开云体育

There's going to be some normal AC voltage detected with a Digital
Volt meter on the input to the blanking circuit. That's because the
0.5 signal is momentarily forced to -8 V at the end of each horizontal
sweep to blank the trace while moving back to the left-hand side of
the screen.

The AC is not sinusodial, but pulsed in nature. The expected signal
measured at test point 87 is shown here:



It is believed the vertical scales published in graph 87 and 88 are
not correct.

Another potential +5 volt noise blanking source is applied to the base
of Q1466 through voltage divider R1466 and R1467. A changing +5 volts
here would definitely vary the blanking threshold voltage at 120 HZ!
This adds additional weight to support the current +5 volt noise
blanking theory.

It all points back to capacitor C1512 or C1513. Can anyone recommend
a supplier for these caps. The parts list calls for Sprague
capacitors, now called Vishay / Sprague. Mouser and DigiKey carry
Sprague capacitors, but can't find the exact replacement parts in
their on-line catalogues.

Ron




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

I checked the blanking input and it reads .5VDC...right where it

should be. However,

.090VAC was also present. Does this seem like I've got some ripple

in my blanking input?

Would that bad/leaky 110V supply cause this?

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

Notice the Regulated +55 Volts signal through the Zener VR1515 at the
bottom of the 110 Volt regulator circuit? It is believed the root
cause is 120 HZ noise on the +55 Regulated supply.




A careful inspection of the +5 volt regulator circuit reveals that
regulated +55V also supplies a voltage divider circuit (R1559 and
R1554) to provide a +5 voltage reference to OP amp U1554A, pin 9. If
the +55 V signal is noisy, the same noise will be reflected in the +5
volt signal with a ratio of approximately 1/10 amplitude of the +55
volt noise.

+5 volt ripple can propagate to the blanking circuit when the voltage
supplied by the intensity adjustment pot is not high enough to block a
noisy +5 volts signal via diode CR1463. The blanking input is
normally around 0.4 to 0.5 volts, so a little bit of ripple is all
that's required to cause a blanking issue.



The most likely caps needing replacement are C1512, C1513. The
schematic indicates +78 volt reading to ground between caps C1512 and
C1513. These affect the +110 V, +55 v and ultimately +5 volt regulated
supplies.

Noise on the +5 volt supply can affect blanking when the intensity
adjustment voltage is less than +5 volts and voltage limiting diode
CR1463 is allowed to conduct.

On my scope, the blanking issue goes away when the intensity is
increased high enough, adding additional weight to this theory.

Ron



"One experiment is worth a thousand calculations."







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

Ok, all voltages (regulated and unregulated) are fine except the

110V supply. I get 120V

unregulated, which I think is fine. I only get 100V regulated.

Also, the 110V unregulated

reads 25VAC and the 110V regulated reads 11VAC. All other supply

voltages (regulated

and unregulated) read 0 VAC. I would suspect the 550uf power supply

cap, but would that

explain why my regulated 110 voltage is 10V low?

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

wrote:

Wow, how did I miss this: the 110 test point reads 100V DC and 11

volts AC. Something

is

up there.

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

How's the +110?
-ls-

glydeck@ wrote:

Jordan,
I don't have a 465B manual with me, but 40 mv rms does sound a

little on the

high side. I believe that would be about 113 volts pp, [(RMS

x 1.414) x

2=P-P not exactly a sine wave but close enough]. Having a

scope to trouble

shoot the scope is always helpful, but in a case like this

I've used clip leads

to parallel an equivalent or larger capacitor across the

suspect power supply

filter caps in the circuit, and then observe the results on

screen. (Make

doubly sure the working voltage of the cap is high enough.)

This test doesn't

always work because the filter cap could be failing toward

short and not

failing toward open thereby negating the added capacitance.

Ron,
Nice picture, labels and all. I can even count on the

graticule 8 small

divisions between the start of each darkened portion. That

translates to an 8

ms period, or a frequency of 125 Hz. This would be well

within the margin of

error to be 120 Hz ripple from the full wave bridge in one of

the supplies.

I agree you have a similar problem with AC mains.

George



In a message dated 9/29/2008 8:17:21 P.M. Pacific Daylight

Time,

jordankersten@ writes:

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?

I also have the same issue with my Tek 465 scope. A picture

was added

to your photo album:

_.<WBR

()

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



****Looking for simple solutions to your real-life

financial

challenges? Check out WalletPop for the latest news and

information, tips and

calculators.

()

------------------------------------

Yahoo! Groups Links

Found these manuals, if someone wants them, tell me where to upload
them, i would upload them to the yahoo files section but it takes too
long, prefer ftp.
tektronics210.pdf
tektronics210prog.pdf
tektronics210serv.pdf
tektronix TDS1000-2000seriesServiceMan.pdf
tektronix TDS1000-2000seriesUserMan.pdf

I checked the blanking input and it reads .5VDC...right where it should be. However,
.090VAC was also present. Does this seem like I've got some ripple in my blanking input?
Would that bad/leaky 110V supply cause this?

Notice the Regulated +55 Volts signal through the Zener VR1515 at the
bottom of the 110 Volt regulator circuit? It is believed the root
cause is 120 HZ noise on the +55 Regulated supply.




A careful inspection of the +5 volt regulator circuit reveals that
regulated +55V also supplies a voltage divider circuit (R1559 and
R1554) to provide a +5 voltage reference to OP amp U1554A, pin 9. If
the +55 V signal is noisy, the same noise will be reflected in the +5
volt signal with a ratio of approximately 1/10 amplitude of the +55
volt noise.

+5 volt ripple can propagate to the blanking circuit when the voltage
supplied by the intensity adjustment pot is not high enough to block a
noisy +5 volts signal via diode CR1463. The blanking input is
normally around 0.4 to 0.5 volts, so a little bit of ripple is all
that's required to cause a blanking issue.



The most likely caps needing replacement are C1512, C1513. The
schematic indicates +78 volt reading to ground between caps C1512 and
C1513. These affect the +110 V, +55 v and ultimately +5 volt regulated
supplies.

Noise on the +5 volt supply can affect blanking when the intensity
adjustment voltage is less than +5 volts and voltage limiting diode
CR1463 is allowed to conduct.

On my scope, the blanking issue goes away when the intensity is
increased high enough, adding additional weight to this theory.

Ron



"One experiment is worth a thousand calculations."







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

Ok, all voltages (regulated and unregulated) are fine except the

110V supply. I get 120V

unregulated, which I think is fine. I only get 100V regulated.

Also, the 110V unregulated

reads 25VAC and the 110V regulated reads 11VAC. All other supply

voltages (regulated

and unregulated) read 0 VAC. I would suspect the 550uf power supply

cap, but would that

explain why my regulated 110 voltage is 10V low?

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

wrote:

Wow, how did I miss this: the 110 test point reads 100V DC and 11

volts AC. Something

is

up there.

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

How's the +110?
-ls-

glydeck@ wrote:

Jordan,
I don't have a 465B manual with me, but 40 mv rms does sound a

little on the

high side. I believe that would be about 113 volts pp, [(RMS

x 1.414) x

2=P-P not exactly a sine wave but close enough]. Having a

scope to trouble

shoot the scope is always helpful, but in a case like this

I've used clip leads

to parallel an equivalent or larger capacitor across the

suspect power supply

filter caps in the circuit, and then observe the results on

screen. (Make

doubly sure the working voltage of the cap is high enough.)

This test doesn't

always work because the filter cap could be failing toward

short and not

failing toward open thereby negating the added capacitance.

Ron,
Nice picture, labels and all. I can even count on the

graticule 8 small

divisions between the start of each darkened portion. That

translates to an 8

ms period, or a frequency of 125 Hz. This would be well

within the margin of

error to be 120 Hz ripple from the full wave bridge in one of

the supplies.

I agree you have a similar problem with AC mains.

George



In a message dated 9/29/2008 8:17:21 P.M. Pacific Daylight Time,
jordankersten@ writes:

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?

I also have the same issue with my Tek 465 scope. A picture

was added

to your photo album:

_.<WBR

()

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



****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]


------------------------------------

Yahoo! Groups Links

Ok, all voltages (regulated and unregulated) are fine except the 110V supply. I get 120V
unregulated, which I think is fine. I only get 100V regulated. Also, the 110V unregulated
reads 25VAC and the 110V regulated reads 11VAC. All other supply voltages (regulated
and unregulated) read 0 VAC. I would suspect the 550uf power supply cap, but would that
explain why my regulated 110 voltage is 10V low?

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

Wow, how did I miss this: the 110 test point reads 100V DC and 11 volts AC. Something

is

up there.

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

How's the +110?
-ls-

glydeck@ wrote:

Jordan,
I don't have a 465B manual with me, but 40 mv rms does sound a little on the
high side. I believe that would be about 113 volts pp, [(RMS x 1.414) x
2=P-P not exactly a sine wave but close enough]. Having a scope to trouble
shoot the scope is always helpful, but in a case like this I've used clip leads
to parallel an equivalent or larger capacitor across the suspect power supply
filter caps in the circuit, and then observe the results on screen. (Make
doubly sure the working voltage of the cap is high enough.) This test doesn't
always work because the filter cap could be failing toward short and not
failing toward open thereby negating the added capacitance.

Ron,
Nice picture, labels and all. I can even count on the graticule 8 small
divisions between the start of each darkened portion. That translates to an 8
ms period, or a frequency of 125 Hz. This would be well within the margin of
error to be 120 Hz ripple from the full wave bridge in one of the supplies.
I agree you have a similar problem with AC mains.

George



In a message dated 9/29/2008 8:17:21 P.M. Pacific Daylight Time,
jordankersten@ writes:

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?


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

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



****Looking for simple solutions to your real-life financial
challenges? Check out WalletPop for the latest news and information, tips and
calculators. ()





------------------------------------

Yahoo! Groups Links

Please go to bama.sbc.edu

Anyone know where or have a copy of the 465B service manual? The one on the bama site is incomplete with schematics cut off and parts missing.

~Jordan~

Wow, how did I miss this: the 110 test point reads 100V DC and 11 volts AC. Something is
up there.

How's the +110?
-ls-

glydeck@... wrote:

I wonder if it's been upgraded with nuvistors...;-)

Hi Rod,



I took a look in my extensive archive file for a Data Sheet on the
012-0482-00 and found no reference to it at all. I was hoping a Data Sheet
on it would at least tell me what kind of cable is used in it. Tek had Data
Sheets on virtually everything with a Part Number like 012-0000-00 so I will
keep looking and post any info here that I uncover.



Stan



PS I think Craig is correct in that it probably really does not make any
practical difference in any measurements you might make using it instead of
normal RG58 and ordinary BNC connectors.



_____

From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of kozey746
Sent: Sunday, September 28, 2008 10:45 PM
To: TekScopes@...
Subject: [TekScopes] A little off Topic, SG504 Output Head



Hi:
I bought a SG504 RF Generator on Ebay with NO Output Head.
Anyone have a Source for one at a Reasonable Price?
The Part Number is 015-0282-00.
Also Looking for a 012 0482 00 50 ohm precision bnc Cable, can this
cable be constructed?
Any info would be appreciated.
Thank's
Rod.
Amatuer Radio Callsign:
VE5RMK

Looks like one of these is up for auction on ebay.

Item number: 130257697066

_
30257697066_
()



****Looking for simple solutions to your real-life financial
challenges? Check out WalletPop for the latest news and information, tips and
calculators. ()

Jordan,
I don't have a 465B manual with me, but 40 mv rms does sound a little on the
high side. I believe that would be about 113 volts pp, [(RMS x 1.414) x
2=P-P not exactly a sine wave but close enough]. Having a scope to trouble
shoot the scope is always helpful, but in a case like this I've used clip leads
to parallel an equivalent or larger capacitor across the suspect power supply
filter caps in the circuit, and then observe the results on screen. (Make
doubly sure the working voltage of the cap is high enough.) This test doesn't
always work because the filter cap could be failing toward short and not
failing toward open thereby negating the added capacitance.

Ron,
Nice picture, labels and all. I can even count on the graticule 8 small
divisions between the start of each darkened portion. That translates to an 8
ms period, or a frequency of 125 Hz. This would be well within the margin of
error to be 120 Hz ripple from the full wave bridge in one of the supplies.
I agree you have a similar problem with AC mains.

George

Hi,

I was just wondering if a Tek 067-0587-01 calibration fixture is
really required to calibrate a 7704A. It is possible to use a
calibrated 7A26 and a function generator instead? I realize that a
function generator won't have the same kind of rise times, but that's
the only difference I can think of. I've never used the fixture so I
don't know how well it works but I think that finding a calibrated
calibrator is going to cost more than what the scope is worth.

Thanks,
Neil

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]