Date   

Re: 7Bxx MOD515C

Leo Potjewijd
 

... except that the four holes in the rear panel are only 3.3mm (could be 1/8 inch though).
Either the rear panel has changed since the article (which is highly unlikely), or the size got converted incorrect. My money is on the last one...

---In TekScopes@..., <davidwhess@...> wrote:
"The plastic molding at the rear of these plug-ins still included the 5mm holes
where Hiro’s fibre bundles were expected to go; an indication of how close to
production this approach had progressed."


Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement

Phil Peri
 

David,


I'd love to see the RAM board, layout, and schematic!



P.


Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement

Phil Peri
 

Now, that's a thought! Try some SMT devices on a carrier, programmable by USB, that will Just Work™.


I could see the door of software experimentation swinging open if I could just upgrade the software through a USB port, that would be very fun to experiment with.


Here is what my ROM board looks like:

http://i.imgur.com/OBS5Tlgl.jpg



P.




Sorry, forgot 2 important 465B items!

 

Sorry, forgot 2 important 465B items!

Also, one complete thermally controlled 465B fan assembly, 670-6002, complete with motor, brackets and impeller, all tested and working perfectly! ($25)

and, one HV multiplier bock 152-0552-00 (unitrode cmx 312), good when removed, ($30)

More to follow next week.
All the best,
Walter & susan
Sphere research corp.
http://www.sphere.bc.ca/test/index.html


Re: Problem after recaping LV power supply on 2445A

 

On 12 Jan 2014 10:33:55 -0800, you wrote:

So i finally managed to get hold of 2 -2ohm 25 watt resistors.
I checked the resistance while both are connected parallel in J232 and J303 and showing around 1.5 ohm with my digital multimeter.Resistors showing 1% printed on them.
The load does not need to be super accurate. When measuring low values of
resistance, the test leads need to be compensated for.

When trying to start the supply, sometimes it starts and gives 5.6 volts at J232 for a minute and then just starts pulsing.
I followed the flowchart and it shows problem in inverter board because i removed comb connectors J233 and J234.
The problem could still be on the secondary side. Either the preregulator is
putting out too much power causing +5Vd to rise or the +5Vd error amplifier is
telling the preregulator to put out too much power.

That leaves some secondary side measurements undone so I will just copy the
questions from my previous post:

You say that the +10Vref sags so I assume you measured test point TP201. What
does the +2.5 volt reference which it is derived from do? It can be measured at
pin 10 of U1300C.

What are the supply voltages for the operational amplifiers on the low voltage
regulator board? They are independent of the regulated outputs. They can be
measured at pin 4 and pin 11 of any of U1270, U1300, and U1371 and should be
about +16 volts and -7 volts respectively.

I would not expect any of the supply voltages or +10Vref to sag if +5Vd is high
at +5.4 volts and if +10Vref sags, the other regulated outputs will follow it. I
am inclined to think that something is wrong with the +5Vd error amplifier built
around U1371C. What are its voltages at pin 8, pin 9, and pin 10 of U1371C?
Note that pin 4 and pin 11 are the supply voltages for the operational amplifier
and are mentioned above.

Then it tells to check Q1050,q1060,q1070, cr1060 and cr1070 for shorts.
I just checked for shorts while they are in circuit and found no shorts.
Is it the proper way or i should remove them out from the circuit to test?
Failures in power semiconductors tend to be catastrophic with shorts being the
most common. I would not start removing parts unless I was planning on
replacing them until I had exhausted other possibilities. I hate soldering the
original part back into the board unless they are unique.

If I was looking for a subtle failure which has happened on occasion, then even
with a curve tracer to test the removed part I would still plan on replacing it
with a new one. At that point, I would be testing the part only for
confirmation and not to verify that it is still good.

Now it says to put isolation transformer and tells to put primary test load.
I would definitely use a line isolation transformer when making primary side
measurements to at least lessen the risk to life, limb, subject equipment, test
equipment, and puppies.

But I would also finish testing on the secondary side before moving to the more
dangerous primary side.

Now looks like i will have to build primary test load.
This would be handy for distinguishing if the problem is with the preregulator
or the inverter. An alternative often used with the similar 22xx series power
supplies is to disconnect the preregulator from the inverter and power the
inverter (and oscilloscope) from a DC power source.

Any suggestions guys? Thanks.
Use better punctuation and formatting like paragraphs?


This Week's Batch of Handy Tek 465-series Items from Sphere

 

This Week's Batch of Handy Tek 465-series Items

Tektronix 465M
--------------------
We have 2 ea. of the complete Vertical and Horizontal Plug-ins, fully checked and tested, but have been in storage for over a year, so as-is now. Look great, just $35 each, plus shipping.  You can see them here: 
http://www.sphere.bc.ca/test/tek1.html

Tektronix 465B
-------------------
We have two Vertical Output Boards 670-6385-00, complete with 1 ea. 155-0115-00 output driver, and 1 ea. 155-0078-10 wideband amp. One is 100% complete ($38), one is missing the 2ea.741 op amps and the two big output resistors ($30).  Were working when removed, but as-is now. Very hard to find the output driver now.

We have one complete Vertical Preamp Board 670-5997  (very big) with both channels, all the pots and all 5 long shafts and two couplers, a real parts bonanza for anybody trying to fix a 465B. Very late board, mint condition, has all parts intact, including the 2 ea. 155-0078-10's wideband amps, and the wickedly hard to find dual fets 151-1090-00.  ($44).

We have one complete Trigger board 670-6000-02, very late production, complete with all front lever switches and hardware. Includes 2 ea. hard to find 155-0217-00 trigger chips, and a 155-0049-02 sweep chip, plus 4 ea. Tunnel diodes. This is a real help to restore an ailing 465B or several as a parts cow, and looks mint. ($48)

Also, one good skirted vertical knob (5mV to 50V) with the red var top knob. Get lots of calls for this, but I just found one set during our clean up. ($10).

More to follow next week.
All the best,
Walter & Susan
Sphere research corp.
http://www.sphere.bc.ca/test/index.html


Changes at Sphere Research for 2014

 

Changes at Sphere Research Corp.

In 2014, Walter & Susan will both be 65, and this will trigger some changes at Sphere.  Sphere has been supplying Tek, HP and Fluke equipment, repair info and service parts on the net for almost 20 years. We have been slowly phasing out the larger and bulkier equipment, and items like CRTs recently simply because of storage problems, we are completely out of space, and paying way too much for what we have.

In 2014, we will sell, give away or scrap ALL the remaining equipment, and offer only parts and some plug-ins after that time. We have to clear almost 2,000 square feet of rented space (about 5-6 tons), and that's the task for 2014.  We are always happy to see visitors, and in spring, once the snow clears, our customers are welcome to come up and sort through many shelves of un-listed gear we will clear out. All will be very cheap, some will be free. You'll have to see for yourself. We also have hundreds of prime, original service manuals; they also need to go to make space, as we no longer do outside service. They will be dirt cheap. We can ship them, but they are heavy, so best to grab them in person.

We also have millions of components, both through hole and smd, from our design activities, and they need to go as well. We are donating large amount of inventory to schools, colleges and universities, so if you know of anybody that needs parts for their electronics programs, let us know. Sphere will close completely in the fall of 2019, or possibly before, if circumstances change, but that will be the latest. Domains, content and inventory will all be sold or gone by that point. Consider this an early warning alert.

In 2014, our direct phone support will be from >>8:30AM to 11:30am, PST<<, Monday through Friday. It is possible we will be able to provide coverage beyond that, but it's best to plan for morning calls, or live with voice mail. Needless to say, our e-mail is 24/7/365, and is really ideal for most things. Every week or so, we will post a batch of particularly useful Tek, hp and Fluke items to the various lists first, then ebay or our site, and if not gone quickly, we will break them up for parts or scrap them. Once these batches go, that will be it, the material will be gone. Please watch for them to avoid disappointment!

We love what we do, and our customers, but the cost so keeping so much material endlessly available is simply prohibitive, and we have to make the footprint a lot smaller. You can find us at: http://www.sphere.bc.ca/test/index.html

All the best,
Walter & Susan


Re: 7Bxx MOD515C

Cliff White
 

The 7104 (and it's 1GHz plugins) used a re-designed connector that was good to a GHz. It was mechanically compatible with all the others, but quite different electrically. See pages 4 and 5 of this:

http://www.vintagetek.org/wp-content/uploads/2011/10/7104-Springer-article-email-res.pdf

Respectfully,
Cliff White, W5CNW
w5cnw@...

On 01/12/2014 11:57 AM, Craig Sawyers wrote:
 

No.  The follower board on the 7000 series edge connector is good to 1GHz+.  The 7104 works in exactly that way. 

 

On the 7A21N the two pins on the 4-way connector at the top are used for DC, and carry the trace position control from the front panel of the 7A21N

 

Craig

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of ditter2@...
Sent: 12 January 2014 17:03
To: TekScopes@...
Subject: Re: [TekScopes] 7Bxx MOD515C

 



No, they were intended for exactly what they are used for in the 7A21N.  The 50 ohm connection through the edge fingers of the circuit board is good, but not great and has reflections that would not allow a really high frequency connection.

- Steve




Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement

 

I did not know either but when I was well along in my planning to retrofit the
old ROM board with 27C64 EPROMs because of the MOSTEK mask ROM bit rot issue, I
discovered that my 7854 was different. The more recent board replaces both the
old ROM board and the old RAM board so it also provides the maximum supported
RAM which is backed up by a battery instead of an external power connection.

I was originally planning on just using an adapter to convert the 2364 memory
pinout to the 2764 pinout:

http://store.go4retro.com/2364-adapter/

On 12 Jan 2014 09:44:09 -0800, you wrote:

Now *that* is *cool* !

I had no idea that Tek made a 'later' board, but I suppose it makes sense.

P.


Re: Problem after recaping LV power supply on 2445A

amit s
 

So i finally managed to get hold of 2 -2ohm 25 watt resistors.I checked the resistance while both are connected parallel in J232 and J303 and showing around 1.5 ohm with my digital multimeter.Resistors showing 1% printed on them.When trying to start the supply,sometimes it starts and gives 5.6 volts at J232 for a minute and then just starts pulsing.I followed the flowchart and it shows problem in inverter board because i removed comb connectors J233 and J234.then it tells to check Q1050,q1060,q1070, cr1060 and cr1070 for shorts.i just checked for shorts while they are in circuit and found no shorts.is it the proper way or i should remove them out from the circuit to test?now it says to put isolation transformer and tells to put primary test load.now looks like i will have to build primary test load.Any suggestions guys?thanks


TM5000 connectors

John Griessen
 

Anyone want some 10 contacts each side board edge connectors
similar to ones in a TM5000 frame for the GPIB wires?

I got some to maybe make an extender for TM5000, but very little interest.
Probably one can troubleshoot all but GPIB, then plug in and remove
to fix that, so no need for it as extender.

http://ecosensory.com/tek/TM5000-20-contact-edge-1.jpg

2 for $1.50 + $1 ship
5 for $3 + $1.5 ship
10 for $5 + $2 ship
20 for $8 + $3 ship
30 for $11 + $4 ship
72 on hand ready to send cheap 1st class $1


Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement

 

If the JEDEC 28-pin byte wide interface is used, then lots of different
currently manufactured memories up to 512 kbits (64k x 8) could be used
including Flash, EPROM, OTP EPROM, EEPROM, and NVRAM with at most a couple of
jumpers.

If the JEDEC 32-pin byte wide interface is used, then memories up to 4 Mbits
(512M x 8) could be used.

In both cases, copying the original memories would be a straight 1 to 1
operation.

On 12 Jan 2014 09:23:41 -0800, you wrote:

Well, I can help with the electrical and PCB design. But I have no idea about what's needed and what the mechanical clearances are like. I could design the best board in the world, but if it doesn't fit...

I just checked on eBay. Looks familiar somehow, were these kinds of cards used in industrial embedded computing back then? I've seen this kind of card somewhere. Probably in my deep junk storage.

Anyhow, wouldn't it be much more fun to have a modern flash device in there with a jtag or (more complex) USB interface?

Who needs those grotty old DIP devices and cranky old programmers and gross old UV erasers?


Re: 2465 help to fix

 

Congratulations.  That looks like pretty good progress.  It makes sense that a failed Q155 could effect all traces.  Im not sure how changing the intensity settings was able to affect Q155.  But obviously, it did.  again congratulations on the progress.

What you have now could be channel noise and/or miss-adjustment of the CRT screen currents.  A previous technician may have tried all the knobs in a futile attempt at diagnosis.  Anything can happen that way.  I would focus on why the scale illumination doesn't work (failed lamps?) in the remote chance there is another power fault.

As for the blurred traces.  The readout numbers do not appear to be blurred in the YouTube video.  The calibrator traces look like mine do when the ground on the probe is longer than 1 inch of wire.  Try setting the bandwidth limit to 20 MHz and see if the traces clear up.  Then do the CRT adjustments on page 5-4 of the service manual.  This should sharpen the traces so you can search for any other problems.   

From: max t
To: TekScopes@...
Sent: Sunday, January 12, 2014 3:32 AM
Subject: [TekScopes] Re: 2465 help to fix

 
Did some steps , tracing back around U650 sequencer i have found
sick Q155 e-c low resistence changed it and while the A1 board disassembled have recap whole electrolitics , now scope
is working start without errors but traces very blard
and cannot adjust well also scale illum. not working
this the new video

http://www.youtube.com/watch?v=TnInYagdtQk&feature=youtu.be

--- In TekScopes@..., machine guy wrote:
>
> I can attest to the need for a bench fan when running this scope without a case.  I use a small clip on fan that can be pointed directly at the instrument.
>
> My first thought for this problem was tht one of the Horiz leads was loose from the scope.  They are accessible from the bottom when the case is removed.  But then I saw the trace can be moved to the left side of the screen.  This seems to say the horiz is working.
>
> I still lean to the idea that something is bleeding the power when knobs are turned but I cant think how since it didn't show when the OP measured voltages as he turned pots.
>
> Im stumped.  Not quitting, just stumped.
>
>
> ________________________________
> From: Don Black
> To: TekScopes@...
> Sent: Sunday, January 12, 2014 2:36 AM
> Subject: Re: [TekScopes] Re: 2465 help to fix
>
>
>
>  
> Have you tried tapping the instrument (gently) to see if it's sensitive to vibration. I think it would have to be very touchy to get these results from the mere vibration of turning a knob but it just seems so general that it's possible. While it could be the CRT it doesn't look like it to me so don't slash your wrists just yet. I've never worked on one of these but is it possible to measure the deflection voltage going to the tube. You should be able to see it jumping all over the place in sympathy with the trace movement.
> At least you've won weird fault of the month award.
>
> Don Black.
> PS can someone advise if this model overheats if operated with the
> covers off and needs a desk fan blowing into it while working on
> it?
>
> On 12-Jan-14 6:47 PM, machine guy wrote:
>
>  
> >
> >I have never seen anything like that.  You are able to put the trace nearly anywhere on the screen but it is usually right of center.  The trace that shows in the video looks like the cursor from the readout board.
> >
> >
> >The fact that you can position the trace right or left, mostly right, seems to say the U800 is working (but not necessarily right).  I am bewildered but will think about it and post back.
> >
> >
> >Perhaps someone with more experience on these will be better help to you.
> >
> >
> >Mac
> >
> >From: max t mailto:maxxim_66@...
> >To: TekScopes@...
> >Sent: Sunday, January 12, 2014 12:24 AM
> >Subject: [TekScopes] Re: 2465 help to fix
> >
> >
> >
> > 
> >Values on those pins is fine , about R352 levels from -4.97v to +4.97v
> >and R351 from 0v to +4.98v , looking the
> schematic seems to be ok ,
> >i have upload a new video with more
> details of scope rotating pots
> >
> >this the video
> >http://www.youtube.com/watch?v=QaHsLDqqg4k&feature=youtu.be
> >
> >regarding corrosions ..the scope is very
> clean there no traces
> >of that i have changed all electrolitics
> but they was almost
> >fine maybe the c1022 with broken
> terminal it was defective
> >or while assembled too much forced or
> manipulated then with age
> >disconnected.
> >
> >--- In TekScopes@..., machine guy mailto:machineguy59@ wrote:
> >>
> >> I have not seen this problem before
> but we can trace the schematic.  My
> next measurements would be to see if the
> voltage at pin2 of R352 changes as you
> turn the intensity and pin 2 of R351
> changes as you turn Readout intensity.
> >>
> >> But it is concerning that changing
> settings on the panel (vert pos, etc)
> changes the horizontal left and right. 
> That may indicate a bad CRT tube.  I am
> sure there are other measurements to
> verify that and perhaps others on the
> forum will have ideas here. 
> >>
> >> For now, I would trace the
> schematic and check voltages beginning
> at the intensity knobs. 
> >>
> >>
> >> ________________________________
> >> From: max t mailto:maxxim_66@
> >> To: TekScopes@...
> >> Sent: Saturday, January 11, 2014
> 12:19 PM
> >> Subject: [TekScopes] Re: 2465 help
> to fix
> >
> >
> >
> >
>
>
>
>
> ________________________________
>
> This email is free from viruses and malware because avast! Antivirus protection is active.
>




Re: 7Bxx MOD515C

Craig Sawyers <c.sawyers@...>
 

No.  The follower board on the 7000 series edge connector is good to 1GHz+.  The 7104 works in exactly that way. 

 

On the 7A21N the two pins on the 4-way connector at the top are used for DC, and carry the trace position control from the front panel of the 7A21N

 

Craig

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of ditter2@...
Sent: 12 January 2014 17:03
To: TekScopes@...
Subject: Re: [TekScopes] 7Bxx MOD515C

 



No, they were intended for exactly what they are used for in the 7A21N.  The 50 ohm connection through the edge fingers of the circuit board is good, but not great and has reflections that would not allow a really high frequency connection.

- Steve



Re: 7Bxx MOD515C

rensetel
 

I have tried to make a picture as close as possible to show the connectors, see attachment
Rens


On Sunday, January 12, 2014 6:33 PM, David wrote:
 
The article I linked was pretty explicit on page 20 that those were originally
for an optical readout system:

"The plastic molding at the rear of these plug-ins still included the 5mm holes
where Hiro’s fibre bundles were expected to go; an indication of how close to
production this approach had progressed."

On 12 Jan 2014 09:03:07 -0800, you wrote:

>No, they were intended for exactly what they are used for in the 7A21N. The 50 ohm connection through the edge fingers of the circuit board is good, but not great and has reflections that would not allow a really high frequency connection.
>
>- Steve



Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement

Phil Peri
 

Now *that* is *cool* !


I had no idea that Tek made a 'later' board, but I suppose it makes sense.



P.


Re: 7Bxx MOD515C

 

The article I linked was pretty explicit on page 20 that those were originally
for an optical readout system:

"The plastic molding at the rear of these plug-ins still included the 5mm holes
where Hiro’s fibre bundles were expected to go; an indication of how close to
production this approach had progressed."

On 12 Jan 2014 09:03:07 -0800, you wrote:

No, they were intended for exactly what they are used for in the 7A21N. The 50 ohm connection through the edge fingers of the circuit board is good, but not great and has reflections that would not allow a really high frequency connection.

- Steve


Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement

snapdiode@...
 

Well, I can help with the electrical and PCB design. But I have no idea about what's needed and what the mechanical clearances are like. I could design the best board in the world, but if it doesn't fit...

I just checked on eBay. Looks familiar somehow, were these kinds of cards used in industrial embedded computing back then? I've seen this kind of card somewhere. Probably in my deep junk storage.

Anyhow, wouldn't it be much more fun to have a modern flash device in there with a jtag or (more complex) USB interface?

Who needs those grotty old DIP devices and cranky old programmers and gross old UV erasers?


Re: About the cable used in oscilloscope probes

 

Difficult to solder metals can often be handled by cleaning and etching with
hydrochloric acid and then depositing copper via electrolysis and an easily
acquired solution of copper sulphate or copper nitrate. I would worry about
strain relief of the wire at the edge of the solder joint though.

12 Jan 2014 09:01:51 -0800, you wrote:

. . .

BTW, as the center conductor is nichrome, you can't solder it. The connections at the terminations are usually crimped on the wire.

- Steve


Re: 7Bxx MOD515C

ditter2
 

No, they were intended for exactly what they are used for in the 7A21N.  The 50 ohm connection through the edge fingers of the circuit board is good, but not great and has reflections that would not allow a really high frequency connection.

- Steve

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