This is a serious situation for a newbie. Perhaps, it is all too simple for the experts in the forum. (I hope!)

At the very outset, this mail is not about pointing fingers at anyone. In fact, at this very moment, the seller of this set is corresponding with me and trying to help me out. 

I purchased a used Tx and Rx unit (Pics attached). Though the Tx said '6 Channel', the seller informed me that I would be actually buying a 4 Ch Tx. I went ahead with the deal. The set arrived and after nearly 2 months, I decided to test it out. To my horror, there is absolutely no response from the Rx / servos.

I am sure that I am doing something wrong, so I am now requesting knowledgeable forum members to let me know where I am at fault.

1. Why is 'A' broken / missing? What could be the cause of that?
2. When I connect a 7.2 Volt Battery pack to 'C', the Green light at 'B' (Gain) keeps blinking. Why does this happen? Is my battery pack of the right specs? Am I connecting it at the right place? 7.2V/750mah is what I am using. When I flick the controls of the Tx, the servos connected to Ch 1,2,4,5,6 (3 is broken/missing) don't respond at all.
3. I have connected the servos to another 6 Ch Tx /Rx and they are functioning fine.
4. Where does 'D' get connected to? The ESC?
5. What is Set Up Adjustment all about?

I am aware that I am a newbie, however, if I could get the 6 Ch set to function perfectly, where am I going wrong with this set?

Please advise.

Cheers!

VC

Just for yr info, in the picture 'rx2', the two slots above "C" are marked as M1 and M2. That would be Mode 1 and Mode 2, I presume. Am I supposed to connect something out there?

Your 'A' is not broken/missing infact the long extension is the A connection which you correctly suggested is the ESC connection. If your connection's are not working then you may have to check up with a multimeter to measure the electricity passing through the channels. if you don't get any reading that means your Rx is dead.

rgrds,
SUMIT.

Can you specify the battery you r using Ni-mh, Ni-cd, Li-po, Li-ion?
You r right, that M1 and M2 r modes.
If you want to more about modes visit this-
http://www.rcindia.org/chatter-zone/mode-1-or-mode-2-pinch-or-thumb/

I am using 1.2 Volts X 6 = 7.2 Volts Ni Cd batteries. What I need to know is that am I keeping any loops open so that the circuit is not being completed? Do I need to plug something in to ensure that it works? Thanks for your inputs. What goes into the m1 and m2 slots?

VC

Looks like this came out a heli (because of the "gain" part). See if you can find it online. I found the receiver, but no manual for it (as it has been phased out already). 

I also feel that people should be careful when buying such items. Unless the seller himself has got it to work outside the heli (he is at an advantage, as he could refer back to how it was wired up inside the heli), it is best to stay away from these "all-in-one" units.

Absolutely agree with Anwar...

Looks like its all-in-one unit. Gyro + ESC + Reciever. Gain means it surely has an onboard Piezo Gyro.

I personally would stay away from such units.

Did you contact the seller? what was the response?

Lets leave the seller out of this now. I will deal with that aspect later. Tell me guys, is it possible to salvage ANYTHING out of this, or is the whole deal a dead loss? Can the Tx be used?

Tx says " 72.830". Can this unit be used with other Rx's ? I presume if the new Rx units are of 72 MHz and I use matching Crystals, it should work (assuming the Tx is not busted too!). Am I right?

Thanks.

hmm.. point how does one determine whether the Tx or Rx is the issue? Got someone nearby with a 72Mhz set?

Your best option is to try a Corona synthesized shift-agnostic receiver.  If the TX itself has an issue, then all bets are off !

I have a 6 Channel FM 72 MHz (72.870) Tx and Rx. This unit works fine. The Crystals were switched from this Tx to the Cyclone Tx. Guess what? Still no go! Dead as a door nail. Tried this Tx with the Cyclone Rx and the Cyclone Tx with the other Rx - still no use! 

Now what?

Here you go..Hope this is the right link..Please confirm with other members..

http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=7527&Product_Name=Corona_Synthesized_Dual-Conv_Receiver_6Ch_72Mhz

I am not very experienced on this, but if you have 2 sets of 72Mhz and one works, then your have one set working.

Now as per logic, if you use the working Tx with the doubtful Rx and it does not work then the problem is with the Rx. If the working Rx is used with the other Tx and the set does not work, then the problem is with the Tx.

If both the above conditions hold true, then both of them are bad.... but like I said, I am also a newbie into this.

Pankaj

Now how many people think like Pankaj? I, for one, do agree with him. Please note that one unit is 72.830 and the other is 72.870. That shouldn't be a problem, should it?
Please let me know what you all think, then I will know what to do.
This is getting serious now.

Thanks.

You cannot  use  any crystal with  any TX Rx combo unless the manufacturer is the same.
Because of these issues :

1) You have to check if the pair is single or dual conversion
2) The shift system also has to match between the tx , rx and the crystals
3) Tx  and Rx  crystals  also need to be the same freq. and  same type as far a 1 and 2 above are concerned

Eg you cannot use futaba crystals on JR and Vice versa

Having  said that most Chinese radios follow the same shift as futaba.

Synthesized receivers like Carona are  shift-agnostic  which means they  over come point no. 2 above  but point 1 above needs to be taken into account .

So work these factors out for your need.

sai

 
Mr. Sai seems to have forgotten that he is speaking to an RC Idiot!

Thanks everybody for atleast trying to help. This seems to be getting more and more convoluted by the moment. Let's see what else the forum has to add.

I refuse to believe that I have been taken for a ride by the seller. There must be a genuine mistake on my part somewhere. I am sure I am doing something wrong. One way or the other, I'm going to get to the bottom of this.

Single or dual conversion is entirely at the receiver end, so any "synthesized shift-agnostic" receiver should not have any trouble with "point 1".  There is no distinction about single or dual conversion at the TX side, so such a receiver will work regardless of whether it is a single conversion or dual conversion.

I don't  know why Carona Specify the synthesized  receivers to be dual conversion  they might as well say single and dual conversion OR Conversion - agnostic  as well.

BTW  they also have single conversion receivers with crystal .

So if the Synth receiver could take care of all these then why do they have single conversion  ones at all 

You may be right I don't know.

All I was trying to say is all these factors have to  be compatible to the tx and rx to work.
 

The separate dual and single conversion models exist in the Corona world for the same reason they exist in the Futaba world.  The dual conversion ones "are supposed to be better ".  (Technical details on the link here : http://www.rcindia.org/radios-and-receivers/fm-receiver-choices/msg11772/#msg11772)

Many people consider that this is just a marketing plot to extract more money from all of us   The fact that JR has no concept of dual-conversion is often pointed out to demonstrate that the advantages of dual conversion are not significant.

VC ,
Not much of gyan is needed just check if these factors tally .
Might be difficult to get this info for the Chinese radios I know but  that is the only way to get them to work.
I can assure you it is not  rocket science but just methodical  checking.

Sai Sir,

All this is Greek to me! I have contacted an expert aero/RC modeller from Assam. If he can't sort it out, I am going to send the entire set to you...... Have a look at it and let me know if there is any hope for it, if not,  I will send it back to the seller and claim a refund. I hope he is reading this now............ >

Just your bad luck Mr. Sai, who asked you to be helpful? 

Just joking Sir, thanks a ton for trying to help. I am giving up this set as a bad joke.

Just made up this one, 'A Cheap horse is as good as a Dead Mule'. (My Original idiom!)

Cheers!

VC - Damn! Why do I have to be the sucker EVERY time?!

Seems another argument for opting for a 2.4 GHz set

Pankaj

I think the supply to the Rx will come through D and not C , you can also connect a 4.8V directly at the servo outputs, you need to identify which pin is positive and wich pin is negative this help you can get from the servo leads or may be given on the Rx case. To me C is the power supply for M1 and M2 which may not be giving supply to Rx.
Are you connecting the servo leads in the right way?

Jitender

Synthesised receiver - like Xtal controlled ones - can be single or dual conversion. Hence the specification. Dual conversion receivers are better at rejecting adjacent channel signals and can - theoretically - allow 10 kHz spacing between channels.

VC, please ignore the above!!

Exactly. Just get your hands on whatever you can find easily (regardless of conversion type).  If you have choice (same availability and similar price, go for dual conversion). 

Even this "adjacent channel interference handling advantage" is a non issue these days, as the quality of the electronic parts involved have greatly improved that this is not considered a routine issue any more.

Anwar, the quality of parts is not the factor. Ask any one who does SW radio  listening - or "DXing" - and he/she will swear by the difference between single and dual conversion.

But it is, admittedly,  a non issue for RC.

 

Having some fun at my expense, are you guys?!
Wait till I grow up and become knowledgeable like you, then I'm gonna show you - "adjacent channel interference handling advantage" and "10 kHz spacing"!!! >

I'm having fun! But seriously guys, thanks a ton for trying to help me out.

Cheers!

VC

Told you to ignore me

But seriously, if you are contemplating getting into the hobby on a long term basis, spend even 20% more than your budget on a good Tx/Rx combo. You will not regret it. There is some pretty decent gear available from the on-line stores without the hassle of imports. Also keep your eyes open for re-sale items. There ARE good deals sometimes, particularly hen people are upgrading or giving up !!

It is a non-issue partly because of the channel spacing in RC, but it was a significant issue in the earlier times when the parts had wider tolerances.  From what I remember reading, crystals were the ones particularly prone to "creeping outside" their intended values, and dual conversion had greater advantage. With such parts working well within then intended/specified ranges, this seems to have become a non-issue (again, so much as JR did not even bother with it).

And yes, my response was RC specific

Sushil,

I guess there are very few people who are as taken up by modelling / aeromodelling as I am. Just that I have never thought about RC Aeromodelling very seriously, until recently. I've been scratch building gliders and stuff for the past 35 years. Most of this time has been devoted to Static modelling. I love scale, details and authenticity.

You are 100% right when you say that I should invest in a good Tx/Rx combo. So far I've been lucky (except this particular set) and people have given me wonderful bargains.

I am on the lookout for a 'proper' 6 Ch unit. Let me know if you come across something. I also need to work on my theory, like you guys, rather than just send something up in the air and pray for fair winds and trust in luck (which, I believe, doesn't exist!).

Cheers!

VC

I don't believe this! After all that we've been through collectively, look what I found........

http://www.rcuniverse.com/forum/m_4613570/mpage_2/key_/tm.htm

Keeping my fingers and toes crossed!

all the best, do post result

Will do Sir!

The moment you get documentation, the game changes    

There is a serious lesson in this though (about the challenges in usage of all-in-one receiver units that come with RTF helis for other purposes).

Hi VC,
Any progress?

Not yet. Just this evening, an experienced RC modeller spent over 4 hrs with me unsuccessfully trying to breathe life into it. Now he has packed it up and taken it home. Let's hope he can bring it back to life. I have given up hope. However, there is a major lesson that I have learnt here.

This reminds me of a quote I saw at the back of a truck - "100 mein 80 log bay-i-man, phir bhi bole mera desh mahan"

Pankaj,

I am not calling anyone a be-imaan. However, I would warn all newbies out there to beware of the Big Bad World and be aware of what your requirements are. Don't just buy something because it looks/sounds lucrative. Also remember, Helis and Planes DO crash and that there are a lot of people out there who are more than willing to unload their junk on you (in return for your money). If something looks/sounds too good to be true - it probably is! Once you have crashed and destroyed a 10 K heli/aircraft, anyone would try to recover a part of the amount through a sale of existing spares,

Make your communication with the seller 'idiot - proof'. So that there is no chance of anyone reverting and telling you later, "Oh! Is THAT what you REALLY wanted? I'm sorry, but I sold it to you in good faith because I thought you wanted something else."

Also remember, Heli Rx's and Aircraft Rx's are different in functionality. You can't always mix and match. Especially remember to avoid Chinese Rx units that come in a single package combining a Rx/Esc/Gyro. Avoid them like plague. Check with the seller and ask him to clarify. If he can't, ask him to post photographs or exact model/component numbers. Do a Google, study, research - then buy. NOT THE OTHER WAY AROUND!!!

Spell it out - tell them WHAT you really need, what you will be using it for - else you will be a suckered like I have been.

It was my fault that I, perhaps, didn't state my requirements to the seller lucidly enough.  I am now hoping against hope that the seller is reading this and offers me a refund of my money. Though I still maintain, in his place and from his point of view - he has done nothing wrong.

With no offence to anybody at all.

Cheers!

VC

There is a possibility of a Futaba 6 channel (6EXA if I am not mistaken) + Rx being available. The Rx is PCM and on the 36 MHz band. This is a relatively rarely used band so the chances of others being on the same frequency would be remote (pun intended)!

Will keep you posted on this as soon as it surfaces (if and when) and have had a chance to look at it.

VC

There's a posting on India RC that might be just what you need!

Check it out.

This is the one : http://www.indiarc.com/forum/index.php?topic=3231.0

Decent deal, if your budget permits.

VC

There is a Futaba 6 CH 2.4 GHz set available. It is in excellent condition and is with the Rx and Tx batteries (Ni Cds), switch harness, and (110 V) charger. No servos. But the asking price - 8K - seems reasonable. Will post pics once it is with me.

Reason for selling: Upgrading.

Dear Sushil / Anwar Sahab,

Thanks for the leads. However, with 31st March on the horizon, I can't think of investing 8 -10 K on a Tx/Rx right now. Especially, since I have just invested in 3 (a 2 Ch, a 4Ch and a 6 Ch Tx/Rx) sets and have not had the opportunity of testing either one of them operationally.

Thanks anyway!

VC

btw vc uncle are u interested in selling any of the sets??

Hooray! Mr. Musawir Mustafa (Aeromodelling Instructor) managed to get the set working. He had to pickle his brains for awhile and I had to scour the net for resources to guide us.The circuit diagrams helped in making some modifications. 3 out of 4 Channels are functional. Thank God!

M1 and M2 are for Motors 1 and 2 (Main and Tail).
E IS the power supply socket.
The wire D (Black, Red, Yellow) does NOT go to the ESC (Rx has inbuilt Brushed ESC), it is for the Gyro. Now it goes into the Channel 5 socket to complete the circuit (since there is no Gyro being used) - This was the crucial step!
Servos are slotted into Ch 2 and Ch 3.

Thanks everyone for trying their best to help out.

Chapter closed.