I don't have the amp here with me. My friend will be bringing it to me this upcoming Wednesday but I wanted to get a heads up on it since I've never encountered this type of an issue in RF BD amps.
The amp will start up in protected mode (protect led lit) but only when the car is in accessory (car not started). The battery voltage is confirmed to be 12 vdc or above. The voltage at the B+ & remote terminals are the same as the battery voltage referenced at the amps negative (ground) terminal. The amp will start up & work fine if the car is started. The voltage with the car running is ~14 vdc at idle.
The amp use to work will off of the battery (in ACC -- engine not running). This conditions only started recently. Is this common to these amps? Any ideas what could be causing this? I post an update I get the amp and can run a few test but if anyone is familiar with this "symptom" I would appreciate any advice or heads up.
TIA
The amp will start up in protected mode (protect led lit) but only when the car is in accessory (car not started). The battery voltage is confirmed to be 12 vdc or above. The voltage at the B+ & remote terminals are the same as the battery voltage referenced at the amps negative (ground) terminal. The amp will start up & work fine if the car is started. The voltage with the car running is ~14 vdc at idle.
The amp use to work will off of the battery (in ACC -- engine not running). This conditions only started recently. Is this common to these amps? Any ideas what could be causing this? I post an update I get the amp and can run a few test but if anyone is familiar with this "symptom" I would appreciate any advice or heads up.
TIA
Were you monitoring the battery voltage with the key in acc while the amp was on?
Your gonna need to get the amp from your friend before you can start doing some trouble shooting.
Could be a battery thats borderline good/bad.
Only time I have seen this symptom is with low battery voltage, and/or a bad TL072C chip on the board but without having the amp yet you cant determine that.
Your gonna need to get the amp from your friend before you can start doing some trouble shooting.
Could be a battery thats borderline good/bad.
Only time I have seen this symptom is with low battery voltage, and/or a bad TL072C chip on the board but without having the amp yet you cant determine that.
seankane, thanks for the heads up. I didn't install this amps. This amp has been in my friend's car for about 3 years now, it has never been finicky about low battery voltage. It use to work well on battery power up to about 11vdc or so.
A new car battery was installed in the car last year, I doubt it's the battery. I do suspect it's U21 (a TL072c) as you suggest but without having the amp in my hands I can't run any tests. I just wanted to see if this is a common problem and if a solution for this issue was documented. Thanks again for your reply. I'll post on the solution or not (hehe) to this issue after I get the amp on Wednesday.
A new car battery was installed in the car last year, I doubt it's the battery. I do suspect it's U21 (a TL072c) as you suggest but without having the amp in my hands I can't run any tests. I just wanted to see if this is a common problem and if a solution for this issue was documented. Thanks again for your reply. I'll post on the solution or not (hehe) to this issue after I get the amp on Wednesday.
Yes U21 could be defective but usually when it is the amp stays in protect but not always. There might be other issues.
Let me know when you get the amp and what you find in your tests. I have repaired many of these amps, thanks to Perry Babin on several.
I like to take notes of problems and resolutions to aid me in future repairs.
Let me know when you get the amp and what you find in your tests. I have repaired many of these amps, thanks to Perry Babin on several.
I like to take notes of problems and resolutions to aid me in future repairs.
I just got the amp in. U21 is good. When this amp is powered with 12.00 vdc the amp stays in protected mode. I get ~96 vdc across the black & red twisted wires but when ref to GND (J6) I get 0 vdc from the red wire and 96 vdc from the black wire. Shouldn't I get ~ +47 vdc (black wire) and -47vdc (red wire) when ref to GND? None of the output & power supply FETs tested (in circuit) appeared to be leaky.
When this amp is powered with 13.8 vdc it comes out of protect normally (in a few seconds) and operates normally. The voltage across the B&R wire is 84.3 vdc, red wire ref to gnd is -41.5 & black wire ref to gnd is +42.7.
Any ideas what the problem might be? I just go it in so I still need to run some more tests. I'll keep you posted.
When this amp is powered with 13.8 vdc it comes out of protect normally (in a few seconds) and operates normally. The voltage across the B&R wire is 84.3 vdc, red wire ref to gnd is -41.5 & black wire ref to gnd is +42.7.
Any ideas what the problem might be? I just go it in so I still need to run some more tests. I'll keep you posted.
Have you checked the thermistor values to make sure those are within spec? That could hold it in protect until the input voltage increased.
I have a schematic for a BD if needed.
I have a schematic for a BD if needed.
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