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Author Topic: Holt H75 electronic ignition repair  (Read 1378 times)

MadeForThat

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Holt H75 electronic ignition repair
« on: October 29, 2022, 11:13:47 pm »
Hi all, have one of Jin's magnificent creations, and have run it a number of times without issue. Today I attempt to fire it up and have no spark. Try new batteries, verify voltages after the switch etc. And all looks right. I don't know if anyone has gone down the road of repairing the ignition system of these engines, but any input would be appreciated. Not really excited to buy a new ignition system, this failed after a handful of runs, and likely is made identical to the replacement.  If I am going to buy a new one I need to know exactly what I did that caused it to fail (so I don't have to keep replacing them) and if it is something I did, why wasn't it more obviously warned about.
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modelbuff

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Re: Holt H75 electronic ignition repair
« Reply #1 on: October 30, 2022, 08:19:16 am »
Recently I experinced the same thing with my engine. After a great deal of investigation I found the problem. The Hall pickup sensor is located in a plastic housing on the side of the gear case. The sensor had slipped part-way out of the plastic housing in a postion where it could not get triggered by the magnet inside the gear case. I pushed the Hall sensor back into the plastic housing and secured the wire with a wire tie. Problem solved.
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Randy Tucker

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Re: Holt H75 electronic ignition repair
« Reply #2 on: November 01, 2022, 08:47:30 pm »
I have had an issue with my h75 on the ignition. First turn it on no spark. If you leave the switch on for about 1 minute it will have spark and runs fine. I've tried new batteries, different brands of batteries, same thing. So now I turn it on, put fuel in tank and oil it and by then it's ready to run. I've had this issue from the start. I've got a new ignition for it but figure run this one till it stops working completely then I'll change it.
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MadeForThat

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Re: Holt H75 electronic ignition repair
« Reply #3 on: November 04, 2022, 06:09:09 pm »
Well I went ahead and bought replacement hall effect sensors, as I noticed that the ignition circuit would fire when black was connected to the blue wires (replicating hall effect pulling down when activated) So far what I am noticing is that it works with the replacement sensor, but 2 wires fire at a time.  I suspect it always did that and I just didn't know/observe it. So I just need to get the new sensor all soldered in and make sure it can't short out. I don't know what caused the failure, if it might have been a stray water drop or jolt from the ignition that fried the hall effect sensor. Not sure, but for 8$ I have 9 more replacements.
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MadeForThat

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Re: Holt H75 electronic ignition repair
« Reply #4 on: November 04, 2022, 06:26:10 pm »
You can buy 10 for about 5$ shipped from china here: https://a.aliexpress.com/_mPUBLtE
 Or if you want replacements quick from Amazon: https://a.co/d/2oEP1qq
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Jim

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Re: Holt H75 electronic ignition repair
« Reply #5 on: November 04, 2022, 06:49:51 pm »
How hard a job to solder in are these?

Thanks for the links.
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Jim

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MadeForThat

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Re: Holt H75 electronic ignition repair
« Reply #6 on: November 04, 2022, 09:27:17 pm »
They are quite small, but if you have a set of "spare hands" it isn't very bad at all, the hardest part for me was keeping some of the heat shrink on the center pin.  These are what I have (but the harbor freight version) https://a.co/d/jaMUMx9
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MadeForThat

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Re: Holt H75 electronic ignition repair
« Reply #7 on: November 04, 2022, 10:15:45 pm »
I've attached an image of the sensor with the colors of the wires as they should coordinate. Take note of the writing on the chip facing up when wiring. Also not sure how this engine is timed, I don't think the chip went all the way into the plastic cover that holds it on the cam gear, so it will be a little retarded (or advanced?) from normal. This was because I used a waterproof heat shrink tube to cover it all, and that added a bit of extra thickness. Won't know if it is an issue til I fire it up!
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Jim

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Re: Holt H75 electronic ignition repair
« Reply #8 on: November 05, 2022, 12:41:40 am »
Thank you!
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Jim

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RedRyder

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Re: Holt H75 electronic ignition repair
« Reply #9 on: November 05, 2022, 06:00:52 pm »
Great info, gents. Thank you!
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steam 4301

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Re: Holt H75 electronic ignition repair
« Reply #10 on: November 18, 2022, 08:01:02 pm »
Just wanted to say i did the replacement on the pick up sensor that MadeForThat posted here and it worked perfect. Got the sensors on amazon. Have to take your time soldering them but works great.
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Brian

MadeForThat

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Re: Holt H75 electronic ignition repair
« Reply #11 on: November 21, 2022, 08:17:54 am »
Great to hear it worked for you as well! I have messaged Jin referencing this thread, I think that a lot of us would probably like to have a few spares of these already wired and laying around and I suspect that would be a lot cheaper for Jin to send replacement sensors rather than the whole ignition. Perhaps prewired will be a product soon :)
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steam 4301

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Re: Holt H75 electronic ignition repair
« Reply #12 on: November 21, 2022, 05:56:54 pm »
I spoke with Jin and he is sending me a prewire sensor.
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Brian

MadeForThat

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Re: Holt H75 electronic ignition repair
« Reply #13 on: November 21, 2022, 09:21:40 pm »
I appreciate that he is willing to send parts for a machine that he has no obligation to warranty. I do fear that if something else in the ignition circuit went wrong I would probably not be able to repair it because it is all potted, (epoxy filled box) but perhaps after a few good years of producing this and earning his profit, Jin will release a circuit diagram so someone with sufficient knowledge could fix/rebuild these circuits.
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MadeForThat

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Re: Holt H75 electronic ignition repair
« Reply #14 on: February 12, 2023, 08:05:47 pm »
@engine-man you will see above how I repaired my hall effect sensor, I am sure it is the same, but you may want to compare.
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