Tek 465 - no trace after shipping

[nick]

The scope looks good and I know the previous owner had no problems with
it. So it was shipped FedX from AZ to NM and arrived with one of the cord
winding feet broken (the one closest to the power supply). It was packed
well but must have taken a good jolt.

No trace. Now this is my first scope and it came with the manual which had
a nice "Basic Oscilloscope Displays" section to get the thing lit up and
take you through the features. I went through it many times double
checking everything and then tried a similar step by step that I found on
the internet.

The backlight on the crt works and is adjustable, the backlights for the
dials light and the fan goes on. The fuse on the bottom circuit board is
ok.

I think whatever is wrong may be related to the jolt it took in shipment.

I wiggled all the connectors I could find but still no trace.

Have you ever run into a similar problem with a similar scope?

Thank you for any info or suggestions,
Nick

 

[Jim Yanik]

The scope looks good and I know the previous owner had no problems
with it. So it was shipped FedX from AZ to NM and arrived with one of
the cord winding feet broken (the one closest to the power supply). It
was packed well but must have taken a good jolt.

No trace. Now this is my first scope and it came with the manual which
had a nice "Basic Oscilloscope Displays" section to get the thing lit
up and take you through the features. I went through it many times
double checking everything and then tried a similar step by step that
I found on the internet.

The backlight on the crt works and is adjustable, the backlights for
the dials light and the fan goes on. The fuse on the bottom circuit
board is ok.

I think whatever is wrong may be related to the jolt it took in
shipment.

I wiggled all the connectors I could find but still no trace.

Have you ever run into a similar problem with a similar scope?

Thank you for any info or suggestions,
Nick

Best way to pack a scope;pour styrofoam peanuts into plastic bags,making
'pillows' of them,tape closed,and use them to pack tightly around the
scope.The bags need to be at least 4 inches thick,*all around* the
scope.I've seen too many damaged items where the unit was placed on top of
a bed of loose styro peanuts and after shipping,drifted to the bottom of
the box with NO protection from shocks.the peanuts were all on TOP of the
unit,useless.



Now for your non-working scope,you need to remove the case,and check the
CRT neck pins to see if one has come off the CRT neck pins.Did you hear any
sound of the CRT anode supply charging up the CRT capacitance? You can
often hear the crackle as the faceplate develops a charge.With the case
off,you can check the HV supply fuse to see if it's broken,or slipped out
of the holder.You can also check the LV supplies with a DMM to see if they
are correct.Tilt the scope and see if you can hear any tinkle of
glass,indicating the CRT neck cracked;or you may see small particles on the
CRT faceplate.(phosphor).If so,you need a replacement CRT.

 

[nick]

Best way to pack a scope;pour styrofoam peanuts into plastic bags,making
'pillows' of them,tape closed,and use them to pack tightly around the
scope.The bags need to be at least 4 inches thick,*all around* the
scope.I've seen too many damaged items where the unit was placed on top of
a bed of loose styro peanuts and after shipping,drifted to the bottom of
the box with NO protection from shocks.the peanuts were all on TOP of the
unit,useless.

I will drink to that...

Now for your non-working scope,you need to remove the case,and check the
CRT neck pins to see if one has come off the CRT neck pins.

All pins attached solidly; pulled the plug off and reinstalled.

Did you hear any sound of the CRT anode supply charging up the CRT
capacitance?
Yes

With the case off,you can check the HV supply fuse to see if it's broken,
or slipped out of the holder.

The only fuse I can see is on the bottom circuit board near the lv power
supply and it is OK.

You can also check the LV supplies with a DMM to see if they are correct.

I have a manual for a 465B (this scope is a 465) and the components on the
bottom board do not coincide with the circuit diagrams in the manual
though they are similar. I need to find a 465 service manual.

There are test pads on the board with leads coming from the lv supply.
Voltages on these are:
1 - +4.03
3 - +77.90
4 - +9.68
6 - +1.96
7 - +77.81
9 - +77.38

Tilt the scope and see if you can hear any tinkle of glass,indicating
the CRT neck cracked;or you may see small particles on the CRT faceplate.

No sound of anything loose and no spots on the faceplate after tilting the
faceplate down and shaking.

Thank you,
Nick

 

[Sam Goldwasser]

No sound of anything loose and no spots on the faceplate after tilting the
faceplate down and shaking.

Not sure if you checked but can you see if the CRT filament is lit?

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

 

[nick]

Not sure if you checked but can you see if the CRT filament is lit?

Looking from the back (around sides of plug) and from the side (where two
wires pass through a one inch hole in the circuit board to the tube),
during the day, I can see nothing light up in the tube.

 

[Sam Goldwasser]

Looking from the back (around sides of plug) and from the side (where two
wires pass through a one inch hole in the circuit board to the tube),
during the day, I can see nothing light up in the tube.

I haven't checked mine but I would expect there to be at least some hint
of an orange glow inside the tube. Check for voltage on the filament pins.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

 

[Jim Yanik]

I will drink to that...

All pins attached solidly; pulled the plug off and reinstalled.


The only fuse I can see is on the bottom circuit board near the lv
power supply and it is OK.


I have a manual for a 465B (this scope is a 465) and the components on
the bottom board do not coincide with the circuit diagrams in the
manual though they are similar. I need to find a 465 service manual.

There are test pads on the board with leads coming from the lv supply.
Voltages on these are:
1 - +4.03
3 - +77.90
4 - +9.68
6 - +1.96
7 - +77.81
9 - +77.38

Are these from the motherboard?(large PCB on bottom of scope)
These voltages seem to be in error.It could be something simle as a failed
LVPS bridge rectifier,or some component loading down a supply and skewing
all the rest of them.(some of the LV supplies depend on others for proper
operation) Or you could have a loose nut or screw jammed somewhere between
a PCB and the chassis.

IIRC,you should have a -8v,+5v,+15v,+50v,-50v,+110v.

The 465B supplies should be similar enough to the 465 for your purposes.
The manual should show the PS test points(on the motherboard) and the specs
for the LV supplies.

 

[Jim Adney]

I haven't checked mine but I would expect there to be at least some hint
of an orange glow inside the tube. Check for voltage on the filament pins.

Do this in a room at night with the lights off. It may be a very dim
glow.

-

 

[nick]

Are these from the motherboard?(large PCB on bottom of scope)
These voltages seem to be in error.It could be something simle as a failed
LVPS bridge rectifier,or some component loading down a supply and skewing
all the rest of them.(some of the LV supplies depend on others for proper
operation) Or you could have a loose nut or screw jammed somewhere between
a PCB and the chassis.

OK, I found the TP's on the board and they are marked with voltages.
Disregard the above voltages as they were taken from the wrong area on the
CB. Here are the new readings:

spec marked at tp my measurement
--------------------------------------
8 -7.98
+15 +14.98
+55 +55.05
+5 +5.01
+110 +107.94

I'm guessing this is whithin spec.

I have a high voltage probe on order and will not be able to test the
-2450 TP until it arrives.

I measured the voltages on the small wires of the CRT neck plug. I can't
find specs on the big wires so I was reluctant to test them until the HV
probe arrives. Here are the measurements from the small wires:

contact number voltage
-------------------------------
5 +40.80
7 +32.80
8 +55.20
10 +79.30
12 -153.40

I also tested between contacts 1 and 14 on the tube which showed
continuity.