Jim, Been there, done that and have the Tee Shirt.? As chuck stated, TEK is not always the best about these locations.? Not sure how this comes about, but even the best have shortcomings.? I gave up on that 475 manual and went back to my old 475A manual and this is what I found.? This is the LOWER front corner of the board on the 475A and this board LOOKS like the same part as the 475. I hope this is of some assistance.? Michael Lynch?479-226-0126 Home Phone479-477-1115 Cell Phonemlynch001@ [email protected]@...
On Friday, August 30, 2019, 3:53:51 AM CDT, James R. Bartlett <james.r.bart@...> wrote: Good morning Michael. Many thanks for the info/link. I downloaded it and it is slightly different to mine. I found the 3, 10 ohm resistors in the +15 volt supply on page 216. However none of them appear in the component list for that circuit.!!!!! I have searched but cannot find R961,R963 and R965 and associated 2.2uf capacitors anywhere except in the main component list. Can you help and point me as to where they might be. Sorry to be a pain but this has me puzzled. Many thanks Regards Jim On Thu, 29 Aug 2019 at 23:11, Mlynch001 <mlynch002@...> wrote: Jim,
? Page 216 of 293 in the version of the 475 manual that I am looking at.
TEKWiki has a couple of versions for that instrument.
here is the link:
< TEKWiki is a great resource.
Best of luck on your repair.
--
Michael Lynch
Dardanelle, AR
|
Hi Jim,
Tektronix has always been terrible about identifying
these little power filter circuits. I rarely can find
them on any part's layout in the manuals.
The schematic where the filters are located is on page
216 of my copy of the 475 manual... But I think you
already know that.
The schematic shows them to be in the Sweep Generator
area, which is schematic <8>,,, Then everything goes
to heck...
However, they can usually be found near the source of
the noise. In the case of power coming onto a circuit
board, that is where the filter will be. In the case
of a noise source like a EHT supply, that's where the
filter will be.
The resistor will always be pointing at the noise source.
-Chuck Harris
James R. Bartlett wrote:
toggle quoted message
Show quoted text
Good morning Michael.
Many thanks for the info/link.
I downloaded it and it is slightly different to mine.
I found the 3, 10 ohm resistors in the +15 volt supply on page 216.
However none of them appear in the component list for that circuit.!!!!!
I have searched but cannot find R961,R963 and R965 and associated 2.2uf
capacitors anywhere except in the main component list.
Can you help and point me as to where they might be.
Sorry to be a pain but this has me puzzled.
Many thanks
Regards
Jim
On Thu, 29 Aug 2019 at 23:11, Mlynch001 <mlynch002@...> wrote:
Jim,
Page 216 of 293 in the version of the 475 manual that I am looking at.
TEKWiki has a couple of versions for that instrument.
here is the link:
< TEKWiki is a great resource.
Best of luck on your repair.
--
Michael Lynch
Dardanelle, AR
|
Good morning Michael.
Many thanks for the info/link.
I downloaded it and it is slightly different to mine.
I found the 3, 10 ohm resistors in the +15 volt supply on page 216.
However none of them appear in the component list for that circuit.!!!!!
I have searched but cannot find R961,R963 and R965 and associated 2.2uf
capacitors anywhere except in the main component list.
Can you help and point me as to where they might be.
Sorry to be a pain but this has me puzzled.
Many thanks
Regards
Jim
toggle quoted message
Show quoted text
On Thu, 29 Aug 2019 at 23:11, Mlynch001 <mlynch002@...> wrote: Jim,
Page 216 of 293 in the version of the 475 manual that I am looking at.
TEKWiki has a couple of versions for that instrument.
here is the link:
< TEKWiki is a great resource.
Best of luck on your repair.
--
Michael Lynch
Dardanelle, AR
|
Jim, Page 216 of 293 in the version of the 475 manual that I am looking at. TEKWiki has a couple of versions for that instrument. here is the link: < TEKWiki is a great resource. Best of luck on your repair. -- Michael Lynch Dardanelle, AR
|
Thanks Michael,
I have a few higher voltage Tants so will use a 35 or 50 volt one.
Can you point me in the direction on the schematic where I can see that
resistor.
Will replace it as well.
Again thanks for help much appreciated,
Regards
Jim
toggle quoted message
Show quoted text
On Thu, 29 Aug 2019 at 19:57, Mlynch001 <mlynch002@...> wrote: Jim,
I found it in the 475 manual as well. Just in a different location on the
schematics. It just took a bit of searching. I have a 475A that I was
able to bring back from oblivion and I was more familiar with that
instrument, manual and the schematics. The two machines are very likely
identical in that area. I have a Type 576 CT that had about 15 ¡°bad¡± axial
Tantalum caps when I first received it, these things were quitting every
time I turned it on, after the 2nd or 3rd failure, I decided to replace
them all, with modern equivalents.
--
Michael Lynch
Dardanelle, AR
|
Re: 502A - Anyone looking to part with one?
Now THAT would be an awesome story to hear! :-D If I ever get the opportunity, you know I will be posting about it!
|
Jim, FYI, found this on Page 216 of 293 in the version of the 475 manual that I am looking at.? The LV supplies are populated with many of these filters.? So a good chance that others are on the verge of failure. ? Hope this helps.? Michael Lynch?479-226-0126 Home Phone479-477-1115 Cell Phonemlynch001@ [email protected]@...
On Thursday, August 29, 2019, 1:57:41 PM CDT, Mlynch001 <mlynch002@...> wrote:
Jim,
I found it in the 475 manual as well.? Just in a different location on the schematics.? It just took a bit of searching.? I have a 475A that I was able to bring back from oblivion and I was more familiar with that instrument,? manual and the schematics.? The two machines are very likely identical in that area.? I have a Type 576 CT that had about 15 ¡°bad¡± axial Tantalum caps when I first received it, these things were quitting every time I turned it on, after the 2nd or 3rd failure, I decided to replace them all, with modern equivalents.
--
Michael Lynch
Dardanelle, AR
|
Re: Tek 576 Curve Tracer HV Transformer winding
Update: 576 Transformer Inductance Resistance AWG mm Turns N AL=L/N^2 AL nH Volts Pin 2-3 305,8E-6 168,5E-3 25 0,45 26 452,4E-9 452 49,8 Pin7-8 918,6E-3 385,0E+0 40 0,08 1400 468,7E-9 469 2700 Turns ratio Volts ratio 53,85 54,22 /g/TekScopes/album?id=94656Core transformer with Alnh=450 aprox -----Mensaje original----- De: [email protected] [mailto: [email protected]] En nombre de Chuck Harris Enviado el: jueves, 29 de agosto de 2019 13:15 Para: [email protected]Asunto: Re: [TekScopes] Tek 576 Curve Tracer HV Transformer winding I'm not particularly worried about the water picking up anything too bad... a few parts per million lead, maybe some PFOA's. I only mentioned it because businesses that don't worry can be fined heavily by their local EPA. I am more concerned about ease of use. The water makes the whole process more likely to cause burns. Hot air in an oven gets you to the same place with no more risk of burns than handling a tin of hot muffins with an oven mit. As I've said earlier, I have done this hundreds of times. IMHO, hot air in a 130C (266F) oven for 1/2 hour works best... -Chuck Harris Andre de guerin via Groups.Io wrote:
Hi, yes have also used the hot water method.
Incidentally its best to test this on a failed transformer of the same time first to get the technique right.I also have used a very small amount IPA to release stubborn windings, this shouldn't damage them butif you use anything else be aware that winding damage is likely.If you're worried about the risks simply do what I did and use the water to make Plaster of Paris.
-Andre
#include "802701.h"
|
Jim,
I found it in the 475 manual as well. Just in a different location on the schematics. It just took a bit of searching. I have a 475A that I was able to bring back from oblivion and I was more familiar with that instrument, manual and the schematics. The two machines are very likely identical in that area. I have a Type 576 CT that had about 15 ¡°bad¡± axial Tantalum caps when I first received it, these things were quitting every time I turned it on, after the 2nd or 3rd failure, I decided to replace them all, with modern equivalents.
--
Michael Lynch
Dardanelle, AR
|
I tied the wayback machine, this may or may not be useful. There are other web archiving crawlers.... On Thu, Aug 29, 2019 at 10:22 AM Dave Brown <davebr@...> wrote: We have inquired about the CRT Cross Reference and that database is gone.
However, the museum published a 1976 CRT Index document. That, along with
the RPR has the same information, just not as convenient to use, I did an
extract of the 154- RPR that covers the part numbers from 1976 to 1986.
That and the index is at
Dave
|
Re: 502A - Anyone looking to part with one?
You know, I recall he was asking $150 for it originally, and after about a week or so he dropped the price to $50. So a tube scavenger reached through the internet with their long straw and sucked the life out of it for another tube amp that will probably only be half built before it's tucked away in their mom's basement next to their empty cans of Mountain Dew and Red Bull. It would be supremely satisfying to see, just once, a story where someone scavenged someone's homebrew guitar amplifier for tubes for their Tektronix scope. On Thu, Aug 29, 2019 at 1:06 PM Jamie Ostrowski via Groups.Io <jamie.ostrowski@...> wrote: Oh geeze, really? I noticed it had said "No Bulbs", but all his photos
showed all the tubes in it, so I wasn't sure what he was talking about.
That's a shame.
On Thu, Aug 29, 2019 at 12:49 PM Jason A. via Groups.Io <jagee228=
[email protected]> wrote:
He also sold all the tubes out of it separately.
|
Re: 502A - Anyone looking to part with one?
Oh geeze, really? I noticed it had said "No Bulbs", but all his photos showed all the tubes in it, so I wasn't sure what he was talking about. That's a shame. On Thu, Aug 29, 2019 at 12:49 PM Jason A. via Groups.Io <jagee228= [email protected]> wrote: He also sold all the tubes out of it separately.
|
Sure, I will upload to those other sites as well. Thanks!
I've just finished uploading a copy up on the wiki under Reference
Material->Fundamentals.
Jamie
toggle quoted message
Show quoted text
On Thu, Aug 29, 2019 at 11:05 AM Tom Gardner <tggzzz@...> wrote: I wish all scans were that legible!
You might like to consider additional destinations, e.g. ftp'ing directly
as
specified in
KO4BB:
or
BAMA:
Contact Information:
<email address obscured in a GIF>
Submitting a Manual
If you have a better copy of any of these manuals or a manual which is
not
listed, and wish to share, you can upload the manual to
ftp://bama.edebris.com/uploads/ . Or, you can email me directly with
the
manual. I accept all formats.
On 29/08/19 16:28, Jamie Ostrowski wrote:
Sorry to respond to an old thread, but I do have a pdf of "Typical
Oscilloscope Circuitry" you can download here:
I've tried writing to a couple people on the wiki to get it uploaded but
haven't received a response from anyone.
|
Re: 502A - Anyone looking to part with one?
He also sold all the tubes out of it separately.
|
Is there any record of it in the web archive site? I'd have to scrounge my emails to find the site.... On Thursday, August 29, 2019, Dave Brown <davebr@...> wrote: We have inquired about the CRT Cross Reference and that database is gone.
However, the museum published a 1976 CRT Index document. That, along with
the RPR has the same information, just not as convenient to use, I did an
extract of the 154- RPR that covers the part numbers from 1976 to 1986.
That and the index is at
Dave
|
We have inquired about the CRT Cross Reference and that database is gone. However, the museum published a 1976 CRT Index document. That, along with the RPR has the same information, just not as convenient to use, I did an extract of the 154- RPR that covers the part numbers from 1976 to 1986. That and the index is at
Dave
|
Hi Jim,
I would be 99% certain that changing the cap will fix it. I've seen identical symptoms and faults in a 7912AD. Browned off 10 ohm resistors and bead tants all over the thing.
?I actually watched one fail, I found two shorted ones, fired it up with the side covers off and it ran fine for about 15 minutes then I thought I noticed a wisp of smoke out of the corner of my eye by the time I saw which resistor was hot the screen blanked!
I've actually replaced them with 35V tants on the grounds that, as someone else who's running in 'bonus time', in another 50 years if they fail a second time my 121st birthday present to myself will be to pay someone else to change them!
Adrian
toggle quoted message
Show quoted text
On 8/29/2019 5:44 PM, James R. Bartlett wrote: Not to worry Michael,
I know the feeling only too well, having used up my 3 score and ten years,
everything else is a bonus? Interesting it is shown in the 475A but not
the 475. Who knows what other errors
might be there, but the resistor IS there !!!! and SMOKED but obviously
not destroyed., glad to have it confirmed as 10 ohms. Might try
disconnecting C 1448 the 10uf Tant and see what happens
Don't like those things and modern electrolyic types are very smaall now
All good fun and a nice way to meet new friends
Thanks for your help.
Regards
Jim
On Thu, 29 Aug 2019 at 16:48, Michael W. Lynch via Groups.Io <mlynch003=
[email protected]> wrote:
Jim,
I guess I need to go back to reading comprehension school! I see that
now. FYI, I have a 475A manual and in that model schematic, that resistor
as R963, Indeed it is a 10Ohm 1/4W 1/2% Carbon Comp resistor. As Chuck
stated EXACTLY, this appears to be a Filter in conjunction with C963 on
+15V (DCPL2). At least this is what the 475A schematic indicates. I did
not find this in the 475 schematic. I will sit down quietly at the back of
the class, speak when spoken to and try to learn from the teachers!
Sincerely,
Michael Lynch 479-226-0126 Home Phone479-477-1115 Cell
Phonemlynch001@[email protected]@...
On Thursday, August 29, 2019, 10:22:59 AM CDT, James R. Bartlett <
james.r.bart@...> wrote:
Hi Michael,
Thanks for the reply.
My query was not about R956 but the one to the left of it and is situated
in the middle
between VR956 and R956, on my PCB component layout most components are
identified
but not this resistorThat is the one that measures 10 ohms.Seems to go back
to C1448 a 10uf Tant
Measuring across C1448 I also get 10 ohms.So need to find out where it
goes and its component number.
I am a patient man and wil keep trying.
Thanks again
Regards
Jim
On Thu, 29 Aug 2019 at 15:40, Michael W. Lynch via Groups.Io <mlynch003=
[email protected]> wrote:
Jim,
Gotta Love that magic smoke! I don't think that is a filter resistor as
described in Chuck's last reply, as I do not see a Tantalum cap adjacent to
the resistor in that part of the circuit. R956 is the current limiting
resistor for the base of Q956 which appears to be part of the sweep
generator circuitry. In the schematic, R956 is specified as a 10K, 1/4W
5% resistor, NOT 10 ohms, so if you are seeing only 10 ohms, that is a
problem. What I would also suggest is to check Q956, plus CR952,CR955,
CR956 and VR956 and verify that these components are all good. Chuck's
advice about Tantalum Caps is spot on and you should check the entire
machine for blown or otherwise defective caps. My brother calls them
"devil caps", they are prone to failure at any moment.
Michael Lynch 479-226-0126 Home Phone479-477-1115 Cell
Phonemlynch001@[email protected]@...
On Thursday, August 29, 2019, 6:55:39 AM CDT, James R. Bartlett <
james.r.bart@...> wrote:
Hello to the group.
I find that I am in need of your assistance. Firsty repairing scopes is not
my forte but I
want to do and learn.
I have a Tek 475, which was working.
However I went to use it the other day and
got the magic smoke. Problem seems to be related to the +15 supply/
Scope switches on,
The smoke came fro a resistor on the A9 board.
However it does not appear to be numbered on the PCB layout as shown on the
downloaded
service manual.
It is located to the left and between VR956 and R956 it meters out at 10
ohms
Is this the correct value ? and what is its circuit number ?
I checked C1448 and that meters out also at 10 ohms.
+ 15 volt supply is 0 Volt
Any thoughts suggestions appreciated .
Many thanks
Jim
|
I have no great objection to replacing a tantalum filter
with a low impedance aluminum electrolytic, but be sure
that you understand that aluminum electrolytic capacitors
loose about 1/2 their value when they hit 0C, and all of
it by the time they get to around -20C. They will not work
well if the scope is left in the car trunk in the winter,
and then brought into the lab and turned on.
Tantalum capacitors have no such loss of capacitance.
If you select the tantalum's ratings correctly, they will
outlast us all by easily 3 score and 10 years. All you
have to do is set the rating to be double the voltage they
will operate at.
-Chuck Harris
James R. Bartlett wrote:
toggle quoted message
Show quoted text
Not to worry Michael,
I know the feeling only too well, having used up my 3 score and ten years,
everything else is a bonus? Interesting it is shown in the 475A but not
the 475. Who knows what other errors
might be there, but the resistor IS there !!!! and SMOKED but obviously
not destroyed., glad to have it confirmed as 10 ohms. Might try
disconnecting C 1448 the 10uf Tant and see what happens
Don't like those things and modern electrolyic types are very smaall now
All good fun and a nice way to meet new friends
Thanks for your help.
Regards
Jim
|
Not to worry Michael, I know the feeling only too well, having used up my 3 score and ten years, everything else is a bonus? Interesting it is shown in the 475A but not the 475. Who knows what other errors might be there, but the resistor IS there !!!! and SMOKED but obviously not destroyed., glad to have it confirmed as 10 ohms. Might try disconnecting C 1448 the 10uf Tant and see what happens Don't like those things and modern electrolyic types are very smaall now All good fun and a nice way to meet new friends Thanks for your help. Regards Jim On Thu, 29 Aug 2019 at 16:48, Michael W. Lynch via Groups.Io <mlynch003= [email protected]> wrote: Jim,
I guess I need to go back to reading comprehension school! I see that
now. FYI, I have a 475A manual and in that model schematic, that resistor
as R963, Indeed it is a 10Ohm 1/4W 1/2% Carbon Comp resistor. As Chuck
stated EXACTLY, this appears to be a Filter in conjunction with C963 on
+15V (DCPL2). At least this is what the 475A schematic indicates. I did
not find this in the 475 schematic. I will sit down quietly at the back of
the class, speak when spoken to and try to learn from the teachers!
Sincerely,
Michael Lynch 479-226-0126 Home Phone479-477-1115 Cell
Phonemlynch001@[email protected]@...
On Thursday, August 29, 2019, 10:22:59 AM CDT, James R. Bartlett <
james.r.bart@...> wrote:
Hi Michael,
Thanks for the reply.
My query was not about R956 but the one to the left of it and is situated
in the middle
between VR956 and R956, on my PCB component layout most components are
identified
but not this resistorThat is the one that measures 10 ohms.Seems to go back
to C1448 a 10uf Tant
Measuring across C1448 I also get 10 ohms.So need to find out where it
goes and its component number.
I am a patient man and wil keep trying.
Thanks again
Regards
Jim
On Thu, 29 Aug 2019 at 15:40, Michael W. Lynch via Groups.Io <mlynch003=
[email protected]> wrote:
Jim,
Gotta Love that magic smoke! I don't think that is a filter resistor as
described in Chuck's last reply, as I do not see a Tantalum cap adjacent to
the resistor in that part of the circuit. R956 is the current limiting
resistor for the base of Q956 which appears to be part of the sweep
generator circuitry. In the schematic, R956 is specified as a 10K, 1/4W
5% resistor, NOT 10 ohms, so if you are seeing only 10 ohms, that is a
problem. What I would also suggest is to check Q956, plus CR952,CR955,
CR956 and VR956 and verify that these components are all good. Chuck's
advice about Tantalum Caps is spot on and you should check the entire
machine for blown or otherwise defective caps. My brother calls them
"devil caps", they are prone to failure at any moment.
Michael Lynch 479-226-0126 Home Phone479-477-1115 Cell
Phonemlynch001@[email protected]@...
On Thursday, August 29, 2019, 6:55:39 AM CDT, James R. Bartlett <
james.r.bart@...> wrote:
Hello to the group.
I find that I am in need of your assistance. Firsty repairing scopes is not
my forte but I
want to do and learn.
I have a Tek 475, which was working.
However I went to use it the other day and
got the magic smoke. Problem seems to be related to the +15 supply/
Scope switches on,
The smoke came fro a resistor on the A9 board.
However it does not appear to be numbered on the PCB layout as shown on the
downloaded
service manual.
It is located to the left and between VR956 and R956 it meters out at 10
ohms
Is this the correct value ? and what is its circuit number ?
I checked C1448 and that meters out also at 10 ohms.
+ 15 volt supply is 0 Volt
Any thoughts suggestions appreciated .
Many thanks
Jim
|
Chuck,
I will continue to learn and contribute when I am able. I do learn from my mistakes. You would make more mistakes than I, only because you work on a lot more equipment than I do. I tend to concentrate my many mistakes into one or two pieces of gear. I am trying to absorb these lessons as quickly and completely as I am able. You teach me a lot, just from your comments!
Many thanks!
--
Michael Lynch
Dardanelle, AR
|
Michael W. Lynch
Mlynch001
Jason A.