears to give a maximum current drain of 3.5 amp. So, play it
safe and calulate for 4 amp

So, work out the power handling. 6volt x 4amp = 24W, so find a 25W 4.5 Ohm
resistor and away you go.

Looking at the Maplins site ( I assume you have a nearby Maplins store),
they sell 10W wire-wound resistors at various values. Wire 3 15ohm in
parallel, and that will give you a 5 ohm resistor (should be close enough.
2x15ohm and 1x10ohm will give 4.2ohm or so) with a power handling of 30W.

 

Give that man a beer.

 

I was going to use "authoritative", but then I thought, nah, let's stir it a
bit...

 

Loz H wrote

Size could be an issue and I don't see any mention of it in the specs on
the Maplin site.

 

platypus wrote

You just don't care do you?

 

Well, I care about your puir wee bike, but for the rest, I don't give a
Blaney. It's only a newsgroup.

 

There is also the option of re-winding the original.

--
Martin:
"For a minute there, you bored me to death."
VTR1000 Firestorm
TDR250 http://ukrm.net/BIKES/Yamaha/tdr250.html
martin dot smith nine zero three at ntlworld dot com

 

Heh, that looks familiar.

They burn out, IMO, quite randomly.

Unfortunately I don't have any spare, sorry.

I'm interested in Loz Hs solution.

 

I couldn't find a 25W wire wound resistor on Maplins but that may be me
being crap.

How would I calculate the amount of this wire and how many turns to
rewind a burnt out one?
http://www.maplin.co.uk/search.aspx?MenuNo=514&MenuName=Resistance Wire&
FromMenu=y&doy=5m10&worldid=3

 

Blimey.

Now there's a concept.

Like "wire", "pig iron" and "nails in fuseboxes"?

 

Packer's been at it, then.