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From: paf@murdu.OZ (Paul Fritze)
Newsgroups: net.micro.mac
Subject: Analog board failures
Message-ID: <1153@murdu.OZ>
Date: Fri, 25-Jul-86 04:09:30 EDT
Article-I.D.: murdu.1153
Posted: Fri Jul 25 04:09:30 1986
Date-Received: Fri, 25-Jul-86 21:09:18 EDT
Distribution: world
Organization: Chem Dept, Melbourne Uni, Australia
Lines: 26
cc: paf



Does anyone know of a source for the Mac analog board line output transformers?
Apparently the early version (black) transformers have proved a common cause of
board failure - 3 of ours out of 20 failed in the past year (2 this week!) -
seems a pity to send a board back when the cause is known.
 
These failures were characterized by assorted crackling, dead or flashing
screen
and smoke from the LHS vents - the BU406 driver transistor (on the heatsink to
the front) was shot in one case and cooking in another. In the last failure,
sparks could be seem emanating from the transformer.
 
Another problem characterized by dead screen and ticking noise was caused by
shorted diode on heat sink immed. in front of transformer causing 12V supply to
fail.
 
The newer apparently reliable transformer (grey) in the latest Mac+ supplied to
us is marked:     MONITRON 157 0026-B  made in Taiwan


-- 
Paul Fritze
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