as_audio,
not using emitter resistors is simply outrageous. Emitter resistors are mandatory for every reason regardless of device technique. This also includes the predrivers.
In this context, operational reliability is not a matter of cost. There is no virtue in upholding bad practices.
not using emitter resistors is simply outrageous. Emitter resistors are mandatory for every reason regardless of device technique. This also includes the predrivers.
In this context, operational reliability is not a matter of cost. There is no virtue in upholding bad practices.
Inform yourself about "ring emitter" transistors with integrated emitter
resistors. However I think purpose of this thread was EC repair help.
resistors. However I think purpose of this thread was EC repair help.
Did a series of tests powering up one of the amps with no bulb limiter and softstart bypassed. No problems. I would prefer to include a softstart circuit though, and are currently looking at a few options. One option that crossed my mind is to keep the relay and limit resistor, and tapping in to the DC on PSU board driving a delay circuit based on a 555. I have a few of those already
as_audio;
I get what you saying about a scope, I really want one. Am currently looking at various PC based options
I get what you saying about a scope, I really want one. Am currently looking at various PC based options
Some useful soft start circuits here:
Soft-Start Circuit For Power Amps
Will run of secondary side instead of the mains side. If you want to run at lower voltage a good soft start will run it's own supply though (separate transformer) to avoid any issues with fuses not blowing under fault conditions, if the main amplifier supply voltage doesn't reach full voltage it can stop the soft start relay engaging. Could result in the soft start resistor smoking/catching fire and the fuse will never blow...
Soft-Start Circuit For Power Amps
Will run of secondary side instead of the mains side. If you want to run at lower voltage a good soft start will run it's own supply though (separate transformer) to avoid any issues with fuses not blowing under fault conditions, if the main amplifier supply voltage doesn't reach full voltage it can stop the soft start relay engaging. Could result in the soft start resistor smoking/catching fire and the fuse will never blow...
Thanks for the link! Very informative. I'm going to read a bit and see if I can't make some decition of what to do.
Seems like a good point though to have a dedicated transformer powering the inrush circuit
Seems like a good point though to have a dedicated transformer powering the inrush circuit
I had planned to update and end this thread earlier but spare time is scarce. Anyhow, I went out and got myself a scope, had to learn how to use it. Then I built a iteration of the circuit in the latest link. This has worked nicely and amps has been in use for some time now. A (late) thanks to all contributions
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