| PM650 |
I've built two p33's with my own boards and they're both experiencing the same problem. The turn on delay is working fine, but the dc protection part is causing the relay to stay off. Here are the voltages I measured:
I've checked both boards numerous times and they are correct.
Any ideas?
Also, I'm having some problems with relay chatter; two relays are being run off each p33, in parallel, each with their own protection diodes but the one of the two for the speaker uses the config. shown on the site with a regular diode and a zener back to back, while the second uses just a regular diode. Could this be solved by connecting the relays in series with the clamp diodes around both? |
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| lineup |
1.25 V is a strange value
I would expect more like 0 V
But this does not explain why relays stay OFF.
When feeding both relays in parallell,
make sure you use a bigger transistor for drive them
TO126 (or TO220)
a normal TO92 small signal is not enough |
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| dx.master |
Hello !
Did you link IN-R and IN-L to GND ?
You must set both channels to the right value.
I build also 2 pc of PCB with this circuit and it work very well afer changing some Resitors!
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| PM650 |
lineup: I am using the standard mpsa92 recomended on the site and have not experienced any problems. Total current drawn by both relays and the resistor is 78mA.
dx.master: I'm not exactly sure what your saying. My speaker grounds return to the central earth point formed by the filter caps on the pcb.
I am only using one p33 per amp, so R2, C2, D1 and D2 are not included in my circuit. Each of my p33's are integrated onto the same pcb as the bridge and filter caps for the amps; is it possible that excess ripple is being injected into the circuit? Some of the taps for the rails are taken between the bridge and caps on the +/- planes.
I can post the board layout if this will help solve any confusion. |
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| dx.master |
please make some photos of your PCB board and show it us.
Thanks. |
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| PM650 |
Here's the top view of the copper:
(the second relay is on a different board)
It may be a bit difficult to follow because this was my first board I've designed. I'm planing to remake these with better material boards (FR4) and I would like the next pair to actually work, so any ideas are appreciated. |
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