Intimidation Professional sub advice please

[zen]

Hi all

Far as i can tell this unit not producing any audio , although customer mentioned it does , but distorted .

Anyway , started by testing impedance of main driver speaker .


Measuring 80R , which i have not experienced before .


Anyone familiar with this unit enough to know ?


Can't seem to find any info on it .

See picture of label on speaker .

[R_J]

Most of the Blastking drivers seem to be 8Ω

[zen]

Thanks RJ for confirming .

Will test with another driver & report back

[zen]

Tried one of my chunky 4 ohm speakers on this unit , but still no audio .

[zen]

Have a feeling there's an issue on the input board .

Became suspicious when i noticed the LED for signal wasn't registering .

Also cannot scope any audio on ribbon lead from input PCB to MAIN , although if i poke around on main , can measure an extremely low peak to peak audio signal.

[zen]

Some progress made on this unit .

Discovered a low reading of 30R between pins 15 & 13 of U15 ( IRS2092S ) , compared to same measurement on other channel , which was over 4K .

It's a drive chip for one of the channel output devices , which seemed to have survived .

Surprised protection mode didn't kick in .

Still not sure about the speaker impedance .

[R_J]

There likely is no protection circuit. I suspect the output mosfets could also be bad, I see what looks like a lead trimming or solder splash on the mosfet lead in the lower left of your picture.

[zen]

Hi RJ , there is an LED on unit labelled protection .

I did notice the solder splash also , but suspect that's during manufacture , as it doesn't seem unit has been opened before .

[zen]

Pulled out the driver , which has a larger diameter than any pizza i have ever seen , 47 CM in fact .

Now impedance reading 1R2 therefore assume it has shorted turns .

I guess it should be a 4 ohm .

Not sure why the high reading before . Quite possibly meter probes not contacting fully .

Any suggestions for a replacement .

[zen]

With the added cost of bass driver customer has decided against repairing .

Not having a particularly fruitful week .