16-volt CB125RS

[immediately files under 'Way Too Much Information']

 

The message <1irr3w5.12n5ail3jeocyN%>
from (The Older Gentleman) contains these
words:

Cover blown!

YAACustoms Ossifer &ICM£5

 

Thus spake () unto the assembled multitudes:

Ha! Don't I know it. My first, er, 'real' bike was an ex-police Ariel
Leader. It had an anti-theft device (of sorts): basically a switch under
the seat which allowed current to go directly to the lights so that they'd
all go pop when they were switched on. After a few sets of lamps blown as
a result of forgetting I'd armed the switch, I gave up using it...

 

Strictly speaking, dissipate the excess energy as heat. The
finned Zener diodes on old British iron did exactly the same thing. A
switched regulator, as on most modern PC power supplies for example, has a
higher efficiency because it varies the ratio of time that input gets
switched to output (wasting little energy as they are essentially in
either an on or an off state), compared to older analogue regulators which
have to dissipate the energy not passed to the output within themselves.

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

I had a GS550B -- the first model sold in Oz -- and never had any
electrics problems with it, even after slotting a Cibie' H55 insert into
the headlight shell. Well, both beams gave up in quick succession in the
middle of the Hay Plains one Easter Thursday night on the way to the
Bathurst races, but luckily I was only a few miles from a servo (they are
_rare_ out there) and I slotted in a Holden sealed-beam unit as a get-me-
there measure. I did once have a dodgy H55 bulb, with a loose end to the
high-beam filament -- switching to low beam, the filament cooled down and
one end pulled away from the support; switching back to high beam gave
nothing, until vibration touched the end of the filament to the support and
the resulting arc temporarily spot-welded the contact again[1]. Not so good
on smooth twisty roads with lots of oncoming traffic... (It could take
several seconds for high beam to "wake up"!)

[1] Or maybe the heated filament twisted enough to maintain contact.

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

Nether are really true
All of the older Jap regulators use the equivalent of a pass transistor
output.
So the more current you are drawing i.e. headlamp on, the hotter it gets.
The opposite of the above, is how a Zener regulator works on a motorbike.


-

 

at least some I've seen have a sod-off resistor which is in circuit when the
headlamp is off.

 

Err, Ivan's description is accurate, but as you say, it also depends
on whether it's a series or shunt regulator. I've not encountered a
switching regulator on a bike yet...

Yep - Early small Yams certainly did. They relied on the battery to
provide some additional regulation for the DC side.

 

"Is there a market?" he wonders...

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

You are so right. Electrex's wiring diagram, bears no relationship to
reality at all.

"It'll have two wires from the alternator. Maybe three, and if three,
the third will be the earth," they said.

Their diagram shows a pink wire and a yellow wire coming from the
alternator. In fact, there are four sodding wires coming from it and
neither Timo nor I could fathom how to plumb the thing in.

We searched online for a wiring diagram for a CB125RS. We couldn't find
one anywhere. Seriously. There does not appear to be one in cyberspace.

So we tried the 'bodge option'. As main beam (35w) didn't seem prone to
blowing, but only dip beam (25w), I stuck in a 35/35w halogen bulb.
Sorted. GEFE[1].

I shall be on the phone to Electrex tomorrow, suggesting they've made a
boo-boo and sent me the wrong wiring instructions.

At least it's now running sweetly.

[1] Good Enough For Ebay[2]
[2] Where it now resides.

 

Weeell, maybe a lighter, more compact regulator?

 

Yo're right: I was thinking mains PSUs.

I *have* heard stories of them (linears) failing through overheating,
but my (admittedly well-placed) Guzzi one doesn't get significantly
warm; I've checked.

I've seen a reg fail due to corrosion when water got in after the
potting compound shrank and cracked on one unit. I have also had an
FZR one fail, but that was definitely an intermittent: the lights
would toggle between bleeding marvelous and adequate. Guess which was
the fault state! I imagine that failure was vibration induced.

 

If it's really direct AC lighting, it does need equal-sized elements. In
fact, I don't recall (on 6V stuff, admittedly) the bulbs were either 25/25
or 35/35, I don't recall a 35/25.

Sounds like it is: the extra wires from the alternator are a bit of a
give-away, probably one pair are going to the rectifier and the other pair
are the AC for the lighting.

's a pity you're so far away, I could probably fix it.

 

Would one of them be the neutral switch wire

light/green-red ?

(Assuming you are looking at the wires within the harness on the outside of
the casing. )



are the other three Yellow White and black/white ?





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Give us some credit here, we twigged that ourselves .

Green, White, Yellow and black/white - the latter goes to the ignition
(coil), White goes into one of the inputs of what we believe to be the
regulator, yellow disappears into the headlamp and is connected to
'pink' via the pilot light setting (and pilot light *only*), with pink
also disappearing into what we believe is the rectifier.

Green goes directly into the rectifier. The rectifier also has pink as
mentioned above and green/white, which IIRC is the other input into the
regulator.

 

Fine, then you won't have any problems sorting the rest of it, which is
equally easy


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<fx: grabs popcorn bag from Austin>

 

Actually, the neutral light doesn't come from the generator, you'll be
surprised to hear. It's totally separate. There are four wires from
the genny: yellow, white, black/white and green. There are three wires
from the rectifier: red, green/white, pink (which is the feed to the
reg).

Electrex's wiring schematic says you should have four wires going to
the four connectors on their unit: yellow, black, pink and red.

I phoned them yesterday, asked where they'd managed to locate a
CB125RS wiring diagram (because we couldn't) and got this immortal
answer: "Oh, well, we couldn't find one either, but we know this unit
will do the job....."

So Christ knows what their RR212 unit is actually intended for, but it
isn't a CB125RS. Anyway, they said to send it back and they'll re-
credit my CC.

"If you find a wiring diagram for a CB125RS, let us know..." was their
parting shot.

 

I didn't say it was, but it IS normally in the wiring harness from the
generator cover as per comment in brackets above.

That would seem to be a combined regulator/rectifier so it would involve
bypassing the original rectifier, not worth bodgering the wiring to achieve
imho.

KTM 250 apparently ;(





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Yes. That. Is. What. We. Were. Trying. To. Do.

Not easy, when the wiring instructions with the unit were utterly
useless and there's no wiring diagram for the bike.