EMP

Hi Ixion, I’m glad you put me on to Kytes - they do some really good stuff at reasonable prices, though the n gauge lighted vehicles were quoted at about $50AUD which is heavy…but I can imagine the labour and skill needed. I know we are off topic now and to any readers looking for the class 31 info, it’s all above here, apologies. 50k ohm pots purchased today - got the log version so will see how they perform with a range of resistors to protect the led. I know I could do the math but brightness is a bit subjective so out with the breadboard. Have a good weekend too. I’m off to watch the Dragons v Raiders (NRL rugby league) otherwise known as footy! I know, I know…lol Cheers Nick

Hi Ixion, I’m running with the bodyshell off at the moment as you suggested to monitor that pesky diode. No noticeable heat detected so far. Re the vehicle LEDs, I think I’ll have to source one of those fire engines or ambulances with flashing lights, my younger son would love it - the cameo could involve a certain class 31 if it doesn’t last the distance haha I know the peco buffer light isn’t exactly prototypical where Its mounted but it looks alright. I just painted the back of it and the magnet wire with some black acrylic paint to block out the light bleed at the back. Next time I’ll get a bit of 1.2mm tube, mount a couple of lights to it and run the magnet wire down through the tube. I might make up an LED dimmer circuit next just for a mini project. I was reading up about PWM control but I think I will start by wiring in a cheap potentiometer to see what that does. I run all my LED off a regulated 12v DC supply. All in parallel and each with their own resistor. Although I can switch the output down to only 3V, I also have a colour signal on the layout and don’t want to dim that. Being able to vary the brightness of my building interior lights and the buffer lights from my mini control panel would be an interesting little experiment as I seem to enjoy playing around with leds at the moment. All the best Nick

Success! Diode D4 from old PCB transferred to new PCB to become D3 and loco back in action, at least for now. Will see how it goes… I have sourced some more diodes and when they arrive, I’ll have a go at fixing the old PCB. Thanks to all for your contributions, but especially Ixion. I sincerely appreciate the time everyone took to help out. All the best Nick

Thanks Ixion. Yes the n gauge 33s from Dapol are very good. I also have a Dapol 26 and mine run super smooth on DC even at very slow speed, very quiet too compared to most of my GF diesels. Those Oxford models are excellent too, I seem to add to my collection whenever I’m supposed to be buying something else! Impressive that Kytes managed to fit lights into that Ford Transit, at least I think it’s a Transit? It’s funny you mentioned Sheldon because I just happened to be flicking through the TV channels last night and they were showing some re-runs of that show and I had it on in the background while wiring up an led - see below… Re the static, the locos were all safely boxed up in the cupboard when I put the grass down. I appreciate the link to the diode spec - I will see if I can source some locally here in Oz, if not I’ll just use the link you kindly provided. Thanks for having a look into this for me. I’ve learnt a lot through our dialogue and am nearly ready to solder the spare ‘sacrificial’ lamb/diode to the PCB to see if I can get this thing up and running again. Yesterday evening I fitted a waterclear 2mm gull wing smd led to one my peco buffers as a trial. Bit of .25mm magnet wire and 45k resistor to get the brightness down. Rated at max 70mcd but this thing was blindingly bright at 20ma. Made by Kingbright, they are true to their name! All the best Nick

A pic of part of my layout to break up all the text…sorry for the digression.

Oh, regarding the diode test reading, it doesn’t provide a measurement unit on screen (very basic digital multimeter) and the manual was not helpful. But it would appear to be millivolts as I tested an axial diode in my spares box and it read about 500 which suggests millivolts as that’s in typical range for standard diode voltage drop I believe. Cheers Nick

Thanks for taking the time to reply Ixion after what was clearly a tiring day for you. I’m grateful for such detail, especially given your circumstances today - a sincere thank you. And, I hope the following days are not so gruelling for you. Re your questions: The controller I’m using is a basic gauge master combi and it delivers pretty much spot on 12v across the tracks at full power. So I don’t think the controller is the culprit, although I guess I can’t rule out a surge, though I do run the controller from a surge protected board. Many years ago I had a Bachmann train set controller but stopped using it when I realised it was delivering 22v across the tracks at 100%. I have only used the Combi with the cl.31. The wiring on my layout is super simple, I have only a single feed to the track, soldered to the underside of the rails. The layout is a 1.2m long inglenook with 2 points/sidings. The points are peco electrofrog with no wiring to them or polarity switching, they just route power to the active track as supplied out of the box. All very simple. All my other Farish and Dapol locos run beautifully on this layout and have done for years. The diode is hard to measure precisely without digital calipers but with my steel rule the measurements you quoted seem to be on the money at around 2mm x 1.25mm. Thanks again for all your help, It is very kind of you to give up your time to provide such comprehensive assistance. All the best Nick

Thank you Izzy. If it’s a common issue, I hope they addressed it with their latest release of the 31 for the sake of others. I was going to buy a few but when they refused to support the replacement they sent me, I decided against it. So they lost a few sales to me and damaged their reputation with me. Hopefully our electronics engineer will chime in with some possible diode specs as I’d really like to buy some spares and repair both PCBs if I can. I will try and fit the one I removed to the newer board in the meantime. On the plus side I am learning how to fix PCBs so who knows, this thread could end up being quite helpful to others. Meil- switches S1 and S2 allow for forward running in either direction with or without the respective rear red lights. Thanks gentlemen Nick

Thanks for your reply Ixion. I have solved part of my mystery as I confirmed diode D3 (in a bank of four) has failed. When tested off board D3 allows current to pass in either direction with only a few ohms resistance. For comparison, I removed diode D4 from my other failed PCB (this too has a failed D3 diode) and tested it in resistance and diode test modes: In resistance mode there is 133ohms fwd biased and infinite reverse biased. In diode mode I get readings of 169 and infinite. The reading in diode test mode is peculiar (to me anyway) as I was expecting to see a fairly low value representing the voltage drop. So I wonder what type of diode it is… Photos attached. Thanks again Nick

Firstly as this is my first post, a sincere thanks to all the contributors here, many times the advice and knowledge here has been a great help. My Cl. 31 (6 pin PCB) has now had 2 PCB failures on DC, the most recent of which was with a brand new PCB spare purchased from Bachmann. Although purchased in 2016, this loco has run for all of 5 mins, literally. Bachmann has refused to help me, stating that spares aren’t covered by warranty, despite the PCB arriving here in Aus with lighting wires which detached from the PCB upon opening the bag! I’ve traced the fault to what I think is Diode D3 on the PCB as the loco will run in direction A only with forward lights and no rear lights. Direction B I have no movement and no lights at all. Testing the PCB lights with my multimeter, both PCB mounted lights are functioning. I think I might be able to resurrect this PCB if I can replace diode D3 as this diode is displaying zero ohms resistance. But I’m happy for any guidance you can provide on what I should be testing on the PCB and how to test it. Given Bachmann has taken my money but refuse to help me, I’m not too keen on buying yet another spare as this PCB seems to be very flaky. I’ve many other Farish locos up to 10 years old that run just fine. Does anyone have any advice as to what specification of diode I would need to source if D3 is the culprit and how I might go about desoldering and resoldering it. Apologies if this question has been asked/addressed before - I did have a good search before committing to join and post. Thanks in advance to the community for your kind assistance. All the best Nick