Date   

Re: 485 as a business dependent daily driver?

Ondrej Pavelka
 

That sums it pretty much up, I will pass the 485 to a friend of mine who
doesn't have a scope and keep my eye out on another 2445B or 2465B as a
backup. With rifa smoke bombs replaced and the leaky SMD caps out I will
hopefully not have any of the hybrid chips failing on me if i keep them
cool enough.

On Tue, Dec 29, 2020 at 2:41 PM Chuck Harris <cfharris@erols.com> wrote:

Nothing can be made 100% reliable as a daily driver, so no,
your 485 might break, and it might need an expensive repair.

If that is your only consideration, go with something new.

The 485 is a nice scope, but with its tiny screen, and lack
of readout and cursor, most would find it tedious to use as
a daily driver. When the 2465 came out, the 465-485 scopes
disappeared from lab benches very quickly. We were getting
them in government scrap lots by the ton back then.

-Chuck Harris

Ondrej Pavelka wrote:
Hi folks,

I scored 485 with few missing knobs and very blurry trace. It was for
about $30 so I didn't expect much from it.
I have 2445B as a main scope I rely on for my everyday work as a vintage
audio repair business. I did bump on a few occasions into 200MHz bandwidth
limit of the 2445B and 485 is really tempting with its smaller size and
higher bandwidth.
Would you say if I invest the time and money into the 485 I can bring it
to state where it can be 100% reliable dependable instrument?
Otherwise I will pass it onto a friend who will repair it to have it as
his only scope but if this has the potential to take the place of the 2445B
(as much as I will miss the cursors) ?










Re: Intermittent power on problems with 2465B

Mark Hatch <mark2382@...>
 

Here is the link I found with part#:

https://www.eevblog.com/forum/testgear/tektronix-2465-power-switch/

Regards,

Mark


Current Probe Questions

 

Hi Mike,



Except for the AM503 the TM5xxx current probe plugins were introduced at a point in time when Tek was facing a bleak financial future. After 35 years of providing parts lists and schematics in their service manuals someone in management decided to remove them to generate additional revenue by forcing customers to return non-working instruments to the factory for repair.



Our members are experienced collectors of Tektronix products. We have many ex-Tek members. We have many circuit design engineers. We have many members with advanced degrees in other fields besides electronics. We provide free assistance to anyone who has a problem with, or questions about, their Tek instruments. Finally, several members of TekScopes own AM503A, AM503B and AM5010 plugins which they cannot repair or calibrate without schematics and/or parts lists.



I personally own several AM503B plugins which over the years have stopped working. With schematics I would be able to identify the cause of the errors displayed and track down the source of the problems. With this many plugins I would also be able to cannibalize one plugin to get the others working.



One of our members has located and scanned the schematics for the AM503A. Another member has provided us with the AM503B ROM code. I appreciate you willingness to assist us maintain our collections of Tektronix products. I hope you are able to find the time to become a regular contributor because we can certainly use your expertise.



Dennis Tillman W7pF

TekScopes Moderator



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Subject: Re: Details on 015-0670-00 Feed-Through Adapter for AM503B?

Hi Jared,

I was one of the designers of the AM503A, AM503B, AM5030 and newer TCPA300/400 products. Let me dig through my parts bins to see if I have one (I think I bought some from RAMs way back?) or at least check the service manual to see if there was a schematic. I remember there was a coding resistor from a pin to gnd and then a short between the output of the power amp into the input of the attenuator for one of the adapters. There was a coding resistor and a coax that went straight into the attenuator input for the other adapter.

Stay tuned,
Mike

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Re: Quick question 564B

widgethunter <tubesnthings@...>
 

Have 561A/Bs and 565 in service and consider them a favorite for general bench work.Had one bad 565 (bad filament winding - my 1st Tek scope) but now own two that work.GREAT scopes, very reliable.

The 500 series was replaced by the 5000 series - it was not the precursor to the 7000s.
Bernd Schroder

-----Original Message-----
From: Cliff Carrie <cliffcarrie@hotmail.com>
To: TekScopes@groups.io
Sent: Tue, Jan 5, 2021 7:49 pm
Subject: Re: [TekScopes] Quick question 564B

I own a 561A and two 564Bs. They were mainstream in the mid 1960s. 10MHz bandwidth and a far sharper trace than you will ever see on a DSO. They all take the same series of two plugins, Vertical and Horizontal; (interchangeable if you like vertical traces or you could use two Vertical units for Lissajous figures and LF phase comparisons). The A version in both cases had a vacuum tube-based LV power supply, the B was all solid-state. Not such a big differentiation since the plug-ins were all hybrid tube/transistor units. There were lots of plug-ins, including sampling to about 500 MHz IIRC, SAs, single and dual differential amps, a wireable dual op amp unit, and up to 4 input channels. I have around 20 different plug-in types. The biggest deal about this family was the 564. It's a split-screen STORAGE scope storing waveforms electrostatically on the phosphor screen using secondary emission, with the upper and lower halves of the screen separately eraseable and settable to storage or non-storage mode. I believe this was the first widely adopted storage scope from any manufacturer. More than any other Tek units, this was the family that popularized plug-in scopes, so much so that HP started by disparaging them and ended by imitating them. One of my 564Bs is a Mod 121, which adds variable time delay auto-erase. The remark that the storage function is "finicky" is mostly only true if you try to calibrate it without following the manual. Once properly adjusted, mine have remained stable. Storage display contrast is a bit low, but very useable within the 10MHz bandwidth. They are also cheap to buy today. They're mostly reliable, with two well known problems: the CRT filament is supplied by a  dedicated winding on the main power transformer but is elevated to -3300V by the HVPS. This has led to failures of the paper insulation on that winding. I fixed my 561A by adding a separate transformer with the secondary rewound (on a side-by-side nylon bobbin) with suitable insulation and leads long enough to reach directly into the HVPS box without splices or terminals. The leads were individually insulated with small tubing (there's only 6.3VAC between them, and double insulated with shrink tubing over that to withstand the 3300V. The other problem is the potting failure on the HVPS transformer. I think it may only affect the B series, but I have never had the problem. The 561/564 family could be thought of as the precursor to the 7000 series, and my main scope today is a 7854.

Cliff


Re: Intermittent power on problems with 2465B

Siggi
 

On Wed, Jan 6, 2021 at 12:31 PM Mark Hatch <mark2382@hotmail.com> wrote:

How hard was it to get to that switch and replace it? I came across the
Digi-Key part# and the part is not expensive.
I seem to remember having to pull the power supply out and separate the
boards, no big deal. This was a number of years ago, and I remember having
trouble getting the switch de-soldered. Most likely I was just
fumble-fingered and/or under-equipped. I can't imagine it'd be any trouble
getting it out with some solder wick or a de-soldering gun.


Re: Intermittent power on problems with 2465B

toby@...
 

On 2021-01-06 12:31 p.m., Mark Hatch wrote:
Siggi,

How hard was it to get to that switch and replace it? I came across the Digi-Key part# and the part is not expensive.
What's the part number?

Thanks


Regards,

Mark





Re: Intermittent power on problems with 2465B

Mark Hatch <mark2382@...>
 

Siggi,

How hard was it to get to that switch and replace it? I came across the Digi-Key part# and the part is not expensive.

Regards,

Mark


Re: A note on PC boards, double and single sided.

David Holland
 

Work in IT. You'll do all 3....

Careful, don't get the ITIL on your shoes.....

On Wed, Jan 6, 2021 at 12:29 PM Leon Robinson <leon-robinson@sbcglobal.net>
wrote:


Brad,
I have had horses for over 40 years and I don't remember going around and
smelling warm horse s*hit, have stepped in some and shoveled a lot.

Leon Robinson K5JLR

-------- Original message --------
From: Brad Thompson <brad.thompsonaa1ip@gmail.com>
Date: 01/05/2021 9:25 PM (GMT-06:00)
To: TekScopes@groups.io
Subject: Re: [TekScopes] A note on PC boards, double and single sided.

Harvey White wrote on 1/5/2021 8:55 PM:

Printed circuit boards are generally made with one of two materials
(there are others), either a paper epoxy (FR-3) or a fiberglass epoxy
(FR-4). There are others, but these are most common.

Paper epoxy (FR-3) has a lower temperature tolerance, is not as
mechanically stable, can be burnt easily, and is constructed of paper
and epoxy holding it together. You see it in a lot of commercial
(expensive or not...) equipment. It is mostly brown...
Hello--
Older imported electronics used a phenolic-based laminate-- typically
medium to dark brown
and liable to losing its traces when the repairer applied too much heat.
Oh, and when overheated
it smelled like warm horse s*it.

73--

Brad AA1IP











Re: A note on PC boards, double and single sided.

Leon Robinson
 

Brad,
I have had horses for over 40 years and I don't remember going around and smelling warm horse s*hit, have stepped in some and shoveled a lot.

Leon Robinson  K5JLR

-------- Original message --------
From: Brad Thompson <brad.thompsonaa1ip@gmail.com>
Date: 01/05/2021 9:25 PM (GMT-06:00)
To: TekScopes@groups.io
Subject: Re: [TekScopes] A note on PC boards, double and single sided.

Harvey White wrote on 1/5/2021 8:55 PM:

Printed circuit boards are generally made with one of two materials
(there are others), either a paper epoxy (FR-3) or a fiberglass epoxy
(FR-4).  There are others, but these are most common.

Paper epoxy (FR-3) has a lower temperature tolerance, is not as
mechanically stable, can be burnt easily, and is constructed of paper
and epoxy holding it together.  You see it in a lot of commercial
(expensive or not...) equipment.  It is mostly brown...
Hello--
Older imported electronics used a phenolic-based laminate-- typically
medium to dark brown
and liable to losing its traces when the repairer applied too much heat.
Oh, and when overheated
it smelled like warm horse s*it.

73--

Brad  AA1IP


Re: SC-502 transistor

Giovanni Carboni
 

So I replaced Q855 with a BD239C and Q860 (it was blown) with a 2N2369 (it is the equivalent of the original 2N5769).
But no oscillation in the HV supply. All the LVs seem OK. Any suggestion? By the way,
at which frequency does the transformer operate?

Giovanni


Re: 500 series Calibration

Dave Wise
 

?Disclaimers: (a) I own 545, 535A, and 547 but not 545B; and (b) my only 545B manual is the scan from BAMA whose last change is for S/N 2290 and A and B TRIGGER schematic pages drawn by CMD dated 565.


The 545, 545A, and 547 manuals all avoid AUTO, and the latter two employ a jumper. (The 545 procedure simply assumes that "0" yields 0V.)


AUTO has effects other than grounding Triggering Level, and using it to do so may result in incorrect calibration.


The Trigger Level cal procedure in my 545B manual is a self-contradicting mess. The B section tells you to set as in Table 5-1 except HORIZONTAL MODE B, but Table 5-1 sets TRIG A to AUTO and TRIG B to AC. At the end it says remove the jumper, without ever having told you to apply the jumper. Looks like some mistakes crept in when this manual was written. I don't have your change information, but I believe it corrects those mistakes.


Use the jumper. If you don't want to play "Operation"(TM) on a live instrument, install the jumper prior to powering on, and manipulate the grounded end as needed.?


Regards,

Dave Wise

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Christopher Hilton-Johnson via groups.io <chj=pchjhome.com@groups.io>
Sent: Wednesday, January 06, 2021 6:16 AM
To: TekScopes@groups.io
Subject: [TekScopes] 500 series Calibration

hi Guys

Am spending the first few days of the newly instigated UK national
lockdown calibrating several 500 series scopes - a 545B and a 547.

In each case there is an intriguing point where the manual, as part of
the A and B timebase trigger level centering calibration asks you to:

for A Time Base Cal- ground the junction of R19 & R20 - both 545B
(Change instructions) and 549 (manual)

for B Time Base Cal - ground the junction of R69 & R70 - both 545B
(manual) and 549 (manual)

Now here is the issue. Finding and connecting to the required junctions
can be/is hazardous particularly for those of us who have something of
the shaky hand syndrome and a well developed sense of self preservation
when working with high voltages in cramped spaces.

But wait: there appears to be a simple solution in every case. With the
timebase trigger switch in the *Auto* position there is a direct path
between those resistor junctions and chassis - the schematic says so and
a simple continuity test with the scope off confirms it. Interestingly
my version of the 545B manual uses this method in the manual, before
changes brought in by the change information.

So am I missing something here? Does the suggested 'jumper lead' provide
magic continuity properties? Is there some hidden feature not shown on
the circuit diagram?

Any ideas why the obviously easy way is not followed, indeed is
specifically disavowed it the case of the 545B change information.

Thanks in advance


Re: Tek 466 and a noob's lack of experience...

 

The 466 is a very nice, fast-storing analog storage 'scope. It's well worth restoring.

Please make sure that brightness (once you get there) isn't too high. These CRT's are much more sensitive to burn-in (may happen within a few seconds) than regular CRT's. It may be a good idea to defocus the trace by setting the focus pot either completely CW or CCW until you watch the screen and have control over it. The image cannot normally become anywhere near as bright as that of a regular 'scope, like its little brother, the 465.

Also, make sure that you put the 'scope in the non-storage mode for fault finding. In essence, it's very much like a regular 465 plus storage, both technically and in operation.

As Keith said, get yourself a Service Manual. Pay attention to the serial number group your 'scope is in. Get it from Artek Manuals (no affiliation) if you can't get a good copy elsewhere.

I wouldn't be surprised if something simple would be wrong, like one of the PS voltages, because of one or more shorted dipped Tantalum caps. Their most common colors are orange/red in these models.

Do *not* adjust any pots until the 'scope is operating and especially, do not re-adjust the internal storage control pots until the non-storage functions are OK.

Raymond


Re: Tek 7904 In Pulse Mode Related to C1511 on LV Regulator

Göran Krusell
 

The purpose of C1511 is to compensate for the stray capacitance that you have from Q1508B base to ground. This is why a typical value would be for example 10 to 47pF and not 0.1uF.
Göran


Re: 500 series Calibration

Chuck Harris <cfharris@...>
 

Hi Christopher,

Fundamentally, I believe it is because there are a lot of
other circuits controlled by the many poles of switch
10B (DC, AC, AC LF REJECT, AUTO).

Check out Schematic #4 and #5's SW10B wafers.

The calibration specifies that TRIGGERING MODE control
should be in the AC position, and the STABILITY control
should be in the CW position.... that would cause SW110
to be in the position shown in the schematic, and would
put the wiper of the STABILITY control at -150V, and
connect it to the grid circuit of V125.

But if the TRIGGERING MODE switch was in the AUTO position,
the switches would connect the wiper of the PRESET ADJUST
trimmer to the grid circuit of V125.

My guess is that would affect the centering adjustment in
some way that isn't exactly repeatable.

-Chuck Harris


Christopher Hilton-Johnson wrote:

hi Guys

Am spending the first few days of the newly instigated UK national lockdown
calibrating several 500 series scopes – a 545B and a 547.

In each case there is an intriguing point where the manual, as part of the A and B
timebase trigger level centering calibration asks you to:

for A Time Base Cal- ground the junction of R19 & R20 – both 545B (Change
instructions) and 549 (manual)

for B Time Base Cal – ground the junction of R69 & R70 - both 545B (manual) and 549
(manual)

Now here is the issue. Finding and connecting to the required junctions can be/is
hazardous particularly for those of us who have something of the shaky hand syndrome
and a well developed sense of self preservation when working with high voltages in
cramped spaces.

But wait: there appears to be a simple solution in every case. With the timebase
trigger switch in the *Auto* position there is a direct path between those resistor
junctions and chassis – the schematic says so and a simple continuity test with the
scope off confirms it. Interestingly my version of the 545B manual uses this method
in the manual, before changes brought in by the change information.

So am I missing something here? Does the suggested 'jumper lead' provide magic
continuity properties? Is there some hidden feature not shown on the circuit diagram?

Any ideas why the obviously easy way is not followed, indeed is specifically
disavowed it the case of the 545B change information.

Thanks in advance







Re: Tek 466 and a noob's lack of experience...

Leanna L Erickson <lle@...>
 

Suggest acquire service manual.
Then check all PS rails for correct voltages.
Probably PS capacitors need replacing.

GL
Keith Wayzata, MN

On Jan 6, 2021, at 9:33 AM, thenrz@gmail.com wrote:

I bought this off of Offerup for $20. I wouldn't have even bothered, but the woman had a lot of good dealings, and I don't feel like she had any reason to lie. The scope among other things were her late husband's. As I have been kick starting my atrophied comp sci brain compartments lately to get back into circuit design with my new desktop CNC that is precise enough to cut some nice tightly pitched boards and a plethora of 3D printers for making whatever else I feel at the time. For the most part, I just want to get myself back to the days of prototyping and beta testing all kinds of electronics for a company I worked for over about eight years.

This Tek seems to be dead. I get a soft green illumination over some of the CRT, but other than that, I cannot make it do anything. There is some semblance of a focused beam when turning on and off the second time. A maybe 1/4" circle shoots in from the left middle and that's all I get to see of anything illuminated beyond the soft glow of about half the screen.

I have nice soldering irons, hot air reworks, a hot air and infrared BGA station, etc. so repair work is something I do a lot of on the side... but as I move into development again, I'm going to need a nice scope along with something I can learn the nitty gritty like with this one...

If this is worth working on, then by all means whatever advice for such an open ended problem would be amazing. If it isn't worth the time/money, *please* let me know so I can more effectively manage my time...

Thanks!





Re: Intermittent power on problems with 2465B

Siggi
 

On Wed, Jan 6, 2021 at 9:10 AM Jean-Paul <jonpaul@ix.netcom.com> wrote:

Mark I have never seen an intermittent power switch on any,Tektronix
scope,
I had an intermittent power switch on my 2465. I seem to remember this
manifested roughly as OP describes, e.g. sometimes it would start, and
sometimes it wouldn't. Got worse over time.
I remember the switch was pretty standard, I could buy a replacement from
Digikey (don't remember the PN, sorry).


Tek 466 and a noob's lack of experience...

thenrz@...
 

I bought this off of Offerup for $20. I wouldn't have even bothered, but the woman had a lot of good dealings, and I don't feel like she had any reason to lie. The scope among other things were her late husband's. As I have been kick starting my atrophied comp sci brain compartments lately to get back into circuit design with my new desktop CNC that is precise enough to cut some nice tightly pitched boards and a plethora of 3D printers for making whatever else I feel at the time. For the most part, I just want to get myself back to the days of prototyping and beta testing all kinds of electronics for a company I worked for over about eight years.

This Tek seems to be dead. I get a soft green illumination over some of the CRT, but other than that, I cannot make it do anything. There is some semblance of a focused beam when turning on and off the second time. A maybe 1/4" circle shoots in from the left middle and that's all I get to see of anything illuminated beyond the soft glow of about half the screen.

I have nice soldering irons, hot air reworks, a hot air and infrared BGA station, etc. so repair work is something I do a lot of on the side... but as I move into development again, I'm going to need a nice scope along with something I can learn the nitty gritty like with this one...

If this is worth working on, then by all means whatever advice for such an open ended problem would be amazing. If it isn't worth the time/money, *please* let me know so I can more effectively manage my time...

Thanks!


Re: Details on 015-0670-00 Feed-Through Adapter for AM503B?

mjmpdx1@...
 

Hi Jared,

I was one of the designers of the AM503A, AM503B, AM5030 and newer TCPA300/400 products. Let me dig through my parts bins to see if I have one (I think I bought some from RAMs way back?) or at least check the service manual to see if there was a schematic. I remember there was a coding resistor from a pin to gnd and then a short between the output of the power amp into the input of the attenuator for one of the adapters. There was a coding resistor and a coax that went straight into the attenuator input for the other adapter.

Stay tuned,
Mike


Re: Intermittent power on problems with 2465B

Mark Hatch <mark2382@...>
 

Jon,

Thanks for confirming that the switch is an unlikely source of issues.

Of course the problem now I that I need to wait for another intermittent failure before I can figure out what is wrong. D**n thing worked *again* first time this morning. -)

Regards,

Mark


Re: A note on PC boards, double and single sided.

 

On Wed, Jan 6, 2021 at 04:26 AM, Brad Thompson wrote:


Oh, and when overheated
it smelled like warm horse s*it.
Being a city dweller, now I know what that smells like...

Raymond

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