Probing voltages on an IC

[audiobeginne]

I have Technics SUV 85A amp and trying to work out why the voltage control is not turning on. I want to measure the Voltages indicated by the schematic of IC 401. Let's say pin 14 has 54 volts. Does the negative probe of the DMM goes to the amp's chasis and the red probe of the DMM goes to pin 14?. What about pin 10 that has a negative voltage. Are the probes going to the probe like pin 14 as well? Are these DC voltages or AC? Thanks

 

[rickl]

Keep the ground lead on the chassis. I use mini grabbers on the phono ground post. I have heat shrink on the probe so only the top is exposed. Electric tape will work too.

Voltage will be DC unless specified.

 

[mbz]

Often any black speaker connector can be used as GND, often easy to clip black probe there.
All above measurements should be DC with black probe connected to GND.

Probing IC's is a bit dangerous, one slip = fried chip. Where possible probe a connected part, eg for pin 5 probe D403 anode.

 

[gslikker]

Apart from that, it looks the IC in the schematic is jotted down by some as seen from the solder side......

This means you need to be extra careful not to mix up things.



Standard way of drawing is pin 1 down on the left, where the mark is on the IC.

Below a link to a schematic where the same IC resides in something else

https://electronics.stackexchange.c...tic-oscillation-in-voltage-amp-with-an7062-ic

 

[kwayde]