ok i figured out most of the amp im working on but when i put a fuse in it pops in sec i checked all through the ouput side everthing is fine. So im guessing the problem is in the power supply side of the amp wondering if the ne5534n's (op amp) if one is bad could that cause the fuse to blow or what should i check in the power supply all the fets diodes test fine.
mike49504 said:
your baud rate is too high
😀
Please post some pics and some model #'s and some history. Schematics will get even more people interested. We want to help but you got to give us enough info to get hooked.
its an ads 860 mx its fine until u hook the remote wire up. with just power and ground the fuse doesnt blow
I hooked my meter leads up to the amp neg lead on the ground terminal and the positive lead on the collecter of the outputs. 1 side of the outputs for the four channels measures 31.75 volts The other side i have nothing like.02 volts so im guesssing i have no rail voltage on the outputs of the other 4 channels. So im wondering where do i go from here?? any help would gretly be appericated
That means the PS is attempting to work if you found some rail voltage. I would double check the outputs for shorts if still blowing fuses, if you can just touch it and see if you get voltage on a speaker output that might tell you what channel is bad. Usually all the rails are hooked together for all channels on a 4ch amp but I am not familiar with this.
Do you mean you only get + rail and not the - rail? If so then check the rectifiers if good look for a short/etc in that rail. If I understand you right, you also need to put your negative meter probe on the common center tap of the transformer to test for rail voltage. Usually all the speaker terminals that do not go to outputs (half) go there. The rails often do not ground properly to the 12v ground.
Do you mean you only get + rail and not the - rail? If so then check the rectifiers if good look for a short/etc in that rail. If I understand you right, you also need to put your negative meter probe on the common center tap of the transformer to test for rail voltage. Usually all the speaker terminals that do not go to outputs (half) go there. The rails often do not ground properly to the 12v ground.
With the amp off, measure the resistance from the emitter resistors to the RCA shields. Do they all read ~0 ohms?
Before, the amp was working properly unless you replaced one particular power fuse. Is that still true?
Before, the amp was working properly unless you replaced one particular power fuse. Is that still true?
The amp was working but was blowing 1 out of 4 fuses. It doesnt blow the fuse anymore and i have 4 chanels working out of 8. I measured the resistors and they all read near 0 ohms. There are 4 torriods in this amp 1 torriod for 2 channels wondering what do i check now im stummped not sure why this amp doesnt work.
Is one power supply popping its own fuse? If they are all separate then you have 4 amps in one. You tested all the PS and output transistors for that 'amp'/amps that blows the fuse/does not work?
the channels that were blowin the fuse work now and fuse doesnt pop the other channels still dont work
Look at the base drive signal (on the center leg) of the power supply drivers for the two working channels with your scope. The drivers are the MPSA06/56 emitter follower pairs (4 drivers per transformer). Compare that to the non-working channels. If I'm not mistaken, the layout is similar for all of the drivers so you should be able to easily find the point where you lose signal.
I'm assuming that you don't have any blown fuses in the channels that are not working.
I'm assuming that you don't have any blown fuses in the channels that are not working.
i checked the mpsa06's and 56's theres hardly anything on them. SO i hooked a scope upto the tl494 and thats working fine its showing that its trying to fire up thoose 4 channels that are dead.
SO the next thing i checked was the optocouplers 3 out of 4 were fine 1 measured very low so i replaced it with a good one. still same problem. so im wondering if this problem sounds like something in the power supply or the output section. any help would greatlybe appericated
SO the next thing i checked was the optocouplers 3 out of 4 were fine 1 measured very low so i replaced it with a good one. still same problem. so im wondering if this problem sounds like something in the power supply or the output section. any help would greatlybe appericated
ok heres my next question im checking the diodes out to see if any are shorted. the diodes are connected together so if i put my meter lead on the striped side of one diode and the posistive lead on another diode next to it i get readings. so im wondering if 1 is shorted will i be able to tell without unsoldering 1 side of each diode
Follow the signal from 9 and 10 towards the drivers of the power supplies. They are virtually identical so you can use the working side as a reference. There will be a point where the signal stops in the dead side. You need to go component to component, don't jump from one end of the circuit to the other.
Also confirm that you have B+ on the center tap of the primary windings of the transformers and on the collectors of the A06 driver transistors.
It's unlikely that you have any shorted rectifiers. Shorted rectifiers virtually always cause excessive current draw. If you read ~0 ohms from the center legs to the outer legs, the diode is likely shorted. Otherwise, it's probably OK.
The problem is likely in the power supply. If the audio section was tripping the protection circuit, it's likely that the entire amp would shut down.
Also confirm that you have B+ on the center tap of the primary windings of the transformers and on the collectors of the A06 driver transistors.
It's unlikely that you have any shorted rectifiers. Shorted rectifiers virtually always cause excessive current draw. If you read ~0 ohms from the center legs to the outer legs, the diode is likely shorted. Otherwise, it's probably OK.
The problem is likely in the power supply. If the audio section was tripping the protection circuit, it's likely that the entire amp would shut down.
ok 1 last question. before i get into this amp there are 4 transformers 1 for each of the 2 channels . wondering if one of the transformers is bad would this cause the problem with having no rail voltage on the 4 dead channels? or would 2 of the channels still work? since there 4. 1 transformer for every 2 channels
If it had a shorted transformer, it would probably either pull excessive current or would cause DC offset (~12v) at the speaker terminals.
mike49504 said:
Go by Perry's post above, you have to start at the start. Go to each dead PS at pin 9/10 and work your way out to where it is not working. Each PS and the amp/channels it powers is another amp, in essence, I'd suggest picking one and working on that.
ive checked pretty much all the parts and all seem fine. My question is im wondering if i put the diodes in wrong how would i figure out what diode belongs where. they are the u1620 and 1620r would a shop that fixes amps be able to tell me what one goes where without to much effort?
If you would have reversed the rectifiers, it would likely have blown the filter caps within a few seconds.
Did you compare the voltages and waveforms between the working/dead halves of the amp?
If so, where did the drive signal stop?
If it stopped at a transistor, did the transistor have supply voltage (12v) feeding it?
Did you compare the voltages and waveforms between the working/dead halves of the amp?
If so, where did the drive signal stop?
If it stopped at a transistor, did the transistor have supply voltage (12v) feeding it?
- Status
- Not open for further replies.