Marshall Master Lead combo, 1978

[N_Cook]

In for more basic problem but query here , should anyone know, as only a
Polish reference out there.
All seems original in there and o/p devices TO3 Motorola, badged SCSP1 and
SCSN1.
Presumably , as only +/-24V rails 3055/2955 would be adequate , if required,
but if anyone knows for sure, for future reference.

 

[Adam Sampson]

All seems original in there and o/p devices TO3 Motorola, badged SCSP1
and SCSN1. Presumably , as only +/-24V rails 3055/2955 would be
adequate

This schematic shows MJ3001 and MJ2501 as equivalents for SCSN1 and SCSP1:
http://www.drtube.com/schematics/marshall/2099u.gif

These are Darlington pairs, so they have much greater hFE than the
2N3055/MJ2955. They're only about a fiver a pair from Farnell.

 

[Phil Allison]

"Nutcase_Kook"

In for more basic problem but query here , should anyone know, as only a
Polish reference out there.
All seems original in there and o/p devices TO3 Motorola, badged SCSP1 and
SCSN1.
Presumably , as only +/-24V rails 3055/2955 would be adequate , if
required,
but if anyone knows for sure, for future reference.

** The devices are DARLINGTONS - dickhead.

Did you not notice the total absence of DRIVER transistors - eh ???

The pair are MJ2501 and MJ3001.




..... Phil

 

[N_Cook]

This schematic shows MJ3001 and MJ2501 as equivalents for SCSN1 and SCSP1:
http://www.drtube.com/schematics/marshall/2099u.gif

These are Darlington pairs, so they have much greater hFE than the
2N3055/MJ2955. They're only about a fiver a pair from Farnell.

The info is out there, for all, in ASCII format now

 

[Phil Allison]

"Adam Sampson"

This schematic shows MJ3001 and MJ2501 as equivalents for SCSN1 and SCSP1:
http://www.drtube.com/schematics/marshall/2099u.gif

These are Darlington pairs, so they have much greater hFE than the
2N3055/MJ2955. They're only about a fiver a pair from Farnell.

** If someone fits 2N3055s and MJ2955s instead of the correct types, the
transistors will run hot but deliver low power.

Seen done it a few times and the repair tech could not figure it out.


..... Phil