Soft start, need some more help
Hi Toecutter
Thanks for the diagram. I have a couple more questions.
I have a double pole mains switch in my amp chassis already, should I still switch the incoming 'N' supply or attach it directly to the pcb Neutral screw terminal?
I have now removed the CL60 / thermistor from across my (in series) 115v AC windings of my transformer. However should I also remove the small capacitor (0.0033 uf) across L to N ? I'm assuming that the softstart board has these functions as it where built in?
Really appreciate your help, can't do this without your technical support 🙂
Hi Toecutter
Thanks for the diagram. I have a couple more questions.
I have a double pole mains switch in my amp chassis already, should I still switch the incoming 'N' supply or attach it directly to the pcb Neutral screw terminal?
I have now removed the CL60 / thermistor from across my (in series) 115v AC windings of my transformer. However should I also remove the small capacitor (0.0033 uf) across L to N ? I'm assuming that the softstart board has these functions as it where built in?
Really appreciate your help, can't do this without your technical support 🙂
Steve,
You can use your double pole switch without a problem.
I don't see that you will need the 3n3 cap either.
The SS circuit incorporates a 'de-bounce' cap to limit switch transients.
You can use your double pole switch without a problem.
I don't see that you will need the 3n3 cap either.
The SS circuit incorporates a 'de-bounce' cap to limit switch transients.
Steve,
Ignore what I said about the 3n3 cap across L-N.
It's for filtering noise on your incoming supply.
You can solder it straight across your IEC connector.
Ignore what I said about the 3n3 cap across L-N.
It's for filtering noise on your incoming supply.
You can solder it straight across your IEC connector.
Since there's no schematic posted yet, I'm wondering -- what's the purpose of the LED? Does it just indicate power to the board or does it do something more useful like illuminate when the soft start is active (meaning, the resistors are in-circuit)?
Hi ottopilot
I just completed my soft start and the LED stays on all the time. I know this does not fully answer your question.
I just completed my soft start and the LED stays on all the time. I know this does not fully answer your question.
Here is the schematic
An externally hosted image should be here but it was not working when we last tested it.
Looks like the LED is just a power status indicator, which is fine.
Got a brain fart though looking at the schematic. If nodes Pwr_Sw1 and Pwr_Sw2 are where I connect a mains-rated switch to interrupt the circuit, won't current flow through C1 regardless of whether the switch is connected? I've looked at the traces on the board and they make sense to me...but this schematic does not. If the Pwr_Sw2 node were shifted relative to C1 and a gap in the circuit path existed between the sw1 and sw2 nodes then that would make sense to me.
Got a brain fart though looking at the schematic. If nodes Pwr_Sw1 and Pwr_Sw2 are where I connect a mains-rated switch to interrupt the circuit, won't current flow through C1 regardless of whether the switch is connected? I've looked at the traces on the board and they make sense to me...but this schematic does not. If the Pwr_Sw2 node were shifted relative to C1 and a gap in the circuit path existed between the sw1 and sw2 nodes then that would make sense to me.
My guess is C1 is too small to allow significant current, it's purpose is to prevent switch arcing. The LED won't light.
Can you use one soft start board for a dual mono configuration or do you need one board for each transformer
Thanks
Deb
Thanks
Deb
I built one today - it goes together very easily and I'm looking forward to testing and installation in the F5T.
Everything before soldering.
The diodes are tiny, do them first.
Leave room under the resistors, they all get hot.
Use anything handy for a guage, this is just a Phillips screwdriver.
Lots of room under the resistors.
AMP blades This happens to be the AC mains side. You can use the blades, bare wire or the Keystone connectors in any/all of the positions.
Keystone connectors. This is the transformer side.
Everything before soldering.
The diodes are tiny, do them first.
Leave room under the resistors, they all get hot.
Use anything handy for a guage, this is just a Phillips screwdriver.
Lots of room under the resistors.
AMP blades This happens to be the AC mains side. You can use the blades, bare wire or the Keystone connectors in any/all of the positions.
Keystone connectors. This is the transformer side.
A round of applause for Mr. Toecutter!
Help Wiring Soft Start Board?
Hi. I just finished building this board, but I'm a little confused as to how to attach this to my amplifier. I have a new power supply in my Hafler DH-500 with 2 separate supplies each with a 64 volt 500 VA transformer and 80K uF for 160K uF total. I basically installed the Musical Concepts PA-4 boards & dual mono power supply upgrade. Everything is in the same case so AC is shared. The live AC wire goes to the center pin of the switch. As you'll see in the attached photos
, the switch is SPDT and creates 2 separate live wires that are turned on at switching at pins 1 & 3 of the switch. Both switched wires go through a terminal strip. The neutral is connected directly to the terminal strip (fuse shown is eliminated as it's part of the IEC, so neutral is a straight run to the terminal strip). Fuse & switch are now both on the live wire. So I believe I would attach the mains neutral AC wire to the neutral tab on the board. Then, it looks like mains AC live to Live/Sw 1 on the board. Live /SW 1 also to the center pin of the switch. Here's where I get a bit confused. Would both live switched pins connect to the SW2? Then would one Xformer tab (XFR1} on the board connect to the terminal strip where the neutral connected and would I run 2 separate wires off the other transformer tab (XFR2) to the 2 points on the terminal strip for the hot wires that were both originally switched through both sides of the switch? Then from the terminal strip to both transformers as it is now (unchanged)? Appreciate any help you could offer. I want to be sure to wire this in correctly before powering anything on Thanks
Hi. I just finished building this board, but I'm a little confused as to how to attach this to my amplifier. I have a new power supply in my Hafler DH-500 with 2 separate supplies each with a 64 volt 500 VA transformer and 80K uF for 160K uF total. I basically installed the Musical Concepts PA-4 boards & dual mono power supply upgrade. Everything is in the same case so AC is shared. The live AC wire goes to the center pin of the switch. As you'll see in the attached photos
OOPS!! The photos don't appear to be in the post, just X's that spin if clicked on. I'm not sure what I did wrong. But they are both in a gallery that I created called Wiring DIY Audio Soft Start. Thanks.
I just checked the switch with a meter and realized that only the 2 switch terminals with the cap across them are switched (1 & 2). So terminal 3 doesn't appear to switch on. The amp works perfectly as wired now, so that wiring is correct. Terminal 3 is not switched on, so I'm not sure what function it's connection serves, maybe as a ground wire back to the terminal strip. So would I just leave that terminal 3 on the switch connected as is to the terminal strip, and just connect pin 1 of the switch to tab SW2 on the soft start board?