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5111 Storage Scope Loss of -30VDC


Bob Wilson
 

A friend gave me this one saying it had never been used. It still had the little paper stuck on the CRT saying how to power it up if it had been off for over a month.
But of course it did not work correctly only having a small dot on the CRT that bounced around.
I eventually found -30 VDC was missing and replaced a shorted 1uf tantlum cap on the storage board. But still no -30VDC.
If I disconnect the -30 VDC wire going to the storage board the voltage comes up. So either the supply is weak or something on that board is pulling the voltage down.
In testing the transistors on the storage board I find some kind of stuff in the socket holes. Maybe thermal compound, I don't know. But now its hard and makes getting the transistor lead difficult to reinsert back into the socket. The TO39 transistor all check good but I have not gone throught the TO99 transistors yet.
Any suggestions would be appreciated.


p mc
 

No idea about the "stuff". Nor do I have a 5111 at hand to look at.

Does the scope work with the storage board disconnected? I can't confirm, but I think it should.


p mc
 

...oh yeah and...

Did your friend pass on any of the story of how your scope ended up unused for 40 years?

pmc


Bob Wilson
 

I found my problem and now its working.
No, I did not ask how it sat unused for that long. He says he has another one that he has been using.
I like the big screen and its fine for my audio work.

Now I would like to get some of my other scopes working. A 5110 with no HV and a 453 that blows a fuse after working a short while.
I'm giving up on 900 series. I have 4 of them that all work but not correctly. I used to like them but I think they were not built to the high standards of the other models.
Bob


Mlynch001
 

I believe that the "stuff" is a sealer of some sort that TEK used on many of their flush socket units. I see this on many of the newer TM5XX plug ins as well as many scopes that use those soldered into the board pin sockets.


--
Michael Lynch
Dardanelle, AR


Tim Phillips
 

from Tim P (UK)
re the 5111 - what was the problem with the -30V ?
I have a 5441 with a low -15V (11V) and a high +30V (+38V)
The LVPS in the 5000-series seem to be very similar. I would be interested
in your investigations and cure
regards
Tim

On Thu, 30 Jan 2020 at 18:13, Mlynch001 <@mlynch001> wrote:

I believe that the "stuff" is a sealer of some sort that TEK used on many
of their flush socket units. I see this on many of the newer TM5XX plug
ins as well as many scopes that use those soldered into the board pin
sockets.


--
Michael Lynch
Dardanelle, AR




Mlynch001
 

Tim P,

I would like to learn the cause and resolution of that problem myself.

Perhaps Mr. Wilson could expand on the actual cause of the problem and his solution?

Thanks!

--
Michael Lynch
Dardanelle, AR


Bob Wilson
 

OK, I must confess I had the replacement cap in backwards. A new cap with the correct polarity fixed the -30V problem.
I still would like some tips on how to troubleshoot the 5110 scope. The horizontal circuit appears to not be working. I think I have read that the transformer is a a common problem.
Bob


p mc
 

Of course I've nev<cough>r put a cap in backwards...

I don't have a 51xx scope, but I looked at a bunch of 51xx manuals & schematics in the course of figuring out 5D10/mainframe interaction (https://groups.io/g/TekScopes/message/163941).

The 5110.pdf manual at BAMA includes change notes up to 1987 so it likely covers your scope. Do you have that? It includes lots of "voltage and waveform conditions" info that should help since you also have a working scope.
http://bama.edebris.com/manuals/tek/5110/

I'm curious: do your 5110 & 5111 have a perpendicular daughter card stuck out the back of the interface board (where the plugins plug in)?

pmc


p mc
 

Tim,

TekWiki has a complete 5441 manual. http://w140.com/tekwiki/wiki/5441
It doesn't have "voltage and waveform" data but has the schematic, board layout, adjustment & Theory of Operation info.

Do you have that?

pmc

On Fri, Jan 31, 2020 at 10:14 AM, Tim Phillips wrote:


from Tim P (UK)
re the 5111 - what was the problem with the -30V ?
I have a 5441 with a low -15V (11V) and a high +30V (+38V)
The LVPS in the 5000-series seem to be very similar. I would be interested
in your investigations and cure
regards
Tim


On Thu, 30 Jan 2020 at 18:13, Mlynch001 <@mlynch001> wrote:

I believe that the "stuff" is a sealer of some sort that TEK used on many
of their flush socket units. I see this on many of the newer TM5XX plug
ins as well as many scopes that use those soldered into the board pin
sockets.


--
Michael Lynch
Dardanelle, AR




Tim Phillips
 

From Tim P (UK)

I have a manual, thanks - in fact, after perusing the schematic, I realised
that my +38 V on the +30V test point is the UNREG voltage.
So, maybe the erstwhile +30V is not being regulated at all. I will check
around the +30V circuitry. Are the Darlington pass transistors (MJE800)
reliable with age ?

Tim

On Sat, 1 Feb 2020 at 21:06, p mc <pmc@...> wrote:

Tim,

TekWiki has a complete 5441 manual. http://w140.com/tekwiki/wiki/5441
It doesn't have "voltage and waveform" data but has the schematic, board
layout, adjustment & Theory of Operation info.

Do you have that?

pmc

On Fri, Jan 31, 2020 at 10:14 AM, Tim Phillips wrote:


from Tim P (UK)
re the 5111 - what was the problem with the -30V ?
I have a 5441 with a low -15V (11V) and a high +30V (+38V)
The LVPS in the 5000-series seem to be very similar. I would be
interested
in your investigations and cure
regards
Tim


On Thu, 30 Jan 2020 at 18:13, Mlynch001 <@mlynch001> wrote:

I believe that the "stuff" is a sealer of some sort that TEK used on
many
of their flush socket units. I see this on many of the newer TM5XX
plug
ins as well as many scopes that use those soldered into the board pin
sockets.


--
Michael Lynch
Dardanelle, AR






Bob Wilson
 

Yes it does have the plug in board on the rear of the Interface board. I think I saw somewhere there two differerent versions of this board. One for single beam and one for dual beam scopes.
For some reason I seem to be switching between two different downloaded manuals for this scope. One has part of the schematics and one had the other half.

Bob


p mc
 

tl;dr: check the 5115 manual at http://w140.com/tekwiki/wiki/5115

I don't know how much 51xx history you know, so please pardon if I tell what you already know.

Maybe you have two manuals from early years when your scope was sold as two products, 5103N & D11, with two separate manuals. Like this:
http://w140.com/tek_5103N_brochure.pdf

After a few years Tek changed 5100-series nomenclature so that each combination became a single product. What was 5103N + D11 became 5111. They also combined the manuals. (This story has a point, I promise) The first turn of combined manuals were simply three things in a single binding: a cover page announcing that the formerly separate manuals were now bound together followed by the two formerly separate manuals. Initially, the D11 display was covered by the "D11/D15" manual. The early 5115 manual simply bound the D11/D15 manual & 5103N manuals together. So (the point), the early 5115 manual covers your 5111. Link above. Presumably, the first 5111 & 5115 manuals differed only by part number and title page. It's "one manual", but really not much different from having two manuals.

Christian Weagle wrote about the 5000-series at http://www.i9t.net/5000_scopes.html
There is lots of info and a few... imperfections. Mr. Weagle disappeared without comment, so it remains as it is.

Thanks for answering re your interface board. I've been trying to work out a conherent history of the 51xx line since researching the 5D10 - which depended on interface board revision. I think maybe late 5111/pre 5111A units did not have that daughter card. Just a piece of a puzzle.