How to DIY troubleshoot a diesel cooking stove and heater electrical issue? - Page 1
Forum section: electronics / beginners

author: pierremontagne
author_rank: Contributor
timestamp: October 13, 2025, 05:11:06 pm
content: I don't want to post a link right out the gate as I guess it will get flagged as a new user? You may look up FJH-1.8-/1C DZ N JP Single-burner Diesel RV Marine Stove.I will try and keep it not too long but might be hard to do that and also give the pertinent detail.12VDC diesel stove and heater combo appliance. Works in the same way as the very popular 'chinese diesel heaters' you see all over the net now just with a stove top to cook on in addition to the heating function.The problem is it suddenly started making a flashing pattern on the controller which does not relate to any of the error codes in the manual. During operation it will cycle through red, amber and green over and over. This could easily be ignored if it otherwise performed fine but a couple of times it has produced an alarming behavior where the fan suddenly makes a huge kind of oversurge and then the whole thing shuts down. You know like when you have a 12V fan running and sometimes there will be some kind of fluctuation in the voltage I am guessing? where it will change pitch for a second or two and settle down again. Well it is just like that but multiplied by about 4 or 5 times. It sounds like it is being forced into overdrive.Any ideas given the above explanation of what the issue might be?I messaged the manufacturers who are in china and had a stilted conversion with them not speaking english very well but they told me to check either if there is low voltage or if the controller has poor contact with the motherboard, which sounds just like wild guesses. I tried both of those and the voltage was at 13.26 and no sign of bad contact for the controller.I think it would be extremely costly to send back or send to a 'professional' such that it would cost more probably than buying a new one which are very expensive anyway.So can you tell me how I could try and diagnose the problem myself using electronics ingenuity?When I recently opened it up to service it I saw that it is very simple in design. It is just a burn chamber and a couple of pipes, one for the glow plug and one for the fuel line with the operation being controlled electronically via a motherboard and the controller. I can't say I understand what is going on regarding that side of things which is what I am asking here, how I could figure that out to get to the root of the problem as getting any kind of support from elsewhere would be extremely costly one way or another.Now one might think that the servicing mucked something up, which I am not ruling out but it was working just fine for several weeks after that and the above issues only presented themselves in the past week or so.

author: amyk
author_rank: Super Contributor
timestamp: October 14, 2025, 02:06:37 am
content: Check for bad capacitors and solder joints.

author: pierremontagne
author_rank: Contributor
timestamp: October 14, 2025, 07:04:03 am
content: Quote from: amyk on October 14, 2025, 02:06:37 amIs there a way to check the circuitry as well for issues on the main board?I am familiar only with using a mutimeter to test wires but is it practical to also check circuit boards too?I mean the same way like how you would test each wire in a system for problems, looking for continuity and current etc. Is it a similar process to test circuits on a board?

author: geggi1
author_rank: Frequent Contributor
timestamp: October 15, 2025, 04:58:20 am
content: Start simple.Do a visual check to see if there are any loose wiring.Then do a visual check of the circuit board and look for bad soldering or components that looks fried.Check the wiring to all external components like switches, buttons, sensors and other wired components.

author: pierremontagne
author_rank: Contributor
timestamp: October 17, 2025 09:09:01 am
content: Quote from: geggi1 on October 15, 2025, 04:58:20 amQuote from: amyk on October 14, 2025, 02:06:37 amI just unscrewed the motherboard to be able to take a look. Took some images but the camera ran out of battery so have it charging.I am not sure but there was jelly like substance that was at the base of both capacitors is it? The cylinder shaped things like water tower shaped and connectors at the bottom?Like thisI wasn't sure if that is damage or if it is just some glue? It seemed to ooze far beyond the location of where they were placed.

author: Psi
author_rank: Super Contributor
timestamp: October 17, 2025 09:11:47 am
content: Quote from: pierremontagne onYesterdayat 09:09:01 amWe would need to see it, it could be evidence that the capacitor has leaked or it could just be some glue they put on to stop it vibrating.

author: pierremontagne
author_rank: Contributor
timestamp: October 17, 2025 09:17:10 am
content: Quote from: Psi onYesterdayat 09:11:47 amHmm from an article I am reading it doesn't seem like it from the visual cues as it states bulging or corrosion whereas this is amber goo.However it states:QuoteThe above certainly sounds like that is what could be causing it. That could cause the seeming surges of power mentioned in the OP right?Shall upload pics shortly.

author: pierremontagne
author_rank: Contributor
timestamp: October 17, 2025 10:01:31 am
content: Quote from: Psi onYesterdayat 09:11:47 amHere are the images. Yea I know not the clearest but I am not taking the thing apart again!

author: pierremontagne
author_rank: Contributor
timestamp: October 17, 2025 10:02:27 am
content: Image.

author: pierremontagne
author_rank: Contributor
timestamp: October 17, 2025 10:03:52 am
content: Image1

author: Psi
author_rank: Super Contributor
timestamp: October 17, 2025 10:52:19 am
content: I can't quite tell from the photos, is it a sticky-mess or is it not-sticky.Glue can be hard or soft but is usually not sticky.Where as leaking capacitor electrolyte tends to be a bit sticky. Usually it gets on things and then dust gets stuck to it.

author: pierremontagne
author_rank: Contributor
timestamp: October 17, 2025 11:38:18 am
content: Quote from: Psi onYesterdayat 10:52:19 amNo, not sticky. I poked it a few times with metal screwdriver and it behaved like glue really. Soft but not very soft.I guess it doesn't matter much as either way the thing isn't working lol. I think I will be looking to get another motherboard whatever the cause of the malfunction may be as I don't see myself being able to fix whatever is causing the issue and from taking it off this looks to be the only electrical component besides the rotary controller.

author: MathWizard
author_rank: Super Contributor
timestamp: «Reply #12 on:Todayat 06:32:06 am »
content: So you contacted the company that makes them ? Or just sells them? And they don't know what the 3 flashing light pattern is ? Are the lights only for error codes ??Besides the fan speed moving up/down sometimes, and the shutdowns, does everything else seem to still work as it should ?How much does your household voltage move around ? (OK it's an RV/boat heater/stove, what input voltage and current does it require ?) I'm just thinking of some of my LED bulbs, that sometimes flicker and even go dim, when my household voltage gets noisy and too low, for these cheap bulbs anyways.It looks like there's a fair bit on the PCB. It would be nice to see what the low voltage rail(s) are doing when this happens, a DMM might see it, but really you would want an oscilloscope to see fast changes.