Increasing the output voltage of the Wehrle PLASTIC voltage regulator
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wehrle.htm-23A
This applies only to the PLASTIC box Wehrle regulator. For
the METAL cased Wehrle, see the article on Bosch and Wehrle
regulators. boschelreg.htm
PLEASE read this ENTIRE procedure THROUGH before deciding if you want to proceed!
***NOTE!: This article was originally written using a Wehrle RED top regulator, model 55-990-001. I have seen other Wehrle versions that had a rubbery potting compound, and these are slightly different. One is a Red topped model 55-990-002. There was a fairly different looking Black topped model I looked at, fairly different layout, also potted, and it was model 55-990-006. THAT particular unit is believed to be one of the Authorities (Police) types, as its voltage setting was about 14.3, when the others are usually closer to 13.8, but I am unsure of it being an Authorities version. I believe there are some even later versions of the standard and higher voltage Wehrle regulators.
Because of the potting, a nuisance to remove, and the different layout....and particularly since almost any regulator with the same three terminal layout (as from autoparts store or junk yard or?) will work, it is perhaps not worth modifying these Wehrle regulators for higher voltage output, since in many instances the cost for a replacement regulator (and even some higher voltage ones) MIGHT be more attractive. YOUR choice here.
Basics:
You will need some 60-40 rosin core solder. A short piece of de-soldering braid. Rosin impregnated or some soldering rosin would be nice to have. You might need some very small drills. You WILL need an accurate digital voltmeter, and you CAN NOT use the voltmeter in the fairing. If your battery in the bike is not fully charged, put it on a charger.
You will need to remove the gas tank for access
to the regulator, and you must unplug the regulator and remove
its two allen head mounting screws. It is not necessary to
disconnect the battery. Once you have the regulator on your
workbench, pry off the red top carefully.
Parts needed: ONE part from #1 below or #2 below, but you need
only ONE part! You should read this entire procedure
through and decide if you are going to use method #1, or method
#2, and you might have to visit your local RadioShack to make the
final decision.
#1. ANY common silicon diode of the a power variety, rated at one
ampere or more. Voltage rating UNimportant.
Available at Radio Shack in all sorts of ways.
Example: #276-1101; 276-1102; 276-1103, etc. These are same as
common industry types 1N4001, 1N4002, ETC. You COULD get a whole
little bag of 25 of assorted diodes from RadioShack, their part
number 276-1653 $2.29 for the bag. There is NOTHING critical
about this part, it is in a very low power circuit.
#2: ***NOTE: This method is neater, as you will replace the
existing part, not adding another part, BUT, there is a potential
problem, in that the common parts described here have TOLERANCES,
and you MIGHT just get one that is a bit too high in ACTUAL
voltage rating, which MIGHT boost your regulated voltage to a bit
too high of a value for your battery. What you need is most any
common silicon diode of the type called a
"Zener Diode", you will need one rated at 8.2
volts (that is a STANDARD value). 5% or smaller % tolerance.
Common number is 1N5237B...and others. RadioShack has an 8.2 volt
silicon diode, package of 2 is $0.89, part RSU11928413. RSU parts
are not normally stocked. You could also use almost any 8.2 volt
zener diode from your local TV repair store or electronics
components store. Rated at 500 mw (milliwatts)...the same as 1/2
watt. Or, you could fit a 1 watt one too. SOME 1 watt units
have leads a bit larger in diameter than the PC circuit holes in
the regulator ...this is true for all the parts in section #1 and
section #2. This will require you to enlarge the existing holes a
teensy amount.
My suggestion is for you to look at your regulator
innards, see what the existing part looks like, and then
you will have a better idea of what to get. ***NOTE that the part
you purchase may well look SLIGHTLY different...perhaps larger,
or marked a bit differently, or colored solid black, or whatever.
It will ALWAYS have a LINE marked nearer to one end.
Doing the modification:
I assume you have already pried off the red
plastic cap...it is held by small projections in the plastic,
centrally, each of 4 sides. Once the cap is removed, you can now
gently press, alternately, the three connection male spade lugs
and the metal heat sink sides, all of which protrude through the
bottom...and the innards will slide out as an assembly. Look
carefully at the side of the printed circuit board that has the
parts, and notice that very close to the center of the board, and
located close to a "row of 6 resistors which have various
colored stripes on them" will be the diode we will describe.
There is another diode on the board, likely physically larger,
but it is NOT near the 6 row. The Wehrle voltage regulator I
looked at had this diode as a glass package, and it had marking
on it of ZPD7V5. Interpreting that for you, it is a zener diode
(a voltage reference device) rated at 7.5 volts.
What you are going to do is either replace that above zener diode
part with a 8.2 volt part (described as #2 above), or ADD a part
(described ass #1 above) that will raise its effective value to
8.2 (approximately). (nerdy types need NOT point out the small
voltage error here, nor the tolerances of the diodes, etc.)
NOTICE that the diode is mounted vertically (as are the row of 6
resistors). It is VERY important that you
NOTICE that ONE end of that diode has a LINE on it.
Be SURE to note WHERE that line end connects
to!!! Be SURE to mark the board with a pencil:
so that the lead of the diode end that has that line, is so
marked, by a line on the board. Being vertically mounted, it is
possible that during manufacturing, EITHER end of the diode
was the longer leaded end....so be SURE you mark that
board!!! Another way of thinking about this: The LINE
end of the existing diode will be towards
the END of the board that has the heat sink and larger squarish
looking transistor that has three leads coming out of it and
mounted to the
heat sink.
Follow THIS method if you are using method #1, ADDING a
diode:
1. De-solder the LINE end of the existing diode. Shorten the lead
of the new to be added common silicone diode at ITS line end, and
carefully solder the line ends of BOTH diodes together.
2. Solder the NON-line end of the added diode, to the place on
the board you previously de-soldered the line end of the existing
diode.
3. Use fairly short leads for this...to avoid stress from
vibration. Do NOT break the leads/glass!! Sharp bends
right at the diode will crack it!
Follow THIS method if you purchased a zener diode, and are
REPLACING the original part:
Remove the old diode, replace it with the new 8.2 volt diode. Be SURE! to have the LINE of the diode connected at the SAME place as the original!
Finishing the job:
Reassemble the unit, after making sure your work
was neat, nothing touches anything else, or can short circuit,
soldering was neat, and you did NOT short the adjacent soldering
pads on the soldering side of the board. If you want to clean off
any excess rosin, common alcohol on a Q-tip or other swab will do
nicely. Snap on the top, and install the regulator.
Testing:
Rather than give a table of values for
temperatures, which are in the Bosch
Electronic Regulator article, I will assume
that the engine is started at perhaps 50-100°F, and that you do
NOT allow the engine to develop such heat that it rises and warms
the regulator. Optimum would be 70°F.
With a digital voltmeter meter across the battery, start the
engine, and within a minute or two, slowly raise the rpm,
watching the battery voltage rise as it recharges, and noting
where the voltage ends up at. If the voltage ends up around
14-14.4, that is fine. If it does not charge, or the voltage is
over 14.7, you did something wrong. 14.5 is the limit you can use
with flooded batteries, and maybe 14.9 with the Panasonic/WestCo.
If you use a slosh (flooded) battery, 14.5 setting on longer
trips will cause the battery to use water faster, although it
probably won't injure the battery. Note that as the
REGULATOR temperature rises, the voltage regulator will
automatically adjust DOWNward, and the reverse is true for
colder. If you use the fairing voltmeter for monitoring your
system while riding, understand that in a good system with a good
connections....the fairing voltmeter will normally read about .3
volt LESS than the actual battery voltage. The downward for
colder temperatures is in TENTHS of a volt.
Revisions:
09/16/2003: minor clarifications, and information on the
other Wehrle regulators at top of article.
12/10/2003: add PLASTIC to type of regulator for this page
and the associated note.
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