Date   

Re: Help needed with no trace no beamfinder on 465 (not b)

Phillip Potter
 

Hi Keith,

I’ve chased my tail like this so many times, my back as permanently twisted. I have to sleep on my side, now!

Next week will bring some clarity, and perspective, I’m sure... see you then, and thanks for sharing this repair.

Phil-in-CA

Phil, N6OMM

On Jun 11, 2018, at 9:15 AM, Keith Ostertag <stuff@card16.com> wrote:

Well... you know how sometimes you feel like you just maybe shouldn't have gotten up this morning? I'm having one of those days...

I evidently wired the substitute 2N3055 wrong and blew my the line fuse... then I began having issues with marginal meter leads and meter batteries (which have been on order)... then I blew the F1419 fuse ...

So, I need to order some more fuses, and get meter batteries, and check my meter leads, but first take a break so I can remember this is supposed to be fun :-)

I'll return to this repair job and this thread sometime next week. Thanks to everyone for helping, and hopefully we will work on it together again soon.

Keith



Re: let's bring this back to life Re: Tektronix 453 high voltage problem

RustySparks
 

Are you sure this is not the typical leaky HV transformer winding problem that seems to affect practically all the 453 series scopes and other similar models simply due to the transformer HV winding becoming leaky because of chemical changes in the epoxy used in transformer assembly over the years?
My 453A has pretty much the same problem with HV, initially it would stop oscillating after being on for 30 minutes or so, got progressively worse after a year or so, eventually wouldn't start at all. It was through this forum that I learned what the problem was. At least one member here has corrected his by rewinding the HV transformer secondary. Pretty amazing project!

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of william_b_noble
Sent: Monday, June 11, 2018 1:51 AM
To: TekScopes@groups.io
Subject: [TekScopes] let's bring this back to life Re: Tektronix 453 high voltage problem

I decided to dig into an early 453. Interestingly it does not match the schematics for the 453 or the 453A - some boards seem closer to the A, some to the earlier one - for example the Z axis board is clearly dated (C) 1965, but its layout matches the board found in the A manual (unless I'm just loosing my mind). This scope sat around for several years after I got it and never plugged it in - when I did plug it in there was initially no light on the CRT (except the scale illuminator) - as I messed with it for about an hour trying to make sure what was wrong, it fired up and showed a spot and vertical deflection, I could center it, but there was no trace. then it stopped. The HV circuit is one of those that will stop oscillating if there is an overload, so it's hard to troubleshoot, and harder without an HV probe. But it's clear that something is overloading the circuit. If I disconnect the cathode and grid bias circuits, it makes HV and powers the CRT filament just fine. I've tried all sorts of things, one at a time, and disconnecting the .015uf 3Kv capacitors by itself doesn't work, disconnecting the diode that drives the grid string does let it work, and the list goes on. I've come to the conclusion without a good way to verify it that it is most likely that at least one of those 3KV ceramic caps is leaky, and if one is bad, the others are probably not far behind, so I've ordered some. The HV diodes are also suspect, though they both seem to act like diodes at 115V (with a 10 W lightbulb as the load), I ordered some microwave oven diodes just to be on the safe side. I don't think my 1M CRT Grid Bias control is bad like was found upthread, when the power supply works, I can adjust the grid bias. But now, if the supply oscillates the current can rise to about 2.9 amps (it's fused at 2 amps) with all the loads connected. The transformer isn't potted, so I think it's probably not the issue.


anyone care to offer some advise on something I could have missed? I'd like to get this scope working just to say that I did it - I have a couple of newer ones to look at next, I figured this one first, it's all discretes, how hard could that be >>>


Re: Help needed with no trace no beamfinder on 465 (not b)

 

Well... you know how sometimes you feel like you just maybe shouldn't have gotten up this morning? I'm having one of those days...

I evidently wired the substitute 2N3055 wrong and blew my the line fuse... then I began having issues with marginal meter leads and meter batteries (which have been on order)... then I blew the F1419 fuse ...

So, I need to order some more fuses, and get meter batteries, and check my meter leads, but first take a break so I can remember this is supposed to be fun :-)

I'll return to this repair job and this thread sometime next week. Thanks to everyone for helping, and hopefully we will work on it together again soon.

Keith


Re: let's bring this back to life Re: Tektronix 453 high voltage problem

william_b_noble
 

Ok, more info. I have no repair history, I got it for scrap price from an e-waste guy who used to sell at a,small flea market. It had a nice manual with it, but for a very different scope.

I have tested the low voltage supplies, they were all close, they are now within a millivolt of their proper value. I tested all the carbon resistors in the hv divider networks, and all but one were within tolerance, the 150k resistor in series with the grid adjust pot had dropped to 30k, so I changed it.

I don't really suspect the diodes, but it pretty much has to be a leaky ceramic cap or two, or a diode, right?

I also suspect some issue on the z axis board, for now, I disconnected it

Thanks


Re: Off Topic: Wanted Spectracom 8212 Chart Recorder Manual

 

I have a PDF of the 8212 recorder manual. I can send it to anyone who needs it; just send an email. to dgminala at mediacombb dot net. It took an exchange of emails with one of the older Spectracom engineers, and a photo of the unit to help him find the right manual, but he graciously sent it along to me.
The 8212 recorder is actually a Simpson model 2750 recorder, which I have verified with the one that I have.
I think that the Simpson manual is the one that was supplied by Spectracom with the unit.

I'll upload the manual to Didier's site later this morning.

Cheers,
Dave M


Re: Help needed with no trace no beamfinder on 465 (not b)

 

Hmmm... Isn't Q1418 connected to P1400? If so, it's easy to replace _physically_... photo: https://groups.io/g/TekScopes/photo/49286/10?p=Name,,,20,1,0,0

As stated previously, I have a 464 that also uses this 151-0140 2N3055, only the leads are soldered, and that scope also has a non-working CRT circuit... at some point this morning I will swap them and see if it makes any difference.

Keith


Re: Help needed with no trace no beamfinder on 465 (not b)

ROLYNN PRECHTL K7DFW
 

A lot has been written here about differences between 2N3055s and it seems not too obvious what were the selection criteria.

=============================================================


Hfe - Beta.


Rolynn
Tek Bvtn and Sunset 1966-1971


Re: Help needed with no trace no beamfinder on 465 (not b)

Tom Gardner
 

On 11/06/18 12:47, Raymond Domp Frank wrote:
On Mon, Jun 11, 2018 at 04:33 am, Albert Otten wrote:

Is it easy to replace Q1418 with another 2N3055?
AFAIR, at least the vertical board must be disconnected (several peltola connectors and the like) and removed. In order to do that, the front BNC's for CH1 and CH2 have to be removed as well as several knobs. No, that's not a quick job.
Also, Keith would probably have to find an old (low beta, low fT) 2N3055.
I've had to remove that on a 475; I expect the 465 is similar.

The four 1/4 inch nuts that secure it to the front panel are a pig: there’s no way a spanner can reach them. Fortunately extension shanks for bog-standard screwdriver bit sets are 1/4 inch; they just fit in the space available and the nuts can be removed.


Re: Help needed with no trace no beamfinder on 465 (not b)

 

On Mon, Jun 11, 2018 at 04:33 am, Albert Otten wrote:


Is it easy to replace Q1418 with another 2N3055?
AFAIR, at least the vertical board must be disconnected (several peltola connectors and the like) and removed. In order to do that, the front BNC's for CH1 and CH2 have to be removed as well as several knobs. No, that's not a quick job.
Also, Keith would probably have to find an old (low beta, low fT) 2N3055.

Raymond


Re: Help needed with no trace no beamfinder on 465 (not b)

Albert Otten
 

On Sun, Jun 10, 2018 at 02:14 pm, Keith Ostertag wrote:


Replacing the fuse with an ammeter I read 120mA.
Hmmm less than I expected, but difficult to say if this could be the problem. I once more checked an original 151-0140-00 and an "arbitrary" 2N3055 (date 1973). Low currents DC gain was 100 for the first one and 150 for the second one.
Is it easy to replace Q1418 with another 2N3055?
A lot has been written here about differences between 2N3055s and it seems not too obvious what were the selection criteria.
Albert


Re: let's bring this back to life Re: Tektronix 453 high voltage problem

Artekmedia <manuals@...>
 

Bill

1) (C) dates have no real bearing on date of manufacture they can be
years apart or even decades apart.
2) Unless you know or have access to the repair history for your unit,
anything is possible as relates to actual board versions in your unit.
If it was repaired at some point in the past by an "Authorized Service
Center" it can have a "later" board installed as part of the repair, by
the early 80's there was already little incentive for these centers to
repair to the component level, swap a board instead, takes less time and
generates more revenue. If it was repaired by some "entrepreneur" using
boards from  an "organ donor - parts scope" the board in question can be either or later than the board it left the factory with.
3) Coming to life after an hour can be a function of some electrolytic
capacitor forming up after time
4) Replacing caps can usually never hurt unless someone gets sloppy with
a soldering iron, after all this scope is getting close to 50 years old.
5) Does the beam finder work at all?
6) Are all the LV power Supply voltages in spec ?
7) Why do you suspect HV diodes?

-DC
manuals@artekmanuals.com

On 6/11/2018 1:50 AM, william_b_noble wrote:
I decided to dig into an early 453. Interestingly it does not match the schematics for the 453 or the 453A - some boards seem closer to the A, some to the earlier one - for example the Z axis board is clearly dated (C) 1965, but its layout matches the board found in the A manual (unless I'm just loosing my mind). This scope sat around for several years after I got it and never plugged it in - when I did plug it in there was initially no light on the CRT (except the scale illuminator) - as I messed with it for about an hour trying to make sure what was wrong, it fired up and showed a spot and vertical deflection, I could center it, but there was no trace. then it stopped. The HV circuit is one of those that will stop oscillating if there is an overload, so it's hard to troubleshoot, and harder without an HV probe. But it's clear that something is overloading the circuit. If I disconnect the cathode and grid bias circuits, it makes HV and powers the CRT filament just fine. I've tried all sorts of things, one at a time, and disconnecting the .015uf 3Kv capacitors by itself doesn't work, disconnecting the diode that drives the grid string does let it work, and the list goes on. I've come to the conclusion without a good way to verify it that it is most likely that at least one of those 3KV ceramic caps is leaky, and if one is bad, the others are probably not far behind, so I've ordered some. The HV diodes are also suspect, though they both seem to act like diodes at 115V (with a 10 W lightbulb as the load), I ordered some microwave oven diodes just to be on the safe side. I don't think my 1M CRT Grid Bias control is bad like was found upthread, when the power supply works, I can adjust the grid bias. But now, if the supply oscillates the current can rise to about 2.9 amps (it's fused at 2 amps) with all the loads connected. The transformer isn't potted, so I think it's probably not the issue.


anyone care to offer some advise on something I could have missed? I'd like to get this scope working just to say that I did it - I have a couple of newer ones to look at next, I figured this one first, it's all discretes, how hard could that be >>>

--
Dave
Manuals@ArtekManuals.com
www.ArtekManuals.com


Re: Just as modern as the day it came out

Pete Lancashire
 

Disagree ?

On Sun, Jun 10, 2018, 7:00 PM stefan_trethan <stefan_trethan@gmx.at> wrote:

Beer goggles?

ST

On Mon, Jun 11, 2018 at 12:22 AM, Pete Lancashire <xyzzypdx@gmail.com>
wrote:
I got to thinking today, how a 7603, 7A18, 7B53A etc looks as modern and
'cool' as it did the day it came on the marked.

Same will all of 7K

-pete Proud of having been there for a few of my years





Re: OT: Old ICs for sale

Tom Gardner
 

On 11/06/18 05:19, G Hopper wrote:
I suppose that for $55 there probably is some value in that offering even if some of the chips are dead. I do have to chuckle since I have some of the same stuff as NOS in my parts drawers and amongst the boxes I've inherited from others. Never really considered the possibility that any of it had value. "There's gold in them there drawers!!!!"
Perhaps more than you might think - and they don't even have to be unused. Look at the fleabay prices for "mustard capacitors" and "germanium transistor"


Re: let's bring this back to life Re: Tektronix 453 high voltage problem

 

I believe microwave oven HV diodes will be too slow to use for the HV diodes in a scope. The scope HV inverter runs at 20 kHz or more. The oven diodes are used at 60 Hz and their reverse recovery time may be way too slow.

Regards

----- Original Message -----
From: "william_b_noble" <william_b_noble@msn.com>
To: <TekScopes@groups.io>
Sent: Monday, June 11, 2018 1:50 AM
Subject: [TekScopes] let's bring this back to life Re: Tektronix 453 high voltage problem


I decided to dig into an early 453. Interestingly it does not match the schematics for the 453 or the 453A - some boards seem closer to the A, some to the earlier one - for example the Z axis board is clearly dated (C) 1965, but its layout matches the board found in the A manual (unless I'm just loosing my mind). This scope sat around for several years after I got it and never plugged it in - when I did plug it in there was initially no light on the CRT (except the scale illuminator) - as I messed with it for about an hour trying to make sure what was wrong, it fired up and showed a spot and vertical deflection, I could center it, but there was no trace. then it stopped. The HV circuit is one of those that will stop oscillating if there is an overload, so it's hard to troubleshoot, and harder without an HV probe. But it's clear that something is overloading the circuit. If I disconnect the cathode and grid bias circuits, it makes HV and powers the CRT filament just fine. I've tried all sorts of things, one at a time, and disconnecting the .015uf 3Kv capacitors by itself doesn't work, disconnecting the diode that drives the grid string does let it work, and the list goes on. I've come to the conclusion without a good way to verify it that it is most likely that at least one of those 3KV ceramic caps is leaky, and if one is bad, the others are probably not far behind, so I've ordered some. The HV diodes are also suspect, though they both seem to act like diodes at 115V (with a 10 W lightbulb as the load), I ordered some microwave oven diodes just to be on the safe side. I don't think my 1M CRT Grid Bias control is bad like was found upthread, when the power supply works, I can adjust the grid bias. But now, if the supply oscillates the current can rise to about 2.9 amps (it's fused at 2 amps) with all the loads connected. The transformer isn't potted, so I think it's probably not the issue.


anyone care to offer some advise on something I could have missed? I'd like to get this scope working just to say that I did it - I have a couple of newer ones to look at next, I figured this one first, it's all discretes, how hard could that be >>>


let's bring this back to life Re: Tektronix 453 high voltage problem

william_b_noble
 

I decided to dig into an early 453. Interestingly it does not match the schematics for the 453 or the 453A - some boards seem closer to the A, some to the earlier one - for example the Z axis board is clearly dated (C) 1965, but its layout matches the board found in the A manual (unless I'm just loosing my mind). This scope sat around for several years after I got it and never plugged it in - when I did plug it in there was initially no light on the CRT (except the scale illuminator) - as I messed with it for about an hour trying to make sure what was wrong, it fired up and showed a spot and vertical deflection, I could center it, but there was no trace. then it stopped. The HV circuit is one of those that will stop oscillating if there is an overload, so it's hard to troubleshoot, and harder without an HV probe. But it's clear that something is overloading the circuit. If I disconnect the cathode and grid bias circuits, it makes HV and powers the CRT filament just fine. I've tried all sorts of things, one at a time, and disconnecting the .015uf 3Kv capacitors by itself doesn't work, disconnecting the diode that drives the grid string does let it work, and the list goes on. I've come to the conclusion without a good way to verify it that it is most likely that at least one of those 3KV ceramic caps is leaky, and if one is bad, the others are probably not far behind, so I've ordered some. The HV diodes are also suspect, though they both seem to act like diodes at 115V (with a 10 W lightbulb as the load), I ordered some microwave oven diodes just to be on the safe side. I don't think my 1M CRT Grid Bias control is bad like was found upthread, when the power supply works, I can adjust the grid bias. But now, if the supply oscillates the current can rise to about 2.9 amps (it's fused at 2 amps) with all the loads connected. The transformer isn't potted, so I think it's probably not the issue.


anyone care to offer some advise on something I could have missed? I'd like to get this scope working just to say that I did it - I have a couple of newer ones to look at next, I figured this one first, it's all discretes, how hard could that be >>>


Re: Off Topic: Wanted Spectracom 8212 Chart Recorder Manual

 

Hi Jim,
Thanks but this seller is pretty typical of those selling manuals. This particular Spectracom manual has been unobtanium for over 10 years that I am aware of. Periodically I search the internet again in hopes that one will show up or that a member of TekScopes might point me to a source who has this specific manual (Spectracom 8212 Chart Recorder) I am asking about, not a seller of readily available manuals such as the Tek and HP manuals that tigertechus has. Virtually all of this sellers manuals are probably available for free on the many download sites that host electronics manuals such as BAMA.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
Jim Olson
Sent: Sunday, June 10, 2018 9:33 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Off Topic: Wanted Spectracom 8212 Chart
Recorder Manual

Dennis there is a guy selling manuals on Ebay that has aquirred a
large inventory of older Tek and HP manuals and he might have what you
need his user name is tigertechus he even had some manuals for the
testing Tek stuff for test and calibrating boxes i got.

Jim Olson



--
Dennis Tillman W7PF
TekScopes Moderator


Re: Off Topic: Wanted Spectracom 8212 Chart Recorder Manual

Jim Olson <v_12eng@...>
 

Dennis there is a guy selling manuals on Ebay that has aquirred a large inventory of older Tek and HP manuals and he might have what you need his user name is tigertechus he even had some manuals for the testing Tek stuff for test and calibrating boxes i got.

Jim Olson


Re: OT: AT5005 spectrum analyzer display

 

You have the one on hand are Chinese type CRT , may not direct replacement .
Tony

From: Ed Breya via Groups.Io <edbreya=yahoo.com@groups.io>
To: TekScopes@groups.io
Sent: Monday, June 11, 2018 10:56 AM
Subject: Re: [TekScopes] OT: AT5005 spectrum analyzer display

The HM5010 manual schematics shows the CRT is D14-364, which googles out to be very common, and Hameg uses it in some of there other products.

Ed


Re: Off Topic: Wanted Spectracom 8212 Chart Recorder Manual

Jim Olson <v_12eng@...>
 

This is also off topic I am a new comer to the site and also getting into Tek o'scopes have picked up some dead 400 scopes to play with.
Found this site by browsing for info, manuals etc. and i have noticed that most of the folks on here are Ham Radio license operators. Is this a requirement to play with the older Tek scopes or just a coincidense as one would be handy setting up receivers and transmitters as I recall from my radio and electronics classes in High School back in the dark ages. i actually had a complete radio set from a WW II Grumman TBM with all the tuning boxes and the Dynamoter ran it off a pair of 12v batteries. Never got my license back then as it was really complicated for a high school kid got it to use in my involvement with the CAP also my pilots license.
have always loved working with electronic busy stuff so I will have fun testing, trouble shooting and repairing these things.
Just a little back ground have been a gear head forever plus amature IT type guy did 17yrs in the Navy air reserve as a Aircraft Electrician on various planes ending with the FA-18.
Enough for now

Jim Olson AE1ret.


Re: OT: Old ICs for sale

G Hopper
 

Well, the seller seems a bit full of himself and full of hyperbole: "...while I’d wager every last chip is good, ..., they are sold as-is."

In other words, "I'll engage in a bit of puffery and unsupported claims, and then disclaim all that by selling them as-is." If he won't guarantee them, he's not really willing to wager that "every last chip" is in fact good, is he?

I suppose that for $55 there probably is some value in that offering even if some of the chips are dead. I do have to chuckle since I have some of the same stuff as NOS in my parts drawers and amongst the boxes I've inherited from others. Never really considered the possibility that any of it had value. "There's gold in them there drawers!!!!"

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