Help Marshall vs65r

[AL78]

-15,99 v zd1 against sleeve input jack

[nickb]

-15,99 v zd1 against sleeve input jack

There is an open circuit between those two points assuming you are sure that you measured pin 4 and not a different one. If you used the picture of the chip I posted earlier then that will be fine. You can now try measuring pin 4 of IC1, pin 4 of IC3 and pin 11 of IC1 to see if we can narrow down where the open is.

[AL78]

pin4 1 v15,73
pin 4 ic3 1,114v
pin 11 ic1 v1,110

[nickb]

pin ic4 v15,73
pin 4 ic3 1,114v
pin 11 ic1 v1,110

IC4 pin 4 is good

You are going to have to look at the solder side of the board. Somewhere there is a break in the connection from ZD1 non stripe side to IC3 pin 4, C1 pin 11 and IC7 pin 4. My guess is a wire link is not soldered properly. You can clip one meter lead to the non-stripe end of ZD1 and then follow the connections from it until you find where the break is.

[AL78]

there is any way we can narrow down it?

[nickb]

there is any way we can narrow down it?

Sorry, no. You'll just have to follow it through. It's not as hard as it sounds.

[AL78]

Ok I'll try thank you for everything I won't bother you again

[nickb]

You are more than welcome.

So, when will the apartment be ready?

[AL78]

The owner of this amp has tons of apt so if you promise to come here and fix the amp I'll put a good word lol thanks

[AL78]

HI I know I know I've promise not to bother.Listen I've continuity between zd1 no stripe and pin 4 ic3.But the reading is -8,77 v.and the same goes for zd1.As soon as I remove the connection I get -15v.What that could be?

[nickb]

What the resistance between ZD1 ( no strip end) and IC4 pin 3 in ohms?

[AL78]

I used continuity test.Listen I will be off for a couple of day at least.Do I need to do the resistance test with amp on or not?What do you think could be?It's very strange

[Enzo]

Continuity test is only for crude measurements. That test cannot tell the difference between a dead short (zero ohms) and say 40 ohms. Yet that difference tells a big story.

[AL78]

What I Don't understand is why without connection beetwen zd1 and ic4 I read -15,5v on zd1 and when I get continuity zd1 also go down.

[nickb]

What I Don't understand is why without connection beetwen zd1 and ic4 I read -15,5v on zd1 and when I get continuity zd1 also go down.

I'm really not sure that I understand what you are saying. The amp should be off when doing continuity tests. The continuity is considered good if the resistance is less than 0.5 ohm or so.