Twisted Sounds 8.5k

[mnhiphop101]

So check for drive on pin 1 of both irs21844s chips?

 

[Perry Babin]

Yes, with the FETs in and when you have no drive reaching them.

 

[mnhiphop101]

No there is no signal on pin 1 of the irs21844s using the speaker negative as ground

 

[Perry Babin]

Are the relays engaging/closing?

Do you see any DC voltage on the output filter inductors?

Is your scope set the AC coupling?

What make model scope?



Please (and this applies to anyone who needs repair help) use your sig line to list all equipment you have, editing it as equipment changes. Include the model numbers.

Oscilloscope (yes or no)
Multimeter(s)
Type of signal source (grounded RCA shields preferred).
Soldering iron
Desoldering pump
Power supply
2 ohm current limiting resistor (hollow cylindrical ceramic 100w preferred)

 

[mnhiphop101]

How do I edit my sig line?

 

[Perry Babin]

Top of page, menu USER CP >> EDIT SIGNATURE

 

[mnhiphop101]

Yes the relays are opening and closing

Yes there is about -6vdc on both output inductors using the speaker negative as ground

Yes the scope is on ac

 

[mnhiphop101]

There is a 3ed inductor on the output side. Idk if that means anything.

 

[Perry Babin]

Use the secondary ground as the reference and recheck for DC.

 

[mnhiphop101]

I thought the speaker neg was the secondary ground.

 

[Perry Babin]

I'm sorry, I misread. It generally is the secondary ground but there are exceptions. H-bridge output have output on both speaker terminals. A few amps (maybe a layout mistake) have the signal on the negative speaker terminal.

The DC is likely causing the amp to go into protect. The relay is likely closing and them immediately opening.

Is the protect LED lighting up?

 

[mnhiphop101]

No protection light
I can here the relay close. It doesnt close then open right away

 

[mnhiphop101]

If I feed a sine wave into the amp and turn the gain up I can hear the amp start to buzz when it starts to clip but I dont see any waves anywhere.

 

[Perry Babin]

If you can see it clipping, it has to have a drive signal.

Does the amp have 6v of DC across the load connected to the speaker terminals?

 

[mnhiphop101]

Ok so I dont know for sure its clipping but it's the same sound I hear on other amps when u turn the gain up to far. This is without a load attached

 

[Perry Babin]

With the amp at idle, do you have rail-rail oscillation?

With the amp on, at idle and a load connected, do you have any DC voltage across the speaker terminals?

If not at first, drive a signal into the amp for a second to see if that will trigger oscillation.

 

[mnhiphop101]

There is 2vcd across the speaker terminals with a load attached when I drive a signal into it

 

[mnhiphop101]

There is no rail to rail oscillation

 

[mnhiphop101]

With the fets out I see the signal but the oscillation isnt rail to rail. Its 5v up and 5v down

 

[Perry Babin]

What's the DC voltage on pin 2 of the 21844s when you lose signal on terminal 1? Black probe on the negative rail.

Do you still have signal on the output of the TL072 and the LM211 on the driver board when you lose signal on the 21844?

Is the photo the current condition of the amp (only one FET per bank, 4 total)?