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G8MNY > TECH 14.11.11 13:09l 105 Lines 5292 Bytes #999 (0) @ WW
BID : 17212_GB7CIP
Read: GUEST
Subj: NORTHEN 650W 2 Stroke Generator
Path: IZ3LSV<I0OJJ<GB7CIP
Sent: 111113/2305Z @:GB7CIP.#32.GBR.EU #:17212 [Caterham] $:17212_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (New Sep 11)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
I bought a non working 63cc one at a junk sale (worked last year!). It seems
identical to the Wolf, Pro User & KINGAVON versions.
On looking into the non-running, there was no intake "suck". This type of 2
stroke engine uses a reed valve, rather than the bottom edge of the piston as a
crankcase intake valve.
Filler Ü Handle ÜÜÜÜÜÜÜÜÜÜÜ
Ú===¿ Û ÞÝ Ú===¿ ÞÝ
/~~~~Tank~~~~~\ /~~~~~Tank~~~~~~\
----------------- -------------------
Mains|ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÙÝ DC|~~~~~³~~~~~~~~~~~|On/off
|(0)= _-~\ÞÝSilincer |MAINS³ choke []|
Choke´Tap Start\\\\\\Plg Ý ³ ø ===== |\
|ÄÄÄÄ¿pull~\\Cyl\ Þ³-----------------| |Pull
|Carb³,\/~~~\\_-~ Alternatorݳ Air |ø|Start
Air | ³ ³ ( ) ³ ³ß Þ³ Filter | |
FilterÀÄÄÄÄÙ\ \___/ / Ý_________________|/
Ú'ÚÄÄÄÄÄÄÄÄÄ¿'¿ ÀÂÄÂÙ ÀÂÄÂÙ
""" """ """ """
ENGINE FAULT
Checking the ignition there was a weak spark OK & there was compression so
tried putting petrol/ether spray into the crankcase through the reed intake
valve, but the engine still did not fire. So I put took the silencer off
(needed painting anyway) & put spray through the exhaust port, this did give a
bang on turning over, so the ignition & timing was OK etc.
The fault was eventually found as a popped out crankshaft bearing oil seal
rubber between the engine & the alternator. This may have happened if there
had been any backfires in the crankcase, as there was non-of the usual spring
clips fitted to hold them in place!
To get to the fault I needed to split the alternator off the engine. A long
bolt through the alternator shaft to holds it on to the tapered crankshaft,
this was the first problem. Fixing the hardly worn seal back in place, using
instant gasket sealant, so that it held it firmly in place (not spinning) was
another.
CIRCUIT
Not having the handbook etc. I have reverse engineered the diagram...
12V 240V STOP
Charging ÚÄÄÄÄ¿ AC ÚÄo\__
+³ ³- _³_ E bn³ ³bk
3A Bridge /// N L ------------
Rectifier ³ ³ |Electronic|ÄÄÄÄÄ¿or
³ ³ (155V) ³ ³ | Ignition | ³
7A ³ 15u 450V ³ 2.3A | Module | 0.2ê³2k2
Trip ³ ÚÄ´ÃÄ¿ ³ Trip ------------ ÚÄ()))))ÄÄ¿
³ gn³ ³ ³ ³ ³ ³ ³ ³ ³ ===== ³
³gn ³ ³ye ³ye bk³ rd³ rd/wh³ bn³ bk³ ³ Coil ³EHT
³ _ ³ ³_ _ ³_ _ _ ³ _ _ ³ _ _ _ _ _ ³ _ ³_ _ ³ _³ _ _ _ _ ³lead
³ ³ ³ ³ ³ ³ | 34ê|( )| ³ ³ ³
³.3ê³ ³3.2ê³ ³6.8ê ³ | Timing |( )| ³ ³ Plug ³
À())Ù À((()Ù ==== À(((()Ù | Pickup ÀÄÄÄÁÄÄÄÄÅÄÄÙ ÚÄ> <5kÄÙ
==== ==== Ú(((()¿ ==== | & Magneto 730ê _³_ _³_
ÀÄ´>ÃÄÙ | /// ///
A L T E R N A T O R | C R A N K C A S E
ALTERNATOR EXCITATION
This is a brushless alternator with the excitation of the rotor magnetically
charged up each half cycle from circulating 90deg out of phase currents from
the exciting capacitor. In the rotor is a diode across the winding to maintain
the current half a cycle after the kick. Excitation only starts at high enough
RPM to ever come the diode voltage drop loss with the residual magnetic rotor
field.
This system is more reliable than the brush type, but does produce a kink in
the load winding waveform & there is no opportunity for voltage control other
than RPM.
CHARGING
As I did not have the plug & lead, I made a plug (- |) from 2 brass strips,
poked these inte socket & though cardbord to form the plug's mold base, &
fitted a cardboard tube. Made the lot into a good mold wi the petro tank
removed up end the generator to get the socket level, spay/grease up the
socket holes & refitt the plug stips & mold. Mix up resin & hardener with
some fiber glass to strenthen the plus base. poor in & tamper down. When set
remove the plug, cut off the cardboard mold, Grind/file off the resin into
the wanted shape, Solder on the new lead to the brass strips noting +/- & tape
the lot up in rubber amalgamating tape, this finnishes the plug.
Although there is a 7A trip (12A to activate) the following bridge rectifier is
only made from 4x 3A diodes in a connector box with now heat sink. To improve
on this I cleaned off all copper the track paint & flowed a thick layer of
solder all over, I also doubled up on the diodes putting 4 more on the copper
side of the PCB. Note he trip does not prevent blowing the diodes on wrong
battery polarity, a 13A fuse in the charging lead will help that!
In practice though on a good battery the charging current is only 3-4A, but
enough to boost a flat car battery in a few mins to turn a car over.
See my TECH buls "Regulating 12V Generator Output", "Cheaper Generators" &
"Petrol Generators for /P SSB".
Y Don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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