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yak 52 fuel instrument

 
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stephenmorrey(at)gmail.co
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PostPosted: Wed May 20, 2009 5:50 pm    Post subject: yak 52 fuel instrument Reply with quote

1.Does anyone know where I can get the schematic for the 52 fuel instrument.� My left wing light panel seems to be working fine.� The right wing panel jumps from 60 L to 40L and then remains at 40L and on very low fuel jumps back to 60L.����� �2. Does any one know where I can purchase a functioning unit or perhaps trade in/ purchase for a functioning unit.�
3.�Does anyone have any suggestions on what might be the problem with mine.� �Thanks Steve Morrey MI USA
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keithmckinley



Joined: 11 Aug 2008
Posts: 434

PostPosted: Wed May 20, 2009 6:51 pm    Post subject: Re: yak 52 fuel instrument Reply with quote

There are plenty of experts on this board and I'm not one of them.

One possibility is: if you have a rheostat type sending unit, over time it can wear, especially in the spot you describe (where you usually have the normal fuel levels).


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dsavarese0812(at)bellsout
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PostPosted: Thu May 21, 2009 3:18 am    Post subject: yak 52 fuel instrument Reply with quote

Steve,
The problem you are experiencing with your fuel instrument is a typical internal failure of one of the circuit boards inside the fuel instrument. Unfortunately there are no schematics for the unit, even at Termikas in Lithuania that repair them. In fact, the only company that I know of that repairs the Yak 52 fuel instrument is Termikas. They have an electronics tech that has figured them out. Although your airplane would be down for about 3 weeks due to shipment and repair, most likely Termikas can repair the instrument. Let me forewarn you, it is somewhat expensive. Recently we had one repaired and the cost was 400 EUROS, plus shipping.

If you would like for me to arrange for Termikas to repair your fuel instrument, please contact me off-list.
Dennis

p.s. I wish our expert electronics guy on this list, Mark Bitterlich, could dig into one (which I can provide) and get into repairing them. Smile hint, hint!


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dsavarese0812(at)bellsout
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PostPosted: Thu May 21, 2009 3:55 am    Post subject: yak 52 fuel instrument Reply with quote

Steve,
One thing you might try is swapping the connectors on the back of the instrument to see if the problem follows the swapped connectors or not. If it does follow the connector swap, it is a fuel sender and not the instrument. If the problem remains on the same side of the fuel instrument after swapping the connectors, it's definitely the instrument.
Dennis

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PostPosted: Thu May 21, 2009 7:07 am    Post subject: yak 52 fuel instrument Reply with quote

Dennis I tried the swap and it does not seem to follow the swap.� I wonder if you know where I can find a non functioning unit that we could send to Termikas .� That way I would at least be able o read one side using my current instrument until I can get a recon unit.� I also wonder if Temikas has any surplus units that are in working order that I could order and then return mine.� I dont know how to communicate with these guys.� Can you give me a contact or otherwise assist me.� steve
On Thu, May 21, 2009 at 7:54 AM, A. Dennis Savarese <dsavarese0812(at)bellsouth.net (dsavarese0812(at)bellsouth.net)> wrote:
[quote] Steve,
One thing you might try is swapping the�connectors on the back of the instrument to see if the problem follows the swapped�connectors�or not.� If it does follow the connector swap, it is a fuel sender and not the instrument.� If the problem remains on the same side of the fuel instrument after swapping the connectors, it's definitely the instrument.
Dennis

[quote] ---


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yakplt(at)yahoo.com
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PostPosted: Thu May 21, 2009 9:43 am    Post subject: yak 52 fuel instrument Reply with quote

This is an area that I have been lucky enough to avoid since mine has not failed yet. But you're right Dennis, it would make sense to have someone that understands these things. I currently have NO IDEA how they work, or even the theory involved on how they do it.� I am guessing it might be a capacitive fuel quantity system only based on how it tends to work.

If you can send me a probe that works and one of the units with some just basic schematics of how they get wired to each other so that I can put it together outside of the aircraft and make it work, I think there is a good chance I may be able to figure it out for you.

Mark



From: A. Dennis Savarese <dsavarese0812(at)bellsouth.net>
To: yak-list(at)matronics.com
Sent: Thursday, May 21, 2009 7:14:59 AM
Subject: Re: yak 52 fuel instrument

Steve,
The problem you are experiencing with your fuel instrument is a typical internal failure of one of the circuit boards inside the fuel instrument. Unfortunately there are no schematics for the unit, even at Termikas in Lithuania that repair them. In fact, the only company that I know of that repairs the Yak 52 fuel instrument is Termikas. They have an electronics tech that has figured them out. Although your airplane would be down for about 3 weeks due to shipment and repair, most likely Termikas can repair the instrument. Let me forewarn you, it is somewhat expensive. Recently we had one repaired and the cost was 400 EUROS, plus shipping.

If you would like for me to arrange for Termikas to repair your fuel instrument, please contact me off-list.
Dennis

p.s. I wish our expert electronics guy on this list, Mark Bitterlich, could dig into one (which I can provide) and get into repairing them. Smile hint, hint!


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PostPosted: Thu May 21, 2009 10:30 am    Post subject: yak 52 fuel instrument Reply with quote

Mark,
Are you sure you want to do this? The reason for the question is if you figure out how it works etc., which I'm confident you will, you'll end up being the "repair facility" for Yak 52 fuel instruments. And you're right. The system is a capacitive system.

I can ship you a spare fuel instrument and a fuel sender and cut and paste the pages from the Yak 52 wiring diagram. But I must have these back in working order. They are very valuable, needless to say.

Email me your ship-to address off-list and I will get them out to you next week.
Dennis

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Rob Rowe



Joined: 10 Jan 2006
Posts: 124
Location: Berkshire, UK

PostPosted: Sun May 24, 2009 10:23 am    Post subject: Re: yak 52 fuel instrument Reply with quote

FYI - this link is to a thread from 2006 on the same topic ...

http://forums.matronics.com/viewtopic.php?t=11961

Out of curiosity I'll see if there are any faulty units in the UK that I can take a peek inside.

Rob R.


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PostPosted: Sun May 24, 2009 4:10 pm    Post subject: yak 52 fuel instrument Reply with quote

Rob, I read your writeup. Well written as usual. Is it possible that instead of the fuel causing a phase shift in the inductive fields of these coils that instead the fuel changes the dielectric value and thus changes the capacitance between the inductors discussed (outer and inner) which then changes phase angle? If so, I get the idea. If not, then I simply do not understand how it could work at all.

Mark Bitterlich



From: Rob Rowe <yak-list(at)robrowe.plus.com>
To: yak-list(at)matronics.com
Sent: Sunday, May 24, 2009 2:23:15 PM
Subject: Re: yak 52 fuel instrument

--> Yak-List message posted by: "Rob Rowe" <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>

FYI - this link is to a thread from 2006 on the same topic ...

http://forums.matronics.com/viewtopic.php?t=11961

Out of curiosity I'll see if there are any faulty units in the UK that I can take a peek inside.

Rob R.


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=245161#245161[b]

[quote][b]


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PostPosted: Sun May 24, 2009 4:26 pm    Post subject: yak 52 fuel instrument Reply with quote

Sent to YAK List and to Personal

Rob, when you use the term "Floating Inductor" in your description of how this system works... do you mean "Float" as in "not connecting to anything electrically" ??? Or "Float" as in "it is actually an inductor enclosed in a housing that actually FLOATS up and down with the amount of fuel in the tank?

If the latter, I see how how the fuel level can change phase angle without capacitance. If the system has absolutely no moving parts at ALL, the only system I have ever studied that can do that is with capacitance.

Mark


From: Rob Rowe <yak-list(at)robrowe.plus.com>
To: yak-list(at)matronics.com
Sent: Sunday, May 24, 2009 2:23:15 PM
Subject: Re: yak 52 fuel instrument

--> Yak-List message posted by: "Rob Rowe" <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>

FYI - this link is to a thread from 2006 on the same topic ...

http://forums.matronics.com/viewtopic.php?t=11961

Out of curiosity I'll see if there are any faulty units in the UK that I can take a peek inside.

Rob R.


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=245161#245161[b]

[quote][b]


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stephenmorrey(at)gmail.co
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PostPosted: Sun May 24, 2009 4:28 pm    Post subject: yak 52 fuel instrument Reply with quote

If this helps. I have tried two instruments with the same results. I get 60 l at full then when some fuel burns down a full jump to 25 L then when low on fuel a jump back to 60L. No lights even fliker as the fuel drops. With one instrument the jump is to 25L. With the other the jump is to 40L. The left side works proper with both instruments. Makes me think sender or harness. Any ideas before I yank the tank? Perhaps some ideas about the sender or the connection. Doesn't seem like a float problem to me since the jump between 60 and 25 then back to 60 isbrepeatable and consistent. Tks Steve.

Sent from my iPhone

On May 24, 2009, at 8:02 PM, Yak Pilot <yakplt(at)yahoo.com (yakplt(at)yahoo.com)> wrote:

[quote]Rob, I read your writeup. Well written as usual. Is it possible that instead of the fuel causing a phase shift in the inductive fields of these coils that instead the fuel changes the dielectric value and thus changes the capacitance between the inductors discussed (outer and inner) which then changes phase angle? If so, I get the idea. If not, then I simply do not understand how it could work at all.

Mark Bitterlich



From: Rob Rowe <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>
To: [url=mailto:yak-list(at)matronics.com]yak-list(at)matronics.com (yak-list(at)matronics.com)[/url]
Sent: Sunday, May 24, 2009 2:23:15 PM
Subject: Re: yak 52 fuel instrument

here:

http://forums.matronics.com/viewtopic.php?p=245161#245161

Quote:
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href="http://forums.matronics.com">http://forums.matronics.com
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PostPosted: Sun May 24, 2009 4:42 pm    Post subject: yak 52 fuel instrument Reply with quote

I have handeled the yak52 sensor and there is a physical float in a tube. Steve

Sent from my iPhone

On May 24, 2009, at 8:20 PM, Yak Pilot <yakplt(at)yahoo.com (yakplt(at)yahoo.com)> wrote:

[quote]Sent to YAK List and to Personal

Rob, when you use the term "Floating Inductor" in your description of how this system works... do you mean "Float" as in "not connecting to anything electrically" ??? Or "Float" as in "it is actually an inductor enclosed in a housing that actually FLOATS up and down with the amount of fuel in the tank?

If the latter, I see how how the fuel level can change phase angle without capacitance. If the system has absolutely no moving parts at ALL, the only system I have ever studied that can do that is with capacitance.

Mark


From: Rob Rowe <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>
To: [url=mailto:yak-list(at)matronics.com]yak-list(at)matronics.com (yak-list(at)matronics.com)[/url]
Sent: Sunday, May 24, 2009 2:23:15 PM
Subject: Re: yak 52 fuel instrument

here:

http://forums.matronics.com/viewtopic.php?p=245161#245161

Quote:
[b]
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
href="http://forums.matronics.com">http://forums.matronics.com
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PostPosted: Sun May 24, 2009 4:53 pm    Post subject: yak 52 fuel instrument Reply with quote

Rob, you wrote this on a former posting, and I think I get it now! <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Quote:
“The fuel level sensing is clever, but relatively complex ... each fuel sender has a 10Khz square wave primary signal induced into four embedded secondary parallel coils (each with a different winding).

On the outside of the fuel sender is a floating inductor that creates a unique combination of "phases" in the four secondary coils depending on the fuel level.

The display unit then decodes the unique phase combinations into a specific fuel bar light ... no electrical moving parts to wear out or spark, no calibration required, accurate to +/- 5mm of fuel tank level under normal operating conditions.”

End quote:

What confused me was the use of the term “float” which to me meant one thing, and to you it meant the real definition of “float” as in “ride on the surface of a fluid”.� Sorry, my mistake.

Basically what I see in my mind here is close to the classic synchro design with AC excitation, but instead of three phases, it uses four. The interesting part is indeed the sliding inductor which I see as not only changing the phase angle of the four separate field levels, but would it not make sense that it would also impact the vector sum of these fields? Think of it as the sending unit being a synchro transmitter (except with four phases instead of three), the floating inductor as the normal “rotating device” in a synchro transmitter, but in this case a vertical movement, that never-the-less would impact the field phase and strength the same way, and the fuel level display instrument as being the synchro receiver. My guess is that the display circuitry is also being fed with the same 10 Khz “excitation” so that it can reference it?

Checking the fuel float transmitter could be done using a 10 Khz excitation signal and then monitoring the outputs on a scope (not sure if there is one output wire or four, …. Or more? I am still weak on that, but anyway… a multi-channel scope should be able to display these signals simultaneously and as you move the float level up and down they should be linear in their change, and it would be easy to see where the problem was/is.

But that takes us down to this… I can see where I could build something to check the probe and give a pass/fail to it… but REPAIRING it, well that would be another story entirely.

This takes us back down the classic path of these aircraft. Repair it, replace it, or re-design it. I am not sure at this point what the best path is. I think that the design could be duplicated, but at the low failure rate I have seen on this device, I question the value of doing it. What is your view?

Mark Bitterlich



From: Rob Rowe <yak-list(at)robrowe.plus.com>
To: yak-list(at)matronics.com
Sent: Sunday, May 24, 2009 2:23:15 PM
Subject: Re: yak 52 fuel instrument

--> Yak-List message posted by: "Rob Rowe" <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>

FYI - this link is to a thread from 2006 on the same topic ...

http://forums.matronics.com/viewtopic.php?t=11961

Out of curiosity I'll see if there are any faulty units in the UK that I can take a peek inside.

Rob R.


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=245161#245161[b]

[quote][b]


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PostPosted: Sun May 24, 2009 5:13 pm    Post subject: yak 52 fuel instrument Reply with quote

Steve,
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
I am working from an unproven assumption on how this system works, but I THINK I am starting to get a handle on it. Maybe not 100%, but with the valuable information provided by Rob Rowe, … I think I get it. The one thing I still need is a full schematic showing exactly how many wires are running from “here to there”. But Rob addressed that in his previous posting which I am going to quote here.

Rob Rowe says:

Quote:
Probably worth you checking the connections at both ends of the cable (not sure how you access the fuel sender though) - there are 7 wires ... earth + 4 secondary coil outputs + 2 primary coil inputs.

I'm not sure of the following as I can only infer the connections from the schematic ...

Sender - Pins 9 / 10 primary winding, Pins 1 - 5 (4 off) secondary winding & earth

Display - Pins 1 / 2 primary winding, Pins 3 - 7 (4 off) secondary winding & earth

There are also intermediate canon plugs located at "Station 4 outside" labeled "1-20" for left tank & "1-21" for the right tank.

I've attached a high level schematic of the above ... note there is an error in that the primary coils are shown as having a common earth, in fact they have a dedicated return line to the 10Khz generator (as per the pin description).

Unquote:

I absolutely concur on what Rob has said. Your problem could VERY easily be attributed to wiring. The way this system works, it could easily do exactly what your system is doing given a missing phase wire. I mean EXACTLY.

Ask Dennis how these wires connect to the tank sending unit, I have no idea. However, you need to check each and every one of them, and I strongly suspect they are going to be shielded wires… make sure you not only check the wires end to end, but also for any shorts from center conductor to shield. Look for bad terminals on the wires due to corrosion, etc. Russian wire simply is not nearly as good as our Teflon grade aircraft wire, so be careful to check these wires carefully. A TDR would sure be nice for this task, but I doubt one is available.. if it is, use it!

Lastly, if we can get a diagram, you will probably have to pull the fuel sending unit. Checking that is something I have some ideas on, but right now… the best you could do might be to carefully check the resistance of the four field windings and make sure they are identical.�

In fact, you just have to have the schematic that Rob has. (So do I!) Given that you could run ohm checks between one side and the other, which MIGHT be helpful.

Steve, this is probably not going to be very easy… unless you want to just dive bomb the probe and hope you get lucky. Hey... and you might!

Mark Bitterlich

p.s. Down the road I am thinking very positively that the way to check problems like this is going to be to use a scope with the trigger set to external and referenced to the 10 Khz excitation signal and then simply using the scope probe to look at the signals from each sending unit. That would tell you immediately which wire, or which field winding in the probe was defective. If you can find a person well versed in AC and Synchro theory with a good scope... you could do that right now.


From: Stephen Morrey <stephenmorrey(at)gmail.com>
To: "yak-list(at)matronics.com" <yak-list(at)matronics.com>
Sent: Sunday, May 24, 2009 8:27:53 PM
Subject: Re: Yak-List: Re: yak 52 fuel instrument

If this helps. I have tried two instruments with the same results. I get 60 l at full then when some fuel burns down a full jump to 25 L then when low on fuel a jump back to 60L. No lights even fliker as the fuel drops. With one instrument the jump is to 25L. With the other the jump is to 40L. The left side works proper with both instruments. Makes me think sender or harness. Any ideas before I yank the tank? Perhaps some ideas about the sender or the connection. Doesn't seem like a float problem to me since the jump between 60 and 25 then back to 60 isbrepeatable and consistent. Tks Steve.

Sent from my iPhone

On May 24, 2009, at 8:02 PM, Yak Pilot <yakplt(at)yahoo.com (yakplt(at)yahoo.com)> wrote:

[quote] Rob, I read your writeup. Well written as usual. Is it possible that instead of the fuel causing a phase shift in the inductive fields of these coils that instead the fuel changes the dielectric value and thus changes the capacitance between the inductors discussed (outer and inner) which then changes phase angle? If so, I get the idea. If not, then I simply do not understand how it could work at all.

Mark Bitterlich



From: Rob Rowe <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>
To: [url=mailto:yak-list(at)matronics.com]yak-list(at)matronics.com (yak-list(at)matronics.com)[/url]
Sent: Sunday, May 24, 2009 2:23:15 PM
Subject: Re: yak 52 fuel instrument

--> Yak-List message posted by: "Rob Rowe" <[url=mailto:yak-list(at)robrowe.plus.com]yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)[/url]>

FYI - this link is to a thread from 2006 on the same topic ..

http://forums.matronics.com/viewtopic.php?t=11961

Out of curiosity I'll see if there are any faulty units in the UK that I can take a peek inside.

Rob R.


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=245161#245161

Quote:
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-Listhref="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/contribution

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ist" target=_blank rel=nofollow>http://www.matronics.com/Navigator?Yak- -Matt Dralle,
on" target=_blank rel=nofollow>http://www.matronics.com/contribution[b]


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Rob Rowe



Joined: 10 Jan 2006
Posts: 124
Location: Berkshire, UK

PostPosted: Sun May 24, 2009 6:08 pm    Post subject: Re: yak 52 fuel instrument Reply with quote

Mark,

Yep ... float as in fishing variety.

The term "phase" is literally translated from the Russian schematic, I suspect it may in fact be as simple as in-phase or anti-phase i.e. 180 degrees out, compared to the source square wave.

In the PDF diagram (in my 2006 post) I tried to faithfully replicate the Russian high level schematic drawing of the sender unit coil windings, as these are worth studying.

It suggests the secondary coils each have unique coil winding patterns that (depending on the fuel level float position) induce an in-phase or anti-phase signal accordingly ... in logic terms a "1" or "0" (perhaps I should say "1" or "-1" in this case).

With 4 secondary coils outputs this suggests 2 to the power 4 i.e. 16, unique combinations (fuel levels) could be deduced ... and the fuel display only employs 10 discrete levels (the top & bottom display levels are non-linear so some combinations may not be used)

The schematics gave no description of how the display decodes the input signals (it simply refers to to them as "phase detectors"), but if I'm right about the logic approach it could be as simple as charging or discharging a capacitor per secondary winding input line. Then using the resultant voltage to drive a Schmitt triggered (transistor?) logic array to control the display lights.

Given capacitors don't tend to age gracefully they could well be a likely failure point ... anyway this is all conjecture until we can take one apart as I may be guilty of making the evidence fit a desired outcome here.

FWIW - I agree that using a scope is probably the easiest way to check the wiring / sender operation ... my new Rigol DSO recently arrived from China, time to try it out!

brgds, Rob


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PostPosted: Sun May 24, 2009 7:19 pm    Post subject: yak 52 fuel instrument Reply with quote

I can not retrieve that diagram Rob. Can I please ask you to send it to: markbitterlich(at)embarqmail.com (markbitterlich(at)embarqmail.com) ?? Please? <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Operational theory:

Let’s talk about this. Your said:
“It suggests the secondary coils each have unique coil winding patterns that (depending on the fuel level float position) induce an in-phase or anti-phase signal accordingly .. in logic terms a "1" or "0" (perhaps I should say "1" or "-1" in this case).

With 4 secondary coils outputs this suggests 2 to the power 4 i.e. 16, unique combinations (fuel levels) could be deduced ... and the fuel display only employs 10 discrete levels (the top & bottom display levels are non-linear so some combinations may not be used)”

OK.

If it operated like this, I find it difficult to understand how a known good display instrument could read properly when full, then drop suddenly to a low value as fuel is used, and then most importantly go back up to a HIGH value as still more fuel is used. A system of progressive binary discretes, no matter how they are obtained, is hard to theorize how such results could be obtainable.

If we take your theory and apply it, my thought would be a failure mode where certain indicator lights might not work, where it might even read the wrong value, but how in the world could it go down to a low value and then jump back up to a higher one?

Let’s study the binary numbers themselves:

0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111

See what I mean? If you permanently alter any bit of the four bit binary word, it can not go down and then back up again. Or am I missing something?

My thought (pure assumption only and with no substantiation), is that the key word is (as you have already said) “phase”. With a phase driven system, it is entirely possible for the display system to actually go backwards at certain points if one or more phases is missing or altered

You said:
“anyway this is all conjecture until we can take one apart as I may be guilty of making the evidence fit a desired outcome here.”

Yeah, me too.. in spades.

Mark

p.s. The scope is the answer. Looks like you will beat me to it. �

p.p.s."Rigol DSO?" Tektronix rules! Well, OK... maybe HP once in awhile. Smile

-------------
From: Rob Rowe <yak-list(at)robrowe.plus.com>
To: yak-list(at)matronics.com
Sent: Sunday, May 24, 2009 10:08:47 PM
Subject: Re: yak 52 fuel instrument

--> Yak-List message posted by: "Rob Rowe" <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>

Mark,

Yep ... float as in fishing variety.

The term "phase" is literally translated from the Russian schematic, I suspect it may in fact be as simple as in-phase or anti-phase i.e. 180 degrees out, compared to the source square wave.

In the PDF diagram (in my 2006 post) I tried to faithfully replicate the Russian high level schematic drawing of the sender unit coil windings, as these are worth studying.

It suggests the secondary coils each have unique coil winding patterns that (depending on the fuel level float position) induce an in-phase or anti-phase signal accordingly ... in logic terms a "1" or "0" (perhaps I should say "1" or "-1" in this case).

With 4 secondary coils outputs this suggests 2 to the power 4 i.e. 16, unique combinations (fuel levels) could be deduced ... and the fuel display only employs 10 discrete levels (the top & bottom display levels are non-linear so some combinations may not be used)

The schematics gave no description of how the display decodes the input signals (it simply refers to to them as "phase detectors"), but if I'm right about the logic approach it could be as simple as charging or discharging a capacitor per secondary winding input line. Then using the resultant voltage to drive a Schmitt triggered (transistor?) logic array to control the display lights.

Given capacitors don't tend to age gracefully they could well be a likely failure point ... anyway this is all conjecture until we can take one apart as I may be guilty of making the evidence fit a desired outcome here.

FWIW - I agree that using a scope is probably the easiest way to check the wiring / sender operation ... my new Rigol DSO recently arrived from China, time to try it out!

brgds, Rob


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Rob Rowe



Joined: 10 Jan 2006
Posts: 124
Location: Berkshire, UK

PostPosted: Mon May 25, 2009 6:30 am    Post subject: Re: yak 52 fuel instrument Reply with quote

Mark,

I'll email you a later version of my schematic with the (2006) error corrected.

You may have read too much into my last post. I didn't say it was a progressive binary sequence, just that there could be a unique logic combination per discrete fuel level.

To that end I've created a logic state table (PDF attached - I'll email you a copy too) that weights the secondary coils by their individual in/anti-phase winding ratios.

By arbitrarily multiplying this logic weighted ratio by 50 to make the numbers easier to interpret, the result is a close approximation of the fuel display readings (within +/- 4% until <20 litres rising to +11% (at) 15 litres).

Now I've only guessed the winding ratios from the Russian schematic drawing, if these were further fine tuned then it's likely a more accurate display could be created.

Note that the display discrete levels do not follow the logic state progressive binary sequence - as I surmised.

Similarly on the PDF I created another table with a "fault" condition on one of the secondary coil sensing logic inputs ... which looks to behave in a similar way to the problem that Steve's experiencing.

Now this is still all speculation as to how it really works but I'm getting a warmer feeling that this is on the right track ... certainly if I was to re-engineer a solution it's the approach I'd want to explore further.

Btw - scopes, if someone else is paying then I'd love a Tek. But it's my money and Rigol are the OEM for Agilent/HP, so I get the bang of a quality lower mid range scope for one third of the bucks.

brgds, Rob R


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PostPosted: Mon May 25, 2009 4:38 pm    Post subject: yak 52 fuel instrument Reply with quote

For anyone following this string…..
<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
I’ve looked at Rob’s diagrams and schematics and think that he is absolutely on the right sheet of music on how this system works. I thought it was all phase related (I.E. Analog in nature) and not any kind of binary counter, in sequence or otherwise. After looking at Rob’s work I have to conclude that I am totally wrong with my assumptions and Rob’s theory of operation is exactly right. Nice work Rob. Really first class.

Mark Bitterlich


From: Rob Rowe <yak-list(at)robrowe.plus.com>
To: yak-list(at)matronics.com
Sent: Monday, May 25, 2009 10:30:32 AM
Subject: Re: yak 52 fuel instrument

--> Yak-List message posted by: "Rob Rowe" <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>

Mark,

I'll email you a later version of my schematic with the (2006) error corrected.

You may have read too much into my last post. I didn't say it was a progressive binary sequence, just that there could be a unique logic combination per discrete fuel level.

To that end I've created a logic state table (PDF attached - I'll email you a copy too) that weights the secondary coils by their individual in/anti-phase winding ratios.

By arbitrarily multiplying this logic weighted ratio by 50 to make the numbers easier to interpret, the result is a close approximation of the fuel display readings (within +/- 4% until


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=245255#245255


Attachments:

http://forums.matronics.com//files/fuel_display_logic_table_147.pdf

[quote][b]


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stephenmorrey(at)gmail.co
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PostPosted: Mon May 25, 2009 4:55 pm    Post subject: yak 52 fuel instrument Reply with quote

Well I did some trouble shooting and now I have confirmed I have a faulty instrument and the sending units are good. Does anyone have any suggestions on trouble shooting the instrument (right side) or perhaps someone knows where I can get a good instrument. Steve.

Sent from my iPhone

On May 25, 2009, at 8:29 PM, Yak Pilot <yakplt(at)yahoo.com (yakplt(at)yahoo.com)> wrote:

[quote]
For anyone following this string…..

I’ve looked at Rob’s diagrams and schematics and think that he is absolutely on the right sheet of music on how this system works. I thought it was all phase related (I.E. Analog in nature) and not any kind of binary counter, in sequence or otherwise. After looking at Rob’s work I have to conclude that I am totally wrong with my assumptions and Rob’s theory of operation is exactly right. Nice work Rob. Really first class.

Mark Bitterlich


From: Rob Rowe <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>
To: [url=mailto:yak-list(at)matronics.com]yak-list(at)matronics.com (yak-list(at)matronics.com)[/url]
Sent: Monday, May 25, 2009 10:30:32 AM
Subject: Re: yak 52 fuel instrument

in/anti-phase winding ratios.

By arbitrarily multiplying this logic weighted ratio by 50 to make the numbers easier to interpret, the result is a close approximation of the fuel display readings (within +/- 4% until


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=245255#245255


Attachments:

http://forums.matronics.com//files/fuel_display_logic_table_147.pdf

Quote:

href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/contribution


[b]


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yakplt(at)yahoo.com
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PostPosted: Mon May 25, 2009 5:50 pm    Post subject: yak 52 fuel instrument Reply with quote

Stephen... WTF Over?

You said: " If this helps. I have tried two instruments with the same results. "

Now you say: "Well I did some trouble shooting and now I have confirmed I have a faulty instrument and the sending units are good."

I'm just curious as to what has changed.

I have not seen any of these parts yet... but according to sources, the cockpit display is merely some switching diodes, and some lamp drivers. A good Avionics Tech might have some luck with it merely by ringing out some components. Easy to say... I've never done it.

I'm not yet ready to tackle this project, but I am working towards it. Sorry to not be able to be of more help.

Mark Bitterlich



From: Stephen Morrey <stephenmorrey(at)gmail.com>
To: "yak-list(at)matronics.com" <yak-list(at)matronics.com>
Sent: Monday, May 25, 2009 8:54:22 PM
Subject: Re: Yak-List: Re: yak 52 fuel instrument

Well I did some trouble shooting and now I have confirmed I have a faulty instrument and the sending units are good. Does anyone have any suggestions on trouble shooting the instrument (right side) or perhaps someone knows where I can get a good instrument. Steve.

Sent from my iPhone

On May 25, 2009, at 8:29 PM, Yak Pilot <yakplt(at)yahoo.com (yakplt(at)yahoo.com)> wrote:

Quote:

For anyone following this string…..

I’ve looked at Rob’s diagrams and schematics and think that he is absolutely on the right sheet of music on how this system works. I thought it was all phase related (I.E. Analog in nature) and not any kind of binary counter, in sequence or otherwise. After looking at Rob’s work I have to conclude that I am totally wrong with my assumptions and Rob’s theory of operation is exactly right. Nice work Rob. Really first class.

Mark Bitterlich


From: Rob Rowe <yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)>
To: [url=mailto:yak-list(at)matronics.com]yak-list(at)matronics.com (yak-list(at)matronics.com)[/url]
Sent: Monday, May 25, 2009 10:30:32 AM
Subject: Re: yak 52 fuel instrument

--> Yak-List message posted by: "Rob Rowe" <[url=mailto:yak-list(at)robrowe.plus.com]yak-list(at)robrowe.plus.com (yak-list(at)robrowe.plus.com)[/url]>

Mark,

I'll email you a later version of my schematic with the (2006) error corrected.

You may have read too much into my last post. I didn't say it was a progressive binary sequence, just that there could be a unique logic combination per discrete fuel level.

To that end I've created a logic state table (PDF attached - I'll email you a copy too) that weights the secondary coils by their individual in/anti-phase winding ratios.

By arbitrarily multiplying this logic weighted ratio by 50 to make the numbers easier to interpret, the result is a close approximation of the fuel display readings (within +/- 4% until


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=245255#245255


Attachments:

http://forums.matronics.com//files/fuel_display_logic_table_147.pdf

Quote:
href="http://www.matronics.com/Navigator?Yak-List">http://www.matronics.com/Navigator?Yak-Listhref="http://forums.matronics.com">http://forums.matronics.com href="http://www.matronics.com/contribution">http://www.matronics.com/contribution

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