Working on a Phoenix Gold MS-2125. It is not producing rail voltage.
I have replaced both SG2525A. The circuitry on this amp is a lot different than the amps I typically work on (Orion's). Anyone have any thoughts on what to check?
I have replaced both SG2525A. The circuitry on this amp is a lot different than the amps I typically work on (Orion's). Anyone have any thoughts on what to check?
Follow the circuit back until you find a transistor. Check that transistor or post the voltage on it's terminals.
Yes, that transistor was shorted. I replaced it and the DC voltage was at +10v on pins 13 and 15. Also had rail voltage. noted that only the 2 LED's on the right channel were lighting up. After shutting the amp down and powering it up again later none of the LED's in the audio section were lighting up and voltage on pins 13 and 15 has dropped to -0.075 although it still has rail voltage...
It sounds like you either lost remote or the transistor failed. If the transistor failed, something it's supplying voltage to may be damaged.
I have remote power. I pulled the transistor and it checks good.
The power LED is coming on. In the attached photo I circled the LED's in the right channel audio section that were previously illuminating as they should but stopped.
Prior to this happening, I had noticed some solder traces that were dangerously close to touching in the audio section of the right channel. I cleaned those traces up and I'm thinking something may have shorted in the process. The caps on this amp seem to hold a charge for sometime.
The power LED is coming on. In the attached photo I circled the LED's in the right channel audio section that were previously illuminating as they should but stopped.
Prior to this happening, I had noticed some solder traces that were dangerously close to touching in the audio section of the right channel. I cleaned those traces up and I'm thinking something may have shorted in the process. The caps on this amp seem to hold a charge for sometime.
Attachments
If you have no voltage reaching the IC and the transistor that you found supplies that voltage and the transistor isn't defective, it would appear that you have a broken connection.
Suspect any traces that run under capacitors.
Suspect any traces that run under capacitors.
I found the problem. My meter wasn't getting an adequate ground.
I have 10.7v on pins 13 and 15.
Still have the problem in the audio section.
I have 10.7v on pins 13 and 15.
Still have the problem in the audio section.
Measure the DC voltage across all 4 of those diodes.
What's the DC voltage on all 3 terminals of the transistor that you replaced?
What's the DC voltage on all 3 terminals of the transistor that you replaced?
The DC voltage on the three legs of the transistor are:
1. +10.8v
2. +10.7v
3. +10.0v
As to the diodes will you please point out which 4 you are referring to?
1. +10.8v
2. +10.7v
3. +10.0v
As to the diodes will you please point out which 4 you are referring to?
Sorry. The 4 red LEDs that are not lit.
What's the supply voltage across the B+ and ground terminals of the amp?
Post the DC voltage on all pins of one of the PS driver ICs.
What's the supply voltage across the B+ and ground terminals of the amp?
Post the DC voltage on all pins of one of the PS driver ICs.
See attached photo for DC voltage readings across the 4 LED's.
The supply voltage across the B+ and ground terminals of the amp is +10.8v
DC voltage of PS driver IC:
1. +0.001v
2. +2.15v
3. +0.20v
4. +0.497v
5. +2.022v
6. +3.623v
7. +1.942v
8. +4.81v
9. +6.19v
10. +0.008v
11. +4.05v
12. +0.001
13. +10.77v
14. +4.05v
15. +10.77v
16. +5.06v
The supply voltage across the B+ and ground terminals of the amp is +10.8v
DC voltage of PS driver IC:
1. +0.001v
2. +2.15v
3. +0.20v
4. +0.497v
5. +2.022v
6. +3.623v
7. +1.942v
8. +4.81v
9. +6.19v
10. +0.008v
11. +4.05v
12. +0.001
13. +10.77v
14. +4.05v
15. +10.77v
16. +5.06v
Attachments
Why is it so low? Increase it to about 12v.
What's the DC voltage on the pins of either of the opto-couplers?
What's the DC voltage on the pins of either of the opto-couplers?
I'm not sure what is pulling it down. There is almost a 2v drop between what the power supply meter is showing and the reading at the amp terminals. I turned it up voltage at the amp terminals is now 12.2v
I'm guessing you are refer to one of the opto-couplers that are to the right and left of the PS driver ICs...
DC Voltage on the opto-coupler on the right in the photo in #14:
1. -2.1v drops very rapidly
2. -2.1v drops very rapidly
3. -0.002v
4. +2.52v
5. +5.06v
6. +3.19v
I'm guessing you are refer to one of the opto-couplers that are to the right and left of the PS driver ICs...
DC Voltage on the opto-coupler on the right in the photo in #14:
1. -2.1v drops very rapidly
2. -2.1v drops very rapidly
3. -0.002v
4. +2.52v
5. +5.06v
6. +3.19v
Do both read the same?
If you increase the supply voltage (at the amp) to about 13.5v, does the voltage at 1/2 top out higher or does it remain about the same?
If you increase the supply voltage (at the amp) to about 13.5v, does the voltage at 1/2 top out higher or does it remain about the same?
I'm not sure what you are asking me "Do both read the same?"
I only able to increase the supply voltage at the amp up to 13v. The voltage across 1/2 remains the same regardless if supply voltage is 12v or 13v.
I only able to increase the supply voltage at the amp up to 13v. The voltage across 1/2 remains the same regardless if supply voltage is 12v or 13v.