Are you sure? 27.6v measured directly across the terminals that you'd connect to the battery in your vehicle?
no sorry, those terminals are 12V (i have them connected to two PC smps in parallel with some load in the 5V to stabilize the 12V because of the high current consumption).
what i call +B is the output of the transformer (toroid) amplifier power supply. Which is +B and -B (please check the picture for more details).
Measurements wetween:
-B and +B = 55.3V
Gnd (car battery -) and +B = 27.5V
Gnd and -B = -27.5V
The peak voltage i have on the F+ (with both protection resistors disconnected) is the +B (~27V) voltage during 1 or 2 seconds (Measured between the input car battery- and the F+ terminals)
Do you think any of these could work as a guide?
https://dl.dropboxusercontent.com/u/15275912/JBL_GTS300.pdf
https://dl.dropboxusercontent.com/u/15275912/JBL-GTO6000.pdf
https://dl.dropboxusercontent.com/u/15275912/JBL-LC-a504.pdf
what i call +B is the output of the transformer (toroid) amplifier power supply. Which is +B and -B (please check the picture for more details).
Measurements wetween:
-B and +B = 55.3V
Gnd (car battery -) and +B = 27.5V
Gnd and -B = -27.5V
The peak voltage i have on the F+ (with both protection resistors disconnected) is the +B (~27V) voltage during 1 or 2 seconds (Measured between the input car battery- and the F+ terminals)
An externally hosted image should be here but it was not working when we last tested it.
Do you think any of these could work as a guide?
https://dl.dropboxusercontent.com/u/15275912/JBL_GTS300.pdf
https://dl.dropboxusercontent.com/u/15275912/JBL-GTO6000.pdf
https://dl.dropboxusercontent.com/u/15275912/JBL-LC-a504.pdf
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Does the 200 series channel work properly after it settles to 0v?
IF so, pull C213. Does that allow it to power up without the spike in voltage?
IF so, pull C213. Does that allow it to power up without the spike in voltage?
Yes it does, after the start-up spike the protection line voltage settles to 0V and everything works fine even if i reconnect the protection resistors to the line.
I think i have fixed it. It is not the best solution but i think it will work without compromising the protection.
What i did was put a 330uF Electrolytic capacitor in parallel with the protection line and the speaker ground (common ground to both L and R when not in bridged mode). I tried to get the capacitor as smaller as possible to avoid delaying the signal, so 200uF was not enough and 470uF was too much, hence 330uF seems to work good.
As the spike is only during the transitory, i guess that in case an steady state offset appears it will charge the capacitor triggering the protection. The only drawback is the delay, but i guess it will be not too much to burn the speakers.
Am i right? or you think this is not a good solution?
I think i have fixed it. It is not the best solution but i think it will work without compromising the protection.
What i did was put a 330uF Electrolytic capacitor in parallel with the protection line and the speaker ground (common ground to both L and R when not in bridged mode). I tried to get the capacitor as smaller as possible to avoid delaying the signal, so 200uF was not enough and 470uF was too much, hence 330uF seems to work good.
As the spike is only during the transitory, i guess that in case an steady state offset appears it will charge the capacitor triggering the protection. The only drawback is the delay, but i guess it will be not too much to burn the speakers.
Am i right? or you think this is not a good solution?
If it's for a paying customer, it's not a good solution. If it's your amp and you don't intend to sell it, you can do whatever makes it work well enough for your intended use.
Nono, it is my own amp.
I would like to thank you VERY MUCH for your help Perry! You have spent a lot of time with this.
Thanks, really! Anything you need, please let me know!.
I would like to thank you VERY MUCH for your help Perry! You have spent a lot of time with this.
Thanks, really! Anything you need, please let me know!.
If you decide to crack on then I have another Weconic at hand: VX2250, maybe it is very similar, (I have not opened it up yet) and we can compare notes.
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