MEP-016 SX460 AVR shuffle?

[Isaac-1]

There is a certain tendency to see failures in some types of components sooner than in others, thankfully though there is no real troubling ones on these boards, as a rule of thumb capacitors will be the first to fail on most electronic devices where there is not a design flaw, however the military used tantalum capacitors instead of conventional electrolytic capacitors which do not suffer nearly as much from age related failure. Having said that the most common point of failure on these boards tends to be the transistors, their failure is often caused by shutting down the generator without first removing the connected load as they simply burn out while the AVR goes to full output trying to maintain voltage as the engine slows down. I suspect the couple of diodes in test procedure are there because they tend to fail with the transistors, one being the final output protection diode and the other being closely related to the 2 transistors in the control circuit.

Ike

p.s. does anyone have a list of the specs for the CR5 and CR6 diodes on this board, or do I need to go out and look up the color banding codes? (well CR5 anyway, CR6 should be easy enough)

 

[Munchies]

Anyone run across the 'technology research corp' replacement regulator?
it is plug and play for the 3kw's 5's and 10's.
I have one in both my 3kw's now from the .mil

Military cost was about $250 Wonder what we could buy singles for.

edit found one

http://www.ebay.com/itm/6110-00-764...61193&pid=100011&prg=1016&rk=1&#ht_886wt_1037

 

[derf]

Electronic Assemblies | Technology Research Corporation

Looks like they made a batch for the govt and would probably make another batch but I doubt they have any on the shelf anywhere.

The SX460 is PNP enough for me, at around $60.

 

[Munchies]

Electronic Assemblies | Technology Research Corporation

Looks like they made a batch for the govt and would probably make another batch but I doubt they have any on the shelf anywhere.

The SX460 is PNP enough for me, at around $60.

I agree on the sx460 being an easy swap, I am getting a 016D back for repair and its getting one in a few weeks.
Yank the VR off of it and repair/save.

Wonder if these guys in florida who made the 'universal' VR can provide schematics/test flow chart etc

 

[Munchies]

I ripped this from ebay in case a mod asks me to remove link.




Purrrttyyy


Okay Isaac can have his thread back now...

 

[coyotegray]

Has the SX460 AVR worked well for everyone..?

I have twp MEP-016b's that have bad VRs so Im going to try installing the SX460 AVR..

Any new information on this ..?

Thanks,
Andy..

 

[powerwagon]

i am getting ready to install a new sx460 on my mp017, now I have to find where the 6 wires from my old vr hockey puck style go? any ideas?

 

[Ray70]

Looking for a little assistance with an SX460. I recently installed one in an MEP-016D, per this thread, fired it up and it worked perfectly.
The customer used the machine for about a week and last night it stopped making power.
I looked at it today and the field and Gen windings appear to be good ( resistance checks out )
The VR is not illuminating it's red LED at all, like it used to upon initial start up ( indicating RPM is not yet up to speed )
I replaced the VR with another SX460 and same result.

When I installed the VR I did not add any provision for a manual field flash since it worked initially without it.

Today I noticed there is a discrepancy in the wiring schematic on the machine's cover where in 1 place it indicates F1 is positive and in another place it says F2 is positive. I wired it according to this thread but I am now wondering if the field wires are backwards??

I'm puzzled as to why the machine quit making power while it was running, but the owner mentioned it was getting wet in last nights snow storm, but I see no evidence of an electrical issue, chaffed wire, burnt smell etc. , everything looks fine.

I am wondering what would the result be if the field wires were attached backwards?
I'm also planning to install a field flashing circuit but was wondering if anyone know for sure if F1 or F2 is the positive?? ( The wiring schematic is now suspect in my mind )

Lastly, can anyone supply details on how they have wired up a manual field flash circuit in an 016D?? Do I need diodes in the wires, or just a small battery and momentary switch wired to F1 and F2?

Lastly, I attempted to induce some magnetism into the field by disconnecting the VR and touching the F1 and F2 wires to a 12V battery for a few seconds ( as mentioned elsewhere on-line for the SX460 ) but still no change.

 

[derf]

Never had to flash one with an SX460 on it.
Diodes?
Other than diodes or a bad SX460 (never seen one but they are made in China, so.......) there isn't much to go bad as long as the windings aren't overloaded and damaged.

 

[Ray70]

I'm giving the award to Derf on this one. Rather than mess with a field flash circuit for the SX460 I pulled the generator apart and found this.



This machine has just over 500 hours on it and the rotor winding has somehow rubbed on the stator and wore through the winding.
Looking at the winding it is somewhat larger in diameter than the outer core. With 500 hours on it I doubt this was a manufacturing defect in the rotor and it seems to be fresh. The owner stores and uses it outside in Western MA. so I'm curious if water could have gotten in it, frozen and swelled up the winding? The end bearing and everything else was fine.
I also have his other matching gen here which has a spun rod bearing on the Yanmar L70 and a scored crank journal, so that machine donated it generator tonight to get this one back up and running. She's back to making power again.

 

[Guyfang]

Ray,

This machine had a history of Main Gen failures. Have seen several, but loooooooooong ago, just like this. We had lots of theories about why it happened. But no one could prove any of them.

For manual field flash, we never used anything other then two D cells taped together, and two wires taped to the ends. We never really had to do much manual field flas, so no one ever simply made something up. I do remember someone who claimed he took a small radio apart and used the batter holder for a field flash "rig" in his shop. It was just the battery holder and two multimeter leads attached. But I never saw it.

 

[derf]

I think the SX-460 is very good at picking up what little residual is present to generate power.
I would think under load the windings would get hot and expand and if it's cold out then the case might contract a little. It doesn't take much to wipe away the enamel coating on the windings.
In rare cases windings test good but will fail under load, only to test good again when not under load.

 

[Ray70]

Yes, once I replace the rotor, the sx460 had no problem firing up once again, with no need to flash it.
I think my error initially was that I quickly tested the excite winding and the 3 stator windings from the leads.
You would have to remove the electronics enclosure to access the end of the rotor to test it, so after reading a few other posts, my first thought was that maybe there was an issue with the field polarity because of the discrepancy I found with the wiring diagram.
I was unsure if potentially reversing the polarity may have somehow discharged it over time, but once I disassembled the head the smoking gun was sitting right there. Not only was the coating worn off, the conductor was ground right through.
The owner mentioned that a hour before it died the power had been flickering. He thought it was due to the machine being out in the snowstorm and getting wet so he covered it up better, which seemed to cure the flickering . About an hour later it totally quit.
I bet the flickering started when the coating first wore through ( although not sure why it stopped ) and once the copper winding was severed, the lights went out for good!

 

[Guyfang]

Have you looked at the bearing on the rotor?

 

[Ray70]

Yes, the bearing is in perfect condition, so the contact is not from movement in the rotor.
When comparing the damaged rotor to the one I replaced it with, the winding of the damaged rotor sticks out beyond the diameter of the iron core where the winding on the replacement rotor is recessed below the core.
The damage rotor almost looks swollen up in the center of the winding and it lasted 500 hours before suddenly making contact with the stator, so I was curious if water could have gotten in and frozen and swelled it up?
Maybe it's a manufacturing defect, but I don't think it would have lasted 500 hours before wearing through.
Definitely odd!

 

[Guyfang]

Have seen his when I suspected, and I am not a rocket scientist by any means. but suspected that the gen set was over loaded, and the over load safety was bypassed. The rotor got hot, and what happens to hot metal, it expands. This could also happen if the cooling air going to the main gen were blocked off.

 

[Chainbreaker]

...The owner mentioned that a hour before it died the power had been flickering. He thought it was due to the machine being out in the snowstorm and getting wet so he covered it up better, which seemed to cure the flickering . About an hour later it totally quit.

Have seen this when I suspected, and I am not a rocket scientist by any means. but suspected that the gen set was over loaded, and the over load safety was bypassed. The rotor got hot, and what happens to hot metal, it expands. This could also happen if the cooling air going to the main gen were blocked off.

Perhaps the owner might have tarped it and air inflow sucked the tarp down restricting airlfow, or it was weighted down by snow thereby inhibiting inflow of cooling air?

 

[Ray70]

I don't think we will ever know... During the night his load is minimal, just the cycling of the blower motor on a small propane heater in his camper and a single light over the door. No fridge, nothing. He said he used a sheet of thick rubber for a cover and was mindful to keep it propped up enough to allow good airflow. Either way the machine is back up and running with a donated generator from his other machine. I think he plans to build a more permanent little structure to house it in now. Something with a roof over it!