Unfortunately our bus is a bit of a distance away at the moment, so minor work is best done by the firm storing it, because it would cost more to drive out there.

I bought a 24 to 12 volt transformer. The local garage advised the man fitting it to connect the live wire to the starter motor. When I got there to collect the bus, the transformer was not lighting up. They tell me it did work, but it would not work for me, engine on or off.

The firm I got the transformer from explained the alternator causes a power spike to feed the starter.

My question is, is this likely to have burned the transformer out.

They have since tested it and say it works, but I'm not sure what they connected it to, 12 or 24 volt.

Does anyone here have any experience with this sort of stuff. Advice will be gratefully received.

My bus number (if any): RCL 2259

Robert

I do not understand why you would have been advised to supply a feed to the transformer from the starter motor. The starter motor would have battery + & - but not for powering accessories, and if your bus has a starter motor with a solenoid then this would be fed separately from the starter solenoid relay. The difference will be if your bus has been modified at anytime and fitted with a Scania,Iveco or Cummins engine, but you still would not take a power supply from this source.
If you are powering a satnav, check to see if it is dual voltage 12/24. The supply for the power point could be taken from the Switch&Fuse Panel Cab Header, which is above and to the left of the driver. The best advice I can give you is to find a good auto electrician preferably who deals with 24v commercial vehicles, and obtain the wiring diagram for the bus before having any work carried out.

Thank you Ed. That is what I thought I was doing when I hired the people at the storage facility garage to install the transformer I specially bought. Over the last few days I have discovered that the garage they use leaves a bit to be desired. Their latest repair left us with what looks like an oil leak. (could be diesel), I'm sure it wasn't leaking before, cause we were in a big warehouse crawling round under there to check the low bar, and no one got any oil on them.

Lucky for us we noticed it early as it was leaking on the Trafalgar Square York stone and the City of Westminster would not have looked kindly on that, had we not cleaned it throughly.

Turns out they did some work on the fuel pump and injectors, but didn't set the timing. I've been talking to Martin from this forum, and will be getting the bus up to him for a good once over, in a couple of weeks. After they advised hooking a live feed to the starter, even I knew there are power spikes needed to turn a big engine like this. My confidence in this local garage has waned, I must say.

thanks for your advice.

My bus number (if any): RCL 2259

I am travelling from Chesterfield to Sidcup (via Telford) tomorrow. Depending on where you are I could call in and sort this problem for you.

David Colin (former LT Electrician)
07866 720046
Demain UK Ltd

My bus number (if any): M1001 RML2276 T806

Sorry I didn't get your message sooner, I am in London at the moment, (normally in Hastings), and have only checked in here now and then. The bus is kept near Oxford. We hope to have it in London soon, but are still working out the details. As it is, it is and adventure getting out to it. I'm taking it up to Martin near Newport, for him to give it a good once over next week.

Very grateful for your offer to help.

One thing you might be able to help me with. The people storing the bus say the cab light runs on just 12 volts. This is why they think my taking a feed from the live cab light wire did not cause the 24 to 12 volt transformer to work.

Sounds odd to me. Do you know if the cab lights usually run on 12 volts, or anything else in the cab for that matter? Knowing that would be really helpful, as I have set some time aside to install this transformer for my SatNav and it would be a time saver knowing what Im dealing with

Thanks again.

My bus number (if any): RCL 2259

There is not normally any 12V on an RM but who knows what modifications have been done.

Where near Oxford is the bus kept. I used to live in Abingdon and my son lives in Didcot so travel there frequently. I am also in or around London and the South for most of April through to June.

David

My bus number (if any): M1001 RML2276 T806

We use a transformer with a plug outlet and fused protection. See http://www.m-99.co.uk/Electrical/12v_Car_to_240v_Mains_Power_In/12v_car_to_240v_mains_power_in.html

These can be clipped on the + and - of a single 12 volt bus battery to generate 220 volts AC for use with amplifiers, promo TVs etc where power is not available at promo locations.

It cannot be used for too long as it of course drains the battery, but it would certainly charge up a GPS. We don't use it when the bus is in motion.

My bus number (if any): RTL 960 RMC 1458 RM 1585 and several RTs

Robert,

Without wishing to upset you it really is so obvious that your knowledge leaves a lot to be desired so instead of clutching at straws take the bus to Ward Jones at High Wycombe, an hour at bus speed from Oxford, and let him sort it out and do whatever else you want. He's the professional, your not!

Claire

The advice from one or two is very clear. either wait for an expert who knows and understands the electrical nuances of the Routemaster (and there are quite a few)
or, take it to someone who does RM electrics and mechanics for a living and can inspect and warranty their work.

I've been more than a little shocked to see some of the post - LT wiring bodges on RMLs in particular. Some are just messy and poorly done, others are downright dangerous and in all seriousness, fire and catastrophe are not far away when it comes to faulty or inadvisable electrical wiring.

I think it was an absolute miracle that so few RMs,( maybe none) ever went up from an electrical fault in service years.
A lot of that credit is down to LT being very thorough and strict about wiring and the electricians - that I knew, were very well trained.

Yeah thanks for your warming tone Claire. As to what I am and what I'm not, connecting two wires to a transformer is hardly brain surgery, and I was under the impression people here are happy to share what they know, as I am. Martin has already offered to help with this when I take the bus up to him next week. I'm just trying to get it done earlier, so I have a SatNav to help me get there.

No one is being forced to reply to my posts, and I am very grateful to those who make positive suggestions.

I'm just trying to learn about our bus here. I thought that was what this forum is all about, not just for dismissing curiosity with,"you have no idea what you are doing, see an expert".

By the way, most messages which start with, "Without wishing to upset you" are in most cases upsetting.

My bus number (if any): RCL 2259

Hello Robert,
I do hope my tone did not offend you, it certainly wasn't intended, on the contrary it is the only advice I can offer as electrical work was not my domain at LT.
The intention is to see you safe rather than sorry and the best advice on that is to take the offer from someone who knows (as I said before, the nuances of RM wiring)
In turn, the best way to learn is from some who really know their way around the vehicles.
Nowadays, with lots of owners from non-bus or engineering backgrounds, I certainly accept that for many, this is an exciting new challenge, while for others they open an horrific can of worms.
With that in mind, help and advice is why this site and one or two others, exist.

I offer advice whenever I can if it's something I know about, or suggest other sources if I don't, as do several others.

I do hope you are not offended by my reply and sincerely apologise if I did, it was not intended. The advice though, does remain the same, it may just seem like two wires and a simple tweak, but on an RM, this never turns out to be as simple as the theory.

Not at all. I get where you are coming from. I do have a bit of experience with car wiring as I rebuilt a 1983 Ford Transit Ambulance into a camper van. I get these buses are different, and I do want to learn.

I should also say, we won this bus, none of us are rich, and I will always do my best to see what the least expensive option is. I'm off to visit the bus tomorrow, and Wednesday off to Martins to get that expert touch. Will report back.

Thanks for your posting Robert.

My bus number (if any): RCL 2259

and yet you are saying it is has been done incorrectly by the person fitting it and you don't know how to do it yourself. Indeed I have explained what to do on several occasions and have doubted the need for 12V anyway as Tom Tom sat navs will generally run on 24V.
For the record, you were not trying to fit a transformer. DC voltage cannot be transformed.
The NICEIC have a bit of a slogan that more or less says anyone can wire something up. Only a professional can do it safely.
If you require a qualified electrician with some 27 years Routemaster experience (which is possibly a bit more than Ward Jones) you have my number.
David

My bus number (if any): M1001, RML2276, T806

Dave If you cannot transform DC voltage, how do these "transformers" we use to generate 200v AC work then? While you are there, we have found a bus with the westinghouse flasg unit disconnected, I don't know how its been done, but is it just wires that could have ben cut? I really cannot remember how there are connected and what to and don't have a bus nearby to check.

Cheers Brian

My bus number (if any): RTL 960 RMC 1458 RM 1585 and several RTs

Hi Brian,
Its probably an 'inverter' you are using , dc to ac .
Transformers are usually used to step down voltages in AC , a good example is an electic trains' transformer , it takes 25kv in and steps it down to 220-300 v ac for auxilaries and control supply and up to around 900 v ac for traction approx ! From there on its rectified (if required) to dc.
mark

My bus number (if any): RML2391 , United Counties 157

Hello Brian

Electronics are used to change DC into AC.

A transformer is simply a device that by applying an AC current on the primary coil produces an induced AC current on the secondary coil. The input and output voltage is determined by the ratio of the number of turns of wire on each coil. In the case of a shaver socket the coils are equal and give the same output voltage as the input (subject to losses). This is to give a seperated from earth voltage that protects you in a room with a bath or shower. Most transformers however increase or reduce the voltage. In all cases it can only be done with AC. Even a 230V AC in, 12V DC out consists of a transformer (230 to 12V AC) follwed by electronic (in the form of either half wave or full wave rectification using diodes) to give you DC. Typical application would be a battery charger.

Flag unit

The flag unit has only 4 connections but according to the drawing 5 cables

Flag Positive should be a blue cable with marker T1.
White Brake Light Positive has a blue cable with T2.
Red Gearbox Light Positive has a thinner blue cable and a red, both with C25.
The Negative is also a blue with marker D6.

If they have been cut then tracing will have to be as follows.

Red and thin blue should be obvious.

Use a 24V lamp connected to a known 24V point and then ascertain which of the three is the Negative by connecting each one until the lamp illuminates.

The final two are easy as one will be live when the brakes are charged and the other when to brakes are down. Connect temporarily and run the engine. If they operate incorrectly swap them around.

I would then fully test by charging up brakes and air and then seperately dischargeing one at a time ensuring lights and flag operate correctly.

Hope that helps

David

My bus number (if any): M1001 RML2276 T806

Thanks Mark and David for the explanations, I was puzzled as to why these devices are called transformers when they clearly are not. When I had train set a similar device was called a transformer rectifier!

Great help, David with the brake warning unit info, I hope there are still some wires there to trace, the RM has been a cafe/bar conversion and lots of wires cut, just hope these wires were cut for no particular reason. From what I have been told the brakes work OK and we will be taking a charging kit for the accumulators, it would be good to get the warning unit working if only for comfort. More details of the bus when the sale is finalised.

My bus number (if any): RTL 960 RMC 1458 RM 1585 and several RTs

I apologise if I have been using the wrong terms. Its a small box which allows you to feed 24 volts in, and produces 12 volts out.

I drove the Kinder bus out to Martin in Wales on Wednesday. Great meeting him and seeing all the great routemasters in his garage. One of them is registered just 8 apart from ours!

Before leaving for Wales from near Oxford, I took Martin's advice and took a live and earth feed from the wiper wires, before the switch, and hooked them up to my converter, (if that is what it-s called). SatNav works fine and I got there. While it does turn off when the electrics are cut off by the cut off this bus has, Martin has recommend that a switch on it would be a good addition. This I will install when I get the bus back.

Martin did find an inverter which transforms the 24 volts to 240 volts, and is powerful enough to run an electric drill and the fridge, obviously fitted in its promo bus stage. This is however on a separate circuit which is good.

Why is the bus still in Wales? More on that later.

Special thanks to Martin.

My bus number (if any): RCL 2259