Digital Designs - Z1, removing short circuit protection?

[ThyDntWntMusic]

I'm wanting to remove, or desensitise the short circuit/low impedance circuit in two of these amps..

Basically, what happens is, the better the supply voltage/current I have available, the more the amps go into protect...

More input voltage = more output voltage = more output current = more protect...

I haven't even looked into how they do this part of the protect circuit, so I'll look into that now and probably update this thread, but if someone has done this before, or could guide me in the right direction, that would be great.

Thanks!

 

[Perry Babin]

R30 on the driver board (270 ohms) sets the reference. Increase the value slightly to reduce the sensitivity. I wouldn't expect the outputs to survive long if driven for long periods of time where the original protection circuit set point was causing it to shut down.

 

[ThyDntWntMusic]

I've hammered on these amps with insufficient battery, and not had issues with protect... the issue was always when I added more batteries, they'd go into protect...

Running them at 0.5ohm daily....

 

[ThyDntWntMusic]

I assume you mean the amplifier driver board, not the power supply driver board.

based on the photo I have, R30 isn't 270ohm.

 

[Perry Babin]

Audio driver. Does it have 2 driver ICs or 4 driver ICs?

 

[ThyDntWntMusic]

it has four IR2184's

 

[Perry Babin]

It appears that R30 on either driver board is 270 ohms.

 

[ThyDntWntMusic]

I dont know what amp you're looking at, but R30 appears to be 20k

 

[SPLing]

On driverboard with 4x21844 (v20) R30=330/1%
R30=270/1% on 2x21844 (dwm3640v30/v40)

but ThyDntWntMusic talking about dd z1, not z1a

UPD: ThyDntWntMusic, on driverboard find something like that

An externally hosted image should be here but it was not working when we last tested it.

 

[ThyDntWntMusic]

What resistor would you change on the above diagram?

I had already found the part of the circuit that looks like that, and thought it was probably R80 or R62 (on the above diagram) that I should change... both of which are 330ohm on my board.

 

[SPLing]

I guess you need to decrease R80, or increase R62 for more power.

 

[ThyDntWntMusic]

I've just finished reinstalling the amps.

I have two strapped, running a 1ohm nominal impedance...

Now the master amp randomly either goes into protect, or sometimes looks like its turned off completely! the power/protect light doesn't turn red, it just goes off!

Currently running three 130ah, 1000cca agm batteries in the back, a smaller agm battery in the front (55ah, 700cca or something) and a 300amp alternator....

See, I used to run this with just two batteries and a stock alternator, and the amps would very rarely go into protect... add more batteries, and a bigger alternator, and now I can't even play music!

 

[ThyDntWntMusic]

Could symptoms like this actually be caused by the short circuit protection? or am I barking up the wrong tree...

 

[ThyDntWntMusic]

There's actually two of that circuit on the board, as there are two (pairs) shunts on the amplifier...

I would really like this amplifier to be working "correctly" by next weekend... but I dont like my chances

 

[SPLing]

the power/protect light doesn't turn red, it just goes off!

sounds like your amp goes to undervoltage protection, but i'm not sure.

 

[ThyDntWntMusic]

sounds like your amp goes to undervoltage protection, but i'm not sure.

more like overvoltage, it does it with nothing playing! it does it with the headunit set to auxiliary input!

But, it can't be overvoltage either, as it does it when playing music, with the voltage sitting in the 12-13volt range...

I might disconenct the subs from that amp, and see if it still does it...

might even try putting an almost dead short across the output with no input connected, and see if it does the same thing...

 

[SPLing]

you need to see how much voltage on:
- 10 leg of SG3525 on PS module
- SD pins of ir2184s
,when your amp is off without red led

it is to understand who is the first out in protect (ps or amp)

 

[ThyDntWntMusic]

I just went and cranked it, in the driveway...

well, first time I turned it on, went into protect, came out, and wouldn't go back into protect again...

Engine wasn't running...

Played music flat out for 30 seconds, voltage got down to just on 12volts, amp didn't go into protect...

You see, a friend of mine has two DD M4 amps... if he fully charges his batteries, the amps do the exact same thing as mine! so half the time, he just leaves them half flat....

WHATS GOING ON?!?

 

[SPLing]

You see, a friend of mine has two DD M4 amps

it is happens only if amps is strapped?

try to modify over current protection (change resistors) on your amp - maybe it help, but be careful

 

[ThyDntWntMusic]

it might only happen when the amps are at 0.5ohm. it might also only happen when they are strapped, but neither of us have really tested properly. but i don't understand why the short circuit protection would kick in when the amp was playing nothing.