Help Marshall vs65r

[nickb]

[ATTACH=CONFIG]42897[/ATTACH]

So guys outputs are back in place I'm ready to do this measurements.I 've put numbers so we will understand is numer 1 R4 the side non connected to ground?

That's Ok but it would be easier IMHO for all just to write the voltages on the diagram and post that.

[AL78]

Can you please check a few post back?thanks post 314

[nickb]

[ATTACH=CONFIG]42897[/ATTACH]

So guys outputs are back in place I'm ready to do this measurements.I 've put numbers so we will understand is
number 1 R4 the side non connected to ground
number 2 R42 the side non connected to d5
number 3 junction r9 d4
number 4 t5 the side non connected to either r42 and r9
number 5 junction d5 and d1
number 6 junction r5 d1
number 7 junction r32 r8
number 8 junction r11 r10
number 9 junction r11 d3
number 10 junction t4 c6
number 11? d13 junction d3?
number 12 junction d2 r13
number 13 junction r12 r 13
number 14 ?
number 15 red speaker ground(?)

Listen since we know outputs are ok can we avoid some of them?
yes I'll write on the scheme no problem
Let me know if all the above are the right one.thanks

number 1 R4 the side non connected to ground OK
number 2 R42 the side non connected to d5 OK
number 3 junction r9 d4 OK
number 4 t5 the side non connected to either r42 and r9 OK
number 5 junction d5 and d1 NO D1/D11
number 6 junction r5 d1 OK
number 7 junction r32 r8 OK
number 8 junction r11 r10 OK
number 9 junction r11 d3 OK
number 10 junction t4 c6 NO T4/R5
number 11? d13 junction d3? OK This is just the positive supply at the collector of T9
number 12 junction d2 r13 OK
number 13 junction r12 r 13 OK
number 14 ? - The negative supply - the collector of T11
number 15 red speaker ground(?) OK

I'm really not sure why you are asking since this is just repeating the information that is on the schematic.

HINT: nearly all of these test points are on one transistor or another. I know seems a lot of measurements but I'm trying to save time by getting all the data needed in one go.

[AL78]

Thank you.I'm asking just to be shure and don't waste anytime,since I'm not a dragon in reading schematics :-).I have a question let's just say that I found 38dc on number 2(just an example) do I have to go on or I can stop?.What I'm asking is as soon as I found 38dc Do I stop and report or report anyway?Second question since I've already changed t4 and t6 t9 and t11 are good,it would be stupid to go buy T1 T2 T5,since I think are very cheap,in case we found out they are gone?

[nickb]

Thank you.I'm asking just to be shure and don't waste anytime,since I'm not a dragon in reading schematics :-).I have a question.Question let's just that I found 38dc on number do I have to go on or I can stop?.What I'm asking is as soon as I found out 38dc Do I stop and report?

Report ALL of them.

[AL78]

Ok listen I'm going to be busy next few day so I don't know when I'm gonna have the time to do it.I'm not given up ok?have a nice sunday

[Dave H]

I'm going to be busy next few day

Me too, I was on the road yesterday. I'm now on the other side of the country.

Who's going to win the 100th Giro then?

[AL78]

Who's going to win the 100th Giro then?

I don'n know I'm more a classics fan flanders pris roubaix milano sanremo.This the giro will pass throught the road I use to go with my mike like milo-fornazzo

[Smoke 'n sparks]

I followed this forum because I also have a ballbuster VS65r

Your info was MOST helpful,but the confusion caused me a migraine.

This story never ended...We got halfway done and then...NOTHING


AArrggh

[g1]

Start a new thread about your particular amp and it's exact fault.
It will be much easier to start from zero than to try and add on to this 10 page thread that dead ended.

[Smoke 'n sparks]

I went over to play my VS65r that WAS playing normally last week down in the studio,but now, the sound coming out is like a bad tube.The quality got bad,then worse,then only sporadic bursts that could wreck the Celestion.It actually sounded like a heater was shorting against the cathode.On both channels.

Being a lazy guy- I went and bought a new TungSol 12AX7 for $19 at GC.Of course ,that wasn't the problem.

So I searched the net for some suggestions.I'm lazy and yet too busy to waste a lot of time on diagnosis.I've already been through so much bench time on both of my VS65's that I could write my own tips.Lucky for us,there's a lot of tips on this and similar Marshalls.

I will go thru some steps

1.Cleaned all input/output jacks.This is hard to do with success because the boards must come out.The contact point on all of them is a very tiny area under the arm that lifts up when you insert a jack.And,with any twenty year old Marshall you're gonna have jack problems.They are PCB mounted,and we all know what great wave soldering techniques Marshall has.One must put real lead into almost every thing mounted on the board to make it reliable,not counting semiconductor or cap,resistor or fuse problems.There are three fuses on this amp-one is glass and two are semiconductors.

2.For a steady state input I used a 1/4 mono jack from a cassette deck into the front panel.Amazing the sound comes out the speaker with bursts of power,(DANGER) and the headphone jack.I guess I'm trying to determine whether the pre or main amp (or both) are malfunctioning.

but this proves nothing.I will have to check voltages in the method that was shown in that 24 page novel with the guy from Italy.
I have read elsewhere that if the effect return will amplify,then it's in the circuit after the input jack that has problems,but that can't be logical-the return is mixed with the main signal and mix level with the effect vol control.I have read that the tube only amplifies the distortion channel, but there is a signal path from the SS clean section to the tube.Somebody will tell the truth-maybe I'll contact Blechley Park

Now this week I must add my Fender HRD 1 is also flummoxed.I am wondering if someone in the studio is a complete jackass and plugging in effects pedals (AGAIN) with the wrong wall rats.Man is this ever tough on an amp to get AC and hum injected into it.But I have seen this before,and it requires thorough analysis to discover that one or two components has failed because of it.

Signal tracing is going to happen next,first I have to find my probe or build a new one.

And I will have to add, the power switch doesn't always turn this VS65R amp on, or maybe it's on-but the LED is going bad-so that's a possibility that some components aren't really getting the line volts to rectify.I noticed the tube wasn't really getting the heater red......

It's gonna take more than a half hour on this one.I'm open to suggestions from more experienced techs.I'm lazy.And busy.



Thank you all in advance.

[nickb]

>>>>>>> "Start a new thread about your particular amp and it's exact fault." <<<<<<<

PS:

I'm lazy and yet too busy to waste a lot of time on diagnosis.

You might as well give up now.

[Smoke 'n sparks]

NIckb

I'm no quitter,just printed all 24 pages of the back & forth with some guy with the same amp, from Italy- only to find that he never replied about a finish.We may never know whether the amp stayed fixed.I'm guessing he gave up.You did your best and I applaud that.

Suspense,drama,diagnosis-what more could an electronics blog have?

You have real patience,a virtue.We all do not have that attribute.Shops around here are gone,victim of high rents and Chinese landfill products.Those that are open,and distant- are charging $125/hr UP FRONT.That's also what the boss charges to fix your car.

Like I posted,I will have to go methodically through the exact sequences you and other folks have posted.It's the best set of tips I have come across on the web so far.

Parts are only 6 miles away.

The signal path from the input jack to the headphone jack is complete and clean.Just no amplification whatsoever.What's coming out of the speaker is clear also,with no amplification,but random powerful bursts of amplified signal enough to damage it.

Regards

[nickb]

I'll help but please start a new thread Maintenance, Troubleshooting & Repair then "Post New Thread" copy the info above from 326 into it and then we can get gong.

Six miles away for parts, huh? Spoiled. My nearest grocery store is 10 miles away...

[Smoke 'n sparks]

Nickb:

I have started the new post as suggested.

You are ten miles away from a grocery store? If only that were my case-it is so overflowing with immigrants and big city noises you would think it's a big town.No,population 12k-just my area with 642 tenements.And four major shopping malls,two interstates,and 8 other highways
MADNESS

they are still building more mini-malls two blocks away,near the THREE Home Depots, Three Shop-Rites

The parts store owner knows his advantage with instant parts retrieval and charges accordingly.He also has highway frontage mall rent to pay.