Model Railway Forum

Wouldn’t it be easier to use a piece of string with levers like the real thing

FWIW I use the MegaPoints system. A bit expensive now for sure but very easy to set up and use via DCC command, push button or switch. I have heard good things about the MERG kit but its all a bit above my pay grade. You'll get there Steve. R-

He will and when he does it will be perfect.

initially.... Assuming the test rig and Serov 4 board all proved OK on voltage tests. I think I would push on a Servo horn so it become very easy to see if the servo moves or judders or twitches etc.
Unplug the setting cable and power up the Servo 4 board with 12v DC. See if the Servo moves when power is applied. Try the switch On then Off to see if the Servo moves or tries to move. Try the servo in the next row of Servo connector and move the switch wire to SV2, then do this with the remaining two positions. This would prove the Servo 4 board
It's also worth checking that the Servo its self actually work should the previous still fail. I have eBay purchased servo testing box that cost £2.95for China but same from a UK supplier they are £3.85 post free. Example... https://www.ebay.co.uk/itm/185420262473 ... SwMtxiepc8

Thanks Brian.
I changed my power supply this morning just to be sure I had a decent regulated supply - I can tick that off the list.
I do get the servos whirring when plugged in or at least some of the time they do. I wonder if they are not compatible or have jammed in some way?
I ordered a servo tester earlier to eliminate that possibility. These servos were a cheap Amazon purchase - the MERG recommended ones from HobbyKing are still on a boat in the South China Sea.
All the voltages check out across both the driver board and the programmer and I checked the routes for the wires before it got too warm in the shed.
I still have to do a proper examination to ensure the components are in the right places and orientation.
I’ll get there........eventually.

PS I told you it was witchcraft.

PPS if I decided to resolder the connections, I presume I should remove the IC chips first (I’ll strap myself to a water pipe to earth myself first ) ??

Yes remove the IC(s) before reflowing soldered joints. Its vital you discharge any Static your body has - Touch an earthed water pipe or Radiator or better is to use a ESD wrist strap and special earth only plug. Example https://www.amazon.co.uk/NOSHOCK-Anti-S ... 25&sr=8-39 While I have one, simply touching something that's earthed will remove static from your body for a short while! Static will kill an IC instantly!

Double check the bite on the IC socket is correct to the marking on the PCB and that the IC when inserted has its Bite mark in the same place. - Easy to get one around the wrong way!

Have you tried the other three servo outputs and of course moved the switch wire too?

I only use Cloned SG9 Servos usually from China ebay sellers Not had one fail as yet

I thought that would be the case when soldering -I installed them one-handed while holding the kitchen tap with the other hand! I will recheck the ‘bite’ just in case.
Yes, I have tried all output terminals and alternative switch terminals and all behave or misbehave in the same way.

Told you it wasn’t simple.

But it is making the overpriced megapoints version more attractive every day.

A very neat servo tester arrived from Amazon just now. All four servos are working perfectly.
It seems increasingly likely that I have made a complete horlicks of building the driver board.

I'm struggling to clearly see which way around the IC has been fitted? But its possibly upside down? It looks from your image like the Bite is at the bottom??



Correct orientation.. Bite at the top.



Link 1 being omitted. I always use the Pull Up option as it helps stop a lot of Servo chatter etc. While not present it should still work, but by fitting the link in the Pull Up configuration can only help.

You know Brian, I was so careful to get the orientation right when I built it.......but still managed to b@lls it up!

I now have four moving servos.

Now on to a test rig and programming - or as I put it, another way to find I got it wrong.

Thanks for your help, I’ll be back for more shortly.