Question on chipping a V51 BoBo diesel

[Zerogee]

Hi chaps,
I recently got a very nice LGB V51 (the most common DB red one, built 1995 according to the gold sticker) on evilBay at a decent price, and have a Massoth XLS on the way from Jeremy to chip it with. In preparation for the chip's arrival (hopefully tomorrow), I started dismantling the loco tonight. Now, there is some very good news - though it is wired as a three-wire setup (pre-MTS), the two motor blocks are actually 4-pin ones, with the yellow and white pins simply wired together! This means that I don't have to go into the motor blocks, which removes one major task from the job.

My question, however, is about the lighting. The three bulbs at each end of the loco are all mounted on a square PCB that slides into the hood at each end of the body; they are 5volt bulbs, and the PCBs carry voltage regulators and diodes for the directional lights. There are three wires (brown, white, green) coming from each lighting PCB and running to the central PCB that carries the multi-position switch. Now, if each BULB had separate wires coming from it, it would be a simple job to wire these together and connect them to the relevant outputs on the XLS - that's no problem, I know what I'm doing there. But with the bulbs being directly located on the PCB along with all the lighting circuitry, I'm assuming that my only route is to solder new leads onto the relevant zones of the PCB to bypass the regulators and diodes - there is presumably no way I can simply connect up using the existing leads, because all the components on the PCB are superfluous under MTS - am I right in thinking this?

Thanks in advance!

Jon.

 

[Nemo]

Thats right Jon, you need to bridge out any resisters so that the bulbs have a direct feed from the chip and return without going through any electrical components. I did it recently with a Mallet and have a V52 to do when my chip arrives. Make sure you alter the lighting output on the chip BEFORE you connect the lights or you will blow all the bulbs.

 

[Gizzy]

One of the reasons I'm planning to ditch the lighting pcbs and make up my own circuit from veroboard and LEDs, once I get around to visiting Rapid Electronics....

 

[Zerogee]

Thats right Jon, you need to bridge out any resisters so that the bulbs have a direct feed from the chip and return without going through any electrical components. I did it recently with a Mallet and have a V52 to do when my chip arrives. Make sure you alter the lighting output on the chip BEFORE you connect the lights or you will blow all the bulbs.

Thanks Steve - yes, I made that rookie mistake once a while back, reset a chip to factory settings and forgot about the lighting output voltage - never again!
Re the lighting PCBs, looking at them it shouldn't be TOO difficult to connect new wires to the relevant areas of the PCB and thus bypass the components on them, just got to figure out exactly where - do you reckon I should actually cut all the unwanted diodes and other bits off the boards altogether just to be safe? I'm assuming so, in case I otherwise miss one that bridges two areas I don't want connected....

Jon.

PS: Gizzy - I'll let you know how I get on, if it all works well then I may be able to save you the cost/hassle of making your own boards up - or do you want to move from bulbs to LEDs anyway?

 

[steve parberry]

One of the reasons I'm planning to ditch the lighting pcbs and make up my own circuit from veroboard and LEDs, once I get around to visiting Rapid Electronics....

When i did mine i just unsoldered all the junk on the old board and fitted new leds in place of the bulbs, also i put in a couple of resistors for the price its worth it just in case the chip sends out 24v, But you now dont have a socket for power take off!!

 

[Gizzy]

Thats right Jon, you need to bridge out any resisters so that the bulbs have a direct feed from the chip and return without going through any electrical components. I did it recently with a Mallet and have a V52 to do when my chip arrives. Make sure you alter the lighting output on the chip BEFORE you connect the lights or you will blow all the bulbs.

PS: Gizzy - I'll let you know how I get on, if it all works well then I may be able to save you the cost/hassle of making your own boards up - or do you want to move from bulbs to LEDs anyway?

I want to fit bi-colour white/red LEDs to work with the direction of travel, for the lower lamps, as well as a hi-intesity LED at the top of the hood.

Probably do my other V52 if it works well....

 

[ntpntpntp]

If it were me I'd rather fit suitable resistors in the wiring, or re-use resistors from the pcb, rather than rely on remembering to adjust the function output voltage on the decoder. Resistors are only a few pennies each. Avoids mistakes if the decoder is reset, and of course if you change to a different decoder at some later date it may not have the same voltage adjustment capability (or you may forget)!

Actually, like Steve & Gizzy I'd probably swap out the bulbs for LEDs and resistors.

 

[Zerogee]

OK, job is nearly done, I thought I'd share a few pics of how I decided to do it in the end. I didn't want to go the LED route this time, thought it was easier to keep the bulbs; so after some careful study of the factory lighting circuit boards, this is what I did:
1) after removing both front and rear boards from the loco, I carefully snipped off ALL the electronic components from both boards, and unscrewed the voltage regulator on each, leaving nothing but the three lamp holders and the (now redundant) auxiliary power socket pins (first photo).

2) I unsoldered the green wire from each board, leaving the white and brown ones connected. Re-using a small length of the green wire, I bridged across between two of the PCB tracks as shown in the second photo. This was the simplest way I could see of connecting the three bulbholders directly to the white and brown wires, which become the new feed and return wires for the lighting board. No cutting of PCB tracks was required, or any other fiddling around - simply soldering the green wire to the two existing solder blobs where components had been cut away - a nice easy solution to the problem. A quick test under a few volts of analogue power confirmed that all was good, the bulbs all lit with no shorting.

As to the rest of the wiring and the actual decoder intallation, it was pretty simple - I located the XLS to a pre-existing hole in the front ballast weight, just on a single screw (with an insulated mounting boss of course) but it seems secure enough. The nice chunky 3watt speaker was mounted to the loco's speaker grille location using a ring of white-tack putty, pressed down firmly in place - as the speaker had no screw holes or mounting lugs, this was by far the easiest way of fixing it but allowing removal at any time if required. Despite the loco being manufactured back in 1995, I was VERY pleased to discover that the gearboxes were both MTS-ready 4-pin types - I hadn't realised they had started to fit them that early. The original factory wiring had the white and yellow pins linked together with a short jumper lead of yellow cable, so that each motor block as wired as a 3-wire (white, green, brown); I simply took all these off, put them in the bits box and used the two sets of white, green, brown and yellow cables that came supplied with the Massoth XLS, joining them together in the middle of the loco (under the cab space, where I had already removed the other bit of PCB than carried the old 3-position switch) and then running a single set of the four cables direct to the XLS. You can see this in the third pic - the blue, orange and red cables are from the front and rear lighting boards (joined to the white and brown ones I left on the PCBs), and the two black leads from the cab interior light go straight to the interior lighting terminals on the XLS.
The small square of green PCB you can see on the left, at the very front of the loco, is a Massoth manual volume control pot plugged into the relevant micro-plug socket on the decoder.

All in all, a relatively simple job!
I hope that this writeup and the pics may be of some help to anyone else undertaking a similar job on a loco of this sort of vintage.

Jon.

 

[Phil]

Looking good.

Could you make a video for youtube if you have it? so we can see your line and hear the V51?

 

[Zerogee]

Hi Phil, when I actually manage to get some track down on my layout (at least just the main loop round the garden perimeter) then I'll try to get a video done; at the moment all the trackbed is prepared, just got to find a few spare days of nice weather to get the track cleaned up and put down into the chippings.

Jon.

 

[Phil]

Hi Phil, when I actually manage to get some track down on my layout (at least just the main loop round the garden perimeter) then I'll try to get a video done; at the moment all the trackbed is prepared, just got to find a few spare days of nice weather to get the track cleaned up and put down into the chippings.

Jon.

 

[Tim Brien]

Jon,
many thanks, exactly what I was after. Just need to work out how to remove the circuit board at each end though.

 

[Zerogee]

Tim - they come out very easily; just flex the board backwards (into the loco) very slightly to free the two lower lampholders from the holes in the front of the loco, then the whole board simply slides out.

Jon.

 

[Tim Brien]

Jon,
many thanks. Boards removed and bridged. Loco all wired now but awaiting purchase of decoder. I noted that a spray can plastic top is a perfect fit over the speaker mount. On other installs the cap placement has improved the bass response from the speaker, giving a deeper more realistic sound.

The Massoth pdf. download lists a 70mm speaker as part of the Massoth XLS package for this locomotive. How one would fit such a speaker in the loco is beyond me. The 3 watt 57mm speaker is a perfect fit in the stock LGB moulding.

 

[Zerogee]

Glad I could be of help, Tim! Yes, the spray-can-cap for a speaker enclosure trick works well, and thanks to whoever it was on GSC here that suggested it. I'd not tried it till after I did the V51 but I may well take her apart again and fit one at some point (trimmed right down to fit under the decoder board). I've used them on a couple of locos I've chipped more recently and yes, it does improve the sound.

I agree about the speaker size, certainly on a model of the vintage of my example; I don't know, maybe the more modern versions of this loco have a larger speaker location (though I can't see why LGB would have changed the main chassis mouldings?). As you say, the 57mm speaker is a perfect fit. If you haven't ordered your decoder and speaker yet, whichever supplier you use should be happy to include whichever speaker you ask for, you don't have to take the default one that Massoth list for it - the speaker is not packed in the box with the decoder by Massoth, they are just bagged and supplied separately even though they are included in the listed price for the XLS, so a good dealer should be happy to substitute whichever size and type you request. I'd suggest the heaviest and most powerful 57mm Visaton speaker that you can get!

Jon.