Marshall VS265 one side dead

[Enzo]

Negaqtive numbers on a resistance scale means there is a voltage in th circuit.

[Captngeetch]

The negative numbers can be ignored , you are looking for continuity , I would suspect as the amp had no load on that side some of the caps are still charged up and affecting your readings.

Just for clarifications sake you have done the test Jazz suggested and there is no problem with that jack?

The attached makes complete sense?

If Yes time to check the headphone socket.

I did the test Jazz suggested and it was still dead. When I plug in headphones both sides work perfectly. Unplug them and only the One side works. Unless I'm mistaken, this means that the channel itself is fine..the issue is getting the output to the speaker itself

[g1]

You are correct, if the phones work, that channel should be good.
As OC mentioned, you need to now move on to the phones jack. The diagram he posted in post #13 shows how both the ext. spkr and phones jacks route the signal to the speaker.
Sounds like both your jacks have problems.

[oc disorder]

So I have to assume the diagram makes sense.
I understand from your first post the headphones work.
I also assume initially you called the side with the red and black wires the left side then the faulty side became the right side !
According to the diagram Red & Black Left and Blue & Brown Right.
When we're looking at an amp without it in front of us the detail is important to get accurate answers.
I'm going to call it good side/faulty side.

If you haven't already , I would remove the back board and examine the solder joins underneath.
Pay attention to the headphone jack and the .33 7watt white ceramic resistor standing up.
While you are there you could measure that resistor .. It's a 1/3 of an ohm so will read as a short circuit .
More or less the same as holding your two probes together.
Now its a matter of bridging the switch in the headphone jack.

If the left side is faulty find the junction of R44 & R45 & D10 & D19. That is where the main amplifier output is.

With the headphone socket not being used the switch should be closed so there should be a connection between the junction above
and the Red speaker out wire.

To check if you are on the right path lets test the good side the right side.
Measure between amp output Right (R36 & R37 D3 & D8 junction point) and the Brown speaker out wire.

This should measure ok i.e. have continuity and virtually no resistance as we know it works.


So if there is no reading between R44 & R45 & D10 & D19 and the red wire we can assume the switch is faulty.
You could try cleaning it with de-oxit and inserting and removing a jack rapid fire style to try and dislodge any fluff or dirt.

If it still wont work time for another jack socket !!

You could check it by temporarily bridging the output of the amp to the brown wire.

If you are never going to use the headphones I would bridge the speaker switches permanently on - at that socket.

Not sure of that pin configuration on the headphone socket as it is a different style to the others.

The tracks would have to be traced back.

EDIT:

In the diagram "VS 265 speakers.jpg" C25 also connects to the Right output R36 & R37 D3 & D8 junction point.

Also C29 (both 100nF 63v)connects to the left side output R44 & R45 & D10 & D19 junction point.

[Captngeetch]

Sorry if I confused you..the right ext is the one not functioning and the red/black wired side is the bad side..i assumed they are the same side..and the wires are on the board right above the right ext jack and the brown/blue are on the far left. Needless to say the right ext jack is dead and the red/black speaker output is dead..regardless of left or right lol.

Both sides show continuity. That's R54 and R55 to the brown wire and R44 and R45 to the red wire...and all of the .33's read good as well. And D10 and D19 show good to the red wire too.

[oc disorder]

Hmmm Somezing iz not right!!

Seems yours has the colours swapped compared to the diagram. So Red and Black are Right and Brown and Blue are Left.

Ok working from the simplified picture in the faulty channel (Red & Black)preferably with a continuity tester that beeps!

Going through it systematically...
1. Test from amp output to speaker red wire spade connector. Should beep or be nearly zero ohms (same as holding leads together).
This is measured from junction point of R44 & R45 & D10 & D19 & C29 (Right Amp) and the red spade connector.
You say this is ok .

2. Test from negative black spade connector to chassis ground.
This checks the negative side of the speaker and the pathway includes the right speaker extension jack and the .33 7 watt resistor
and the 10 ohm resistor that connects audio ground to chassis ground.
This is measured by putting one probe up the black negative spade connector and the other on the chassis ..
assuming the earthing arrangement is intact.
You may get aprox 12 ohms here.
If not check the soldering where the .33 goes to ground.

I'm afraid I've run out of ideas now. Unless the headphones are faulty and wired in mono I cannot see if all those connections are intact
why that side doesn't work. At least you have an identical "side" that works to compare readings with.

Back to JPB !

[Captngeetch]

Not sure if this helps or not, but I was rechecking the D19 diode to red/black wire and with the speaker connected I get sound thru the speaker..just crackle and scratching noises as I made contact, and D9 diode causes a loud popping.

[oc disorder]

Not sure if this helps or not, but I was rechecking the D19 diode to red/black wire and with the speaker connected I get sound thru the speaker..just crackle and scratching noises as I made contact, and D9 diode causes a loud popping.

Well from this end I have to assume a lot .. eg was the amp on or off. For noises around D9 I would assume the amp was on.
Now if it was , what were you measuring and what setting on the meter?
When rechecking D19 was the amp off and did you have an ohms setting on the meter or continuity (beeping) ?
The schematic tells me that is the left amp and also has Red and Black wires as D19 and D9 are in the left schematic.

From what you have said, I would say in very vague terms that the speaker does seem to be connected to the output of the amplifier in that faulty side.

Here we have to go back to the beginning and you have to prove to us the headphone socket is working in stereo.

That is the only clue that made us believe the amp was working on both sides (Left and Right) and that it must be
the speaker or speaker connections that were faulty.

The amps have an inbuilt mute if nothing is plugged in. That makes it nice and quiet when idling.

So you need something plugged in to the input jack for this to "unmute" !

When you plug the headphones in, the hiss or residual white noise should be slightly different to either ear. A kind of spatial hiss.

Move the h/phones off center to your ears so you don't deafen yourself.

Both sides working ?

Turn amp off.

Find CN2 . It's the input to your good side with the brown and blue speaker wires. It has 3 wires .Think they are a little white plastic plug on one end.

Unplug that and turn the amp back on. Can you hear any thing in the headphones ?

[Captngeetch]

P

Well from this end I have to assume a lot .. eg was the amp on or off. For noises around D9 I would assume the amp was on.
Now if it was , what were you measuring and what setting on the meter?
When rechecking D19 was the amp off and did you have an ohms setting on the meter or continuity (beeping) ?

For both the amp was on and checking continuity

The schematic tells me that is the left amp and also has Red and Black wires as D19 and D9 are in the left schematic.

From what you have said, I would say in very vague terms that the speaker does seem to be connected to the output of the amplifier in that faulty side.

Here we have to go back to the beginning and you have to prove to us the headphone socket is working in stereo.

That is the only clue that made us believe the amp was working on both sides (Left and Right) and that it must be
the speaker or speaker connections that were faulty.

The amps have an inbuilt mute if nothing is plugged in. That makes it nice and quiet when idling.

So you need something plugged in to the input jack for this to "unmute" !

When you plug the headphones in, the hiss or residual white noise should be slightly different to either ear. A kind of spatial hiss.

Move the h/phones off center to your ears so you don't deafen yourself.

Both sides working ?

Yes, both sides working thru the headphones

Turn amp off.

Find CN2 . It's the input to your good side with the brown and blue speaker wires. It has 3 wires .Think they are a little white plastic plug on one end.

Unplug that and turn the amp back on. Can you hear any thing in the headphones ?

Both sides work....but now BOTH SPEAKERS ARE WORKING !!! Tested it with chorus on and it sweeps left and right like it's supposed to. Maybe the CN connections were dirty ?

[oc disorder]

Well could have been dirt fluff muck somewhere... btw not a good idea to check continuity when amp is on.

Spose call it fixed and put it down to another of lifes little mysteries. Muck in loop jack sockets , headphone jack sockets... and recently extension speaker sockets!

Well hopefully the fault wont rear its ugly head again. Must have disturbed something in the process.

Big amp. Wonder what a piano accordion would sound like with the chorus on ?

Glad you got it working.

[Captngeetch]

Well could have been dirt fluff muck somewhere... btw not a good idea to check continuity when amp is on.

Spose call it fixed and put it down to another of lifes little mysteries. Muck in loop jack sockets , headphone jack sockets... and recently extension speaker sockets!

Well hopefully the fault wont rear its ugly head again. Must have disturbed something in the process.

Big amp. Wonder what a piano accordion would sound like with the chorus on ?

Glad you got it working.

I appreciate everyones input..pointed to the right areas to look..just aired her out and she's back to sounding awesome again..checked both ext jacks and they are working properly as well.

Thanx again...Jazz too !!