djg
Groundie
Posts: 4
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Post by djg on Mar 22, 2014 13:32:54 GMT -5
I have a Homelite 923 chainsaw that I changed over to solid state ignition (Nova II) , seems to work good for a about a 1/2 tank of gas and the chips fails. I have replaced the ignition coil and spark plug wire when the 2nd module failed as the shop a bought it from thought that it may have been weak and was causing the module to fail. Just went to cut some wood with the saw and it lasted 1/3 of a tank before it failed. Any ideas what would cause this as it is a pretty simple hook up, as i have wired per the manufactures print please see picture. Is there a different module that may work better. Any help is greatly appreciated. Dave
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dewaynep
Saw Builder
Homelite Parts
Posts: 206
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Post by dewaynep on Mar 28, 2014 7:54:33 GMT -5
Here's a possible answer from the other thread on Black Magic theory:
"I read this thread to learn more about the topic, then googled it. I found a thread from a different forum in which a guy reported that he burned up three of these modules in a Mac before he realized he was mounting it too close to the coil pack. He reported that he moved it farther away and had no more problems."
Maybe your module is too far away to get good cooling air from the flywheel or from the post above, it is too close? I would try attaching the next module directly to the coil mount screw.
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Post by sweepleader on Mar 28, 2014 14:59:40 GMT -5
Maybe you have already put some heat sink grease between the module and the fan housing, maybe not. The stuff is available at Radio Shack or most auto parts stores for use between electronic modules and their heat sink, to improve heat transfer. If you have that in there already and the housing is not too hot to touch, there must be something besides heat going on. Dewayne's advice could do it. Dan
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djg
Groundie
Posts: 4
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Post by djg on Mar 29, 2014 16:37:03 GMT -5
Guys, Thanks for the advise, I don't think its getting hot ( as I only cut two small logs ) but I am not sure. I just got another module and I am bolting it right on the frame of the coil so the module is closer to the fan for cooling and it should have a better ground. I thought maybe I was getting a bad ground, but I didn't think about a heat issue so will see what happens. Thanks again for your support Dave
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djg
Groundie
Posts: 4
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Post by djg on Mar 30, 2014 23:51:43 GMT -5
Mounted the new IC module right on the coil bolt down bar. Grounded the chip on the coil bracket so I had a good ground and the chip was in the cooling path of the fly wheel. Wired the module reverse polarity (as I have wired all the other modules straight polarity), spark plug had a good bright spark and the saw ran good. I cut small wood for about a tank with no problem, then a started cutting big rounds on the second tank of gas, the saw lasted about half tank before the chip died again. I am wondering if the coil and flywheel induce so much current when the saw is running hard that it opens a circuit in the IC chip. I checked the chip ohms ( 2.8ohms) before and after it failed and same reading on the chip so I am not sure what is going on. Could it be that the 932Xl saw coil produces more current in the circuit than the new saws that this module is for, or should i try mounting it on the outside of the saw to see f the heat is causing the problem ( not sure on this as the saw was not that hot). any help greatly appreciated. Dave
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Post by sweepleader on Mar 31, 2014 7:19:21 GMT -5
You have more stamina than I would with that project.
Have all the chips been the same manufacturer? I don't know how that matters other than they might not be "strong" enough or "compatible" with that coil. Is the coil defective? Is a different manufacturer's chip going to be better? I have no idea.
Anybody else out there had success with this model saw and a chip? What did you use for a chip and how did you mount and connect it?
Dan
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djg
Groundie
Posts: 4
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Post by djg on Apr 1, 2014 22:42:35 GMT -5
All the chips have been the Nova II, I replaced the coil at the chip venders request, (old and new had the same ohmic value) Right now I am thinking about using a different IC chip mfg as I think this Nova may not be compatible the the 923 saw. Any thoughts Dave
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Post by powerking on Jul 11, 2014 9:36:34 GMT -5
My guess is the voltage on the primary winding of the coil is much higher than the design of the Nova ignition module is rated for and is blowing out the MosFet switching transistor. After all, these were designed to be a general purpose replacement for points on lawnmower engines which run up to 3600 RPM's. Two-cycle engines can run up to 10,000 RPM's. A rotating magnet and a transformer coil is basically an A.C. alternator; as the speed increases, so does the voltage on the primary & secondary.
Tom (PK)
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Post by seafoam71 on Oct 23, 2014 20:34:24 GMT -5
I have just installed a nova 2 in my xl-12 tonight. started on the 1st pull awsome spark idled perfectly started to throttle it up and ran great, so i opened her all the way up and out blew $$$24.00 the nova blew. must of ran 2-3 min. so I know it didn't get to hot. I did see on here a picture of 1 installed on a sxl 12 and it looks from the picture that the guy used the red wire on top of the coil not the black 1 from coil ,points, kill switch?? could just be the way the picture looks but I'm curious as he claims he has good luck with his.. The directions looked very easy and fool proof didn't think I'd have a problem, I've used similar chips in older cars with great results. I'd like to make this work rather than buy new points.
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Post by powerking on Oct 27, 2014 16:05:39 GMT -5
Some of these aftermarket points eliminators had a separate type designed for 2-cycle engines. I don't know whether the Nova-2 is spec'd for either 2/4 cycle. But per my previous post in this thread, the primary voltage goes too high at peak RPM's and blows the Mosfet or other semiconductor in the module.
Tom (PK)
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Post by hotshot on Dec 4, 2014 9:30:27 GMT -5
I suspect it is the common Chinese junk components inside the Nova II trigger that causes the big failure rates, and not the Homelite 923 coil. This is assuming that you do have a good ground (scrape the paint off, down to shiny mag) when you mount it.
If the distributors don't or won't warrant these for a year or two, I would not buy another one.
Why don't you buy a Stihl 1118-400-1001 trigger?, and install it just like you did in the airstream. You may have to pull the flywheel key out & run "keyless", with the flywheel advanced a half a key to a full key width for earlier timing though. Advanced is in the CCW direction/rotation on the flywheel.
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xl76
Dumpster Diver
Posts: 29
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Post by xl76 on Dec 5, 2014 21:30:39 GMT -5
I have removed points and condenser and installed blue in colour solid state ignition it works great any questions just ask
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eric
Groundie
Posts: 1
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Post by eric on Jan 3, 2015 15:07:23 GMT -5
I'm dealing w the poulan/dayton issue w the nova ll chip failure...I've been through two now and not willing to buy again...you purchased a "blue one"? Thanks in advance Eric
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Post by elexro2 on Sept 28, 2018 13:07:08 GMT -5
Mounted the new IC module right on the coil bolt down bar. Grounded the chip on the coil bracket so I had a good ground and the chip was in the cooling path of the fly wheel. Wired the module reverse polarity (as I have wired all the other modules straight polarity), spark plug had a good bright spark and the saw ran good. I cut small wood for about a tank with no problem, then a started cutting big rounds on the second tank of gas, the saw lasted about half tank before the chip died again. I am wondering if the coil and flywheel induce so much current when the saw is running hard that it opens a circuit in the IC chip. I checked the chip ohms ( 2.8ohms) before and after it failed and same reading on the chip so I am not sure what is going on. Could it be that the 932Xl saw coil produces more current in the circuit than the new saws that this module is for, or should i try mounting it on the outside of the saw to see f the heat is causing the problem ( not sure on this as the saw was not that hot). any help greatly appreciated. Dave View Attachment Can you please take apart one of the damaged ones and see what actual components are inside so it s going to be $1.5 instead of $15.... maybe share with us... thanks
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Post by undee70ss on Sept 28, 2018 14:37:59 GMT -5
Can you please take apart one of the damaged ones and see what actual components are inside so it s going to be $1.5 instead of $15.... maybe share with us... thanks Original poster hasn’t logged in since 2014, very unlikely he will respond back. I have no experience with nova chips.
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Post by alberti on Oct 2, 2018 15:56:13 GMT -5
Hi all,
Just joined your Homelite site for some info on my XL700. I just installed a Nova II 31-8786 ignition module. I had done my Stihl 015L with another brand and it works great. The XL700 module went in awesome and got great spark on the bench. Fueled up and it started/idled well. After less than one minute it shut down & wouldn't fire at all. Took the machine back in and couldn't get a spark again.
I had cleaned everything well and all connections are good. Any ideas why she won't fire? It never got hot enough to do any damage.... Thanks!'Dave
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Post by rowdy235 on Oct 2, 2018 16:44:57 GMT -5
People have had similar experiences with chips, dont know what fails but something does and its lights out.
I'd get a replacement one.
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Post by undee70ss on Oct 4, 2018 4:53:10 GMT -5
Hi all, Just joined your Homelite site for some info on my XL700. I just installed a Nova II 31-8786 ignition module. I had done my Stihl 015L with another brand and it works great. The XL700 module went in awesome and got great spark on the bench. Fueled up and it started/idled well. After less than one minute it shut down & wouldn't fire at all. Took the machine back in and couldn't get a spark again. I had cleaned everything well and all connections are good. Any ideas why she won't fire? It never got hot enough to do any damage.... Thanks!'Dave Where did you mount the chip? I read on another forum that there are places that they shouldn't be mounted.
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Post by rarefish383 on Mar 3, 2019 4:31:35 GMT -5
This is an old thread, but I’ll post and maybe it will help. I put a NovaII on one of my Super 1050’s and it’s run great for close to ten years. I ran the wire out from under the flywheel and bolted it to a factory hole in the case. So, it’s several inches from the coil. Maybe the failures are mounted too close. I did notice that the saw seemed harder to crank over. I was told at the supply house I got the chip from, they thought the chip advanced the timing a little. I also found that all of my 1050’s cranked easier if the throttle was cracked open, whether with the trigger lock or a finger on the trigger. My 99 cc Mac 550 does the same thing. I was told that saws with reed valves do that, Joe.
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Post by rarefish383 on Mar 4, 2019 15:06:05 GMT -5
Here's a pic of where I put the NovaII on my Super 1050. My profile says I joined in 2009, that's when I was working on this saw, so it's lasted 10 years. I don't use it much anymore because the fuel tank started leaking, but I put a shot of mix down the carb every couple months and it still barks. I bought 2 gaskets and can't find them or I would have replaced it.
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