I have been trying to repair this amplifier since 3 months.
It has been a headache!!
All the internal parts apear be fine.
The problem is:
It ignites of intermittent way.
turn´s on 15 seconds and turn´s of 5 seconds, turn´s on 15 seconds and turn´s of 5 seconds, etc.
Please help me before I take and...
This is the pic:
It has been a headache!!
All the internal parts apear be fine.
The problem is:
It ignites of intermittent way.
turn´s on 15 seconds and turn´s of 5 seconds, turn´s on 15 seconds and turn´s of 5 seconds, etc.
Please help me before I take and...
This is the pic:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
more pics
I found other measurements rare in the power source:
They are without remote, only positive and negative applied
I found other measurements rare in the power source:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
They are without remote, only positive and negative applied
Without remote, those voltages are normal. If you apply remote, the voltage on pin 1 of the FETs will go to ~3-5v. The voltage on the rectifiers will probably go to approximately ±35v.
How many amps of current does the amplifier draw at idle (remote voltage applied, no audio).
Does it shut down with no speakers connected?
Are any of the indicators LEDs lighting except for the power LED?
Does the power LED go off when the amp shuts down?
What are you using to power the amp?
How many amps of current does the amplifier draw at idle (remote voltage applied, no audio).
Does it shut down with no speakers connected?
Are any of the indicators LEDs lighting except for the power LED?
Does the power LED go off when the amp shuts down?
What are you using to power the amp?
Perry Babin said:
The voltage on the diodes go 44 and -44 !!!!!!
4 amp current when apply remote.
Shut down only with speaker connected and at high vol.
Only the green led is turn on, and is always present.
I’m using one 12.5 v regulated power source (ASTRON) 1 - 25 A.
Today happen something different.
[img=http://img61.imageshack.us/img61/6824/dsc00944dw4.jpg]
[img=http://img61.imageshack.us/img61/6824/dsc00944dw4.b484ea5d27.jpg]
two resistors was burn, R300 and R301
¿this gives a track to find where is the problem?
The voltage on the diodes go 44 and -44 !!!!!!
**** That's good. The board says the rail voltage should be 53v but its producing rail voltage so the power supply is probably OK.
4 amp current when apply remote.
**** That seem a bit high but could be due to the bias current being set too high.
Shut down only with speaker connected and at high vol.
**** This could be due to the 25 amp Astron power supply being insufficient to power the amp at high output power. When you get the amp working again, try running one channel at a time to see if the amp shuts off. If it plays at high power with 'either' channel and only shuts down when both channels are running at high power, the amp may be working properly and is simply shutting down due to low voltage.
Today happen something different.
**** If I'm not mistaken, those are (were) 10 ohm resistors. They are used extensively to provide protection for the regulated ±15v power supply. The caps provide additional filtering near the op-amps. I don't know why they would have failed. It's not likely to be part of the original problem. Is it possible that you didn't have the preamp boards plugged in correctly to the main board? You have to be careful connecting them. You need to replace them to see if they burn again. If they do, you may have a defective op-amp in that area.
**** That's good. The board says the rail voltage should be 53v but its producing rail voltage so the power supply is probably OK.
4 amp current when apply remote.
**** That seem a bit high but could be due to the bias current being set too high.
Shut down only with speaker connected and at high vol.
**** This could be due to the 25 amp Astron power supply being insufficient to power the amp at high output power. When you get the amp working again, try running one channel at a time to see if the amp shuts off. If it plays at high power with 'either' channel and only shuts down when both channels are running at high power, the amp may be working properly and is simply shutting down due to low voltage.
Today happen something different.
**** If I'm not mistaken, those are (were) 10 ohm resistors. They are used extensively to provide protection for the regulated ±15v power supply. The caps provide additional filtering near the op-amps. I don't know why they would have failed. It's not likely to be part of the original problem. Is it possible that you didn't have the preamp boards plugged in correctly to the main board? You have to be careful connecting them. You need to replace them to see if they burn again. If they do, you may have a defective op-amp in that area.
I don't have information for the 300/2 but in the 300/4, Q500 is one of the power supply FETs. The power supply FETs in most of this series of amps is an IRFZ44.
In the 300/4 Q510 is an IRFZ34. If your amp uses the 3843B to drive Q510, it's likely an IRFZ34. An IRFZ44 would also work in that location.
If you have a scope, monitor the voltage on pin 20 of the audio driver board (looking at component side of driver board, it's the last pin on the right). If it's not very near 0v on one channel or you see a short pulse on one channel, you need to determine why it's going high.
In the 300/4 Q510 is an IRFZ34. If your amp uses the 3843B to drive Q510, it's likely an IRFZ34. An IRFZ44 would also work in that location.
If you have a scope, monitor the voltage on pin 20 of the audio driver board (looking at component side of driver board, it's the last pin on the right). If it's not very near 0v on one channel or you see a short pulse on one channel, you need to determine why it's going high.
Is the diode in parallel with the 33 ohm resistor OK? You'll have to pull one end to check it.
Does the yellow transformer look like it's overheated (windings showing through the yellow tape)?
Do the waveforms look similar to these?
http://www.bcae1.com/temp/jl500slashonelowvtransformer.swf
Does the yellow transformer look like it's overheated (windings showing through the yellow tape)?
Do the waveforms look similar to these?
http://www.bcae1.com/temp/jl500slashonelowvtransformer.swf
The diode in parallel it’s fine. Another near diodes is fine too.
The transformer not show visible overheat
When disconnect remote, The amp still turn on 5 seconds more.
In the same order:
Scope is setting to 5us, 5V.
Pin1
Pin2
Pin3
Pin4
Pin5
Pin6
Pin7
Pin8
Pin9
Pin10
The transformer not show visible overheat
When disconnect remote, The amp still turn on 5 seconds more.
In the same order:
Scope is setting to 5us, 5V.
Pin1
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Pin2
An externally hosted image should be here but it was not working when we last tested it.
Pin3
An externally hosted image should be here but it was not working when we last tested it.
Pin4
An externally hosted image should be here but it was not working when we last tested it.
Pin5
An externally hosted image should be here but it was not working when we last tested it.
Pin6
An externally hosted image should be here but it was not working when we last tested it.
Pin7
An externally hosted image should be here but it was not working when we last tested it.
Pin8
An externally hosted image should be here but it was not working when we last tested it.
Pin9
An externally hosted image should be here but it was not working when we last tested it.
Pin10
An externally hosted image should be here but it was not working when we last tested it.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.