The Case Of The Confused Controller. Can You Solve The Mystery?!

[Rob Buckle]

Now that I have your attention...

I'm hoping someone can explain to me what's happening with an Acoms Techniplus (Mk 5) controller I have. To hopefully help you to better help me I've attached photos you'll need to consult. They are:

Photo 1 - Two number Acoms Techniplus Mk 5 controllers I own. Both were acquired through ebay. The one on the left works as normal. The one on the right is not the same! Notice that at the top, on the left hand side, there is a switch...

Photo 2 - The same controllers with the back removed to better see what's going on inside...

Photo 3 - Enlarged view of the controller with the switch.

If I use the controller without the switch on a Clod Buster I've refurbished everything is fine, so I know this controller and the Clod are okay. If I then use the controller with the switch I make the following observations:

1. The left/right stick works the msc servo instead of the steering servo;

2. Moving the switch - which has 3 positions to select from - to position 1 (pointing away from you as you hold the controller in your hands) moves the steering servo to maximum (turn) left. Moving the switch to position 2 (vertical out of the top of the controller) moves the steering servo to neutral, i.e. the Clod would drive straight. Moving the switch to position 3 moves the steering servo to maximum (turn) right;

3. The forward/reverse stick does nothing.

Does anyone know what is happening here? What was the intent of the person who installed the switch? Mostly, however, I would like to know if the controller will (or is likely to) work normally if I remove the switch and its connectivity to the circuit board.

Cheers,

Rob

[Yonez]

Now that I have your attention...

I'm hoping someone can explain to me what's happening with an Acoms Techniplus (Mk 5) controller I have. To hopefully help you to better help me I've attached photos you'll need to consult. They are:

Photo 1 - Two number Acoms Techniplus Mk 5 controllers I own. Both were acquired through ebay. The one on the left works as normal. The one on the right is not the same! Notice that at the top, on the left hand side, there is a switch...

Photo 2 - The same controllers with the back removed to better see what's going on inside...

Photo 3 - Enlarged view of the controller with the switch.

If I use the controller without the switch on a Clod Buster I've refurbished everything is fine, so I know this controller and the Clod are okay. If I then use the controller with the switch I make the following observations:

1. The left/right stick works the msc servo instead of the steering servo;

2. Moving the switch - which has 3 positions to select from - to position 1 (pointing away from you as you hold the controller in your hands) moves the steering servo to maximum (turn) left. Moving the switch to position 2 (vertical out of the top of the controller) moves the steering servo to neutral, i.e. the Clod would drive straight. Moving the switch to position 3 moves the steering servo to maximum (turn) right;

3. The forward/reverse stick does nothing.

Does anyone know what is happening here? What was the intent of the person who installed the switch? Mostly, however, I would like to know if the controller will (or is likely to) work normally if I remove the switch and its connectivity to the circuit board.

Cheers,

Rob

Just removing the switch will probably do nothing different than leaving it in the neutral position.

There's a yellow item (looks like capacitor but the image is too fuzzy), what looks like a zener diode, and a resistor soldered in there too. At the very least those must go along with the switch.

From this side of the print that's all I can tell. Unless there are modifications on the other side of the print, just soldering off those and making sure every other wire is identical to the unmodified version should do it. Also check that no paths have been cut. But it is the other side of the print that is the business end. If anything has been removed or altered there, it may be much harder to fix.

Your detailed picture is really a bit too fuzzy to tell any more.

[sosidge]

I'm surprised the channels are reversed compared to the other controller because the wiring on the back seems to be going to the same place.

I'll hazard a guess that it is a home modification for boat racing, some classes have a microswitch motor control which doesn't generally need switching off!

[Rob Buckle]

Thanks Yonez,

I've taken another look at the board in the two controllers and it appears only to be in the region of the "yellow item" that changes have been made...on both sides of the circuit board.

I've attached additional, non-fuzzy images for you to see better what has been done to each side. The images are:

1. Original circuit rear

2. Amended circuit rear

3. Original circuit front

4. Amended circuit front

Bear in mind that the differences at top-right in the first 2 images (rear of circuit) are at bottom-right in the last 2 images (front of circuit) as the circuit board has been flipped to take the pictures.

Hope this helps.

[hoppi05]

I cannot help with the question you asked here but i have just thrown the entire innards of one of these controllers in the bin! if it helps i think i can fish it out and send you it if you cover the postage....

[Rob Buckle]

I cannot help with the question you asked here but i have just thrown the entire innards of one of these controllers in the bin! if it helps i think i can fish it out and send you it if you cover the postage....

Rescue those innards!

Seriously, I'm very grateful for the offer and gladly accept...assuming the innards still work of course (may I ask why you threw them out?) Please confirm the cost of postage by PM if the innards are in a fit state to send once fished out?

[hoppi05]

Rob i chucked them becasue when i saw them in an old RC box last week i just thought am sick of them they have been hanging around for years n slung them in the bedroom bin!?!?! very unlike me but i was cleaning up at the time which is also very unlike me lol i must have got confused!... if they are still there i will pull them out for you....

now i cannot comment on there ability to work they had been in an untouched box for years and in another box before that! the transmitter did work but i cannot remember why i stripped it??? i am sure the case broke near the aerial and thats why not be cause it was malfunctioning? if they are in the bin when i check in the morning i will check them out to see there real condition but consider them yours (all be it the postage )

[Theibault]

Just looks like a Tank set up. Lot's of guys add the toggle for a fire switch. Controls sound like they are set up for tread/turret.

[Yonez]

Thanks Yonez,

I've taken another look at the board in the two controllers and it appears only to be in the region of the "yellow item" that changes have been made...on both sides of the circuit board.

I've attached additional, non-fuzzy images for you to see better what has been done to each side. The images are:

1. Original circuit rear

2. Amended circuit rear

3. Original circuit front

4. Amended circuit front

Bear in mind that the differences at top-right in the first 2 images (rear of circuit) are at bottom-right in the last 2 images (front of circuit) as the circuit board has been flipped to take the pictures.

Hope this helps.

So it looks like R18 on the front has been removed as well. If you're handy with a soldering iron, that should not be hard to replace. It looks like it may be the same resistor as the one on the lower right on the back. I.e. it may have been moved.

Compare it to R17 and check that the colored lines are the same.

If not, you can use this page to decode the resistor:

http://davidgbrown.tripod.com/pages/resistor.html

A replacement should be easy to find.

[mike_o]

I agree woth Yonez,

R17 and R18 have been moved/changed. Mount two resistors of the same value as in the "original" board, remove the added components on the back, and you should be good to go. In case you can't find resistors in the correct (small) size, you can mount them vertically, as done on the modified board - no harm done in that.

Also, look out for places where the PCB-wires have may been cut. A connection may have been cut using a dremel-tool or a even scalpel, which leaves very little trace.

The mods appears to have been done nice and professionally, so there is a good chance to get the transmitter back to original functionality.

Good luck!

[Yonez]

Regarding what to buy:

It's kinda hard to read the stripes from the picture.

Would you agree that the ones for R17 and R18 on the unmodifed controller has stripes gold-yellow-red-brown?

Note: R18 just means that it is resistor number 18 on the print. The original assembly instructions would have a list of the correct part spec for each position. It does not however mean that it is an 18 Ohm resistor, even though this is easy to confuse for the UK standard notation for resistors.

A page explaining the process: http://wiki.xtronics.com/index.php/Resistor_Codes

It's been ages since I did this, so please verify my findings.

To start decoding we follow their instructions:

Gold is always the last stripe, so we're seeing the resistor upside down.

The correct stripes are then brown-red-yellow-gold.

Since it is a 4 band code, we have 2 lines for value, one line for multiplier and one for tolerance (accuracy).

On the decoder link we therefore select brown for the first stripe (value 1), red for the second stripe (value 2) and yellow for the multiplier (4 zeros). Gold decodes to a tolerance of 5%.

That gives us 120000 or 120kOhm +/-5%

Since this is a low wattage application you should be fine with any 120kOhm resistor of 5% or less tolerance. Regular .25Watt ones should be enough I think.

Maplin, eBay and others should satisfy your needs. Resistors are laughably cheap.

By the way: Notice that R17 on your modified board also looks like it's been added later. So desolder that and replace both R17 and R18.

[Rob Buckle]

Well folks,

I cut the wires and very carefully removed and replaced the two resistors R17 and R18. After a bit more investigation on my part yesterday I'd come to the same conclusion as Yonez that a 120kOhm +/-5% resistor was required. However, Maplin didn't have a resistor that looked identical to the 4-band brown-red-yellow-gold resistor from the controller. The resistor they did have, which I've been told is a more modern suitable replacement, is a 120kOhm +/-1% resistor.

Now nothing works at all. Oh well, it's not a huge loss if the controller is wrecked as it was no use to me in its present state anyway. I'll take another look at both controllers and compare, as I'm obviously missing something small but critical. Will report back shortly.

Rob

[Yonez]

Well folks,

I cut the wires and very carefully removed and replaced the two resistors R17 and R18. After a bit more investigation on my part yesterday I'd come to the same conclusion as Yonez that a 120kOhm +/-5% resistor was required. However, Maplin didn't have a resistor that looked identical to the 4-band brown-red-yellow-gold resistor from the controller. The resistor they did have, which I've been told is a more modern suitable replacement, is a 120kOhm +/-1% resistor.

Now nothing works at all. Oh well, it's not a huge loss if the controller is wrecked as it was no use to me in its present state anyway. I'll take another look at both controllers and compare, as I'm obviously missing something small but critical. Will report back shortly.

Rob

That's too bad.

Take new pictures, maybe we can spot the difference.

[SKIPP]

is there something unusual about r6?

not sure?

don't really know electronics.

skip

my mistake must be just a different

resistor,sorry.

[hoppi05]

Rob i have found the parts not sure how useful they will be PM me if you still want them and i will send them up for you at some point next week.... and whilst your tinkering with the transmitters i think i found the innards of an acoms receiver so ill stick that in too...

[Rob Buckle]

PM sent. Can't write properly with this silly iPod keyboard!

[hoppi05]

Rob i got your PM and these are the parts i have let me no if they are of use to you and ill sort out sending them your way....

[Rob Buckle]

Hoppi05,

I decided to take one last look at the faulty controller before confirming to you to send the parts. I haven't had the chance look at the controller since I replaced the resistors. Well, it seems I...

...very carefully removed and replaced the two resistors R17 and R18.

...less carefully as I'd thought, as no sooner had I opened up the back but one of the replaced resistors fell out. Oops. Long story short; I have put the resistor back in position and the controller appears to be back to normal and working as expected. The controller is no longer confused.

I'm very sorry to have had you look out the innards on my behalf, but it does appear that I will no longer require them. Thank you for your generous offer, and for the help of all those who posted in the thread.

Rob

[hoppi05]

No problem Rob its not a problem i was simply returning the favour other people on this forum have offered me in the past.

well if no one wants these parts whey will be binned (again lol) tmoz.....