DSP/Amp Problem (Reversed Polarity)

[Riley1]

I'll make these checks tomorrow. Weird thing though, I was running late and had to leave so I didn't have any time to check this out but I used a second meter to check voltage on the terminals while I had the other meter checking current draw and I couldn't get a voltage reading. I must have been doing something wrong.

I don't think it's a power supply problem, It's a pretty robust power supply. (20A@12V/120A@5V). I think something else is going on.
Thanks,
Rick

 

[Riley1]

VCar 'Should' be the same voltage as what your power supply is putting out, and that goes directly to pins 3 and 17 on that chip you measured... if you are getting less than 12V, then one of two things is happening:

This has been a constant, when the voltage drops at the terminals it also drops at pins 3 and 17. The voltage only drops when the remote in jumper is hooked up at the terminals. But when the jumper is in place the power light stays on.

 

[Riley1]

Had my meter hooked up wrong, that’s what rushing will get ya.

Current draw is .01A without remote power in, voltage is 12V steady at suggested check points. Current .71A with remote power, voltage drops to 7V +/- at all suggested check points and ramps up to 11.5V every 20 seconds.


Let me try to summarize where I think I’m at.


Without power on the remote in terminal it appears all of the previous checks are good. It’s when power is put on the remote in terminal that when the voltage problems start, the power light stays lit. Just for the sake of argument let’s take the power supplys out of the picture as I don’t think it’s an issue. What component could be causing the voltage issues with power on the remote in terminal. My understanding is the remote in power is what turns this thing on. The 12V to the remote in is supplied by the radio when it’s turned on. When this unit gets the remote in power there is supposed to be a momentary delay and then it’s supposed to send 12V to the remote out to turn on other amplifiers.


Tried something different. One power supply on +12V and one on remote in. With just 12V on remote in I have 1.6V at pin 5. When I turn on the +12V ps the remote 12V is stable at the terminal but the +12V drops to 7V, turn off the remote power and the +12V comes back up.


Possible issue in this circuit?



Thanks,
Rick

 

[Gryd3]

Had my meter hooked up wrong, that’s what rushing will get ya.

Current draw is .001A without remote power in, voltage is 12V steady at suggested check points. Current .71A with remote power, voltage drops to 7V +/- at all suggested check points and ramps up to 11.5V every 20 seconds.


Let me try to summarize where I think I’m at.


Without power on the remote in terminal it appears all of the previous checks are good. It’s when power is put on the remote in terminal that when the voltage problems start, the power light stays lit. Just for the sake of argument let’s take the power supplys out of the picture as I don’t think it’s an issue. What component could be causing the voltage issues with power on the remote in terminal. My understanding is the remote in power is what turns this thing on. The 12V to the remote in is supplied by the radio when it’s turned on. When this unit gets the remote in power there is supposed to be a momentary delay and then it’s supposed to send 12V to the remote out to turn on other amplifiers.


Tried something different. One power supply on +12V and one on remote in. With just 12V on remote in I have 1.6V at pin 5. When I turn on the +12V ps the remote 12V is stable at the terminal but the +12V drops to 7V, turn off the remote power and the +12V comes back up.


Possible issue in this circuit?

View attachment 25054

Thanks,
Rick

Pin5 ? Of what device? We were reading pins 3 and 17 of the voltage regulator.
The fact that the voltage dips on ALL suggested test points is not a good thing... It may be a 'robust' power supply, but it does not sound like it's working properly.
The voltage on Terminal 1 should always be 12V. There is only two reasons it wouldn't be:
1 - The wire you are using is far too thin which causes a voltage drop when you try pulling current. (But you are only reading a current draw of less than 1Amp... this should not be a problem.
2 - The power supply is having trouble... Reading 0.71Amps is a far from the 5A capable from that supply, there should be no reason it's dipping... (Unless it's detecting a short circuit... but you would see more than 0.71A...)

Does your power supply have a current set or current limit knob?

 

[Riley1]

Pin 5 was at the voltage regulator. No current limit setting on either power supply, just voltage adjustment. Neither one of them are new but two completely different power supplies doing exactly the same thing? I guess I’m going to have to try to come up with another power source, I don’t think I have any other power supplies available that are up to the task. Maybe I’ll just temporarily install it in the car this weekend.

Thanks,
Rick

 

[Gryd3]

The part I am hung up on is the fact that your power supply cannot keep a stable 12V...
If the Amp was having issues and resetting itself, you should see 12V the majority of the time with a brief spike or drop if the power supply is slow to compensate. The Amperage reading 'should' be the one to jump around, not the voltage.

 

[Riley1]

Hooking it up in the car should shine some light on this. It should be warm enough this weekend to stick it in the car and play around a bit. In the mean time I'm going to look around at work to see if I can turn up another power supply. Until I find a decent power source I'm just spinning my wheels and wasting your guys time.

Thanks,
Rick

 

[Gryd3]

So I would very much like to confirm the following details:
0 - Voltage at (or as close to) the Power Supply Output
1 - Terminal 1 (Battery Input)
2 - Any point 'After' the 25A Fuse. (On the 12V side of D2 or D34)
3 - Any point 'After' the L20 Inductor. (+ side of C95 or C38)
* The black terminal must be placed and left on the power supply negative, or Terminal2

I know you have done this already, but you included a number of other details that cloud the exact results you had found. Please do this first without the jumper. Then once more with the jumper. Do not use two power supplies, use only one.

Without Jumper:
0-
1-
2-
3-

With Jumper
0-
1-
2-
3-

(You may choose to measure current at the same time... but 3/4 of an Amp should be nowhere near causing a voltage drop that large from 12V, which is why I suspect an external problem and want to be crystal clear on the measurements.)

 

[Gryd3]

Hooking it up in the car should shine some light on this. It should be warm enough this weekend to stick it in the car and play around a bit. In the mean time I'm going to look around at work to see if I can turn up another power supply. Until I find a decent power source I'm just spinning my wheels and wasting your guys time.

Thanks,
Rick

A Car battery will have a much much higher current capacity, be mindful of this when you test, and it may be worth NOT doing a current reading with a meter in this setup in-case there is a short. You don't want the Amp to kill your multi-meter. Voltage checks only here.

 

[Riley1]

I'll do the checks tomorrow.

Thanks,
Rick

 

[Riley1]

Here's what I have.
All points without jumper are 12V, with the jumper they all drop to 6.95V but ramp up to 11.5V every 20 seconds or so and then drop back down.

Thanks,
Rick

 

[Gryd3]

Here's what I have.
All points without jumper are 12V, with the jumper they all drop to 6.95V but ramp up to 11.5V every 20 seconds or so and then drop back down.

Thanks,
Rick

That must've been with the power supply?
I think we need a better test-bed before we continue...
@dorke , do you have any suggestions on how to resolve this? The voltage fluctuation occurs right up to the power supply source. It's not giving any indication of fault with the Terminal, traces, Fuse or Inductor.
Recent post states a 0.71A current draw which should not be enough to cause the power supply to dip this much...

 

[Riley1]

Yes, those readings were taken using the Condor Max-403-0512 http://www.slpower.com/data/collateral/MAX-500-Old_DD.pdf. The first reading was taken right at the PS terminals.

Thanks,
Rick

 

[Gryd3]

Yes, those readings were taken using the Condor Max-403-0512 http://www.slpower.com/data/collateral/MAX-500-Old_DD.pdf. The first reading was taken right at the PS terminals.

Thanks,
Rick

Certainly is a capable power supply...
Confirming you are using output #2 and nothing more on that power supply?

 

[Riley1]

Certainly is a capable power supply...
Confirming you are using output #2 and nothing more on that power supply?

Yep, a couple of #12 wires 3' long. Not saying it couldn't be bad but the thing that has me wondering is I get the exact same results with the 3A PS. Sure wish I could find a third one...unopened.

Rick

 

[dorke]

That must've been with the power supply?
I think we need a better test-bed before we continue...
@dorke , do you have any suggestions on how to resolve this? The voltage fluctuation occurs right up to the power supply source. It's not giving any indication of fault with the Terminal, traces, Fuse or Inductor.
Recent post states a 0.71A current draw which should not be enough to cause the power supply to dip this much...

Only thing I can think about is maybe the P.S used has a fold-back current limit.

I would try it in the car without an amp-meter as you suggested.

 

[Riley1]

I'll get it in the car this weekend and report back as to what I find.

Thanks again to you both for the help. It is surely appreciated.
Rick

 

[Riley1]

Trying to think ahead to my next move. If I should have 12V (with remote jumper) at the check points listed below with the board hooked up in the car where should I go next? Check the voltages at U4?


0 - Voltage at (or as close to) the Power Supply Output
1 - Terminal 1 (Battery Input)
2 - Any point 'After' the 25A Fuse. (On the 12V side of D2 or D34)
3 - Any point 'After' the L20 Inductor. (+ side of C95 or C38)


Thanks,

Rick

 

[Gryd3]

Trying to think ahead to my next move. If I should have 12V (with remote jumper) at the check points listed below with the board hooked up in the car where should I go next? Check the voltages at U4?


0 - Voltage at (or as close to) the Power Supply Output
1 - Terminal 1 (Battery Input)
2 - Any point 'After' the 25A Fuse. (On the 12V side of D2 or D34)
3 - Any point 'After' the L20 Inductor. (+ side of C95 or C38)


Thanks,

Rick

The first goal we need to reach is making sure our supply is behaving properly... which means that 0, and 1 should be as steady as possible @12V with and without the jumper in place.

If the jumper is put in place and the amp pulls too much current, it could have caused a fault in the original power supply making it dip to 7V... if it does that with a 12V car battery, it will blow the 25A fuse... Not ideal but give us information we need.
If the voltage stays steady, we walk down the line and poke and prod each component from the Terminal1 all the way to the voltage regulator. If it stays at 12V all the way then we are looking good so far.
Readings of the voltage regulator will tell us if it's acting up... but we can't be sure until we can properly provide a nice reliable 12V to it.

 

[Riley1]

I've got a 15 or 20A in-line fused #10 wire coming off a distribution block to feed this unit. I'll see if I blow that one first. Thinking back to when this happened I hooked up the 12V and remote in properly, hit the reset button and nothing happened other than the power light coming on for 15 seconds or so. I'm going to try and get this done tomorrow afternoon.

Thanks,
Rick