[time-nuts] OT - Tek 7L18 ROM
Chuck Harris
cfharris at erols.com
Mon Nov 9 13:12:54 UTC 2009
Hi Dave,
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.
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.
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 ;-)
-Chuck Harris
Dave Baxter wrote:
> If no one else has said this.
>
> Check the mainframe power supplies. The 7L18 is a thirsty beast.
>
> If anyone can back up the rom images, well done. It's one of the
> "classic" machines internally driven by the "Original" microprocessor,
> the Intel 4004! The Rom's will be of a similar vintage, multi rail
> supplies etc I suspect.
>
> (I've only ever seen one other instrument that used a i4004 CPU, a
> Finnegan GC oven!)
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