Vibe slick A3 problem

[Perry Babin]

Does the amp produce audio with the current settings?

Does the 12v return if you change the settings?

 

[kirkmiles]

Theres still no output from channel 4? Do those figures sound about right? Or does it look like theres a problem with the ic? I have double checked and there is an input onto the board but no output to the mainboard.

 

[Perry Babin]

The DC voltages look OK (the op-amp is likely working properly) but having 0.2v on three of the pins is strange.

You'll need to find all of the pins that have audio for ch3 and then for ch4 and post a list or a marked up photo to show each.

 

[kirkmiles]

I have had another play and ive found if I move the crossover switch to high or low the voltage on PIN 7 IC9 raises to from little to 12+v DC? If i keep switching between the flat,high and low the amp goes into protect mode? any ideas?

 

[Perry Babin]

Have you checked all pins on all of the other op-amps to see if any have 12v?

 

[kirkmiles]

Theres no 12/14v volts on any other op amp. When the crossover is on flat the voltages read as previous post. When I switch to high/low the voltage starts low and slowy works its way to 14.2v(near supply volts) as if its a cap charging up? when i switch it back to flat it drops back to .2v?

 

[Perry Babin]

Set it so that you get ~12v on pin 7 and post the DC voltage on the other pins.


Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:

 

[kirkmiles]

Pin 1: 0v
Pin 2: 0v
Pin 3: -0.001
Pin 4: -15.11
Pin 5: Puts amp in protect mode when touched?
Pin 6: 14.2
Pin 7: 14.2
Pin 8: 14.9

 

[Perry Babin]

Follow the trace back from pin 5. What does it connect to?

Are there any broken traces or bad solder connections on that trace?

 

[kirkmiles]

Pin 5 IC9 connects to C409 and R149(circled in pic). I think R149 connects to one of the pins on the HPF pot? and C409 goes down to GND? Why would touching the pin put the amp into protect mode? What is the solder blob on the top of the board?

ImageShack® - Online Photo and Video Hosting

 

[Perry Babin]

Touching the pin with the meter may be causing a strong transient if there is a bad connection on it (or on any point along the trace it's connected to).

I can't tell what the solder blob is in the image. There are others in the center of wires that are basically jumpers to the other side of the board.

I see something that's VERY likely to cause problems. For each of the components that has solder on both the top and bottom of the board at the end of the component where the wire lead goes through the board, you need to desolder both sides, scrape (use sandpaper or a screwdriver) to remove the solder down to the copper on the lead and then re-solder them. Most amp manufacturers know better than to use this type of connection on CEM boards because they almost always cause problems with reliability.