Re: [dead tek 485] Can i fix it ? (newbie here)

Harvey White

In most of the manuals of that era (and they got less detailed and less "nice" as time went on....

You'll find that Tektronix published a lot of theory of how their scopes worked.  They also had troubleshooting information, check A, then B, then C, and so on.  They had performance verification, and also calibration procedures.

It's going to be worth it to get a good manual (I can recommend ARTEK, for one) for the appropriate serial number range for your scope, they cost (typically) under 20 USD, and the ones from ARTEK are particularly nice.  A problem with some other scans is that they are low resolution, which means that when you zoom in to get the value or designation of a part, those numbers are just blocks.  Check around, and if there's a good high resolution scan, it's preferable, perhaps even if you need to spend money. However, you can start with the free stuff and spend money if you need to.

With any piece of electronic equipment, it naturally floats or sinks depending on the power supply voltages.  TTL chips, for example want 5.0 volts + .25, or -.25, but won't be guaranteed to function properly at all conditions if the supply voltage is outside those limits.  Tektronix was very good at telling you the voltage ranges, and (almost equally important) the ripple of those voltages.  Once you start looking at the power supplies, you may well need another oscilloscope for measurements that a multimeter just won't do.

First check the supplies, then go from there.


On 1/6/2021 4:02 PM, wrote:
Hi guys

Happy New Year to all.

I'm new in the group.
I've bought a working (supposed to) Tek 485 for a few euros here in France : received it and tried it for ~10mn. I powered it off and cannot power it on again...
I know this is an old beast but I'd really like to have it up and running on my hobbyist electronic bench.

=> I'm not an electronics expert but know how to read schematics, use a multimeter and a soldering iron to replace faulty components. I'm in my fifties and thus understand perfectly the dangers of dealing with High Voltages....
Do you think fixing this 485 scope is within my reach, with my basic knowledge ?

I've got the Service Manual and probably my first steps will be follow Reed Dickinson "Troubleshooting tips" from this topic :

I'll be glad to ear from you, any advice will be really appreciated !
Thanx in advance.

Jose L. Marcos

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