DCC Sound & The Farish Class 70, A Bittersweet Experience

[Graham Radish]

Well this is my second farish class 70, and as i have said before these are an absolute swine to work on, their bodies are very narrow meaning wiring and decoder placement has to be 100% perfect or the bottom wont go back on, well iv'e managed it at last, this uses the zimo micro sound decoder from digitrains in Lincoln, but even with such a small pcb you have literally 1mm margin of error, tolerances are so tight even a single decoder wire that's not routed properly will stop the loco going back together.
On my previous class 70 i did the all wheel pickup mod, and i have done the same to this one, in my eyes its a must for smooth running and for n gauge locos in general, while i don't even have the option of fitting a 25v 470uF capacitor due to there being no room inside, i do not like them anyway, especially when using traincontroller.

 

If your loco doesn't move properly with 12 pickups then there is definitely something wrong with the track or wheels/dirt for example.  The key to perfect running lies in contact quality and weight, a capacitor will not cure this only proper maintenance will, for this i use the very expensive (but totally worth it) DeOxit D100 contact cleaner, i bought a 2ml tube of this two years ago and still have a quarter of it left, so as you can see you don't need much, only the tiniest of drops per pickup and one small drop on the inside of each wheel, this stuff is incredible, as you run your loco it cleans and ensures pristine electrical contact, for ensuring perfect track contact i use Servisol super 10, applied on a cotton bud to the rails, this stuff is also magical. I have used Servisol for the best part of 20 years now.

 

Right back to the 70, with much help from here concerning decoder settings (as the yellow wire 'Fo' for the rear lighting was damaged) i have managed to get everything working properly, i have learned so much about CV settings now and i'm very grateful for this so thank you!

 

These are all the settings made in order for everything to function:

 

 

DIRECTIONAL LIGHTS 
CV34=4, CV35=0

 

SWITCHING FROM SUSI TO LOGIC LEVEL FOR CAB LIGHTING 
CV124=BIT7

 

FUNCTION KEYS FOR CAB LIGHTING (DIRECTIONAL)
FORWARD, CV430=20 (FUNCTION KEY 20) CV432=6
REVERSE, CV436=21 (FUNCTION KEY 21) CV440=5

 

ENGINE COMPARTMENT LIGHT
CV42=8 (FUNCTION KEY 8)

 

RESISTOR VALUES
CAB LIGHTS=270 OHMS
ENGINE COMPARTMENT BACKLIGHT=470 OHMS

 

 

Here above you see i have also added an orange LED for the engine compartment backlight, for this i pierced 4 holes in the correct places with a needle, then fitted a surface mount 1206 SMT orange led to the inside of the roof (a piece of cut down led strip with just one LED and a new resistor) then used a 2.5cm piece of a laminating sheet as a diffuser, this carries the light so now the single led lights up all the holes made at just the right brightness with a 470 Ohm resistor and the light looks slightly holographic. On the real locomotives these lights are there for diagnostics and they are very noticeable especially at night, for this i used the F8 key to turn it off and on (CV42=8 brown wire) and i tell you what as well since i discovered single core decoder wire i won't use anything else now, its much easier to work with and its stronger for jobs this fiddly.

 

Everything's put back together now and all is well, however i will say this, i DO NOT recommend adding DCC sound to this loco if you are a beginner, i seriously think it would put you off DCC for life! they are horrible to work on, i rate this job on this loco at 9/10 in difficulty, even a class 08 would be easier.

 

Speaking of the sound, this is where it gets interesting, while i could have mounted an ESU sugar-cube type speaker to the top of the chassis, i would have needed to file down the top of the chassis (not really a problem) but i fitted my speaker to the fuel tank area, i ground down enough of the bottom of the chassis that i needed then fitted the bare speaker (without backbox) to underneath the motor area with 1mm double sided 3M sticky foam, this gives me much more room on the top of the chassis for wiring,  the speaker is downward firing and the whole of the fuel tank is now the 'back box' i also added strips of this foam to the edges to seal it up against the sides of the removable baseplate, but i didn't seal up the underside of the fuel tank, i cut out parts of it discretely without damaging it to the point that it looked a mess, once i made the holes needed i glued in a piece of "modders mesh" with poly cement, this is plastic mesh used to filter dust away from PC fans, it was perfect for the job, underneath now looks like a proper speaker grill.

 

While some of these types of speakers will sound ok once you attach a totally sealed back box, it will also totally kill any treble in the sound resulting in it sounding muddy and muffled, the main sound level is set to 128 (half way)

 

Even though this is working perfect this will be the last class 70 i buy, they're just too fiddly to work on and very frustrating at times, class 37's/66's/58's and shunters for me from now on. 
Advice: when working on any n gauge loco you must wear vinyl/cotton gloves, the small decals will get destroyed with constant bare finger handling, this is much less of a problem with OO gauge locos, but still, wear them anyway because a single static charge can kill the decoders logic chip.

 

EDIT: I have removed the factory pickups they are a waste of time, instead i've soldered ultrafine copper wire directly to the pickups and routed them to the chassis screw terminals, no more cutouts or stalling now its perfect. this is pretty much the way lima do it.

 

Some pictures to follow shortly... 
 

Edited July 4, 2020 by Graham Radish
Pickup mod number 2

[Ron Ron Ron]

Errrr, Graham, I think you've posted in the wrong section.

Should this be part of a blog or something?

[Graham Radish]

21 hours ago, Ron Ron Ron said:

Errrr, Graham, I think you've posted in the wrong section.

Should this be part of a blog or something?

Yep sorry about this haha