This amp is giving trouble booting up, even on an un-restricted PS. It boot/cycles about 2 dozen times before finally powering up 'fully', but its not right none-the-less.
I followed threads here: https://www.diyaudio.com/community/threads/arc-audio-arc2500-cxl.373647
The amp will only power up every time always if I lift R110/R181/R185/R128, and D23. I replaced U19 and didn't help.
Im getting little to no -17vDC regulated. Noticed both regulators run extremely hot, LM317, 337. I replaced both and put both into an insulated sync so that they won't overheat out of the sync.
Still not getting negative regulated voltage.
Rail voltage is OK at +-68vDC
What is P1 pot in the center of the audio side? its full CCW and doesn't seem to be changing anything atm.
I followed threads here: https://www.diyaudio.com/community/threads/arc-audio-arc2500-cxl.373647
The amp will only power up every time always if I lift R110/R181/R185/R128, and D23. I replaced U19 and didn't help.
Im getting little to no -17vDC regulated. Noticed both regulators run extremely hot, LM317, 337. I replaced both and put both into an insulated sync so that they won't overheat out of the sync.
Still not getting negative regulated voltage.
Rail voltage is OK at +-68vDC
What is P1 pot in the center of the audio side? its full CCW and doesn't seem to be changing anything atm.
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Does P1 possibly set the threshold for the rails to switch from low to high voltage?
Post an image showing the resistors you removed. I don't see them on the clarion diagram.
Post an image showing the resistors you removed. I don't see them on the clarion diagram.
I won't be able to help much without knowing what the resistors correspond to on the clarion diagram.
Are the resistors programming the regulator within tolerance.
Are the resistors programming the regulator within tolerance.
The Clarion APX1000 diagram matches this Arc CXL2500 amplifier.
Yes R6/R11 and R5/R10 are within tolerance.
I started removing a few pre-amp Opamps to see if any were causing a drag on the negative side but no luck yet.
Yes R6/R11 and R5/R10 are within tolerance.
I started removing a few pre-amp Opamps to see if any were causing a drag on the negative side but no luck yet.
Check for bad connections on the programming resistors. The meter should be reading those resistors.
With all but the opamps back in circuit, I observe 1.6k on C2 and 3.7k on C9. What next?
I correct my last statement. I had removed ALL opamps, LM393, regulators, and lifted reg programming resistors and got those previous measurements. I probably jumped too far ahead however I would like to note that with all those components lifted/removed, I observed -36vDC at the -VCC and +9vDC at the +VCC pads of all components tied back with the output pads of the regulators. I may not be correct but I'm thinking rail voltage is somehow bleeding into the regulation circuit.
I correct my last statement. I had removed ALL opamps, LM393, regulators, and lifted reg programming resistors and got those previous measurements. I probably jumped too far ahead however I would like to note that with all those components lifted/removed, I observed -36vDC at the -VCC and +9vDC at the +VCC pads of all components tied back with the output pads of the regulators. I may not be correct but I'm thinking rail voltage is somehow bleeding into the regulation circuit.
Im back to working on this amp a year later. I still have D23, R110/R181/R185/R128 all lifted as its the only way the amp will power up and stay up.
During power up and power down cycle, the amp passes audio out speaker terminals for about 1.5 seconds each operation. Once the amp is fully powered up however the signal on speaker terminals is massively distorted and offset.
Regulated voltage is good at +-17.2vDC during power-on and power-off cycles, however when the amp is fully powered up there is no negative regulated voltage; only positive.
On U2 negative regiulator
Powering UP, Powered-ON, Powering DOWN:
1: -16, -0.75, -17.2
2: >-68v, -68v, >-68v
3: -17.2, -0.75, -17.2
During power up and power down cycle, the amp passes audio out speaker terminals for about 1.5 seconds each operation. Once the amp is fully powered up however the signal on speaker terminals is massively distorted and offset.
Regulated voltage is good at +-17.2vDC during power-on and power-off cycles, however when the amp is fully powered up there is no negative regulated voltage; only positive.
On U2 negative regiulator
Powering UP, Powered-ON, Powering DOWN:
1: -16, -0.75, -17.2
2: >-68v, -68v, >-68v
3: -17.2, -0.75, -17.2
Why would this amp be producing +-68V rail? The rail caps are only rated for 50V. The Clarion APX1000.2 schematic indicates the amp should be +-50v. Is the LM337 shutting down due to over voltage range? I have a very small insulated metal sync on the regs because they would hit 140F in about 10 seconds but this doesn't seem too abnormal considering the ~50v drop they're trying to do.
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Referencing non-bridging speaker terminals
U8 is an MPSA56
Up / On / Down
1: -17.2 / -1 / -17.2
2: -10 / -1 / -10
3: Jumps from -10 to -61 / -61 / 0
U11
Up / On / Down
1: -23.6 always
2: +20 / -24.6 / +20
3: 0 always
4: 0.442 / 0.25 / 0
5: 5.16 always
6: 0 / 0.119 / 0
U8 is an MPSA56
Up / On / Down
1: -17.2 / -1 / -17.2
2: -10 / -1 / -10
3: Jumps from -10 to -61 / -61 / 0
U11
Up / On / Down
1: -23.6 always
2: +20 / -24.6 / +20
3: 0 always
4: 0.442 / 0.25 / 0
5: 5.16 always
6: 0 / 0.119 / 0
Let's try this in a different way, with the amp on, if it's producing rail voltage when it's on.
U8
Black on pin 2
DC on pin 1?
DC on pin 3?
U11
Black on pin 1
DC on pin 2?
Black on pin 4
DC on pin 5?
U8
Black on pin 2
DC on pin 1?
DC on pin 3?
U11
Black on pin 1
DC on pin 2?
Black on pin 4
DC on pin 5?
OK see these readings:
U8
Black on pin 2
DC on pin 1: 0.2
DC on pin 3: -24.6
U11
Black on pin 1
DC on pin 2: -0.664
Black on pin 4
DC on pin 5: 4.92
U8
Black on pin 2
DC on pin 1: 0.2
DC on pin 3: -24.6
U11
Black on pin 1
DC on pin 2: -0.664
Black on pin 4
DC on pin 5: 4.92