hifonics output driverboard help

[mnhiphop101]

im only getting output on 1 of the 4 banks. Ive already replaced both 21844s chips and all of the d2 transistors. the arrows on the picture are the pins that are supposed to have output to the banks. the green arrow is the only one with signal on it.

 

[mnhiphop101]

also I am getting input from the rca's to the driver board on pin 5 and 7 of the middle set of pins

 

[Perry Babin]

Are the outputs in the amp?

Have you ever worked with these ICs? They're very easy to damage when soldering them onto the board.

 

[mnhiphop101]

No but I've done a decent amount of smd soldering and I slipped the probe and smoked one and and replaced it a 2nd time and still have the same issue so I dont think it's the 21844s chips

 

[mnhiphop101]

No the outputs are not in

 

[mnhiphop101]

From what I read in the tutorial I shouldnt need the output fets in. When I feed it 100hz thru the RCA Jack's I get a 100hz ac wave on only 1 bank

 

[mnhiphop101]

Using the primary ground

 

[Perry Babin]

You have to supply the high-side with B+ if you want high-side drive. That's what the 9v battery section is for, although I think using low voltage rails is a better option.

The other IC may be damaged if it has 12v supply and an input signal.

 

[mnhiphop101]

Ok so then I should be getting signal to 2 of the 4 banks then, right?

 

[mnhiphop101]

I think I have enough information to figure it out now. Thanks for your help.

 

[Perry Babin]

Yes, the two low-side banks, if the rectifiers are in the circuit.

Read the 9v section and supply the high-side with B+ to see if you get high side.

I've damaged those 21844s installing them. They're easy to damage. The failures have been all sorts... low impedance on the input dragging the signal down, high-side no output (even with applied 9v) but the low side was OK...

 

[mnhiphop101]

How often do the lm311's fail?

 

[Perry Babin]

Rarely. If you have signal on either IC, the signal is getting well beyond the 211/311.

 

[twilliar]

The 21844 is an easy chip to diagnose with outputs installed. There are 3 main questions to ask yourself while troubleshooting these. Pay attention to your scope assuming you are using one.
1- Do you have an input signal on pin 1? If yes go to 2, if no then back up to the 211/311
2- Do you have the low drive on pin 6? If yes go to 3, if no chip is bad (this will ride the negative rail)
3- Do you have the high drive on pin 12? If yes the chip is good and move to output resistors, no chip is bad.

As Perry said these chips are finicky! All the way to ESD damage. I hang my wrist strap on my rework stations just for these chips.

 

[mnhiphop101]

Ya I replaced it for a second time being more cautious with my heat and that resolved the problem. Thank you to everyone that chimed in.