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Gday all.

I have a Sanwa Dash AM RX and Sanwa SM-631 servo.

I tested it a while ago, and had no luck. Guessed it was the 4xAA battery holder was the problem. (Casing is cracked)

Tried it again tonight with an ESC, and still doesn't work.
Tried setting up the ESC with everything plugged in, and couldn't even set it up. (throttle, brake etc)

Plugged the Sanwa steering servo into an Acoms set (TX, RX, speed control servo), nothing worked.
Noticed the steering servo was quite hot, unplugged it, then the Acoms speed control started to work.
Is the Sanwa incompatable with the Acoms gear? Different polarity maybe?

I then tried the ESC on the Acoms set, same motor as before, set it up, everything ran fine.

Each test was with the same Acoms TX, and same Xtals.
The Sanwa RX should(?) work with the Acoms TX, going by answers from a previous thread I posted on TC.

Not sure what's going on.

Is the RX stuffed, or are the mixed brand TX/RX combo incompatible after all?

I hope all that made sense!

Any help would be appreciated.
Cheers.

I had an Acoms set up once that did have a different polarity than the servo.
But that Tx/Rx was from the seventies.

Installed a Robbe Rocar esc on it and a modern servo also.
Disengaged the (battery holder) feed for the Rx by a direct current through the esc.
Servo started melting before my eyes when I connected the battery pack.
In my case it produced smoke instead of just warmth because of the different current maybe.

So my guess - you were right on the polarity.
I'll read your post again and see if I understand the troubleshoot right.

The Acoms TX is a Techniplus AP-229mkII, from mid to late '80s.
The Sanwa RX and servo would be from the same era.

It was hard to explain all that without posting a novel!
Sorry if it was confusing to read.

I'll go and have another look at the Acoms too.
And I can understand it's not easy to explain the set up because there's more than a few parameters.

Edit : Mmmm... I see the Acoms I was using is an AP-227.

I might just put the Acoms gear in it for now to get it running.
That gear is from another car, so will have to put it all back to run that one.

I guess I could buy a Sanwa TX to match, but if the RX has had it, I'm back to where I started from.

I want to upgrade to 2.4GHz eventually though, so I'd probably be better off putting the money towards that, instead of getting another AM TX.

Just a brainstorm and a short on line research (so don't mind if I miss the target) :

* Slightest of possibilities it's a 29 MHz Tx vs a 27 MHz Rx.
* Here was a line about the difference in age but that is not the case.
* Is the crystal compatible...
* I read Acoms and Sanwa/Airtronics do have reversed polarity!

Handy tool for this kind of situation :

www.phoenixmp.c...ories.html

Hopefully you didn't fry the servo like I did. Maybe you could check with a single battery.
I bought a new servo (after melt down) and changed the polarity on it. That worked. Servo was a GWS.

And a quote from TC :
Just a thought..are the xtals proper ACOMS xtals? if they are made for a different brand, they might not work.. I fly RC aircraft, so I use a lot of 35 meg gear, mostly Futaba, with some Hitec too. As long as I use a Futaba xtal in a futaba Tx/Rx and a hitec xtal in a Hitec Tx/Rx, then everything's fine! Same goes for Sanwa too, although the channel numbers are different, same for JR.

There I am again with eBay - not that I have stock or anything :

shop.ebay.com.a...Categories

Mostly looking at the first item. Rx like this and a reversed polarity on the servo might do the trick.

Btw - don't know about Australia, but here you can buy a new 40MHz FM set up for about 35-40 euro.
Receivers are also must cheaper than for a 2.4GHz. Even heard 40 MHz has faster response.
Might not be a useable freqency in Australia but there's more of them in the FM department.
A 2.4 is of course the "cool" way to go. No antenna sticking out either.

Thanks for your help Edou.

The TX and both RXs are 29MHz.

I thought xtals were all the same, and could be used in any brand radio gear?
I have mixed and matched xtals no probs on my FM gear. Might have just got lucky there?

I don't think there are any hassles regarding RC frequencies here.
There may be some frequencies reserved for flying, but not sure on that one.

2.4GHz are cheap as chips here.
Can get a TX/RX set for AU$43 landed from HK, or $45 landed from Aussie vendor.
Extra RX for $13, Aussie vendor also.

Think I might just wait a couple of weeks and grab some 2.4 gear.
There are a few cars I'll be running with other people, so the 2.4 will be less hassles regarding interferance etc.

Falcon#5 wrote:

Thanks for your help Edou.

No problem, glad to help out - I'm always curious about the solution to questions like these anyway.

Falcon#5 wrote:

I thought xtals were all the same, and could be used in any brand radio gear?
I have mixed and matched xtals no probs on my FM gear. Might have just got lucky there?

I thought so too, but I guess there can still be small differences in connection.
Most of them are interchangeable I suspect. Might be you just got unlucky here.
I'll do a little experiment later this week with a set of Robbe Xtals and one that's Acoms.
Should be interesting to see if that works. These two Tx/Rx combos are from different eras also.

Falcon#5 wrote:

2.4GHz are cheap as chips here.
Can get a TX/RX set for AU$43 landed from HK, or $45 landed from Aussie vendor.
Extra RX for $13, Aussie vendor also.

Wow - that's awesome pricing. No point in getting a used Rx from Israel for 20 bucks then.
That tool for checking polarity was an interesting find I think. Very helpful to have lying around.

Falcon#5 wrote:

Think I might just wait a couple of weeks and grab some 2.4 gear.
There are a few cars I'll be running with other people, so the 2.4 will be less hassles regarding interferance etc.

For that money I'd probably be running 2.4 GHz too...

Btw - I thought the reversed polarity thing was more of an era thing (like wire colouring) but I found out it's about brand.
Kind of silly (and potentially desastrous for the servo) that they would randomly pick a current direction.

I think the Sanwa servo is fried.
I pulled it apart last night, and doesn't smell too good!
I wonder how many other servos have perished from the random polarity choice by manufactures?
That little tool could be very worthwhile having.

I had a look at the HobbyKing site last night, and found some cheaper 2.4 stuff.
Blokes on TC are using them and have no complaints.
Tx + RX set AU$21, extra RX $6 each. $10 shipping up to 2kg. (From the Aus warehouse).

For that money, I don't think I can go wrong!