Waltron servos

[Ian RiddickParticipant @ianriddick46987]

I have returned to model boats from a previous interest in the 1970's. At that time I used 27Mhz Waltron 4 channel sets. I have a large number of servos from that period and wondered if it is possible to reuse those servos by changing the plug that connects to the receiver for a modern hitec or futaba plug connection.

[Ian RiddickParticipant @ianriddick46987]

Possible reuse of Waltron Servos

[Dave MilbournParticipant @davemilbourn48782]

No. I think Waltron servos were four or even five wires. Modern servos have just three wires, are much more reliable, faster, smaller and more accurate – and cost pennies. These days the radio is probably the cheapest part of the whole package so leave the Waltron in a cupboard or see if there's a collector who wants it.

Dave M

[Ian RiddickParticipant @ianriddick46987]

Dave, I appreciate modern servos do not cost a fortune. It was just that I have about 16 of these servos and wanted to reuse them if possible. They are three wire servos but the plug is male rather than female and they are actually smaller than a standard futaba servo. If however they will not work say with my Spektrum ar400 tx then I will bin them.

[Charles OatesParticipant @charlesoates31738]

Hi Ian, I remember the old male plug servos from Futuba gear I had in the 1970s. As they are 3 wire ones they have a good chance of working with today's gear if re-plugged, but I also have a vague memory that the signal rate has changed since then. I might be wrong. Why not put a modern plug on one of the servos and try it? Plugs are very cheap from lots of suppliers. Most receivers have the negative at the edge of the case, then positive, then signal on the inner pin. Diagrams are on the web. I recently re plugged some old Sanwa stac servos from the 1980s and they are fine.

Chas

[Dave MilbournParticipant @davemilbourn48782]

Ian

If there are three wires then that's a relatively recent servo – probably with a ZN409 chip inside it. My experience of Waltron goes back to the kits, several of which I assembled for folk back in the early 70's.

What colours are the wires? They will be negative, positive and signal pulse but there are several different colour-codes in use. Futaba is Black/Red/White: Fleet is Red/Black/White; Hitec Black/Red/Yellow; JR-Graupner Brown/Red/Orange and the old Sanwa Black/Black/Black with red stripe. If you connect one up to the receiver incorrectly then the only way you'll damage it is by reversing the positive and negative. That will leave you with only 15 to play with! Still cheaper than buying new ones. If you're wary about damaging the receiver then use a servo tester instead. You can find one on E-Bay for £2.50!

Dave M

[Dave MilbournParticipant @davemilbourn48782]

I've just read a review by Rex Boyer of the Waltron 4-5 from 1970's. The servos were E K Logitrol four-wire linear ones with SLM polarised connectors so Ian's set is probably a newer one. The interesting things are the signal frame rate, which is 27ms, and the pulse width for each channel which is 1.6-2.4ms. These compare with the current industry (i.e. Futaba) standards of 20ms and 1-2ms. If Waltron continued with these for your set then you could have a problem. The frame rate shouldn't matter but you might just find the servos jamming up at one end if used with modern receivers. Fixing this would entail removing the output gear from the servo gear-train and refitting it in different positions relative to the feedback pot until the neutral position of the gear is at half-stick movement and the end-points don't stall the motor.

If the servo cases are bright canary yellow then the chances are they're Horizon, and I never had any luck with Horizon radio gear. If they're a pale caramel brown then they may be Kraft servos, which are at the opposite end of the reliability spectrum. I sometimes wish that Phil Kraft was still around and making radio sets. IMHO they were the best radios ever.

Dave M

Edited By Dave Milbourn on 26/11/2017 11:54:18

[Ian RiddickParticipant @ianriddick46987]

Dave, Thanks for the replies, the wires are red, blue and black. I also have the following info from when I purchased the Walton set in the late 70's. "These servos are our latest subminiature integrated circuit type,the amplifier in the servo is a three wire type designed around SIGNETICS integrated circuit chip which contains all 27 transistors, including the bridge connected output transistors". The output power of the servo is 1.6 Kg and current consumption on load is 80-150 mA.colour of the servos is orange. Several are also branded Cosmos and these are coloured red.

Ian R

[Ian RiddickParticipant @ianriddick46987]

Dave, Thanks for the replies, the wires are red, blue and black. I also have the following info from when I purchased the Walton set in the late 70's. "These servos are our latest subminiature integrated circuit type,the amplifier in the servo is a three wire type designed around SIGNETICS integrated circuit chip which contains all 27 transistors, including the bridge connected output transistors". The output power of the servo is 1.6 Kg and current consumption on load is 80-150 mA.colour of the servos is orange. Several are also branded Cosmos and these are coloured red.

Ian R

[Ian RiddickParticipant @ianriddick46987]

Dave, I think these are the servos I have. http://www.vrhc.co.uk/Heli%20Gear/Radio%20gear/Waltron/1974-10%20-%20Waltron%204-5%20sporstman%20test.pdf.

Ian R

[Dave MilbournParticipant @davemilbourn48782]

Ian
I would guess that the red and black are Pos and Neg respectively; it would be unusual if they weren't. If you have the battery wiring harness then that will have the same polarity/pin-out and, as has been pointed out, the negative pin is usually the one nearest to the edge of the case. Signetics were famous for the 555 series of chips while the ZN409 was a Ferranti, I think. I can't help with the ID of the servos.

Dave M

[Ian RiddickParticipant @ianriddick46987]

Dave, reading the article further, these servos are quoted as being black, not the colour of mine although the appearance is the same.

Ian R

[Ian RiddickParticipant @ianriddick46987]

Dave,

Thanks for the comments will check the battery harness and buy a servo tester, thanks again. ian R

[Dave MilbournParticipant @davemilbourn48782]

Ian

That's a later review than the one I read, which was 1971. The signal frame rate and pulse widths were by now more-or-less to industry standard. I don't know who made A&M or COSMOS servos, though. Ref my earlier comment about receiver pin-out, I was forgetting that in those days the servos were connected to a large "flying" socket with several inputs in the one block. Compare that with a modern 2G4 'park-fly' receiver which weighs practically nothing and includes the connector pins!

DM

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