Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Radio Equipment => Topic started by: Klunk on March 26, 2019, 06:41:27 am

Title: old 27 and 40 kHz radios end point adjustment
Post by: Klunk on March 26, 2019, 06:41:27 am

is there anyway that you can make an end point adjustment to older radios??? this Whirlwind drum servo i have is now fixed.  when i connect it to my 2.4 system it warbler, so I turned the EPA down to 85% and it works.  when i put it back in the original boat with a Sanwa 40mhz radio it warbles again! yes it has a 6v supply etc. so i need to be able to change the EPA On the sanwa......anyvideas you old modellers
...ps I'm 52!

Title: Re: old 27 and 40 kHz radios end point adjustment
Post by: DaveM on March 26, 2019, 08:05:01 am

https://www.componentshop.co.uk/p96-servomorph.html (https://www.componentshop.co.uk/p96-servomorph.html)
DM (and I'm not 52......any more)

Title: Re: old 27 and 40 kHz radios end point adjustment
Post by: Netleyned on March 26, 2019, 08:37:10 am

Is there not a little adjusting screw on the case near the bottom? I seem to recall mine having one.
Ned 52 +24

Title: Re: old 27 and 40 kHz radios end point adjustment
Post by: John W E on March 26, 2019, 09:39:54 am

Hi Klunk

]Is your transmitter a SANWA CONQUEST MK 11 FM,  if so, there is no ease adjustment to the end points unless you are capable of doing major surgery on the circuit board  - just had a look inside my old one 

Just out of interest if you have the same transmitter as me, are you running it on a 9.2 volt battery pack ? if so try running it on dry cells 8 x1.5 v 12v

as I have had similar problems when using 9.2 v s 

john

Title: Re: old 27 and 40 kHz radios end point adjustment
Post by: Netleyned on March 26, 2019, 09:43:43 am

Quote from: Netleyned on March 26, 2019, 08:37:10 am

Is there not a little adjusting screw on the case near the bottom? I seem to recall mine having one.
Ned 52 +24

The adjusting screw is on the winch, not the tx.
Should have made that clear :embarrassed:
Ned

Title: Re: old 27 and 40 kHz radios end point adjustment
Post by: Klunk on March 26, 2019, 09:47:46 am

done that. didn't work. wondering if that's gone kaput!

Title: Re: old 27 and 40 kHz radios end point adjustment
Post by: Ken G121 on March 26, 2019, 07:16:18 pm

Have you considered going to eBay and getting a servo end point adjuster. I have used them on 40 MHz as my radio does not have the facility and adjusting end points mechanically at servo end can be a sod. With an end point adjuster it sets up in seconds set neutral and both end points. If you find they are wrong when you change radios just reset again, as long as you put it where it can be accessed easily it is honestly set up in seconds
Regards. Ken

Title: Re: old 27 and 40 kHz radios end point adjustment
Post by: RST on March 26, 2019, 08:24:59 pm

I'm pretty sure you can do this on any radio if you fancy a bit of DIY.  I certainly did it on my 40MHz F-14 Tx back in the day -it's still fine after 20 years...

I'm sure I got the idea from Model Boats or Marine Modelling mag.  If you look at the back of your "stiks" inside the Tx case it's a small potentiometer of whatever value -I can't remember 4k7 or 10k etc.  When you move the stick it may not go to full travel, but the mid-point is somewhere in the middle.  All you really need to do is change the resistance of the pot to change the servo position.  When I did mine I used a toggle switch and two adjustable pots, one adjusts + on the stick throw, and the other pot adjusts on the - of the stick throw.  The switch makes it "dual rates" so off for normal and "on" for the adjusted throw.

If you go across the original stick pot in parallel with the new pot it will reduce the resistance.  Reduced resistance is the same as moving the stick less etc.  Sounds complicated but it's really very much the opposite and you can split an analogue channel into many, analogue pre-set positions on a servo, or using a sumple multi-switcher decoder using the same technique!

It works very well.  Sub £5 of parts, mount it on a really simple double postage stamp sized bit of veroboard and hide it in the Tx case.  You need to drill a hole for a toggle switch though.  The only downside -and I seem to remember the original warnings is you need to adjust the pots quite finely because if you go too far out of balance, then it adjusts the neutral position when the stick is thrown.  I never had much trouble, perhaps just one or detent on the trim to correct at most.

...Or these days just buy one of the £12-14 variants of the plug-in gizmos which plug inbetween the Rx and the servo.  I think I got my last one from ebay.  Think it's a Turnigy, but Component shop does the same (but a much, much bigger unit), and I think Model Radio Workshop do the same...

https://modelradioworkshop.co.uk/shop/servo-control-devices/servo-end-point-adjuster/

...Has anyone ordered from the above company before?  They have a few useful gadjets listed.  I actually need an end point adjuster myself for a micro boat wih a 7.2v Ni-Mh pack, but the motor is only a 380 and I figure it will work well reducing the max motor speed using a 10A viper micro ESC.

Rich

Title: Re: old 27 and 40 kHz radios end point adjustment
Post by: John W E on March 27, 2019, 08:36:17 am

yes. I have dealt with this Company in the past several times via Ebay - and they are pretty good - they have always been reliable to me.   Admittedly I got the basic diesel engine and steam engine sound units from them.  :-))


John