开云体育

A while ago we had some discussion of the Chinese "GT-2" copy of the Tek
570.

Now a friend has sent me this Czech auction listing, which appears to show
a Russian copy of a Tek 575 curve tracer:

Hello from China!
The Chinese QT-2 is a copy from TEK570, not GT-2.Maybe Cninese JT-2 copy from TEK575.
Hsu

Just turned off the auto-ranging and took readings again. They all read about .003VAC
except the +55 rail. It reads .040VAC. Is that enough to cause my problem?

--- In TekScopes@..., "jordankersten" <jordankersten@...> wrote:

I checked my DC voltages for ripple by using my dmm in AC mode and measuring the

DC

levels. On the +5 rail I got .003VAC, on the -8 rail I got .007VAC, on the +55 and +15
rails my meter made this never-ending cycle of auto ranging and wouldn't show a

reading.

Does this mean I've got ripple? It's not showing AC voltages anywhere they're not
supposed to be and I think I recall using this DMM approach to finding ripple and the

auto

ranging thing did the same thing, but that scope was fine.

--- In TekScopes@..., "rlc9878" <rchildre@> wrote:

I also have the same issue with my Tek 465 scope. A picture was added
to your photo album:


These are my settings:

1) Set Horizontal sweep to 5 milliseconds per division.
2) Set Vertical to Channel 1.
3) Set Channel 1 to Ground.
4) Center trace vertically.
5) Set Trigger Mode to NORM
6) Set Trigger Source to Line to synchronize to 60 HZ.
7) Reduce the intensity (counter-clockwise) to a bare minimum to see the
trace.

I'm thinking +15V power supply is the culprit, but not sure.
Unfortunately, I don't have another scope to test this one. Using the
scope to test itself is no good because the blanking circuit blanks
it's own trace.

But, it's definitely caused by 60 HZ noise, somewhere...
Ron





--- In TekScopes@..., glydeck@ wrote:

Jordan,
Absolutely. If your triggering off of the mains, and the dashes

are in sync

with the mains it pretty much proves that the Z modulation is most

likely

supply hum. I would agree with your assessment of the power supply

caps being

suspect. That was the root cause when I fixed my 533A. Your 465

is truly a

great scope that you will enjoy when you get it all tuned up.

Good luck,

George



In a message dated 9/29/2008 4:45:05 P.M. Pacific Daylight Time,
jordankersten@ writes:

Also, the dashes in the lines move along the trace...if the trigger

is set

to Line, the dashes stop and the trigger led lights. Would this be

a sign that

it's AC line hum? If so, would power supply caps be the likely cause?

~Jordan~







****Looking for simple solutions to your real-life financial
challenges? Check out WalletPop for the latest news and

information, tips and

calculators. ()

I checked my DC voltages for ripple by using my dmm in AC mode and measuring the DC
levels. On the +5 rail I got .003VAC, on the -8 rail I got .007VAC, on the +55 and +15
rails my meter made this never-ending cycle of auto ranging and wouldn't show a reading.
Does this mean I've got ripple? It's not showing AC voltages anywhere they're not
supposed to be and I think I recall using this DMM approach to finding ripple and the auto
ranging thing did the same thing, but that scope was fine.

The state of the store is normal I've been shopping there for 20+ years and they have moved most of the test equip to Ebay as the Tech industry is dead in NH so there are few local customers. What they have in the store now is mainly small parts and industrial surplus (for which there still is a local market) they are also the local NTE parts distributor. But if you do buy the stuff on ebay you can pick it up there saving on the shipping.



Ebay wrote:

I also have the same issue with my Tek 465 scope. A picture was added
to your photo album:


These are my settings:

1) Set Horizontal sweep to 5 milliseconds per division.
2) Set Vertical to Channel 1.
3) Set Channel 1 to Ground.
4) Center trace vertically.
5) Set Trigger Mode to NORM
6) Set Trigger Source to Line to synchronize to 60 HZ.
7) Reduce the intensity (counter-clockwise) to a bare minimum to see the
trace.

I'm thinking +15V power supply is the culprit, but not sure.
Unfortunately, I don't have another scope to test this one. Using the
scope to test itself is no good because the blanking circuit blanks
it's own trace.

But, it's definitely caused by 60 HZ noise, somewhere...
Ron





--- In TekScopes@..., glydeck@... wrote:

Jordan,
Absolutely. If your triggering off of the mains, and the dashes

are in sync

with the mains it pretty much proves that the Z modulation is most

likely

supply hum. I would agree with your assessment of the power supply

caps being

suspect. That was the root cause when I fixed my 533A. Your 465

is truly a

great scope that you will enjoy when you get it all tuned up.

Good luck,

George



In a message dated 9/29/2008 4:45:05 P.M. Pacific Daylight Time,
jordankersten@... writes:

Also, the dashes in the lines move along the trace...if the trigger

is set

to Line, the dashes stop and the trigger led lights. Would this be

a sign that

it's AC line hum? If so, would power supply caps be the likely cause?

~Jordan~







****Looking for simple solutions to your real-life financial
challenges? Check out WalletPop for the latest news and

information, tips and

calculators. ()


[Non-text portions of this message have been removed]

I have to retract my recommendation for esssurplus. I visited today, and the store is pretty much cleared out. Looks like they are moving exclusively to eBay. There is still some very vintage equipment in the store, but not much of value. Coincidentally their eBay listings now have a lot more small items listed.

Also, the dashes in the lines move along the trace...if the trigger is set to Line, the dashes
stop and the trigger led lights. Would this be a sign that it's AC line hum? If so, would
power supply caps be the likely cause?

Also, the dashes in the lines move along the trace...if the trigger is set to Line, the dashes stop and the trigger led lights. Would this be a sign that it's AC line hum? If so, would power supply caps be the likely cause?

~Jordan~

glydeck@... wrote:

If it's 5 ms / div I'd suspect power supply hum. I had a symptom on a 533A
that looked like that.

He said 2 mS, but that's the culprit. ~8 mS period is roughly
120 Hz. There will be much hum on at least one test point.

-ls-

I added some more photos with a signal attached. You can see some "ghosting" in the signal and some noise as well.

~Jordan~

Jordan Kersten <jordankersten@...> wrote:

Photo was added under an album named "Tek 465B Z-axis?" It shows no
signal, just a trace showing the problem.

What's your time/div setting for the picture?
-ls-

Photo was added under an album named "Tek 465B Z-axis?" It shows no signal, just a trace showing the problem.

~Jordan~

Hi Scott from Vermont here.

I've been using TEK gear since college in 81 ( you figure my age)

I have a 336 SonyTek scope which is in great shape cept the power
supply won't light up.

I dont think it's a major thing but if there's a schematic out there
for the power supply, I'd be like "whoopie!!" if I could get one.

I also own a 547 ( screen-timebase issue project) and an LC30 L/C meter

Thanks

Anyone know how to attach pics in this forum?

~Jordan~

Hello everyone, I have a Tektronix 465B with a small issue: There seems to be some Z-axis modulation of some kind. I will attach a pic of the screen. When there is supposed to be a straight trace, you get some chops in the trace. It is most noticeable at slower times. Also, at faster times, there is a slight bending up of the beam on the left side. Any ideas? ~Jordan~

Jordan,
Absolutely. If your triggering off of the mains, and the dashes are in sync
with the mains it pretty much proves that the Z modulation is most likely
supply hum. I would agree with your assessment of the power supply caps being
suspect. That was the root cause when I fixed my 533A. Your 465 is truly a
great scope that you will enjoy when you get it all tuned up.

Good luck,

George

Hi Kelvin:
Who are you and where are you. Asking for help and not giving an address is rather short sighted. Lets try again,
Deane E. Kidd
27270 S.W. Ladd Hill Rd.
Sherwood, OR. 97140


From: Kelvin
To: TekScopes@...
Sent: Sunday, September 28, 2008 11:36 PM
Subject: [TekScopes] DM44 badly behaved


I have just accepted a Tek475A plus DM44 for the school electronics
club. However, the DM44 has some problem with the display multiplex.
Does anyone have aschematic diagram they can send to me please?
Thanks

Ahh...Good point. Forgot the part where it's a full wave bridge. -- George

Jordan,

For your scope there should be a big knob just to the right of the screen.
Just above the knob it will be marked A and B, Time/Div, and Delay Time. You
should have a clear skirt on the knob with two black lines radiating from
the center. The value (number) that is between those two black marks is the
current time per division. setting of the timebase.

I suggested 5 ms only because there were three dark lines in the trace, and
at that time base setting that would be just enough time for approximately
three cycles of 60 Hz across the screen.

George