Building an Obsolete Prototype AVR Replacement for a Honda EM500
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- Опубликовано: 8 сен 2024
- I recently made a video on this Honda EM500 generator. A subscriber sent it to me after it started producing almost 200 volts out of the 120 volt outlet. The ultimate issue was that the automatic voltage regulator (AVR) had failed. The part was obsolete and not available new or used. Even worse Honda potted the board with a resin that could not easily be removed and did not publish any circuit diagrams. I did manage to find a new old stock AVR for $200 from a seller out of the Netherlands. I purchased what was the last one available for sale in the world.
A lot of these 40+ year old generators are new failing. Mechanically they are sound, but the electronics in the AVR are going bad. After publishing the first video a few came forward and offered to assist with designing a new replacement board. I sent the failed board to Bill. Within weeks he had produced several design options.
Today I am going to gather some more data, choose an AVR design and build a prototype board. I have zero board building experience. Should be interesting.
Generator Model: EM500
AVR Part: 32350-892-632
First Honda EM500 Video
Vintage Honda EM500 - High Voltage Problem
• Vintage Honda EM500 - ...
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#HondaGenerator #GeneratorRepair #SmallEngineRepair #SmallEngine #DIY #Fixed #Troubleshooting #howto
AVR, Alternator, Automatic Voltage Regulator, Depotting, EM500, Fixed, Generator, Hertz, High Voltage, Honda EM500, Honda, How To, How-To, Kill A Watt, Load Test, Obsolete, Oscilloscope, Prototype, Repair, Small Engine, Too Much Power, Troubleshooting, Vintage Honda
Hi generator fans, thanks for all the "Kudos". I am the "Bill" James mentioned. After looking through the comments, I thought I would provide answers to the most asked questions plus, add some details to the tests done in the video to hopefully minimize confusion. First off "AVR" stands for Automatic Voltage Regulator, which is fully electronic, as opposed to electro-mechanical voltage regulators used on cars from the 1960's and before. De-potting the original circuit was very difficult. I had to curve the potting away using a soldering iron and Honda's board construction was very similar to pocket transistor radios manufactured in Asia in the 1960's; parts were laid over parts squeeze the circuitry into a given space. The de-potting operation ended up being a destructive type, as removing the top layer of components, damaged both upper and lower layers. As each component was lifted from the board, a schematic was made of its attachment to the rest of the circuitry and, in many cases, the part marking was lost during the "dig" so, I had to calculate some of the lost values to make up a complete reverse engineering effort.
The original Honda AVR circuit was not reparable (not even close). That was the most tenacious potting material I have even experienced. As mentioned, just trying to get to the defective part would have certainly destroyed probably half of the circuitry on the board. I never did do a failure analysis due to the de-pot being a destructive effort. However, in looking at the circuitry, I could formulate a failure theory. Most likely, the switching transistor shorted out.
In coming up with a replacement circuit, I tried a simple circuit first, that basically fed the voltage regulator supply voltage to the field winding. The result was unsatisfactory due to very poor generator voltage regulation. For round 2, I decided to mimic the operation of the original circuit but, use newer parts that were more suitable for the job, in addition to using parts that are easily sourced, now and in the future. This seemed like the minimum risk approach. Basically, the regulator circuit pulses the field winding during each positive and negative cycle, with the duty cycle varying as necessary to keep the generator output voltage constant. I wasn't happy with Honda's original AVR circuit, it appeared to be an unstable circuit that was fixed by throwing various parts at the circuit until it behaved satisfactory.
Working with James was a learning experience for both of us. We did all of the work using E-mail since we live about 1,000 miles apart. I designed and documented, while James attempted to build and test the proposed circuit, along with taking test data on the generator and Honda AVR. I assumed James had prior circuit board building experience but, the little bit he had was so long ago, most was forgotten, however we got through. I actually appreciated the less than perfect board construction because, if the board functioned properly, it increased my confidence level the board would perform well in real world environments.
The scope plot of the switching FET was connected to the drain. The N-channel FET is being used to ground the field winding when it is pulsing the field. The other field coil winding is connected to approximately +18Vdc. However, the confusing part is, the scope plot is inverted so, what looks like a positive pulse, is actually the FET turning on and grounding this line. There is a "catch" diode used to short out the field winding discharge when the FET turns off. The somewhat goofy/non pulse shape of the response is due to the field winding ringing as it discharges.
Miscellaneous - I was planning to re-layout the board using surface mount components, the proto board used in the video was for Proof of Concept only. I don't plan to use a 10 turn pot, I want a 3/4 turn pot with a very limited adjustment range. The pot also needs to be moisture and fuel resistant so, not your typical pot. Yes, I do plan to look at control loop stability under various inductive and capacitor loads, along with surges, load disconnects/connects, and whatever other torture methods I can come up with to make sure the product is reliable out in the field.
I love the fact that not only does my old Honda have a second life. But as a test bed it can give other old generators a new life. Excellent!
Most generators fail because of improper maintenance. Taking care of a generator or any small engine( most of the time) will make it last a long time.
@@fcdrummer1806 yeah that generator was well cared for and the forty years I owned it before I donated it to the channel. It always started as easily for me as it did in this video.
@@louisbigelow1866 I can see that. It doesn’t take much to clog a carburetor. It’s easier to do a bit of preventative maintenance then having something go wrong in the future.
As a retired EE this was a fun video. I think anyone who had built or troubleshoot prototypes has let out the magic smoke on occasion. Glad to see you and Bill have been able to reverse engineer the AVR to breath life into these old generators.
Do you have any resources to figure out how to reverse engineer a simple AVR like this?
Hey Tom, that smoke sneaks out every so often. Problem is, I have never been able to find a component smoke refiller. It's probably on the back shelf at Walmart next to that spray that keeps amplifiers from oscillating and oscillators from amplifying.
Dust off the old PhD (post hole digger) and please give me feedback
on the idea of using the sense voltage tap AC, bridge rectified to
provide signal input to a transistor output optocoupler, or
( even a vactrol could work), with the output then used to
modulate an adjustable PWM. Hardware Hackers Rule !
When I was in school for Computer/Electronics Engineering Technology, my first experience with this was when I was building a variable benchtop power supply and I put the op-amp in upside down. I flipped the power on and SNAP I saw a spark and smoke rising from that op-amp. Pencils have erasers for this reason.
@@billharris6886 My Walmart doesn't have anything in electronics pieces, I have to rely on Digi-Key, Element 14 or Sayal for that kind of thing.
was *NOT* expecting to see you take a shot at rebuilding the AVR for this old fella... glad to see old equipment revived, however means possible, even if it fails... EVERYTHING is a learning process when it comes to fixing/restoring old equipment as such.
Well, my high school physics teacher told us essentially what Ms. Frizzle has been saying on the Magic School Bus: "Take chances, make mistakes, get messy!" His was more in the way of, "we learn from our and other people's failures, as in order to learn, we have to fail first."
@@WJCTechyman good grief.... I used to watch that show and remember that line fondly.
I passed this video on to a friend of mine who teaches a basic electrical class. Nice job Jim on taking a chance. Also, kudos to Bill.
The wire connector is a DJ7061A-2.8-11/21 connector. Just check the connector pitch since 2.8 is usually standard but looks like it can be multiple pitches. Hope this helps
You beat me to it.
I was going to suggest checking sources for Japanese motorcycle parts, because it looks like the same style used for switchgear connectors (headlight+turn signal switch etc), but that part number pins it right down. Thanks!
very enjoyable to see you pushing these boundaries. Great input from your viewers. Kudos to Bill.
This was an outstanding "deep dive" far beyond what I normally see on this channel. Congrats on building the AVR. It would be most helpful to see the full schematic, but from the very brief frame shown, I see the linear version as a simple voltage comparator driving a MOSFET. In the second version AVR (PWM) you comment about the negative going pulse when the generator is under moderate load. I think this is back EMF from the windings. You might consider adding a protective diode in parallel with the MOSFET to help protect it. I assume there is already a reverse diode inside the mosfet device. One other observation to note are the sharp edges on the waveform as these will create radio interference on the AC line which will act as an antenna and radiate. Granted 95% of the users will not have a problem with this, but a shortwave or ham radio operator definitely will.
Keep up the great work!
The "body diode" inside a MOSFET can be used sometimes, but they're notoriously slow, and a great many applications will use an additional external diode in that spot to deal with that issue. Not having a clue as to what the circuit is actually doing, I couldn't say whether this will make a differene or not.
@@Roy_Tellason Not only are in die diodes slow, they are unreliable too. There may be some flyback voltage as the OP said and over time this does for the diode. An external one would be a good choice in any event for an inductive load.
Note that the oscilloscope plots are actually showing an inverted signal. We are using an N-channel power FET with the source grounded. The voltage is about +18Vdc when the FET is switched off, 0Vdc with the FET turned on.
I did include a high speed switch mode "catch diode" to discharge the field winding when the FET turns off. The somewhat goofy trace is due to the flybacking of the field winding.
I made sure the FET is not switching fast to minimize radio interference. Since the oscilloscope is set to display a 60 Hz trace, the FET appears to be switching fast. I considered using a full linear regulator to feed generator but, there is no good way for the circuit to dissipate the substantially higher wattage this regulation method produces. Also, I tried to model the AVR operation after the original circuit to minimize developement risks but, use newer available parts.
I'm no electronics expert but that original Honda AVR shocked me. I would venture to say it's no wonder the AVR failed. Guessing too that those cool little gens had a high AVR failure rate. If you combine the heat of the running generator with the heat generated by the AVR operation, it's only a matter of time before AVR failure occurred. Back when the original AVR was made component size was larger. Now with all the micro size components available it seems totally feasible to engineer a replacement that will hold up long enough to make it worth the effort. Like many good ideas this one only had to wait for technology to catch up. Well done James and Bill
Hi James, I have enjoyed watching your channel for a number of years and enjoy every moment of it. I enjoy designing PCB as a hobby (I am an EE) and think that saving these old generators is highly worthwhile endeavor. I would be delighted to gift an AVR PCB design to you and your channel to keep these generators out of landfills once you have settled on a working prototype design. (Would be happy to agree to an NDA as well.) Kevin
❤ Way over my head. Congratulations it was clear as mud to me. 😊😊😊
If the meters on your power supply are off, take a look on-line for the user manual, its available on the manufacturers web site. The manual in figure 11 where the adjustment pots are R64 = A zero, R56 A meter adjust, R54 V meter adjust and and R21 is -5V adjust.
This was absolutely FANTASTIC. Your talents and willingness to share them are most appreciated! Kudos to yourself and Bill for coming up with a solution!
I appreciate the extra effort to keep older machines in service. It is something I try and do with my stuff also. You want to see the machine actually be worn out when you retire it. It's no fun when a device is scrapped, and you KNOW that it just needs one piece/part to recover.
I thought you told us that you did not know any electronics James. You described and explained that extremely well. I can think of ways to do this using purely analogue techniques. Mind you digital electronics can do things more simply and more cheaply. With Bill de-potting and reverse engineering the Honda design there is not much point coming up with a totally different design. He knows the design is fundamentally sound and does work. Thank you for sharing your work.
Legacy automotive regulators used output voltage of the alternator (rectified) applied
across a solenoid that attracted an armature piece that had adjustable spring tension
like a relay armature to operate a contact slider as a linear potentiometer or rheostat.
Same as for a fuel gauge sending unit, a fine gauge resistance wire coil, the position
of a wiper contact would allow more or less current, exactly like a potentiometer. The
simplicity and ruggedness of those devices made them extremely reliable and easy to
adjust or troubleshoot or replace. I understand the advantages of technology but not
all of the alternative legacy technology is in any way defective. A problem is in most
cases it was more expensive to manufacture, easier for anyone to repair, lasted longer,
and provided the consumer more in return for their purchase expense. What is actual
progress may depend on a more subjective valuation, other than what is trending now.
@@artpatronforever Yes, the older cars I owned used electro-mechanical voltage regulators for the alternator and dashboard instrumentation. The nice thing about the mechanical stuff, it gave an indication it was dying instead of the electronic version's abrupt failure. The premise with going electronic is, with the lack of moving parts, reliability should be better - that is, if it is designed right (the BIG IF).
Any electronic control circuitry can use either digital or analog design and end up with the same level of precision but, the question is: at the expense of how much circuitry? In this AVR redesign, I'm actually using a combination of the two to maximize performance with a minimum parts count.
@@billharris6886 A useful advantage for the mechanical regulators
is adjustability for people who use their cars for many short trips.
Alternator output is easy to adjust upward slightly to keep a battery
charged. It is also preferable for having diode blocks not inside the
alternator as an integrated module. With separate modules alternators
run cooler and last longer. And a failed discrete part is more easily
replaced. Most commonly the bridge rectifier fails or the regulator
fails while the alternator itself is still working. Unit replacement
designs are meant to be unserviceable and are built accordingly.
@@artpatronforever I never have encountered an automotive mechanical voltage regulator, either DC generator or alternator types. Adjusting these was a trial and error balancing act, you had to bend contact arms and return springs to adjust the regulation voltage. Then you had to go back and fine tune these settings to produce a constant output voltage versus load. Mechanical voltage regulators also constantly generated voltage transients on the 12 volt line. This was due to the rotor being fed excitation power from either ground (no charge), 12 volts through a resistor (half charge), or a full 12 volts (full charge) by a set of bouncing contacts.
I completely agree about using a remote mounted 3-phase bridge rectifier for the alternators AC output (with good heatsinking of course). Living in Florida most of my life demonstrated how easily the alternator assembly (with internal rectifier and electronic voltage regulator) can overheat in the summer with stop and go traffic with the air conditioning running "full tilt".
@@billharris6886 Hello Neighbor in Florida. Just by coincidence a
Honda EM500 has a 12V DC output rated 8A. How convenient and
thoughtful of the manufacturer. There is more than one way to skin
a cat. Since all of the main winding outputs are taps, an AVR only
regulating one of the taps is done and the other taps follow that
regulation with themselves regulated also. Any AVR variant that
is suitable for 12V regulation could be associated with the 12V DC
output. The lucky coincidence is that 12V vehicle regulators are
cheap and common and might be easily adaptable to function as
an AVR, in a variant configuration. There are many custom design
variable adjustable output vehicle regulators and modifications
in the public domain from car audio enthusiasts that could be
helpful. I am certain that many of the vehicle regulators also
have pulse width modulation outputs and that sense signal
inputs can be incrementally changed by use of 1 or more
diodes, that steps the regulator output response to match
the fraction of a volt of each diode voltage drop. So even a
a sealed and potted regulator can be adjusted incrementally
for voltage increase by a string of series diodes. (Edit: I did
review and this diode adjustment works on 3 wire electronic
type automotive regulators but is not applicable to the PCM
computer controlled regulators that have a PWM output. )
The diode blocks are separate on some of these modules.
But the Honda EM500 needs 16V DC at peak demand for
the Stator Exciter for Rotor, and a power MOSFET follower
would work just fine there, to mirror the PWM output of
the 12V nominal vehicle regulator, as a current sink for
the Stator Exciter for Rotor coil, supplied by bridge rectified
and capacitor filtered basic local power supply from the
former EW Exciter Winding that earlier powered the AVR.
The adapted 12VDC vehicle regulator would likely best
be powered from the 12VDC output of the tapped main.
But it could possibly be powered by a different local
source conditioned and regulated to fit its requirement.
Anyway, sorry for stream of consciousness pedantics.
But where there is a will there is a way, and an automotive
regulator could adapt as an AVR for any generator having
a tapped main with a 12VDC output. Maybe it is ghetto
engineering, but when it comes to Afro Engineering
during a power outage, it may be good to improvise
anything to keep a man out of the dog house. On the
old automotive mechanical regulators, are you familiar
with a Filco Crown Jewel Regulator ? ( Edit 2: After a
review of the PCM controlled vehicle regulators that
do have a PWM output function, I see the PWM signal
is originating with the PCM (engine computer) where
the actual voltage regulation sensing is done also)
So it is only the 3 wire automotive electronic regulators
that would be possible to adapt for use, and should
work, but would not necessarily have a PWM output.
Depending on the internal circuits of the electronic
3 wire regulator, it may be an analog output or it
could be PWM, a detail I do not know. A follower
power transistor output would be needed in either
case because of the 16V maximum needed by
the EW Exciter Winding for the rotor at full output.
A 12VDC regulator could switch that 16V supplied
separately but a 12VDC regulator could not directly
source a needed 16V for full generator power output.
Very interesting, but I would have liked to have seen the un-potted regulator, the reverse engineered cuircuit and the new circuit. Keep up the interesting videos.
Hi James...Nice work on the AVR. It functions beautifully..... The strange "tail" in the MOSFET when the FET turns is probably flyback. When the FET shuts off, the inductive load is still carrying a charge and goes back to the FET in the opposite polarity. Depending on the specs of the FET, it could eventually damage the FET and render the circuit inoperative. Most FETS can handle this as the FETS are tested for this but again, cheap components aren't tested fully or are downgraded (test failures for certain specs) and shipped out. An example of downgraded components are computer CPUs. There are generally a very limited number of die (the silicon) on a wafer (how the die are manufactured). A silicon wafer cost is extremely high and the test yield needs to be very high to make it cost effective. So if a CPU is tested and, for example, some of the internal memory fails, The bad memory is turned off through fuseable links or "trimmed" and sold as a 256K instead of a 512k memory capable CPU. I would opt on the side of caution for this application and purchase automotive grade components as they are electrically tested from -40c to 125C (consumer electronics are tested to 25c only) and are subjected to a whole battery of mechanical and electromechanical tests (the qualification testing for automotive components takes almost two years) that will ensure the AVR a long life. "Hope this helps"
Congrats on the successful PoC with this one Jim. Nice work putting it all together to confirm regulation under various loads. And hats off to Bill as veteran EE to reverse explode the circuit for you to build, that takes talent and patience with such limited support from the OEM. It's an artform to create complex onboard electronics in confined spaces because of all the factors required (safety/space/thermals/serviceability/cost). As an owner of a two EM500's and one EM600, It would be great to have an option for replacement since two of the three of these machines are not usable due to overvoltage issues (185v+). Thank you very much for the update and please keep us informed if these ever become available for purchase.
Now that’s an award winning video! You’ve gone where you’ve never been before!!
A 6 pin Molex connector cable with latching male to female plugs, 18 ga. conductors,
could be cut in the middle and spliced in to provide standard connectors. There are
different ways to build an automatic voltage regulator, very likely a better regulator
can be made as a replacement than the design Honda used originally. Many of the
AVR modules may be interchangeable equivalents that operate the same way. So
an obsolete part may have several different substitute variants specific for other
model generators that will also work as a sort of universal substitute that isn't
identical to the OEM part but is close enough to be used.
This channel offers an extraordinary range of blended technologies. At the bottom of it all it is mankind just being himself, curious and willing to get his hands dirty. Love it.
Just love it; James is evolving into R & D now...good luck with a workable final product!
You are literally the best part of the internet. Thanks for making such great videos, this was a standout. I really enjoy your smart, patient, and methodical approach to troubleshooting and problem solving.
I really enjoyed this one, Jim. Brought back memories of building electronic circuits or working on them down to the component level. Hats off to Bill.
Really marvelous! Took me right back to the '70s and my teenage electronics hobby time in England.
The local TV repair shop actually made a prototype motor control circuit just like this for me to fix my old (even then) Philips cassette recorder that had too much wow and flutter.
Thanks so much for this!
Not a power MOSFET though in those days!
I have an em400 that the evr had failed I found one on eBay for 300 dollars. There is no way I would pay that much when I can buy a brand new AI inverter generator for 400 bucks. Great job.
Best thing to do with these old generators, is connect the sense to the field, so it puts out 200v ac, then use it to power a Victron or similar "universal" battery charger. These chargers work with ac or dc 100 to 300v and use switch mode to give the constant output voltage. 400W is useful as a battery charger in a RV.
Excellent content! Loved every minute! LOL at your “magic smoke” comment. Many thanks Bill as well. Wish you the best finding a board maker and connectors.
Good on you for having a go at making up an AVR.
Companies like JLpcb will be able to make you up a batch of printed boards. Going forward, life will be one heck of a lot easier just to assemble your components onto a pre-printed board👍🏻
I was going to make the exact same comment. Jlcpcb charge just $2 for 5 PCBs, plus shipping and taxes.
If required they will even fit (most of) the components for you with just a small set up fee ($8) plus the cost of components, but be sure to choose basic rather than extended components wherever possible as there is a fee of about $3 tool change for each extended component. That may worthwhile if you want to offer (almost) complete boards while having to do the minimum work.
If you were having 10 or even 50 boards made the set up fee and tool change fee is still the same so the cost per board is reduced.
If you use surface mount components the board will easily fit into the required space.
@James Condon If you want to send me the diagram I can soon knock up a pcb layout for you.
Thanks for the PC Board tips!
Great job ! I was hoping someone would reverse engineering this AVR, a little fine tuning then comes the hard job of trying to shoe horn that into a package that'll fit the generator. Outstanding.
Wow James! A great video, and you are going to great lengths to keep quality generators out of our landfills etc. Considering all you had to solder in, hook up, monitor, record data, and screen shot you did an awesome job! Some generators are like a reliable old car to some, and they grow fond of them and don't want to toss them due to non available AVRs etc. and in general we see Gens. being built more cheaply and less reliable these days. Great work!!
I love stuff like this! I've seen lots of different AVR modules on Ebay, some of which seem to be a universal (and often externally mounted) design. It would be interesting to experiment with a couple of those on various generators to see how well they work, and if it would be a worthy upgrade for "standard" generators.
Usually AVR is build with voltage reference source (i.e Zener diode or some ref. IC), a comparator, excitation current amplifier (simply transistor or MOSFET) and resistor divider from rectified output as control input. Not a problem for a good electronics engineer.
Edit: Good job with this AVR circuit, it holds the voltage beautifully, better than the original. 👍
Thanks Adam, the circuit topology you mentioned is what I used for the AVR.
Quite interesting seeing this design. Be sure to post for Rev B of the AVR. I'm sure it is very possible to go from the breadboard you have to form-fitting design. Keep it up!
Building "Unobtainium"? Good on you, James! 😍 I hope this project becomes a success and also a template for other discontinued components.
If you can't find exact 6 pin plug. Think about de-pining 6 pin socket, use a new molex plug & socket on both ends of cables. Also 3D printer users may be able to print a curved case slightly bigger that still fits, and have if free for uses to print there own case for circuit board.
I think this was your COOLEST video yet!😊
What a great project!
Wow, that even made me nervous Doc., great job you and Bill did.
Definitely one of the best videos done on repairing a generator with a faulty AVR. You have many comments on offers for help and seeking assistance for repairs, this could keep you busy for a while. Great work James.
This is absolutely amazing! This also makes me wonder if some DIY AVR could be made to improve cheap generators to have a better quality output power? Once you have a working circuit and component design it should be easy to get some more efficiently packed PCBs made to fit the space it needs to.
Hi Matthew, yes the most basic generator is a brushless type where the field winding is powered from an AC capacitor. This type has the poorest voltage regulation and is substantially affected by engine speed. While it is possible to convert one to an electronic regulator, that modification could be quite extensive.
Agreed, a compact PC board layout is the next step, although this project is a spare time project so, it will probably another year before we can get to it.
As an electronic guru tech this was an amazing video to watch James! Hopefully someone in the comments will reach out for designing a similar sized PCB to fit the footprint inside the generator. I cannot imagine that there will be much of a market for this particular AVR but you have opened the doors for reverse engineering other AVRs! Yeah!!
Probably not a huge demand on and old 400 watt generator, but a fun project non the less.
@@jcondon1 absolutely! A few more tweaks with some community effort and Im sure it will be ready! Great video and project!
@@jcondon1 Well, never mind then.
lol, I pulled the front power head cover off of a husky build generator 5k running watts. Because I was told it did not make power, well when I did that I saw aluminum droplets come out and I’m like “hm” well turns out the mail coil winding was burnt to a crisp and the whole power head was dead. The rotor looked good though.
Hi James, check your meter manuals mate, some of them will have a feature where if you hold a certain button when you switch it on, it will overide the auto shut off and stay on. Bob UK
Yes some do have a way to disable the auto off.
I have two of those generators with bad voltage regulators. I really liked them as they started very easy, and were quiet.
Cheers
Warren
Outstanding content for this video. You and Bill way smarter than me. 😅
Great site you have James. There is much knowleage to be aquaired here. Thank you and those who add to this site also.
Jim - kudos! The quality of your video, lighting, an d audio just keeps getting better and better. And that's probably what it takes to keep viewers. Love your channel and I'm totally jealous of your new rework mini heat gun - great tool!😁 Thank you
The mini heat guns is my sons. I “borrowed” it,
Some notes from an old control systems designer - You have to tune the Loop Gain and the frequency characteristic to optimize the things. The gain is basically set on the operational amplifier to provide load independency. The "speed" of the control loop is tuned with capacitors around the amplifier. That means possible filtering of the measured (sense) voltage, but also the speed of the amplifier and maybe the response of the FET. All this is affected by the inductance that the FET is driving. That "closes the loop". What I see in your scope results is you have pretty close desired gain. You could probably improve the loop timings, as the jitter in the pulse width suggest a little improvement should be possible.
The reverse polarity "tail" on each pulse width modulation cycle is typical for the inductive load that the excitation coil represents. You could affect it by having either a series or parallel resistance for the coil, so that the effective L/R time constant is closer to your wishes. But as you can see from the amplitude and duration of the tail, it is determined by the energy stored in the excitation coil (inductance) and that energy is proportional to the excitation current (actually squared). During the "ON" pulse, the current runs through the transistor part of the FET, but when the FET is turned "OFF", the coil current wants to continue, in same direction. This forces the inverted voltage, as the current then runs either through the parasitic diode in the FET structure, or through any added diode on the board for the "Freewheeling" path. In principle you can affect the appearance with changing the mentioned L/R ratio, and/or increasing the pulsewidth modulation frequency. Typically all those changes increase the circuit heat losses somewhere, so the changes become an optimization task. Sorry for so much talk, instead of offering to do the board design. I just promised to revise a rather big design I did in 1990 -1992. Some components have become obsolete in the mean time, and patching the board for the substitution components is becoming too labor intensive.
Looks like a connector from either dash headlight area or voltage regulator from an old Honda bike. Wish i could help more.. Well done James!
Love to see this level of fix to bring something back to life. What a great video James and Bill!
Wow a new level of repair. Good work Jim and friend's.
Thanks for the video, I found it really interesting, you did well building the AVR when you have not done anything like that before
Thanks James and Bill for tackling this problem. I only wish I could understand electronics more. I've taken boards out of many things and wondered how these thing work :) Just never had the time or brain power to learn it!
Fascinating… I was hoping to see a little emotion with your impressive achievement James.
Nice job
Would have been interesting to see the schematic and theory of operation
That was a cool video James. Very interesting and informative. I've never fooled with PC boards except for removing and replacing. I did have a technician repair one for me at a plant site I worked at quite often. It was out of my flatscreen and videos on you tube told me of the problem board and pieces to replace to resolve it. That was 12 to 13 years ago and she still plays well.
Nicely done James, You done good.....
Mike M.
Jim this is awesome ,designing the replacement board is awesome you and Bill have turned a parts machine into a useful product again I love this stuff it takes you from a parts replacer to a designer ,A tip of the hat to Jim and Bill for the design of the AVR
Thanks both for putting this out there
Well, James, you lost me after the first five minutes, but that’s certainly not your fault! Up to now I’ve been able to gain bits and pieces of generator knowledge from you to the point that I almost understand most of the videos you’ve done. This one, on the other hand, shows me I have a lot more to learn in order to understand what’s going on under the (AVR) hood. As usual, a well produced video, so thanks a lot. 🔧👍
On your black meter. Hold the “F1” button down and the turn it on. That should disable the auto off feature.
Thank for the great vids.
I sent an email about the connector. Cycle terminal should have it.
Best video yet. It is pretty cool watching remote hands accomplish prototyping a board in the field. Takes a fair bit of kit to acquire not only all the data points, but quality data points. Well done.
My compliments to Bill for his work. Is it possible to repair the original AVR now that it is unpotted. You have gone far beyond what any shop would do in resurrecting the old Honda because we all know you enjoy a good challenge. A PCB is the way to go.
I love the old wire caged shop trouble lights of which I have two, both with LED bulbs so they will not destroy themselves "when" dropped. The one trouble light is from the late 40s when we got electricity on the far.
Me thinks your PhD in electrical engineering is showing and that's a good thing, very interesting and nicely done
Bill is the master. I am just an apprentice.
A bunch of meters have a second function when you power them on that typically allows the light to stay on, the power to stay on, or both. It has long been a Fluke thing to hold down the light button when you turn on the meter and the light will stay on, or, after you press the light button it stays on when powered up that way. Many Kleins will stay "power-on" when powered on in the right way, but will "beep" every set number of minutes to let you know it is still on. Many meters have the second function instructions (not Kleins) molded into the back of the case. Just FYI if you didn't already know.
Yow Got it soldered and together and it worked first time.....Hats off to Bill for that desgin Don't fall into the digi key rabbit hole too far!
Im happy to lay you out a board for free. Plenty of years experience in design and dfm.
Great video! I recommend Altium Designer and JLCPCB for PCB design and manufacturing. They are pretty inexpensive and quick.
Great job, James! Back with fresh content!
You gave a sneak peek on the live stream and I was curious if this was going to go anywhere. Thanks for the video.
Sometimes it's easier to design something from scratch rather than reverse engineer someone else's mistake.
That magic blue smoke is a marvellous thing.
Have you considered 3D printing the AVR plugs?
The 3D printing is an option but, very costly in comparison to someone already making the finished connector so, that's where we are looking at the moment. Thanks though for offering a possible solution!
This is the most informative generator channel I have seen. It taught me a lot of information regarding maintaining generators and small engine equipment. I also did some research for the hertz to rpm conversion. 1 rpm = somewhere around 0.016-0.017 hertz. Setting the generator speed at 3660 is at 61 hertz. To get 61.5 it’s generally a good idea to go for 3700 or slightly above because the engine speed will never be constant. It will always change a little. Also it depends on the load and what your doing with the generator. If I was going to place a heavy load on the generator, I would set the engine speed a little faster(around 62-63 hertz) so the engine will not drop below 58 hertz or 3500 rpm. And slightly increase the sensitivity of the governor a bit to help out. Also it’s imperative to change the oil frequently and shut your fuel valve off after your done and let it run until it quits. Or you can drain the bowl on the carb. Also letting a piece of equipment sit without being run will destroy it(if it’s gas powered). At least take it out once a month or 2-3 months and let it run for 20 mins. I take my generator out once a month and let it run for 20 mins and never had an issue. Proper equipment maintenance is key.
Nice job, and no smoke !
This is fascinating. I wish you would go into depth about how all this works. This is the area I know virtually nothing about.
Pure Star Trek to me - but still learning - thanks James 👍👍
What an excellent project and results. And, I don't even own this generator... Super-kudos! I did not read all of the comments, but if you are still looking for someone to design the board, I can help with that. However, I am retired and can not pay for the prototypes. I use KiCad and can provide the finished files. I should be able to produce a form factor to fit the original shape and space. If the housing is less than 4" long, we should be able to use the Asian board houses to make the prototypes. Say ten copies for about $30/shipped. If you want to pay for the parts, I can do the soldering, as well. I like to solder... Even SMD components are no problem. If I may join your team, let me know and I will send you an email to establish communications. I am excited and hopeful to be included!
Awesome job Jim, and kudos to Bill who reverse-engineered it!
So glad it’s not just my soldering that looks like garbage. Always works though!
The last board I put together was a radio kit in the 80s. It never worked :(
@@jcondon1You put one of the diodes on backward…or something. 😉
Great video, James, as always. Kudos to Bill as well, a great effort on his part.
Big Clive!!
Well fellas you are very clever I'm a plumber and loved every minute of the video just trying to understand some of it, keep it up James your videos make my week
Wow, bold move recreating the AVR! If you get a working ciruitboard design put together, it could be layed out in free software like KI-CAD, and then printed in mass at any number of printing companies, they will even install parts and solder if you want. BTW, I'd put a heat sink on the Mosfet for the heck of it. As for the switching on the MOSFET, if your o-scope is setup right, It looks like the MOSFET is dropping into the negative voltage region while switching. You may need a different MOSFET, or some additional componants to smooth the switching some.
700Pcs Automotive Electrical Wire Connectors Kit and 315Pcs 2.8/4.8/6.3Mm Wire Connectors on EBAY I use these they fit Honda connectors perfectly and they are really cheap. You will also need a crimper I use Pro's Kit 6PK-202b. Love watching your videos, worked in electronics for 55 years. Radar/analog computers/power drives/television/projectors/cameras/stereo/vcr/cd/dvd. Now just ride my Goldwing and fish.
You guys are Great. I have the same model handed down from my father, and it has the same High Voltage issues. I still use it around my property for power tools. (Trimmers, Skill Saws, etc.) I have to watch what I do plug into it. I have been looking for an OEM AVR for well over a year without luck. Been keeping up with your videos on the issue and I would love to be the first one to purchase a prototype board.
great work on bringing life to old but still usable equipment, if everything works out with the replacement board there are companies that make printed circuit boards ready to solder components to.
This was entirely marvellous! I hardly understood, say, 1% of what was going on because my area of expertise and understanding is as a PhD Physical Organic Chemist. So I can think about one set of invisibles (atoms, molecules, enery, entropy etc) but volts, amps, sense windings, excitation winding etc, etc for me is largely huh? Perhaps it's age: my A Level Physics was 1967-9 . . .
All that said, kudos to Bill, you and everyone who made the parts that you assembled.
Trly wealth is socially-produced!
(Illth, incidentally, also . . . .)
Very nice AVR design. This is one of my favorite videos of yours. Looking forward to the next installment.
I work on large generators with very complex AVR's. Those are driven by digital controls and configurable via computer. It's so easy compared to having to chose resistors and engineer new boards! Loved your scope testing at the end, too.
The problem I would have anticipated would be getting the output control loop stability right. You want the output to correct for load changes quickly but without significant overshoot (optimally damped). Get it wrong and you could see wild oscillations that never settle.
So fun to watch you work. Amazing video. Nice job. Thanks for sharing
Incredible work!
Thank you.
As an electronics hobbyist, I appreciate the work in reverse engineering an unavailable product. I'd suspect the ripple on the output of the voltage regulator is either inadequate capacitance in the filter cap on the load side of the regulator or the regulator is running near the edge of its current capability. Not having seen the schematic, I can't troubleshoot any closer than that. Having 125 volts at the bottom of the adjustment range could have been misreading the code on a resistor or swapping two resistors in that area of the circuit. I'm sure Bill will have an excellent idea of where the problem is ;-)
Forget the like button, WHERE IS THE LOVE BUTTON? Great work - both you and Bill!
Outstanding work, love to watch your videos.
Awesome job bud..I bet ur happy with ur work on board...
Welcome to bread boarding. I’m 80 and still doing it. You can make all kinds of projects
I like the Picture-in-a-picture editing you do!
It's good to see old equipment a second life 12:06
Interesting James. I had been thinking of suggesting to you that you take a series of these same measurements of several of the larger units you work on so you can then make a test jig to test all those VR's you have in your junk pile. Might find some good ones!