UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > General Vintage Technology > Success Stories

Notices

Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

Reply
 
Thread Tools
Old 10th May 2023, 10:59 pm   #1
high_vacuum_house
Octode
 
high_vacuum_house's Avatar
 
Join Date: May 2003
Location: Belper Derbyshire
Posts: 1,767
Default An old Hornby power controller restoration

Good evening,
A quick restoration this afternoon as the weather was bad. This time it was a Hornby railway power controller from the mid 1980's

I purchased this to make up a model railway layout and upon power up was completely dead from the variable supply to the tracks. Tapping it and wiggling the switches would make it cause brief spurt of power.

It is a vey simple supply with 15V AC output for signals and point motors and a variable DC supply for the track to run locomotives. The power switch really just switches the bridge rectifier from half wave to full wave supply. The speed controller is little more than an in-house made wirewound resistor.

To open it 6 rivets have to be drilled out of the case, the 2 switch dollys need removing and the power knob removing as well.

The 2 switches (one for direction change and one for low and high power) are not a bought in part from a component supplier, but made in house and are easily disassembled.

Here was the cause of the almost dead supply. The switch sliding contacts were brass strips and tarnished. This came up well with some Brasso. The other major problem was with the springing of the moving contacts. The sponge strips they used had deteriorated over many years and had lost all of its springiness so that the contacts were not being pressed onto the fixed contacts. I found some silicone sleeving was an ideal replacement for the old sponge and once fitted into the contact carrier, the sliding contacts were making good contact with their fixed contacts. You can see the difference in the third picture.

After cleaning the case, switch dollys and the power knob, reassembly was straightforward and I replaced the drilled out rivets with 4BA nuts bolts and washers to complete the work. The power controller now functions faultlessly now.
Attached Thumbnails
Click image for larger version

Name:	hornby before.jpg
Views:	346
Size:	98.3 KB
ID:	278029   Click image for larger version

Name:	hornby open.jpg
Views:	302
Size:	53.4 KB
ID:	278030   Click image for larger version

Name:	hornby switch.jpg
Views:	303
Size:	31.6 KB
ID:	278031   Click image for larger version

Name:	hornby switch 2.jpg
Views:	291
Size:	47.6 KB
ID:	278032   Click image for larger version

Name:	hornby contact.jpg
Views:	253
Size:	51.3 KB
ID:	278033  

__________________
A proper radio is one that needs to be moved with a wheelbarrow !!
high_vacuum_house is online now   Reply With Quote
Old 10th May 2023, 11:02 pm   #2
high_vacuum_house
Octode
 
high_vacuum_house's Avatar
 
Join Date: May 2003
Location: Belper Derbyshire
Posts: 1,767
Default Re: An old Hornby power controller restoration

Finally after the case and controls being cleaned and then reassembled.
Attached Thumbnails
Click image for larger version

Name:	hornby competed.jpg
Views:	157
Size:	100.5 KB
ID:	278034  
__________________
A proper radio is one that needs to be moved with a wheelbarrow !!
high_vacuum_house is online now   Reply With Quote
Old 11th May 2023, 8:56 am   #3
Cathovisor
Banned
 
Join Date: Dec 2022
Location: Peterborough, Cambridgeshire, UK.
Posts: 418
Default Re: An old Hornby power controller restoration

They're mid-70s - I had one with my train set in 1976.

Never as good as the offering from Hammant and Morgan.
Cathovisor is offline   Reply With Quote
Old 11th May 2023, 5:00 pm   #4
Uncle Bulgaria
Nonode
 
Uncle Bulgaria's Avatar
 
Join Date: May 2016
Location: Cornwall, UK.
Posts: 2,149
Default Re: An old Hornby power controller restoration

I like the replacement with BA - just what I'd have done!
Uncle Bulgaria is online now   Reply With Quote
Old 11th May 2023, 6:28 pm   #5
The Philpott
Dekatron
 
The Philpott's Avatar
 
Join Date: Aug 2016
Location: Colchester, Essex, UK.
Posts: 3,936
Default Re: An old Hornby power controller restoration

Reminds me I must get my Hammant & Morgan Safety Minor sorted out. (Originality set aside as a nice chunky Paignton knob with chromed pointer is now in place on the front!)

Dave
The Philpott is offline   Reply With Quote
Old 11th May 2023, 9:46 pm   #6
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,136
Default Re: An old Hornby power controller restoration

I bought a Hammant & Morgan Duo for 2 at a charity shop a few years ago. It gets occasional use with its 12 V DC auxilliary output connected in series with my Farnell L30-2 when I need around 42V when periodically cycling the three SLA batteries that power my electric bike to check their capacity. Charge using the H&M and L30, discharge using three 12V 21W bulbs in series. It is also used to control the speed of my 12V Expo Mini drill.
emeritus is offline   Reply With Quote
Old 12th May 2023, 1:37 pm   #7
duncanlowe
Nonode
 
Join Date: Jan 2016
Location: Stafford, Staffs. UK.
Posts: 2,483
Default Re: An old Hornby power controller restoration

I had one similar, back in the 70s too. Not sure if it's in the loft, but if it is this will be a great guide to reviving it.
duncanlowe is offline   Reply With Quote
Old 12th May 2023, 5:49 pm   #8
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 10,823
Default Re: An old Hornby power controller restoration

This controller comes from the original peak period of my childhood / early teens interest in model railways and at the time I was quite the Hornby fan and I wanted an all-Hornby setup including the controllers, but when I went specifically to buy a controller like the one which is the subject of this post the owner of the model shop persuaded me to buy a Hammant and Morgan 'Duette' instead.

I had something of a model rail revival about a decade ago and I spotted an H&M 'Duette' like my original one in the 'shed shop' at Grosmont on the North Yorkshire Moors Railway. It was clearly second hand, priced at 40 and I couldn't talk them down, they were adamant they would be able to get the asking price for it. So those H&M units are still well regarded after all this time, although maybe not so much sought after now because DCC (Digital Command and Control) seems to be very popular now.
SiriusHardware is offline   Reply With Quote
Old 13th May 2023, 11:00 am   #9
Cathovisor
Banned
 
Join Date: Dec 2022
Location: Peterborough, Cambridgeshire, UK.
Posts: 418
Default Re: An old Hornby power controller restoration

Depends. H&M controllers are sought after by Hornby-Dublo collectors instead of the "classic" A3 controller - for newer models with analogue control. Gaugemaster feedback controllers are favoured where folk don't want the expense of DCC.
Cathovisor is offline   Reply With Quote
Old 26th May 2023, 4:26 pm   #10
Graham G3ZVT
Dekatron
 
Graham G3ZVT's Avatar
 
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,516
Default Re: An old Hornby power controller restoration

Mine was an A2 like this

Click image for larger version

Name:	A2.jpg
Views:	88
Size:	85.9 KB
ID:	278789

I got it in 1959 and it disappeared along with a load of scrap metal from the cellar of my late in-laws house about 15 years ago. I still have the engine from the set, but I won't risk posting a locomotive picture.

The transformer spent more time being abused with my electrolysis and electroplating experiments in later years.

I too drilled out the rivets, it was to replace the mains lead, but it was long enough ago for 4BA to be far more likely to be at hand than M3/M4.
__________________
--
Graham.
G3ZVT
Graham G3ZVT is offline   Reply With Quote
Old 2nd Jun 2023, 11:30 am   #11
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 10,823
Default Re: An old Hornby power controller restoration

A friend (early 1970s) had a hand-me-down-from-Dad Dublo set complete with 3-rail track mounted on tinplate 'ballast'. The controller was either an A2 or A3 judging by images I have seen recently, including in the post above. I can't be sure which, it was so long ago.

I had a very clear memory of what my first (1960s) model train controller looked like but I couldn't find anything like it in searches for Hornby controllers, and that turned out to be because it wasn't a Hornby branded unit as such, but a Triang 'P4' or 'P5', similar to the one in the attached (Web found) image.
Attached Thumbnails
Click image for larger version

Name:	Triang_P4.jpg
Views:	74
Size:	73.0 KB
ID:	279090  
SiriusHardware is offline   Reply With Quote
Old 2nd Jun 2023, 1:58 pm   #12
Aub
Octode
 
Aub's Avatar
 
Join Date: Mar 2005
Location: Nuneaton, Warwickshire, UK.
Posts: 1,936
Default Re: An old Hornby power controller restoration

I had an A2, like Graham's above, with my first Hornby Dublo 3 rail set . Must have been about 1960. Later, as more track was added, my dad got me a H&M Duette. I still have that, but not the A2.

Cheers

Aub
__________________
Life's a long song, but the tune ends too soon for us all.
Aub is offline   Reply With Quote
Old 2nd Jun 2023, 6:24 pm   #13
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,136
Default Re: An old Hornby power controller restoration

The book "The Hornby Dublo Story" (by Michael Foster) includes extracts from letters written to the author by Mr Ronald Wyborn, ex-Chief Electrical Engineer of Meccano Ltd. He has this to say about the A2 and A3 controllers.

"The A2 and A3 Power Units provide another example of our determination to produce a quality article. The transformers which formed part of these units were designed to be strictly in in conformance with British Standards, and production testing was carried out on the most advanced equipment we could devise. .....

Awareness of this attitude towards quality must I think have gradually spread, because in the latter half of the '50's I was invited to represent the British toy industry on a permanent committee of British Standards. This was useful as it allowed me to help provide a bastion against some of the shoddy products beginning to make their appearance from abroad. It also helped me later on to obtain acceptance into the appropriate standard for a short-circuit proof transformer which I had devised and developed in an attempt to bring down cost by removing the necessity for any form of electrical protection. We had gone into production with this when later still I was also successful in getting it approved by the International Electrotechnical Commission on safety transformers at a specially convened meeting in Copenhagen. "



Does anyone know anything about this short-circuit proof transformer design? My A3 controller does have a cut-out that works on the 12V controlled output, where a bulb lights up and a cut-out operates at a current greater than about 1A, but this does not protect the 15VAC auxilliary output. My cousin managed to burn out the transformer of his contemporaneous Triang controller due to a short on its AC output.

Last edited by emeritus; 2nd Jun 2023 at 6:27 pm. Reason: typos
emeritus is offline   Reply With Quote
Old 3rd Jun 2023, 7:54 am   #14
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 21,877
Default Re: An old Hornby power controller restoration

Quote:
Originally Posted by emeritus View Post
Does anyone know anything about this short-circuit proof transformer design?
Short circuit proof transformers are quite common.

Traditional electric welders frequently get short circuited as the electrode gets scratched across the work as the operator attempts to start the arc. alco, it's not uncommon for electrodes to get stuck onto the work.

This is achieved by having deliberate leakage inductance built into the welder's transformer. Usually as a movable piece of core to 'waste' some of the flux and act as a control to set the welding current.

This technology predates its use in model train controllers.

Most people don't have electric welders, but they do have microwave cookers. The magnetrons in these cookers are RF oscillators, and seen from the power supply's perspective they look like a negative resistance. They need a high voltage power supply, but it has to be current controlled to stabilise their power output. The job is done by leakage inductance designed into their transformer. This isn't enough to make the transformer completely short-proof, but it's enough to suit what the magnetron does to it.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline   Reply With Quote
Old 3rd Jun 2023, 7:31 pm   #15
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,136
Default Re: An old Hornby power controller restoration

Thanks for the explanation, that makes sense. The curriculum included power engineering in the first two years of my electronics course at college, including transformer design, but short-circuit proof transformers were not on the syllabus.
emeritus is offline   Reply With Quote
Old 3rd Jun 2023, 7:39 pm   #16
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 21,877
Default Re: An old Hornby power controller restoration

Aye, the principle is that with the flux shunt, even with the secondary shorted, the primary still has enough inductance to limit the primary current. It's a very smart idea and so subtle that if you weren't aware of it, you wouldn't know it was there.

In valve amplifier output transformers and RF transformers we bust guts to minimise leakage inductance, so it comes as a shock to find it has its uses.

Other wild transformer-y things which play games with core characteristics are magnetic amplifiers (Transductors) and fluxgate magnetometers.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline   Reply With Quote
Old 4th Jun 2023, 12:44 am   #17
Techman
Dekatron
 
Techman's Avatar
 
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 4,744
Default Re: An old Hornby power controller restoration

Quote:
Originally Posted by SiriusHardware View Post
Triang 'P4' or 'P5', similar to the one in the attached (Web found) image.
That's exactly the power supply that I was bought as a youngster to replace the expensive to run double 6 volt lantern battery box that had originally come with the train set - I've still got them both.

The high/low red plastic switch lever unfortunately broke off early in the life of the unit. It was also used as a power supply for other things when I first started messing with electronics - not the ideal unit for such things.
Techman is offline   Reply With Quote
Old 5th Jun 2023, 7:45 pm   #18
wireman
Hexode
 
Join Date: Feb 2021
Location: Edinburgh, Scotland, UK.
Posts: 468
Default Re: An old Hornby power controller restoration

I should have a Horby catalogue from that era but I can't find it at the moment, I can look it out if of interest. My controller (which I still have) was an H and M clipper.
wireman is online now   Reply With Quote
Old 6th Jun 2023, 6:50 pm   #19
Cathovisor
Banned
 
Join Date: Dec 2022
Location: Peterborough, Cambridgeshire, UK.
Posts: 418
Default Re: An old Hornby power controller restoration

Quote:
Originally Posted by emeritus View Post
The book "The Hornby Dublo Story" (by Michael Foster) includes extracts from letters written to the author by Mr Ronald Wyborn, ex-Chief Electrical Engineer of Meccano Ltd. He has this to say about the A2 and A3 controllers.
Random thought.

Could Ronald Wyborn have been related in any way to Ekco's Chief Engineer, John Wyborn?

The A3 controller is here: https://dublonutz.blogspot.com/2016/...ontroller.html

These controllers were superseded in the Hornby 2-rail era by the "Marshal" range before finally, Rovex took over.

Last edited by Cathovisor; 6th Jun 2023 at 6:59 pm.
Cathovisor is offline   Reply With Quote
Old 6th Jun 2023, 8:52 pm   #20
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,136
Default Re: An old Hornby power controller restoration

Thanks for the A3 link.The rubber mains flex of my A3 is showing no signs of deterioration, so I have not yet needed to drill out the rivets to replace it. It has not been exposed to extreme temperature changes.

My friend had one of the later Marshall controllers. My recollection is that, rather than providing continuous adjustment, it applied power in four or five discrete steps.

Last edited by emeritus; 6th Jun 2023 at 8:56 pm. Reason: typos
emeritus is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 6:54 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2023, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.