Tektronix 7633 cannot accept 7L13

[Mat Nieuwenhoven]

Hi,

I've tried to fit a 7L13 into a 7633, and it won't go in completely, the last
2 mm get stuck. Other modules go in OK, the 7L13 is somewhat longer at the
left side. The problem turns out to be caused by metal cover plates over the
two PCBs that are between the vertical module connectors at the back of the
bottom space where you put in the modules. If I remove the cover plates, it
is OK. The exploded drawing in the service manual doesn't show these plates.
The PCBs are labeled there A4 (left PCB, trigger selector if I understand
correctly), and A4 (vertical interface).

Question: are these cover plates original? Can they be removed without bad
effects? The 7633 serial number is 704234 . I have seen a 7613 without these
covers.

Thanks, Mat Nieuwenhoven

 

[Jim Yanik]

"Mat Nieuwenhoven" <m.w.c.nieuwenhoven@dontincludethis.upcmail.nl> wrote
in
news:zjpavrhjraubiraqbagvapyhqrguvfhcpznvyay.jxyi1z0.pminews@news.chello.
nl:

Hi,

I've tried to fit a 7L13 into a 7633, and it won't go in completely,
the last 2 mm get stuck. Other modules go in OK, the 7L13 is somewhat
longer at the left side. The problem turns out to be caused by metal
cover plates over the two PCBs that are between the vertical module
connectors at the back of the bottom space where you put in the
modules. If I remove the cover plates, it is OK. The exploded drawing
in the service manual doesn't show these plates. The PCBs are labeled
there A4 (left PCB, trigger selector if I understand correctly), and
A4 (vertical interface).

Question: are these cover plates original? Can they be removed without
bad effects? The 7633 serial number is 704234 . I have seen a 7613
without these covers.

Thanks, Mat Nieuwenhoven

I don't recall seeing cover plates on any 7633 interface boards while I
worked at TEK(US-Orlando). I'm fairly sure you can remove them without
problem.

I believe you should check your LV PS electrolytics,and IIRC,there was a
fan mod for 7600 scopes using 7L spec analyzer PIs.
The SA plug-ins draw a lot more current and make a lot more heat.

You also may have to change a current limit resistor on the LV regulator
PCB.
IIRC,you bridge one of the current-limit resistors with another to raise
it's current limit point.

Unfortunately,I can't recall which one or the values.Sorry about that.
The service manual schematic may show the change.
and it may already have been done to your scope.

--
Jim Yanik
jyanik
at
kua.net

 

[Mat Nieuwenhoven]

On 18 Mar 2008 21:53:17 GMT, Jim Yanik wrote:

"Mat Nieuwenhoven" <m.w.c.nieuwenhoven@dontincludethis.upcmail.nl> wrote
in
news:zjpavrhjraubiraqbagvapyhqrguvfhcpznvyay.jxyi1z0.pminews@news.chello.
nl:

Hi,

I've tried to fit a 7L13 into a 7633, and it won't go in completely,
the last 2 mm get stuck. Other modules go in OK, the 7L13 is somewhat
longer at the left side. The problem turns out to be caused by metal
cover plates over the two PCBs that are between the vertical module
connectors at the back of the bottom space where you put in the
modules. If I remove the cover plates, it is OK. The exploded drawing
in the service manual doesn't show these plates. The PCBs are labeled
there A4 (left PCB, trigger selector if I understand correctly), and
A4 (vertical interface).

Question: are these cover plates original? Can they be removed without
bad effects? The 7633 serial number is 704234 . I have seen a 7613
without these covers.

Thanks, Mat Nieuwenhoven




I don't recall seeing cover plates on any 7633 interface boards while I
worked at TEK(US-Orlando). I'm fairly sure you can remove them without
problem.

Thank you for your reply. I've removed them. The scope came originally from a
professional UHF/SHF equipment designer, I've mailed him if he had added them
(and why).

I believe you should check your LV PS electrolytics,and IIRC,there was a
fan mod for 7600 scopes using 7L spec analyzer PIs.
The SA plug-ins draw a lot more current and make a lot more heat.

You also may have to change a current limit resistor on the LV regulator
PCB.
IIRC,you bridge one of the current-limit resistors with another to raise
it's current limit point.

Unfortunately,I can't recall which one or the values.Sorry about that.
The service manual schematic may show the change.
and it may already have been done to your scope.

I don't think it is a problem. I measured power consumption with a 7B53A /
7A22 / 7A26 combination at 146W (230V) . With the 7L13 it is actually slighty
less, 145 - 141 W . But I'll check the manual anyway. The backplate of the
scope says 'max 170 W' .

Thanks again, Mat Nieuwenhoven