marshall vs100 blown fuses

[guitardude10890]

ok when i got the amp it didnt work and it time to fix it. well i found out that i have an electrical problem in the output curcuit. well i just reasently took out t1 from the curcuit and it still blow the fuse so i know the problem isnt after T1 (transister 1) and i was wondering what to check next. i can find a shematic for you at this web site http://www.drtube.com/schematics/mar...v100-62-02.pdf
please help me
donnie

[Jazz P Bass]

With the power off try testing T9,T10 & T11,T12 for a shorted condition.
These are the output transistors.
T1 is 1/2 of the differential pair input stage.

[guitardude10890]

i tested T9 T10 T11 and T12 and they all checked out fine what eles should i check

[Jazz P Bass]

I would start at the beginning.
The lower part of the schematic is the power supply.
There is also the preamp to consider. That is where the tubes are.
The IC's need + - 15 volts.
Check T 13,14 & 15 of the power supply.
All the diodes, specifically the bridge rectifier.
It looks like Conn 14 can be disconnected. If so disconnect it from the rest of the amp. That is your high voltage rails.
I do not know what equipment you have. A variac would be nice. An ammeter in series is always good.
Short of that a 60 watt lamp in series with one of the AC legs will help.

[guitardude10890]

ok i still need to test T 13 14 and 15 i already know all the diodes are good because thats the one of the first things i did and their all good and my dad put a new bridge rectifier in it so i know thats good so ill get on testing T13 14 15 thanks again Donnie T

[guitardude10890]

i have tested T13 14 15 and they all look good this thing is being a pain

[Jazz P Bass]

At this point you have to back up.
You have the schematic, right.
Start at the beginning.
Disconnect the load off of the power supply.
+L & -L are on one connector.
Disconnect it.
Power up the amp & check +L & -L.
These are your high voltage rails.
If o/k, move on to the IC voltages. +15Vdc & -15Vdc.
If o/k then you have to find exactly what is "loading down" the power supply.
Start there.
Isn't this Fun!