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Post by loco8107 on Jun 26, 2019 13:48:51 GMT -8
Hi all- I posted a while back about my 2 locos I bought used (Proto GP15 and an Atlas GP38) having a big difference in starting speeds. Finally got to take them to the LHS today. The GP15 runs great but sounds like the flywheel is rubbing against something which I’ll have to take another look at later (I had said before it was a little noisy mainly at slow speeds). The 15 didn’t take much throttle at all to get going but the 38 uses a lot to get going- most of the way up. The LHS has the Tech II power pack which I also have at home. He said it’s possible the motor may be worn (it’s a BNSF H1 unit from years ago) or the gears may be in need of oil, or it may be how that run came out. He even took a CR Quality Atlas B40-8 to compare and that one took nowhere near as much to get going. I’m very happy with the 15 but not so sure about the 38. Any thoughts??
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Post by sgoti on Jun 26, 2019 13:59:05 GMT -8
Is the GP38 equipped with a dual-mode decoder? They will run on DC only, but take a *much* higher starting voltage than a straight DC-only model.
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Post by canrailfan on Jun 26, 2019 16:39:12 GMT -8
If the GP38 has an Atlas Dual Mode decoder it sounds like the decoder is configured for DC/DCC. There is a jumper plug on the decoder to make it DC only. The instructions are at the following links on Atlas's website: #342 HO 4-function DUAL-MODE™DECODER#340 HO 2-function DUAL-MODE™DECODERThe Atlas description of these early decoders was confusing. The modes determined by the jumper are not "digital" and "analog" but DC/DCC and DC. Remember that to be NMRA-compliant DCC decoders had to support DC operation also. The instructions for the #342 decoder are more specific than those for the #340. Hopefully just moving the decoder configuration plug will resolve your issue. |
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Post by Deleted on Jun 27, 2019 4:48:04 GMT -8
The GP15 might have a wire touching the flywheel...
I agree with the other guys on the Atlas Dual Mode Decoder. Check and make sure (if it's equipped) to run on DC track...with the jumper in the right place.
If that's not it...the circuit board could be bad.
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Post by loco8107 on Jun 27, 2019 12:49:13 GMT -8
Thanks for the answers so far. I only run DC so I’ll try that as soon as I get a chance.
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Post by llxlocomotives on Jun 30, 2019 13:02:26 GMT -8
Both motors should sustain movement on DC around 2 volts. It is important to know what kind of electronic module is in place. The typical P2K light boat d will keep the motor from starting until power supply voltage is between 4 & 5 volts. The tech II will put out around 17 volts at top speed with a PWM signal at low power. This PEM will confuse decoders even set to accept DC.
Binding in the drive will also cause the starting voltage to be high. If you turn the fly wheels by hand you should not feel any resistance. I would get to the bottom of the problem before you run it much more. You could burn the motor out by trying to run near stall.
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