751D pulsing on startup

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MrThrasher

New Member
Hi all. I’m installing five 751D switches to Five PECO motors/solenoids. The power supply I’m using is an old laptop psu (18.5V DC, 3.5A). My issue is when I have more than two switches and turnouts wired up they pulse on and off at startup as if there Isn’t enough power. After it pulses for a while everything clicks into place. I add a forth switch and turnout. It has weaker pulses and doesn’t stop. The instructions say 12V but I have tried that and they wouldn’t turn on at all. What am I doing wrong? Is it possible to install a CDU with the 751D switches?
 

Greg@mnrr

Section Hand
Are you using a momentary contact switch to control a single switch machine? If the power is left on to a 751D type switch operator, the twin coil machine(s) could burned out. Sounds like you are operating the two machines and leaving power to the machines.

The preferred way is one momentary switch to one turnout switch machine. I would use a On-Off-On switch that returns automatically to the Center Off position after movng the toggle to either On position. Most twin coil switch machines use 12 volts to operate.

I would purchase an inexpensive wall wart 12 volt power supply for the switch machines. What brand 751D switch machine operators are you using?

Greg
 

MrThrasher

New Member
Are you using a momentary contact switch to control a single switch machine? If the power is left on to a 751D type switch operator, the twin coil machine(s) could burned out. Sounds like you are operating the two machines and leaving power to the machines.

The preferred way is one momentary switch to one turnout switch machine. I would use a On-Off-On switch that returns automatically to the Center Off position after movng the toggle to either On position. Most twin coil switch machines use 12 volts to operate.

I would purchase an inexpensive wall wart 12 volt power supply for the switch machines. What brand 751D switch machine operators are you using?

Greg
Sorry, I should have clarified that I’m using the Ken Stapleton 751D switches. They’re momentary.
 

Greg@mnrr

Section Hand
Interesting web-site for the switch machine controllers.

By the way, did you check the output of that computer power supply? It may be short in the voltage department and not able to handle more than perhaps one 751D switch machine if that. It looks like there's capacitors on the 571D by Stapleton and if the transformer isn't charging them, then they will not operate the switch machines.

Greg
 
Last edited:

MikeGTW

Signalman, ESQ
Hi all. I’m installing five 751D switches to Five PECO motors/solenoids. The power supply I’m using is an old laptop psu (18.5V DC, 3.5A). My issue is when I have more than two switches and turnouts wired up they pulse on and off at startup as if there Isn’t enough power. After it pulses for a while everything clicks into place. I add a forth switch and turnout. It has weaker pulses and doesn’t stop. The instructions say 12V but I have tried that and they wouldn’t turn on at all. What am I doing wrong? Is it possible to install a CDU with the 751D switches?
Do ;not use a cdu on the 751 it all ready is one in miniature also are you sure that psu is DC if it is you run the risk of smoking those caps on the 751 since they are rated at 16 V That is why Ken says use only 12VDC 2A power supply NO higher voltage
I have about 20 of the 751D on one 12VDC ps and it is only 1.2 amp and they work fine I do have a couple 12vdc 3a I can use if I need to

If you have it all wired correct get a good power source I'm pretty sure your old laptop supply has seen better days DO not use it
 

MrThrasher

New Member
Do ;not use a cdu on the 751 it all ready is one in miniature also are you sure that psu is DC if it is you run the risk of smoking those caps on the 751 since they are rated at 16 V That is why Ken says use only 12VDC 2A power supply NO higher voltage
I have about 20 of the 751D on one 12VDC ps and it is only 1.2 amp and they work fine I do have a couple 12vdc 3a I can use if I need to

If you have it all wired correct get a good power source I'm pretty sure your old laptop supply has seen better days DO not use it
Mike, Are you using PECO motors? The installation instructions say 14-18VDC at 3amps for PECO. I’ve tried to get more info from Ken. He just told me that my PSU needs to be a linear power supply. The laptop PSU I have is a switching power supply. I’m not crystal clear on the difference. So now I’m having trouble finding 18VDC linear power supply’s. I have found a few 12VDC 1.5Amp linear PSUs so I might just buy one to try. Thanks for the guidance.
 

MikeGTW

Signalman, ESQ
Not using PECO motors I have atlas and Tru Scale All of them (peco atlas tru scale) use 12 to 18v) my home made cdu used 16vac and put out about 22v So Ken's 751D using 12v probably put out 16-18v
I'm not sure why the switching supplies don't work but I did try some and got the same thing you did pulsing Maybe it's the mosfets or just the design but they don't like the switching supplies
You said you tried a 12v supply you had and it didn't work what amp is it might be to low
So here's a 12vdc 2amp power supply from Jameco and it is linear I confirmed it with them the part number is Jameco Part no.: 2218003
They are $11.95 ea and their shipping is real cheap And I looked on amazon nothing
just for info a 12v 2a switching supply weighs 6oz a 12v 2a linear weighs 1.5lbs
get one of these and you'll be in business

see if this works https://www.jameco.com/z/DFU120200R-2-1-12-Volt-2-Amp-24-Watt-Unregulated-Wall-Adapter_2218003.html

the do have a 12vdc 3.4amp and it's cheaper $6.95 but I thought it's overkill for this
 

MrThrasher

New Member
Not using PECO motors I have atlas and Tru Scale All of them (peco atlas tru scale) use 12 to 18v) my home made cdu used 16vac and put out about 22v So Ken's 751D using 12v probably put out 16-18v
I'm not sure why the switching supplies don't work but I did try some and got the same thing you did pulsing Maybe it's the mosfets or just the design but they don't like the switching supplies
You said you tried a 12v supply you had and it didn't work what amp is it might be to low
So here's a 12vdc 2amp power supply from Jameco and it is linear I confirmed it with them the part number is Jameco Part no.: 2218003
They are $11.95 ea and their shipping is real cheap And I looked on amazon nothing
just for info a 12v 2a switching supply weighs 6oz a 12v 2a linear weighs 1.5lbs
get one of these and you'll be in business

see if this works https://www.jameco.com/z/DFU120200R-2-1-12-Volt-2-Amp-24-Watt-Unregulated-Wall-Adapter_2218003.html

the do have a 12vdc 3.4amp and it's cheaper $6.95 but I thought it's overkill for this
Thanks a ton. I put in an order. I’ll report back when it arrives.
 




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