[time-nuts] OT - Tek 7L18 ROM

[Christopher Hilton-Johnson]

Chuck Harris wrote;
>That is an issue that needs to be re-emphasized.  You can't read
>the EPROMS in a 7L18 without using multiple rail supplies.  +5V
>alone won't do it.

The ROMS in the -01 version of the micro board are MCM68316E and are 5v
items.

>Also, the 7L18 draws too much power for any of the 4 slot scopes.
>In spite of what the manual says, It is designed to operate in one
>frame only, the 7603.

May be so, but both my 7L18s work happily in 4 slot mainframes & on
flexible extenders as well, either with or without another PI in the
left most compartment.  All contacts must be clean though & no dicky
tantalums etc.

>The biggest problem I found with mine was the tantalum electrolytic
>caps on the mother board kept failing.  Also there are a pair of
>shottky RF diodes being used as +/- 15V power supply isolation diodes
on
>the YIG oscillator that fail, killing the phase lock capabilities.
>They need to be replaced with some real diodes ;-)

Oh yes indeed, and in many of the other sub assemblies as well eg PLL
for a start.

Chris HJ