Tektronix 4051 repair.

[Pete Lancashire]

I would start looking at the Display DACs (Vol 2 p 2-10, and 2-11)  Each
DAC consists of a 6820 PIA, then LS TTL Latches, diodes, and discrete & dip
resistor arrays. Then an OP Amp. to do the summing. Today it would all be
one IC.

In character mode these two DACs set the base position of each character,

Bring the cursor up to the top left and as you type look at the output of
the X DAC it should be a staircase, Do the same with the Return key, and
watch the Y DAC.

The Bottom of 2-11 are the DACs that are the dot positions for each
character.

Vol 1 pages 6-19, 20 , 21 and 22 describe how the DACs work

Manuals are on bitsavers

http://bitsavers.informatik.uni-stuttgart.de/pdf/tektronix/405x/







On Thu, Sep 22, 2016 at 12:19 PM, jim stephens <jwsmail at jwsss.com> wrote:

>
>
> On 9/22/2016 12:08 PM, Charles Anthony wrote:
>
>>
>>> Before the smoke escaped I recorded this short videoclip to show the
>>> behavior when typing on the machine and running simple PRINT/GOTO
>>> program.
>>>
>>> http://sendvid.com/k4s7k806
>>>
>>> This link took me a fake virus warning honey trap.
>>>
>> -- Charles
>>
>>
>> Sendvid may be a honeytrap, but in lynx on linux, where i usually test
> such, it went to sendvid and sent two cookies.  Probably safe.
>
>