Trying to connect up dg583s with a sierra sound unit but coming up with problems!
sound is irratic
Iain Collingwood said:
Trying to connect up dg583s with a sierra sound unit but coming up with problems!
sound is irratic
Ian, put the video up on youtube or somewhere we can get it.
Your diagram does not show the 2 resistors that set the regulator output voltage.
The Decoder is running PWM to the motor which should confuse the sierra to be either idling or full blast, can you describe the issue if we can’t see the video.
Greg
Greg I think it is a voltage issue, I’m not getting a constant 6v to the sound board seems to fluctuate a bit
Hi Ian, when I was a Sierra dealer we used Tony Walsham SSI board which provided 12v to power the sierra boards. Higher created a overload. So he settled on 12v.
Don
The 12 volt supply was actually part of the circuit Soundtraxx recommended for the Sierra interface.
You can actually use the Sierra with a PWM motor driver. What you must do is completely isolate the Sierra from all other connections (including the sound triggers), except the track pick ups and power it via the separate battery. You cannot use the DCC triggers without an isolating device such as a relay.
Much simpler to use an opto coupler.
BTW I still have some older SSI boards available. Go to https://www.rcs-rc.com/pages/Parts-Install-kits then scroll down to the last item.
I was going to go to the isolation issue once I got the voltage he was providing… without the values of the resistors next to the regulator, you have no idea what the voltage is.
Greg
It seems to be the an issue with the power regulator board I have had made, works fine with a super cap setup. tony do you have a power regulator board setup for this?
regards Iain
Greg Elmassian said:
I was going to go to the isolation issue once I got the voltage he was providing… without the values of the resistors next to the regulator, you have no idea what the voltage is.
Greg the board is putting out 6v from the decoder but when I connect it to the Sierra board it fluctuates the voltage.
Where are you connecting the 6 volt regulator pcb? Sierra pins 2 and 4?
Tony Walsham said:
Where are you connecting the 6 volt regulator pcb? Sierra pins 2 and 4?
Where the battery connected to the sound board
Back to basics:
Voltage regulator: (battery substitute)
- I pulled up tech bulletin #7, that has that circuit shown.
- The page BEFORE the one shown gives the values for the resistors R4 and R5.
- R4 is 220 and R5 is 1k and that sets 7 volts on the regulator output.
- I looked at your pictures and verified these values with the color codes
Measure your circuit and see that voltage you are getting on the output, if it is not 7 volts you have a problem.
A comment on a possible problem:
I know this is a 3 amp regulator, but when PROPERLY HEATSINKED. I have damaged an LM317 that was not heatsinked with just ONE amp. The Sierra can pull about 1/2 amp. With DCC voltage as an input, you could be dissipating about 20-7 = 13 volts and at 1/2 amp, could be 6.5 watts, which far exceeds the capability of that regulator without a heat sink.
At the limit, the soundtraxx board can run at 12 volts, which would then only require 8 volts drop in the regulator, which comes to 4 watts dissipation, which is a bit more managable but still requires a heat sink.
also, from the tech note:
After installation, fine tune the decoder and the Sierra systems. Adjust the Voltage Start (CV 2), Acceleration Rate (CV 3), and
Deceleration Rate (CV 4) of the decoder to more closely match the sounds to the motion of the locomotive. For Sierra diesel systems,
you may wish to adjust the RPM Sensitivity of the Sierra board using Set Up Step 2 so that maximum RPM is reached at throttle
settings of 25%, 50%, or 100%.
So start by measuring the output voltage and check the heat of the regulator (carefully)
After that report back. I think you need the optical isolation that Tony mentioned, but I know at the time Sierra said you don’t need.
Greg
Greg Elmassian said:
Back to basics:
Voltage regulator: (battery substitute)
- I pulled up tech bulletin #7, that has that circuit shown.
- The page BEFORE the one shown gives the values for the resistors R4 and R5.
- R4 is 220 and R5 is 1k and that sets 7 volts on the regulator output.
- I looked at your pictures and verified these values with the color codes
Measure your circuit and see that voltage you are getting on the output, if it is not 7 volts you have a problem.
A comment on a possible problem:
I know this is a 3 amp regulator, but when PROPERLY HEATSINKED. I have damaged an LM317 that was not heatsinked with just ONE amp. The Sierra can pull about 1/2 amp. With DCC voltage as an input, you could be dissipating about 20-7 = 13 volts and at 1/2 amp, could be 6.5 watts, which far exceeds the capability of that regulator without a heat sink.
At the limit, the soundtraxx board can run at 12 volts, which would then only require 8 volts drop in the regulator, which comes to 4 watts dissipation, which is a bit more managable but still requires a heat sink.
also, from the tech note:
After installation, fine tune the decoder and the Sierra systems. Adjust the Voltage Start (CV 2), Acceleration Rate (CV 3), and
Deceleration Rate (CV 4) of the decoder to more closely match the sounds to the motion of the locomotive. For Sierra diesel systems,
you may wish to adjust the RPM Sensitivity of the Sierra board using Set Up Step 2 so that maximum RPM is reached at throttle
settings of 25%, 50%, or 100%.So start by measuring the output voltage and check the heat of the regulator (carefully)
After that report back. I think you need the optical isolation that Tony mentioned, but I know at the time Sierra said you don’t need.
Greg
Greg I connected a cap bank instead of the regulated power supply and that seems to fix issue
regulated power supply is putting out over 6v without the sierra sound board connected but with it connected to load the voltage fluctuate’s
iain
Yep, you are overheating the regulator, and it is going into thermal shutdown, and the voltage drops
How hot is the regulator (the silver and black thing standing up with no heat sink) (While running and blowing whistle for example)
What is your track voltage?
I’m being persistent because you appear to STILL be overloading your power supply… the super cap evens voltage fluctuations out but it does not MAKE power, the power still comes from the regulator board, meaning IT IS NOT FIXED YET.
Greg
Greg, I disconnected the power regulator and just used the cap bank so regulator not connected at all and worked fine?
ill set up a decoder with regulator to see what the temperature is doing
regards Iain
How are you powering the Sierra? straight from the decoder blue and ground?
Would you PLEASE tell me what your track voltage is? I suspect now you are running too much voltage to the Sierra, and will shortly destroy it.
There’s a limit to the max voltage that board can take on a consistent basis.
You have been warned. Read this page and note the part on voltage vs. time to destruction on your sound board.
18volt crest power supply feeding a Piko DCC system
Should last about 1 day at that voltage… good luck… (should be no more than 12 volts, Tony will confirm)
if you measure voltage from the decoder you should see 16v plus
Greg
So are you saying terminal 7&8 should only have 12v max? Or the red and black wire connection?