sem's charging coil replacement!

hi guys, just few minutes ago i manage to start my 1994 fe 600 WITHOUT the freaking charging coil
the charging coil (black and red leadings) is always the one that gets open and causes all the problems at the sem stators.

i only used 1 component for this operation and the results were really unbelieveble !! unfortunatelly i have no further time this week for a ride report, i only test it stationery.

i used neither a battery for this and the good thing is that it is fully adjustable for the optimum result.

i just want to complete testings so as to share the circuit with you everybody.

by the way, total cost for this was about 2.5 euros.

any comments will be appreciated

hello everyone,
after playing around with some batteries and some inverters for replacing the charging coil, i concluded that my first thought of using a 220/12 volts transformer connected in reverse is the best.

all is needed is a 220/12 volts tranformer (actually i use an industrial 400/24 volts one) 4 diodes for rectifiying and one electrolytic capacitor rated as 2 or maybe 4 microfarads / 450 volts for "smoothing" the output.

i connected the secondary coil (12volts) directly between the yellow leads of the stator (that are connected in paralel) and the blue one.

this this gives the transformer constantly about 13 volts in the secondary coil in a constantly changing frequency (increased revs=increasing frequency).

the result is about 220-250 volts (it depends on the frequency) at the primary coil.

then it has to be rectified with the bridge and the capacitor to give a maximum of 300 dc volts more than enough to supply the cdi.

connect "-" to the frame or the black lead and "+" directly to the red lead of the cdi and VOILA!

i get about 40 volts at kickstarting (at least!!).

the HINT is the selection of the transformer:

if possible to have a ferrite core because high frequencies beside higher voltage
generate losses too.

must have low impendance at the primary coil (bellow 200ohms if possible).

it is better to use one of about 100VA.

some 12 volts halogen lamps use some very compact transformers of a 100w power.

Almost done that.
Not on the SEM though, it was done on a 50 cc Victoria moped engine.
A transformer rated at 4W @ 50/60 Hz was (more than) enough! There was no regulator to bring the AC out of balance. The frequency was not as high as the sem will give in a husa engine. The discharge capacitor was only at 0.5 to 1uF and 400V. So it was easier to make it work. It even overcharged the capacitior and eventually it... Umm... Didn't I describe this previously? Wait a bit...
Here:http://www.husaberg.org/index.php?name=PNphpBB2&file=viewtopic&t=2408&start=0
Diodes and especially bridges for 50/60 Hz are not optimal, the berg will produce up to 1000 Hz. The Victoria couldn't have produced much more than 100 Hz! Try fast diodes instead. Also, try to run it without the smoothing capacitors. The voltage from the original charger coil is far from smooth. Also, the regulated electric tension from the lighting coils is AC with overlayered DC which is something that transformers do NOT like, the DC part that is. DC will lead to magnetic saturation and excessive heat build up in what you use as the primary winding (which was originally intended as a secondary one). Either filter the DC out with a large bipolar capacitor or else get a symmetrical regulator.Then will perhaps your small transformer be more than enough in your case too.
Maybe could one lighting coil be used unregulated if a suitable inductor was connected in series to protect the discharge capacitor from too high voltages at high revs. But that would take some experimenting.
A 100 VA transformer for 50/60 Hz is a bit too large, if you can get an aircraft transformer, they are designed for 400 Hz and are much smaller for the same power.
Your trick with a transformer is definitely what I'll try as soon as the stator breaks. But it has been around for a number of years and it just won't quit. But when the day comes...
An inverter is an alternative. Especially if the bike has got a battery. Emco is one inverter brand that could be considered unless you want to design your own.

Good initiative with the transformer. Thats the way they should have been built from the beginning.

Regards

thanks for the good points smogasbord, core saturation from the dc current is sotmething i intent to eliminate with a capacitor as you correctly mentioned.

a for the 100va is for now what i could possibly easily found in my storage house !

the problem i came up with smaller ones is that they had high output impedance so there was excessive voltage drop in rpms more than 2000

thats why for now i went with 100va one.

inverters needs a bit of attention (i mean the ones you can buy). they need very good power supply with not lot of voltage variations and harmoniques.
might also need a 1:1 transformer at the output.

an alternative idea is to built a simple oscilator with an ic 555 which can be supplied flawessly with a voltage from 5 volts to 15, and feed a reversed transformer.

thank you very much for your experienced advice and if any one else has a point is welcome

i also tried unregulated lighting coils with a smaller transformer but the voltage drop was the same with the dc overlayered voltage

The voltage drop can also come from the diodes if they are not well chosen as well as from the smoothing capacitors. At the higher revs the regulator skews the waveform to give more DC and all these things will work against you as revs goes up.
The classical 555 is great for many things. But look at for instance IR2153, IR2155, you will be delighted!, and there are probably even newer and better stuff around nowadays. These are bipolar oscillators and drivers in the same package and are useful with ferrite transformers operating at very high frequencies which therefore can be very very small for the power they produce. I'm sure that you can find suitable application notes on the internet to inspire you to make a good design. HOw much power does the discharge capacitor really require?, it should be possible to calculate it somehow. It will be proportinal to the revs, me thinks.

I hope to read about your progress here at the forum in the near future.

Regards

i will keep my progress posted,
it works perfect for now and with no heat produced from the transformer at all.
its size is about 7 by 7 cm but no problem i have plenty of room under the seat

Hello OIK and Smorgasbord

I have electrical troubles with my FSE 650 2002. It seems that the SEM charging coils are the cause (but i'm still not shure). Please take a look at my new topic at http://www.husaberg.org/index.php?name= ... pic&t=6998.

Are you in the opinion that the method you described in this topic "sem's charging coil replacement!" could be easily applied to my 2002 berg ? Any changes should be implemented ?

One more question (which might sound stupid but please take account that i'm not an electrical engineer..) : do the lights still function with your method ?

Thank you in advance for your reply.

hi jmb, of course you can do this modification to your 650 and get rid for good the sem problems. mine is working like a clock for about 50 hours now (from february 07 until now-temperatures from -5celsius to 48 celsius).
well by reading your post i would first eliminate the possibility of a faulty stator and a faulty cdi.

to test my cdi i just connected a simple 4 wire cdi out of a honda c90. it cost me 5 euro and 2 euros for the external hv coil necessary.

if you get a nice spark with the testing cdi then indeed your cdi has gone.
be sure to find a 4 wire cdi (ground-pick up signal-charging voltage-hv coil output).

you can also use this cdi for experimenting with the transformer modification which is highly recomended.

if you decide to do this please notify me so as to do this together step by step fo as to avoid any mistakes because several measurements must be taken first.

see at my gallery at the most recently pics and locate the white 50w trans i use now.

jmb said:

Hello OIK and Smorgasbord

I have electrical troubles with my FSE 650 2002. It seems that the SEM charging coils are the cause (but i'm still not shure). Please take a look at my new topic at http://www.husaberg.org/index.php?name= ... pic&t=6998.

Are you in the opinion that the method you described in this topic "sem's charging coil replacement!" could be easily applied to my 2002 berg ? Any changes should be implemented ?

One more question (which might sound stupid but please take account that i'm not an electrical engineer..) : do the lights still function with your method ?

Thank you in advance for your reply.

Click to expand...

of course the lights are functioning

sorry but i read the post partially!!

under no circumstance i would buy a new stator , since there is sparks around , send your old one if it is faulty and if you don't decide to go with the trans mod.
sparks rewind stators has saved a lot of trouble from our people here in uhe :wink:

does anyone have a diagam to do this conversion , i am prepared to try it out , and i see no reason why it should'nt work perfectly, i have a spare cdi so , if it blows , then it blows, i have heard that sparks does an excelent job on sems , but no one made any progress by not experimenting a bit?and why oh why do we need to use these stupid four little unreliable coils anyway, as we know that they are going to pack up eventually and leave us stranded miles from home.I just wish someone would manufacture a complete ignition set up that is as reliable as japanese electronics, they would soon be very very rich, and i would buy one .

scrapveiw said:

does anyone have a diagam to do this conversion , i am prepared to try it out , and i see no reason why it should'nt work perfectly, i have a spare cdi so , if it blows , then it blows, i have heard that sparks does an excelent job on sems , but no one made any progress by not experimenting a bit?and why oh why do we need to use these stupid four little unreliable coils anyway, as we know that they are going to pack up eventually and leave us stranded miles from home.I just wish someone would manufacture a complete ignition set up that is as reliable as japanese electronics, they would soon be very very rich, and i would buy one .

Click to expand...

I think Oyk rides his on the road I think yours is enduro, the transformer could be a bit vulnerable to water and dirt and once in these conditions you might find the electricity going else where to where it should, OK if you can keep it dry.
The only reason the OEM ignition stator is so unreliable is the way it is put together and the quality of materials used, where mine are totally different.
I give 12 months guarantee with my rewinds and after over a 1000 out there I am yet to see one returned.
As for the Japanese ignitions I have rewound bucket loads of them they used to fail for the same reason as the SEM but in later years they have become very reliable.
But feel free to go down the transformer route it is an interesring experiment and I'm sure it could be very reliable.

Regards

Sparks.

hi, if you read carefully though my post and you have some basic electronics - electricity knowledge you will figure the diagramm easily.

if you are not inclined i recomend let someone who is inclined to help you out cause there is some risk involved with the wiring-might damage your cdi if for instance if you don,t rectify the output with a bridge.

if i have some time this week i will make up a jpg showing the wiring.

what model you have?

if it is has a batery the capasitor at the output must be one of a bigger size (20μf propably) because in "E" models one winding is used for lighting (one yellow wire) rated at 70 watts, which results in a simultaneus voltage drop for some milliseconds when turning on the lights. this some times lead to the engine to turn off. with the capacitor no problem.
this is my transformer:

http://www.husaberg.org/index.php?set_a ... _photo.php

it is 220/12 volts, 50 watts very compact and strong. with some "personal care" it can become 100% water resistant. me and 2 more bergs that i modded use it for more than a year flawless.

the cost of the transformer is 5 euros and the estimated mounting time 1 hour ( this is my ussual time for a battery model because i use to solder every wire connection for security).

propably this weekend i will also upload in my gallery the simple electric diagramm.


regards

thanks for the replies guys, i tried the transformer route and it works! but i still have the same problem allthough it did run better, but when i stopped it ,it would not restart.thats what it was doing before, ive checked the valve clearances ,checked the cam timing ,messed about with the auto decomp, changed the carb , changed the sem,changed the coil pack,changed the plug?checked all the ohms readings, even changed the flywheel...and then i put it all back to original wiring spec because the spark jumped 10mm on the original set up?????.....what else can it be , i am beginning to think that i have been supplied with a duff plug,and i was still at it at 3 am this morning, but then it back fired again and the kick start snapped in half when i was tryin to kick it up for the millionth time, my left leg is now thicker than my right,HELP!!!,i feel like taking a hammer to it.ive been a mechanic for 22 years and some of those years were as a motorcycle mechanic too. ive got to admit that this one has realy got me scratching my head..........regards......ian

forgot to say , its a 1995 fc501 ,

cured it , i think, the problem was a brand new NGK spark plug!, went to the bike shop this morning and purchased 5 new plugs , i put the first one in gave it a bit of choke and a good hard kick and she fired up and ticked over like a brand new berg, and it restarts now .....but , oyk when you read this i would still like to go down the transformer route so that i can attatch it to my bike and use as a switched back up just incase, the sem dies when i am out, i used an old trans former out of an old radio cassette 220/9v , it worked fine, i then tried one out of an old TV which was 220/12v but was twice as big in overall size than the radio cassette one it produced a spark but it was weak, also my generator lighting circuit has two yellow and one blue ,i had to join the two yellow together and use the blue to make the circuit to the transformer, is this ok to do that?..........regards .....ian.

hi, glad you find the problem.
in fc models you will need to put an ac voltage regulator to keep your voltage down to 12 volts.
now if you connect directly the two yellows and along with the blue without the regulator you will ruin the cdi.

you can adapt a universal regulator also.

to test a transformer if it is suitable you have to test it in a bench.
feed 12 volts at the secondary and measure the output voltage with no load connected.
then put a 5 kohm resistor in the output and measure voltage again. if voltage remains high then it is ok.
if the voltage drops very low then you need to go to a higher wattage rating.

in no case a cassete transformer will do.

if you put it on you can only idle , when you open throttle the engine will die due to the higher load of the cdi in higher rpm.

thank you for your info, the rad cassette transformer did actually allow the bike to achieve maximum rpm with no hiccups , i think the best thing to do is get a transformer identical to the one you are using and go from there, because yours is still working with no probs,the bike i have has all the lighting circuit including regulator and they worked ok, so i can regulate it, i did go and buy a 220/12,100va lighting transformer from the local electrical store , but i was dissapointed to find that it is not a true transformer inside , its full of capacitors and semiconductors chips and things and two circular very tiny coils , so cant be used , hence the radio cassette and telly transformers, so what i need is the exact make and model of your transformer , i looked at the pic in your album but i cant make out all the writing on it. you are a clever chap and have been a great help ...thank you .....ian

hi scrapview, i believe my transformer is ACA which propably is an unknown brand made in greece!

well go to a electricians shop and ask for a 50watts HALOGEN lighting transformer i believe with a bit of search you can find one like mine