BU0836X possible problems

[Mach7]

Looking for anyone with experience with the 836x interface board.

I have used this board for a number of years, and decided to relocate the board on my simpit for 'easier' access.

The other day I noticed that the middle chip was getting quite warm. That is to say if you put your finger on the chip, after a bit of time the chip seemed to get very very warm. The chips on either side of the board seem to be regular room temp.

The strange thing is, once you remove your finger, then touch the chip again, it takes a while to determine if the chip is hot...that is to say it seems to vary in temperature during operation.

I have a number of pots and switches hooked up to the board, and everything works fine with no issues.

I have to admit that I never paid too much attention to the heat of the board, as it was always quite concealed within the pit.

Do these chips get warm as they operate?

I sent an email to bodnar support team, but they have not got back to me as of yet.

-Jim

[727737Nut]

What Ohms rated pots are you using?  Anything less than 5K and the current is higher and chip will run hotter.  As long as is is below 50c youll be fine.

[Caflyt]

I have always thought these boards were virtually indestructible and very forgiving. I have used the BU0836X for years without as much as a hiccup.....until last week.
I had some sort of "spike" on one USB hub and it subsequently KILLED my 0836x AND my SimWorld Simbox CAN controller which were connected to the same hub. All other USB components are fine.

The Bodnar card has looked the other way when I have employed my Fisher Price level of electronic expertise in the past but finally bought the farm. I think (as 727737Nut said) you should be fine with it running a bit warm but if you notice the board starting to disconnect from Windows periodically it may be starting to fail.

By the way......does anyone have a good joystick axis card available for pennies on the dollar?
I need one..... .    (Seriously)

Please PM ME.

[Mach7]

Thanks guys.

@727737nut;

I am using rotary pots I pulled out of of an old joystick for my aileron and elevator, so I am not sure of there values, but they must be within specs if they came from a joystick made specifically for flight sim.

I also use slide pots, (three in total) for my lift spoilers,flap control, and thrust control.

Not sure about the pot ratings from the joystick, but the slide pots are ALPS RS1 series part number RS6011Y1600Q. they have a 60mm travel and according to the data sheet are rated at 10 ohms.

The funny thing with this is when I initially touch the chip, it is not immediately warm or hot to the touch...but if i leave your finger on it, you can sense the feeling of heat build up.

Now....if I remove my finger for a bit and do the process over again, the same results occurs, that is to say the chip does not feel hot for the first couple of seconds.

If one was to touch the chip quickly and remove ones finger, you would not discern that the chip was overly warm.

Anyway Rob, if they can operate up to 50 degrees C, I won't worry about it.

-Jim


832C- 50kb

[Mach7]

Here is some additional information,

I forgot to include that I am using a HITEC servo poteniometer for my nosewheel steering input. Not sure what ohms this is rated at...but it works fine with all connected, and I have never had an issue.

So right after I sent my last message...i fired up the sim and after a bit the center chip was too hot to even touch...so I disconnected the usb input and it cooled down. I reconnect the supply and everything was fine...that is to say the chip did get warm as usual, but not hot like the initial power up.

I disconnected the +5 volt lead from the 836x board from the RX connection (where my NW steering is connected. But the board seems to operate the same way temperature wise, so my suspicion of that pot creating the problem is probably not warrented.

All the other pots are the previously mentioned 10 ohm slide pots for thrust lever, flaps, and lift spoilers.

I have modified the real control column and used pots (rotary) from an old flight sim joystick,,,,so I assuming these pots are compatible with the bodnar board.

I am getting no warnings or disconnects from the board, and everything connected to the board works perfectly.

I have some  switches connected to it for  parking brake, engine start, landing gear, to name a few items...but these are just on off type switch connections, so I cannot see the chip(s) getting overheated for these items.

And just to reiterate, there are 4 microprocessor chips on this board, the two outside chips are cold as cucumbers, whilst the only chip getting warm is the center chip, and it feels as though the heat is generating from the middle of the chip itself, and not the ends.

any thoughts?

Maybe this is the way the board is supposed to work?

The problem (if there is one) would be better explained if my flight controls or other items stopped working in conjunction with the chip heating up....but like I said everything works perfectly.

no doubt this chip has been getting warm for years, it is just that I have never had the board exposed before to check them...(i recently relocated the board for ease of access).

I have also double checked all connections and there are no shorts in the system

-Jim

[iwik]

Craig:
What about a Arduino Pro Micro(Leonardo ) for $5 and MMJOY2.
Les

[727737Nut]

Jim,

If you are using 10Ohm slide pots which I didn't know existed, that is your problem.  Minimum 1K  and usually 5K to 10K is better.  Think of ohm's law, less resistance = more current which = more heat. 

Rob

[Mach7]

Actually made a typo on the slide pots. the data sheet identifies them as 10k ohm pots.

Also, ran the sim tonight for an hour or so, and the chip(s) were nice and cool....there is something that is going against the grain to heat up that middle chip, as it only happens on occasion.

I thought it had to be associated with the axis inputs (elevator/aileron/NWS/flaps etc). but I am thinking now it might be associated with the electric elevator trim switch.

The elevator switch is aircraft specific (it's a real one), with a split switch design.

The trim switch is connected to a toggle input #24 on the board (not an axis input). When I initially reset the computer, the the middle chip began to heat up, I decided to check on all my 836x connections, just to see if they were all working fine...they all worked except the electric elevator trim...

By this time the board was quite hot to the touch, so I disconnected the usb input, reset the computer and plugged it back in. All connections tested and worked fine, including the electric trim, and it remained that way for the rest of the night.

Before this I had disconnected all the +5 volt inputs to all of the axis, (leaving the ground and control inputs connected), and the chip still became warm...so I don't think it is slide or rotary pot related...(I am assuming that disconnecting the 5 volt supply should isolate these items from the board (?).....

Anyway, whatever it is it only occurs once in a while. Not having much trust in the board anymore and worried it might overheat and cause damage.

[Mach7]

Update,

So I have run the sim for a better part of the week now....turning it on and off and checking the 836x board 'chip' tempertaures...and everything seems to be running fine...(so far). The chip, although it is 'warm' is not overheating like it used to.

Maybe one of the pots got dirty and gave an over amount of resistance...not sure...but for now the problem seems to have subsided.

Thanks again for all the input

-Jim

[Mach7]

Here some additional information with respect to my.

I originally thought it was the centre chip getting warm, and now I am pretty sure it is the capacitor next to the chip...at least I think it is a capacitor (see attachment).

I have disconnected all switch and pot connections, yet this little item still gets a bit warm.

So....is this normal, or is there a problem .

Thanks

-Jim

[Trevor Hale]

HI Jim, 

although I do not have a solution to your little issue, I would ask that you read this post " HERE "

Just for your own safety.... Until you find this issue, Keep the Main Power off to your simulator when you are not near it.

[Mach7]

Thanks Trevor,

I remember reading that post. I always make sure the entire sim is shutdown if not in use.

Also, I think that little item next to the chip is a "bead thermistor". I have an email sent to Bodnar electronics, but I don't have much faith in a response.

I have however ordered another board....so will see what happens.

-Jim

[KyleH]

That will be a capacitor.
It's there to de-couple noise on the power inputs to the microcontroller. It should not get warm.
If the proper ratings for pots etc have been observed, the microcontrollers themselves should also not get hot.

It is possible that one of the parts have been damaged. ESD from moving the board could have damaged the microcontroller such that one of the internal circuits are now drawing too much current.

[Mach7]

Hello KyleH,

So...what are the proper pot ratings?...I cannot seem to get any information from Bodnar, and there is nothing on his site that gives advice on this. I also emailed them directly but they are reluctant to give out any information, other than the microprocessor chip should not get warm.

[Mach7]

Here is what I have connected to the board with respect to pots,

I have 3 ALPS RS6011Y50K slide potentiometer...60mm travel which are rated at 10K ohms,

Two rotary pots, one for aileron and one for the elevator, (with respect to these pots...I do not have the data on these, however they were recovered from an old joystick, so I am assuming that the pots are compatible).

The only other suspect pot I am using would be for my nosewheel steering. I am using a pot that was taken from a HITEC RC servo motor. Not sure of the rating on this one, but I think it is 14k ohms.

Even with all the pots disconnected, the capacitor gets warm when the board is plugged in.

any thoughts would help

[KyleH]

Can you read the part number off the chips? I can't quite make it our off your photo.

Without knowing the circuit design I can only guess at values, but anything over 10k for each should be fine. Assuming 5V and a 10k pot would be 0.5mA through the pot. 
If it's designed as it should be with the pots wiper going to an analog input, and the supply side at the power rail, it wouldn't matter the value to the microcontroller. But it would put stress on the components supplying power to the pot if the value was too low.

If it is getting warm with everything else disconnected, it indicates to me the part itself is probably damaged. Parts heat-up when they have too much current going through them. As the capacitor is most likely a noise decoupling cap for the microcontroller, there should be essentially no current going through it since capacitors block DC.

[Mach7]

Hello KyleH

I tried to get a read on the chip type, but over time the legends must have worn off, or maybe removed them through the construction process....hard to say.

Could using a pot with too high or low of a resistance value damage the board? If that was the case you would think that Leo would put a disclaimer or warning on his web site. He does recommend some pot manufacurers, and does state the pot should be 10k ohms or above, but there is little information other than that.

I am also very careful with static discharges, so I can say for certain that the board was not subjected to ESD.

As far as the heating up of the micro/capacitor is concerned, the ohmic resistance of the pot should not matter. Its end terminals will be supplied with 5V from the board's power supply and the centre terminal will be applied in the micro to an A/D (analogue to digital) converter. That measures the voltage on the pin and works out where the wiper is positioned. So different values of pot only affect the 5V power supply.

Am I not correct with this statement?

I may have made a mistake ordering another board...i am thinking now that these boards are very delicate and a mixture of pot types lead to failure(?)

[KyleH]

Hello KyleH

I tried to get a read on the chip type, but over time the legends must have worn off, or maybe removed them through the construction process....hard to say.

They are usually laser etched into the plastic. One trick we use is to dab a bit of board cleaner or alcohol on a cotton swab, and wipe across the top of the chip then quickly look at it under a magnifier. The liquid will highlight the edges of the etched text

Could using a pot with too high or low of a resistance value damage the board? If that was the case you would think that Leo would put a disclaimer or warning on his web site. He does recommend some pot manufacurers, and does state the pot should be 10k ohms or above, but there is little information other than that.

I am also very careful with static discharges, so I can say for certain that the board was not subjected to ESD.

As far as the heating up of the micro/capacitor is concerned, the ohmic resistance of the pot should not matter. Its end terminals will be supplied with 5V from the board's power supply and the centre terminal will be applied in the micro to an A/D (analogue to digital) converter. That measures the voltage on the pin and works out where the wiper is positioned. So different values of pot only affect the 5V power supply.

Am I not correct with this statement?

You are correct with this statement in general. If it is designed like 99% of these designs are, then yes the micro is only hooked up to the wiper of the pot, and too low a value of pot will only cause a large current draw from the power supply parts.
However, it is remotely possible that the circuit has been designed such that the microcontroller enables the pot through one of it's pins before reading. If that is the case then you have to be careful about pot values, and would need to be stated in any documentation. I think this is an extremely remote possibility but you never know.

If it is actually the capacitor heating up....then it's a defective capacitor. All other pots etc would have no effect on that part.

[Mach7]

kyleH

Thank you for your input, this information at least puts me at ease regarding my pot installation.

Knowing Leo, these boards would have been designed pretty tough.

I have since got an email back from Bodnar Electronics, they have never had an incident of a defective or incompatible pot causing problem in the board, but at the same time do not seem too concerned about the heating of the chip/capacitor as they state if the board is still working fine it is probably "nothing to worry about".

I have since ordered another board, but want to make sure I am not doing something wrong with my existing installation to damage it...which I don't think I am.

The only suspect pot would be the one I took out of an old HITEC RC servo motor. I checked the ohms rating on this pot and got a value of 140k ohms.

It is interesting to note that the board design as changed somewhat from the original 836x i bought so many years ago....so maybe there was always an existing problem that was solved through board design.

The only other thing that I have done...(see attachments), is that I have connected ALL the outputs of the board to terminal block for ease of connection as I continue to build my simulator. Now these connections are just basically 22 gauge wired connected to the terminal block through a terminal connector.

These "open" connections are just waiting for me to connect a switch for operation.

I will try to clean the chip and post my results here.

-Jim

[KyleH]

It is interesting to note that the board design as changed somewhat from the original 836x i bought so many years ago....so maybe there was always an existing problem that was solved through board design.


-Jim

The design change looks like it went from through hole parts to surface mount. This is likely due to component sourcing/building issues not necessarily a design issue.
It is a lot easier & cheaper these days to buy and install surface mount components than through hole.

Other thing to keep in mind. If you are able to keep you finger on the part, it is likely around 50ºC or less. I can see an E/ on the end of those part numbers, and with Microchip that means those are 125ºC parts.

[Mach7]

Just chatting with a buddy of mine as well, he believes that the capacitor may have become damaged, although highly unlikely, this would be the only probable solution to this point.

The heat transfer from the capacitor/chip is sort of weird in that, you can placed your finger on the chip and it does not seem immediatley hot right away, but after 10 seconds or so you can feel the heat which appears to increase in temperature.

When you take your finger off and place it right back on, the chip feels a bit warm, but not hot, unless you leave your finger on it again for another 10 seconds or so.

I can leave the unit online all day, and the heat transfer as explained above is the same...that is to say if you were to go to the board right now after it was on line for a period of time, and just touch the chip, but not leave your finger on it, you would comment that the chip/capacitor was warm, but not hot or uncomfortable to touch.

If you then left your finger in that area for 10 seconds or so, you would think that it was warm to hot.

As i stated in previous threads, only one time did the chip get very hot to the point where I unplugged it. Not sure of the reason for the heat build up, but it occurred quite a few hours after it was online.

This is probably where damage was done...however the board still works fine and has never disconnected from the computer during operation.