@shanebou24 - Good luck on first startup!
Have safety goggles on, fire extinguisher handy, and cross you fingers!
Have safety goggles on, fire extinguisher handy, and cross you fingers!
so I cooked my 12-inch coaxial Wharfedale.
got her up to -84V and +83V at 110ish AC
then the LED 212 turned on the speaker fried i pulled power but the damage was already done.
got her up to -84V and +83V at 110ish AC
then the LED 212 turned on the speaker fried i pulled power but the damage was already done.
You are kidding I hope?!
Wait a second, you were listening to music already? I would use a cheapo test speaker for initial tryouts unless you have a SSR protection. It’s been so long but I think that this amp has a built in SSR speaker protection so we’re you playing music very loud?
if you did fry your Wharfdale, sorry to hear that. Please tell us what happened in more detail.
Wait a second, you were listening to music already? I would use a cheapo test speaker for initial tryouts unless you have a SSR protection. It’s been so long but I think that this amp has a built in SSR speaker protection so we’re you playing music very loud?
if you did fry your Wharfdale, sorry to hear that. Please tell us what happened in more detail.
Last edited:
its what i had hanging around I've bean testing with it for years.... not that i should of but i have quite a few of them
no sound at all had the line in at 50% volume and the bias resistance to 0 ohm
no sound at all had the line in at 50% volume and the bias resistance to 0 ohm
What an exciting way to start!
I take it the amp still works at this point?
If you have trimmed R134 to be a low as it will go, then turn it on and adjust bias for 18mV across the source resistors as XRK showed in post #359.
It would also be interesting to check the variation of the source resistor voltages as that tells us about the variation in MOSFET gate voltage.
I take it the amp still works at this point?
If you have trimmed R134 to be a low as it will go, then turn it on and adjust bias for 18mV across the source resistors as XRK showed in post #359.
It would also be interesting to check the variation of the source resistor voltages as that tells us about the variation in MOSFET gate voltage.
looks like some thing in the area of v114 and v134 is getting very hot.
I’ll have to revaluate later today
The FE board may need some repair
I’ll have to revaluate later today
The FE board may need some repair
Hmm, it looks like we neglected the VAS current trimmer. This needs to be set before the bias is set. If there is no obvious malfunction then do this:
With the output bias all the way down, adjust the VAS trimmer until the collector of V132 is at 0V to ground.
Then raise the output stage bias to 18mV across a source resistor.
With the output bias all the way down, adjust the VAS trimmer until the collector of V132 is at 0V to ground.
Then raise the output stage bias to 18mV across a source resistor.
is this X117 labeled "VIAS bias adjustment" ? VAS current trimmer adjust collector of V132 is at 0V to ground.
This is X136 trimmed R134 to be a low as it will go, then turn it on and adjust bias for 18mV
Is R134 a typo don't you mean 136?
What about X111 labeled "VIAS adjustment"?
Okay
Measure across the large 0.22R BPR resistors. There are 6 measurements. They should all be similar about 18mV across these
What about R147 and R146? What am i looking and how would i adjust?
I’ll let Keantoken respond. But I think start with the pots in the minimum position as described. Then adjust to get the correct bias current value.
Yes, I meant R136 for the bias adjustment. The VAS current adjustment is X111 and should be near V109.
CX117 is NOT the VAS bias trimmer, but the LTP offset trimmer. Do we have a better schematic?
Sorry for the delay, DIYaudio stopped sending me notifications randomly again...
CX117 is NOT the VAS bias trimmer, but the LTP offset trimmer. Do we have a better schematic?
Sorry for the delay, DIYaudio stopped sending me notifications randomly again...