Another chainsaw dyno...

[Red97]

If it has 3 load cells (strain gauges) and all 3 are off the scale I would question the health of the AtoDs in the computer that sample each load cell. If an AtoD is just open, it can fail at full scale like that (way up at 1500 for each).

Just those 3 wires? Maybe each is its own cell?

In the troubleshooting it says if the raw tq is over a certain limit. It is likely faulty strain gauge.

 

[malk315]

Just those 3 wires? Maybe each is its own cell?

In the troubleshooting it says if the raw tq is over a certain limit. It is likely faulty strain gauge.

Your picture is definitely just one load cell -- the thinner central area looks like what flexes. For each wire to be their own signal, you would still need power and ground -- the red and black are likely excitation voltage and round and the white wire is signal.

So you don't have 3 sets of 3 wires? I guess each could be a signal from 3 different places on the load cell for redundancy and power and ground are elsewhere. But it sure looks like power, ground, signal. I'm not sure though why you have 3 separate readings as if it has 3 separate load cells.

I'm trying to look at the documentation for it on dyno-mite's website.

 

[RI Chevy]

Dis sh't is wicked teknickle .

 

[malk315]

Did it flex too much and short out where I have circled in red? Was that Pit in the aluminum always there or is that from arcing when whatever saw went beyond the limit of the gauge. Did I read right that you ran a Smitty built saw on there from Brett? If there's any one saw builder that could break it LOL.

Interesting that the gauge looks like it has a 4th connection spot for a 4th wire to sample it in differential mode.

Change out the strain gauge first and then if that doesn't fix it, send the computer back to DynoMite (land and sea?)...

 

[malk315]

Doesn't look much different in concept to the one I used. This one red is power, black ground, and white and green wires for differential signal that gets fed to and atod I read 400 times per second. That also gets calibrated with a known weight and I think we could do up to 10 or 20 ft lbs with the reduction of wheel sprocket to saw sprocket. Used a hall effect sensor to read rpms of the wheel and convert to saw rpms. Someday I'll get back to mine. Covid but a huge damper on things.

Sent from my Pixel 3 using Tapatalk

 

[Nutball]

Maybe that's the ground wire connection point

 

[MustangMike]

Oh Man, Bret broke our toy!!!

(And yes, he does spell it with one T, w/o any duct tape!).

FYI, the first ported saw I ever ran was Bret's over bore 660, and my fist ported saw was ported by Bret (an 046). That was my "monster saw" for a long time!

 

[MustangMike]

How about some tidbits of info?

Jeff, your making me look mature!

And by the way, nothing broke on my Asian saw!!!! (but it does have an OEM Elastostart rope/handle).

 

[RI Chevy]

Well...
Don't go that far Mike...lol

 

[Sawrain]

View attachment 248328

Interesting that the gauge looks like it has a 4th connection spot for a 4th wire to sample it in differential mode.

Could be using a full bridge as a half bridge strain gauge?

Is the unused connection point Linked directly to the red wire, or anywhere else? That we can’t see in the photo.

 

[Red97]

View attachment 248328

Did it flex too much and short out where I have circled in red? Was that Pit in the aluminum always there or is that from arcing when whatever saw went beyond the limit of the gauge. Did I read right that you ran a Smitty built saw on there from Brett? If there's any one saw builder that could break it LOL.

Interesting that the gauge looks like it has a 4th connection spot for a 4th wire to sample it in differential mode.

Change out the strain gauge first and then if that doesn't fix it, send the computer back to DynoMite (land and sea?)...

I never noticed that spot. It just reads high. It was encased in silicone.



You can see where the white wire had tore free from the silicone.

Maybe too much vibration?

If I pushed on the silicone it would read somewhat normal. But that isn't possible on a run.

If it was mechanical, it acts as if it skipped a couple teeth. Still scale up/down just way high.

Sorry I have the dumbs with electrical/computer

I do know lots of dyno/diy dyno guys have said not many have had luck repairing these. For whatever reason.

 

[malk315]

I never noticed that spot. It just reads high. It was encased in silicone.

View attachment 248330

You can see where the white wire had tore free from the silicone.

Maybe too much vibration?

If I pushed on the silicone it would read somewhat normal. But that isn't possible on a run.

If it was mechanical, it acts as if it skipped a couple teeth. Still scale up/down just way high.

Sorry I have the dumbs with electrical/computer

I do know lots of dyno/diy dyno guys have said not many have had luck repairing these. For whatever reason.

If it didn't short and white wire is intermittent, you can find someone who is good w/ board level soldering and re-solder that wire or take a stab at it yourself. The key is a quality solder iron setup that can do surface mount stuff easily.

We had that happen on the gauge we were using on ours and Bill is a very capable board level solder guy -- he re-soldered the wires and that gauge still works today.

Hope you can get it sorted! It's possible pushing on the white wire is also influencing the gauge but more likely poor electrical connection -- that would certainly do it.

Cheers.

 

[Red97]

If it didn't short and white wire is intermittent, you can find someone who is good w/ board level soldering and re-solder that wire or take a stab at it yourself. The key is a quality solder iron setup that can do surface mount stuff easily.

We had that happen on the gauge we were using on ours and Bill is a very capable board level solder guy -- he re-soldered the wires and that gauge still works today.

Hope you can get it sorted! It's possible pushing on the white wire is also influencing the gauge but more likely poor electrical connection -- that would certainly do it.

Cheers.

Thank you for all the help.

I was just pushing in the area like the bird was sprung.

I'll call the manufacturer and see what they have to say in the am.

 

[N8TE]

Thank you for all the help.

I was just pushing in the area like the bird was sprung.

I'll call the manufacturer and see what they have to say in the am.

That chip needs to be totally adhered to what its measuring or it won't work

 

[Red97]

That chip needs to be totally adhered to what its measuring or it won't work

It does act as if it is lifted, or sprung...

 

[Egg Shooter]

This guy gets it

Best I've tried so far.....even at 300:1 surface to tape ratio.

 

[Egg Shooter]

No idear.
I do know that 2 horizontal and 2 vertical bands of Gorilla Tape will keep a 394 inside 6 unattached pieces of cardboard resembling a box from Montana to Michigan. Mail lady delivered it to the garage hanging onto the rear handle

What da fug?

 

[Nutball]

If it didn't short and white wire is intermittent, you can find someone who is good w/ board level soldering and re-solder that wire or take a stab at it yourself. The key is a quality solder iron setup that can do surface mount stuff easily.

We had that happen on the gauge we were using on ours and Bill is a very capable board level solder guy -- he re-soldered the wires and that gauge still works today.

Hope you can get it sorted! It's possible pushing on the white wire is also influencing the gauge but more likely poor electrical connection -- that would certainly do it.

Cheers.

If the mfg is no help, and nobody here is an SMD soldering pro, I could take a crack at it. I've done some hobby SMD soldering with a good enough success rate.

 

[huskihl]

What da fug?

Just a old 394

 

[Red97]

If the mfg is no help, and nobody here is an SMD soldering pro, I could take a crack at it. I've done some hobby SMD soldering with a good enough success rate.

I gotta give them a call in the am. See what they say. Maybe they have a arm all ready to go. Or if they still do repairs on these old things.