Can we get plugin lamps working in the Tektronix 7603?

Most of the plugins for the Tek 7603 workhorse scope will not show
their lights when their switches are pushed in with the 7603 (and
apparently a lot of other early Tek scopes), whereas they do show in
the 7904 and other high numbered models. Is their a way to rectify this
on the 7603?

 

[Robert Baer]

bobd426@yahoo.com wrote:

Most of the plugins for the Tek 7603 workhorse scope will not show
their lights when their switches are pushed in with the 7603 (and
apparently a lot of other early Tek scopes), whereas they do show in
the 7904 and other high numbered models. Is their a way to rectify this
on the 7603?

Look at the schematic of a plugin that works that way, and see what
voltage line at the connector is used for those lights.
This assumes that there is a unique line for that function.
If so, then modify the scope to supply that voltage.

The schematic to my R7704 shows: pin 14A as lights common and pin 9A
as +5 lights, so the lights are indeed seperate.
he power supply has, in efect, a seperate winding and rectifier for
the +5v lights line (unregulated).

 

[Jim Yanik]

Robert Baer <robertbaer@earthlink.net> wrote in
news:41F4A47A.21293B6B@earthlink.net:

bobd426@yahoo.com wrote:

Most of the plugins for the Tek 7603 workhorse scope will not show
their lights when their switches are pushed in with the 7603 (and
apparently a lot of other early Tek scopes), whereas they do show in
the 7904 and other high numbered models. Is their a way to rectify this
on the 7603?

Look at the schematic of a plugin that works that way, and see what
voltage line at the connector is used for those lights.
This assumes that there is a unique line for that function.
If so, then modify the scope to supply that voltage.

The schematic to my R7704 shows: pin 14A as lights common and pin 9A
as +5 lights, so the lights are indeed seperate.
he power supply has, in efect, a seperate winding and rectifier for
the +5v lights line (unregulated).

and look at the interface schematic of the 7603 and see if there's a line
that supplies power to the plug-ins for the lights.

I would not fix what is not broken.

--
Jim Yanik
jyanik
at
kua.net

 

[CBarn24050]

Subject: Re: Can we get plugin lamps working in the Tektronix 7603?

The diagram doesn't show a 5v supply for the lights. You could take a supply
from the graicule lamp supply (12v unreg) through a 7805 regulator and down to
the interface board. But is it worth it?

 

Thanks for the insights so far!

The 7603 does not furnish power to the plugin lamps on the plugin
connections used for that purpose on later 7XXX scopes. It would seem
so easy to do this, that I can't believe Tektronix did not do it, as
some plugins obviously could use it to help the operator easily see
their state, like the 7S11 and 7T11 and some of the timebases.

Interestingly, the 7D20 plugin has a ton of lamps and it would be very
difficult to use if they did not light. The lamps light on the 7603
using special 5V(sub)L (Lamp?) power generated from the host's +15V via
a convertor on the 7D20's PS board.

I guess I was looking for why Tektronix did not do it before I burn up
a plugin or scope power supply modifying my 7603 by running 5V to the
proper pin. Maybe it is as simple as some plugins would draw too much
from the +5 volt line lighting the lamps.

Does anyone see any reason that Tektronix did not do this "simple"
thing to make some plugin's more effective?

 

[Jim Yanik]

bobd426@yahoo.com wrote in
news:1106732521.616602.276500@z14g2000cwz.googlegroups.com:

Thanks for the insights so far!

The 7603 does not furnish power to the plugin lamps on the plugin
connections used for that purpose on later 7XXX scopes. It would seem
so easy to do this, that I can't believe Tektronix did not do it, as
some plugins obviously could use it to help the operator easily see
their state, like the 7S11 and 7T11 and some of the timebases.

Interestingly, the 7D20 plugin has a ton of lamps and it would be very
difficult to use if they did not light. The lamps light on the 7603
using special 5V(sub)L (Lamp?) power generated from the host's +15V via
a convertor on the 7D20's PS board.

I guess I was looking for why Tektronix did not do it before I burn up
a plugin or scope power supply modifying my 7603 by running 5V to the
proper pin. Maybe it is as simple as some plugins would draw too much
from the +5 volt line lighting the lamps.

That is probably why.
IIRC,those tiny lamps draw around 60ma each.

Does anyone see any reason that Tektronix did not do this "simple"
thing to make some plugin's more effective?

Only the TEK engineers know for certain.

--
Jim Yanik
jyanik
at
kua.net