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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Marshall Master Lead combo, 1978
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. |
#2
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Marshall Master Lead combo, 1978
"N_Cook" writes:
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. -- Adam Sampson http://offog.org/ |
#3
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Marshall Master Lead combo, 1978
"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 |
#4
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Marshall Master Lead combo, 1978
Adam Sampson wrote in message
... "N_Cook" writes: 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. -- Adam Sampson http://offog.org/ The info is out there, for all, in ASCII format now |
#5
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Marshall Master Lead combo, 1978
"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 |
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