Perry, do you have a page on how to check the dead time of the output of the amp and how to adjust if needed? Working on a Crescendo 12K. Generic Korean half bridge. The amps been repaired by someone before. When I got the amp, the power supply was burned up and outputs shorted. One bank of output shorted on two of the amp sections. As you can see in the pick. I've removed the bad outputs. Is it necessary to replace the banks of good outputs? Also replaced the driver IC on the driver board. I'm using hot air now. It was blown up. I'm going to up the value of the cap on the turn on signal. Delaying the turn on giving the rails more time to come up before the drive. Upping from a 22uf to a 33uf. I understand it could have been abused before. Just trying to cover my bases.
Attachments
Is the far left transistor on the bottom row the 12v regulator for the 21844s?
To see the deadtime, you need to display both the high and low drives at the same time and look at the rising/falling edges to see how much of a gap there is.
Is half of the amp still working?
To see the deadtime, you need to display both the high and low drives at the same time and look at the rising/falling edges to see how much of a gap there is.
Is half of the amp still working?
Yes the far left transistor is the 12v reg.
Replaced the driver board and transistors. Powered it up and it blew 4 transistors on the other side of the board. Which is strange because it blew the same driver chip. That chip doesn't even drive the side that blew. Currently replacing both driver chips on the driver boar. All outputs are out. Gonna check the drive signals at the input of the driver chips and at the outputs. I know I can't check the high side drive without adding a battery.
Replaced the driver board and transistors. Powered it up and it blew 4 transistors on the other side of the board. Which is strange because it blew the same driver chip. That chip doesn't even drive the side that blew. Currently replacing both driver chips on the driver boar. All outputs are out. Gonna check the drive signals at the input of the driver chips and at the outputs. I know I can't check the high side drive without adding a battery.
Is the circuit similar to the one in the following thread? If so, can you give the value of the resistor?
DS18 HOOL-SPLK5
DS18 HOOL-SPLK5
They are not similar. The 12 reg is on the opposite side of the board from the one in the other thread. There is a resistor in front of the 12 reg on my board. It is 1K ohm. don't know if that helps.
Quick question. The outputs in amps like these are usually grouped in banks of four driven by the driver. I know if an output shorts all outputs in that bank should be changed because the others could have been weakened. Is it necessary to change all the outputs in banks that didn't short. I hope this makes sense.
Have you powered the amp up with the dead half of parts removed to see if the other half works perfectly?
Also have you checked DZ2 ?
I’ve noticed when the outputs blow in these amps it also takes out DZ2 .
At least the ones I have repaired DZ2 has been shorted
I’ve noticed when the outputs blow in these amps it also takes out DZ2 .
At least the ones I have repaired DZ2 has been shorted
Perry, the other half seem to be working perfectly.
caraudioguy2100, all of the diodes in the power supply check good. DZ2 on this amp is on one set of the power supply mosfets. Is the diode you're talking about somewhere else?
caraudioguy2100, all of the diodes in the power supply check good. DZ2 on this amp is on one set of the power supply mosfets. Is the diode you're talking about somewhere else?
If the other half is working perfectly, it may be OK. This is where you make an executive decision... Replace ALL and know that everything is right or replace half and have a pretty good idea that all is right. If this were one of the amps that used the 7812 for the 21844 regulator I'd, at least, replace the 21844. I've never had to repair one with this regulator.
Don't have that diode on this one. This one has the dual 12v regulators. No diode around them at all.
The pics you posted earlier in this thread are of the amp your working goon or pics from somewhere else ?
I used the pics you posted as reference for the diode
I used the pics you posted as reference for the diode
caraudioguy2100 I am so sorry for the confusion. I was looking at an Ampere 8K. Yes the Crecendo 12K does have that diode. I have two of those I'm finishing up on. Thanks for the heads up about the diode. I will check them. What's the value of the zener?
On these amps and other half bridge amps, should the signal unmute before or after the speaker relay engages?