# Aristo GP40 and P5 problem



## supagav (Feb 8, 2008)

Hi guys, 

I was just wondering if anyone could help? 

I recently installed a Digitrax 583AR in my new Cotton Belt GP40, and everything seemed fine, lights worked etc. Since then I've installed a P5 from Phoenix and I can't seem to get it to work properly. When its on my rolling road and the motors are switched off the loco is fine, revs up and down, horn/bell etc. As soon as you switch theem back on you lose the function control and it becomes very intermittant. To make matters worse, when I take it out on the main line, it seems to lose the speed step signal as the prime mover sound returns to idle even when the loco is moving! 

I called Phoenix and they said it sounded like the motor noise could be interfering with the DCC signal and gave some ideas. I followed their advice and disconnected the track and motor connections, instead wiring them directly on to the solder pads of the decoder, but sadly it made no difference! /DesktopModules/NTForums/themes/mls/emoticons/sad.gif I'm really stumped with this one! Has anyone had a similar experience? Any help or advice would be very much appreciated! 

Thanks and all the best, 
Gavin


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## Jim Agnew (Jan 2, 2008)

Gavin, is the address for the P5 the same as the address for the 583AR?


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## supagav (Feb 8, 2008)

yes, the address is the same for both, 7600 which is the loco number. When the motors are switched off the sound works perfectly with the loco, correct direction and right prime mover revs for the the speed step shown on my throttle. The problems start when I switch the motors back on, then the P5 appears to lose the DCC signal. 

Thanks, 
Gavin


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## Greg Elmassian (Jan 3, 2008)

very similar thread in the forum, seems to be motor noise bothering the P5 from reading the 2 other threads, and from hearing from 2 master installers. 

try chokes and rf filters to the motors, also you might eliminate the silly regulator circuit on the GP40, I think it uses the same PIC processor as on the SD45 to regulate the voltage of the lights. This will probably make you wire the lights directly to the decoder (with dropping resistors). 

Regards, Greg


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## supagav (Feb 8, 2008)

I'll check that out Greg thanks. I'm sure I've got some chokes left over from a battery install I did a little while back so I can test it out with that, fingers crossed! Will try rewiring the lights as well. 

All the best, 
Gavin


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## K27_463 (Jan 2, 2008)

Here are some additional tips: How long are the wires(green) to the p5? Did you cut them short? If so, lengthen them again to about about 12 inches. Then, twist these wires together as tightly as is practical from the p5 back to your connection point. This will introduce common mode rejection filtering and if noise is jumping onto the dcc feeds, will help to reduce or eliminate it. Second, if the GP 40 has low hours, put it up on rollers and run it for 4-6 hours in each direction. This will polish the commutator and fit the brushes to the armature better, and should greatly reduce noise from the motors. This is a no cost solution that often works well in cases of noise. 
Jonathan


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## supagav (Feb 8, 2008)

Thank you for the tips Jonathan. Yes I did cut them shorter, will lengthen them again and try it out. Secondly, yeah the loco is very new, will try leaving it running on the rolling road. 

Thanks again, 
Gavin


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