[time-nuts] OT - Tek 7L18 ROM

[Adrian]

Christopher Hilton-Johnson schrieb:
>> Hello all,
>>     
>
>   
>> I have an old 7L18 spectrum analyzer that used to serve me well on the 
>> higher bands.
>> Unfortunately, the controls have got into complete disorder.
>> It seems like one or both of the ROM's are dead.
>>     
>
>   
>> Anyone have / knows where to find ROM images of the 7L18?
>>     
>
> Adrian
> Can I suggest you post this to the tekscopes group - they have answers
> to pretty well everything Tek
> Having said that I do not know of any ROM images out there - I have 2
> 7L18s but have never got around to making ROM backups - never been able
> to find the ROMs to burn.
>
> Assuming it is the digital section at fault (eg no panel controllable
> frequency on the readout display)Several pointers;
> 1) If not used for a long time, the connectors, both internal and to the
> mainframe can go very dirty.  The PI uses lots of power & needs every
> connector to be doing its job.  Some users say remove & slam in the PI
> several times to help wake it up (very brave/stupid ones do it with
> power on)
> 2) digital parts can be affected by gone bad electrolytics pulling down
> the supplies or eg: affecting the processor reset circuit.
> 3) in my case the processor board had a defective RAM - no response to
> controls because no boot, although it would get to different stages of
> the boot process before halting.  (Got a replacement chip from that
> auction house)
> 4) because the various sub sections/boards are so interconnected the
> best way to trouble shoot is to have a 2nd 7L18 (or at least a second
> processor board)available for board substitution.
> 5) you can make extenders which allow board level trouble shooting - the
> digital bit runs quite slowly and a logic analyzer will help if the
> problem lies further down the line.
> 6) finally, if you can back up the ROMs, I would like to place an order
> for a set!
>
> Chris HJ
>
>
>   
Chris,

thanks for the hints.

I found two Tek groups, but none of them allows to read posts w/o 
joining. So, I can't tell which one to join.

I've already tried the plugin in my special home-brew test bed, which is 
a parted out mainframe with the backplane board cut out.of the chassis, 
so I can connect  the required supply voltages) while I'm working on the 
open plugin.

Most of the front panel controls do 'something', but not what they are 
intended to. So, I can hear some relays clicking when I turn the span or 
sweep knobs, but the trace doesn't chang accordingly. Also, the ref 
level display is frozen, and on the center frequency display some digits 
are dark, though it changes in a chaotic manner when I'm turning the 
knob. Thus, it seems like the program is generally running, but it 
behaves as if the according data are totally corrupted.

I could read ROM 1, but it was not stable. At least I managed to get an 
image that could 3...4 times be successfully compared to the ROM.
ROM 2, however, contains only 'CA's, though changes into various 
patterns when knocked, warmed up or cooled.
So, given I have some luck, ROM 1 is still alive, but ROM 2 is likely 
defective.
Btw. I figured out that the ROM's are mostly compatible with M2716's. 
Just Vpp (pin 21) would have to be connected to +5V to get the M2716 
running in the instrument (the origlan ROM's have pin 21 tied to GND).

Adrian