Converting an early Spectrum GE 70 Ton Switcher to DCC-possibe?

[OntarioTodd]

I just purchased a NOS GE 70 Ton switcher (81111) and would like to convert it to DCC (and sound). Is this possible? What decoder would I use?
Thanks
Todd

[Yampa Bob]

Hi Todd
Is it possible for you to post a picture of the loco, with the shell off? I am vaguely familiar with one version of the 70, prior to the current release. IIRC, it had two powered trucks with open frame motors.

Regards. 

[OntarioTodd]

Sorry, I don't yet have a photo of insides but I did snap a quick photo of the instructions showing the schematic of the loco as well as the photo from Ebay (where I bought it):





Hope this helps!
Todd

[RAM]

That is the two motor model.  It is possible but  it is a lot of work.   

[Rangerover]

It is possible but  it is a lot of work

I have 2 of these and was thinking of doing the same thing. I do believe the motors are insulated from the chassis and there seems to be enough room in there. I would think all you have to do is solder the 2 motor wires in parallel add the harness and decoder and go! Could I be right ?

[Tylerf]

Wow those have dual motors, the dd40 has 2 motor but I'm amazed that switcher has them. Anyways as long as that model doesent use the chassis to directly connect the pickups to the motors and lights like the dd40 requireing a great amour of isolating and hard wiring you shouldn't have a hard time. If there isn't enough space for an HO decoder you can always use an N scale one.

[RAM]

I did a search and came up with this.  It is for the 44 tonner, but they are the same.  Response to wire a Bachmann Spectrum GE 44 ton switcher for DCC
Lenny--in my DCC Update series in Model Railroading magazine I showed how to do this. It would have been the Aug, Sept or Oct issue in 1997. Also in the current (Feb 99) issue I tell how to install a Lenz SD60 N-scale decoder. I now suggest using the Digitrax version since it has FX lights and you can install a beacon etc, and it has instructions for replacing the LED's with bulbs. I'll cover that installation in the May 99 issue.

[Yampa Bob]

The usual practice is to do a stall test, but I would be reluctant to do so on the two motor model.  A friend had one and had problems with splitting drive gears. 

As an alternate, if you can hook up an ammeter and test the current draw, just retard the loco so it can't move yet still allow the drive wheels to slip and spin.  If the current draw at wheels spinning doesn't exceed .5 amp (1/2 amp), a 3/4 amp 123Z decoder should work ok.

[Rangerover]

 I now suggest using the Digitrax version since it has FX lights and you can install a beacon etc, and it has instructions for replacing the LED's

OK I'm a dummy when it comes to decoders. Does this decoder have sound?
I fried one Bachmann decoder in well 4 years now out of 26 dcc loco's. That was a year ago and it's still "deadlined", just too busy doing my scenics and addition, I bought a replacement, lenz, that I got cheap on eBay, but thinking maybe a better decoder, I've been doing a lot of research on all this stuff and I think I can do this. I want to put in a few decoders and take a break from the scenics for awhile, got about 20 cars with bad couplers and bought Kaydee's to replace, gave up on Backmann EZ mate, even the Mark2 are becoming problematic, they seem to get weak. I pull more than 20 weighted cars and they uncouple. They are at the proper height, I used a gauge.

[Rangerover]

As an alternate, if you can hook up an ammeter and test the current draw, just retard the loco so it can't move yet still allow the drive wheels to slip and spin.  If the current draw at wheels spinning doesn't exceed .5 amp (1/2 amp), a 3/4 amp 123Z decoder should work ok. 




Bob is tht a standard for current draw and if it does exceed that do I just add 1/4 amp to the amount of current draw? I do have and use an ammeter?

Geez I feel like I stold this thread from the OP.

[Yampa Bob]

I don't agree with the usual method of measuring stall current, by just pushing down on the loco until the motor stalls. This puts strain on the motor and drive gears.  It's best to stop the motor itself by holding onto the output shaft with tiny pliers or other method.

I did full stall tests on my locos prior to decoder install, they were all under 3/4 amp. (.68 -.70), so I used one amp decoders (DH123).

I have one powered truck from an old 70, my friend sent me his chassis parts for salvage.   

The wheel pickups attach directly to the motor brush terminals via small phosphor bronze spring strips, located inside the casting.  Isolating the motor and pickups would be a very tedious job, not something I would care to attempt.

[Rangerover]

I did full stall tests on my locos prior to decoder install, they were all under 3/4 amp. (.68 -.70), so I used one amp decoders (DH123).

Thanks Bob, I understand now.

Isolating the motor and pickups would be a very tedious job, not something I would care to attempt.

I'll take another look at that and make sure. I'm only getting my feet wet here and maybe I'll try the cheap decoder I have before I install an expensive sound decoder.

That's why I bought the Bachmann EZ Command with the 5 amp booster 4 years ago.  The simplicity!