Tektronix 7603/7613 Repairs

[dave_k]

I recently acquired 4 Tek 7000 series scopes (with plugins), a pair of 7603s and a pair of 7613s. The idea is to repair/restore these in my spare time, so updates might be slow.

Starting with a 7603 and the first unit I check is 100% dead. Others who have repaired these have replaced the main filter caps in these scopes. I figured that is a good place to start before checking the regulator board.

Rather than replace the original Mallory electros with NOS ones I elected to use modern equivalents. Most (if not all) modern electros are snap-in PCB mounting using 10mm spaced leads. The original caps had 4 leads around the perimeter with a 5th leg in the middle. Over lunch one day I came up with a neat answer to this square peg/round hole dilemma.


The original cap is on the right, replacement with adapter on the left. PCB was made by iTead (US$1 per board) and the mounting pins are from Harwin (p/n H2101-01).


Completed replacement of all 6 caps. I am still waiting on the delivery of a smaller adapter board for the 1 electro with a different footprint.


The PCB pins were selected to space the adapter board away from the main PCB as seen here.

Finally, the original caps were used to link PCB tracks together (to allow other tracks to pass underneath the cap). I have seen other repairs where wire links had to be installed along with bodging in the replacement cap. This adapter board neatly solves that problem too. 

To be continued...

[Rupunzell]

Very nice. This would be a good product offering.

Bernice

[PaulAm]

I use a similar adapter when repairing 465s.  On those scopes if you use very long leads instead of pins, you can thread the new cap into position without having to disassemble the scope.

Always use 105C caps from a reputable manufacturer if available.  And then check them before installation anyway.

[dave_k]

Very nice. This would be a good product offering.

Bernice

I am happy to make the gerber files available to anyone who wants them...

[dave_k]

UPDATE: I have received the smaller adapter PCB from iTead.



Now the rectifier assembly is complete.



Next step is to begin looking at the regulator board. More to come....

[dave_k]

It's been a while but I have had a little bit of time to work more on the 7603.

The regulator board checked out OK, except for one bad transistor (Q931) which was stopping the +15v rail from working. The original part is a 2N5859, best replacement I could find was a 2N5320.

So with the rectifier and regulator boards checking out it was time to try a first power up. Still nothing, no power light because something is still loading down the +5v rail. After some more probing it turns out the culprits were on the main interface PCB.



2 out of the 3 larger electros measured dead short (never seen an electro do that before!) It's not the easiest PCB to remove so it too was totally re-capped. I also learned the Main Interface PCB is a 5-layer board - high tech for a early 1970's design.



Finally the unit powers up and produces something on the screen.



Next step is to remove all the front panel controls for switch cleaning, etc. before trying to solve the issues with the fuzzy and wonky display (possibly a problem with the horizontal amp).

[dom0]

Nice work.

The blurred display could be caused by a number of things. I'd first check supply ripple - wideband, not with a multimeter. Trace the signal from readout board (easier to access than the main board) to the deflection plates to see where the noise is added ; might be an oscillating amplifier stage. Somewhere I read about a troubleshooting technique for all the Tek scopes with differential signal paths: short the diff pair at every stage from the horiz/vert amp going backwards and see where the problem starts showing up. Never used it myself, though.

[dave_k]

Well, the cause of the display problem was an anti-climax! Only one of the 2 horizontal plates was connected.



So now I have another problem to solve. From this you can see the trace coming from the plug-in is displayed nicely, but the readout generator is kinda 'ghosting'.



I hope the problem is a out-of-spec passive component and not U510 (Tek 155-0022-00 channel switching IC).

[AF6LJ]

Very nice. This would be a good product offering.

Bernice

I agree, I was thinking about having to make some of those for another resteration project I plan on getting on next year. Those are nicely made.

[AF6LJ]

Very nice. This would be a good product offering.

Bernice

I am happy to make the gerber files available to anyone who wants them...

That would be great.

[AF6LJ]

Very nice work, you are making good progress.

[c4757p]

I have a scope from the same family that might need the PSU caps replaced too - I'd also like the Gerbers

[dave_k]

Okay .. I'll post them here

[c4757p]

Thanks dude!

[AF6LJ]

Thank You Sir 

[dave_k]

Time for a brief update regarding the fuzzy readout; the characters appear fuzzy only in the vertical direction, as if there is some sort of oscillation occurring on the vertical drive from the readout board.

I did some more high-level troubleshooting and swapped out the horizontal amp PCB from the other 7603. The result was everything now sharp and in focus. So now to solve the question, how does a kaputt horizontal board cause a vertical issue with the readout?

[AF6LJ]

I am just wondering out loud.....
Does the fuzziness of those readout characters change with sweep settings.

[DimitriP]

Bad ram  in the character generator circuit will cause fuzzy readout ...if that lives on the Horizontal board you might have a wiiner.

[dave_k]

I am just wondering out loud.....
Does the fuzziness of those readout characters change with sweep settings.

No .. the sweep rate of the readout is generated independently.

[dave_k]

Bad ram  in the character generator circuit will cause fuzzy readout ...if that lives on the Horizontal board you might have a wiiner.

There is no RAM .. it's a 100% analogue design.

[DimitriP]

Bad ram  in the character generator circuit will cause fuzzy readout ...if that lives on the Horizontal board you might have a wiiner.

There is no RAM .. it's a 100% analogue design.

Not quite 100%
From the readout board, the it connects to horizontal board using J508, that would be a good neighborhood to take a look at.
 
As for the the  readout board, there is an adjustment for a
row match R2183,
Column match R2214
and vertical separation R2291
that might be worth fiddling with

[AF6LJ]

I am just wondering out loud.....
Does the fuzziness of those readout characters change with sweep settings.

No .. the sweep rate of the readout is generated independently.

Good to know, I might have to download the manual for this scope, these things are really interesting to me..

[miguelvp]

I am just wondering out loud.....
Does the fuzziness of those readout characters change with sweep settings.

No .. the sweep rate of the readout is generated independently.

Good to know, I might have to download the manual for this scope, these things are really interesting to me..

I have one of each.

The 7613 I got with a 5110 for $50 for both in really bad shape:

But they did clean up pretty good:


The 7603 came from a friend and needed some repairs:
https://www.eevblog.com/forum/repair/repairing-tektronix-7603-oscilloscope/


So far I have 12 7000 series plug-ins and 3 for the 5000 one.

Btw, analogs rule, free running I got  609,190 waveforms per second on those 40+ year old scopes, more than the pathetic 5,000 wfps with memory depth set to the minimum 14K points on my Rigol DS2000 (sure it can go up to 50,000 but only at 700 points memory depth), on normal operation with any decent memory depth well, it tanks bad, but it's really useful since it's in memory so not really a complaint just to point it out.

https://www.eevblog.com/forum/testgear/first-personal-'scope-purchase/msg681691/#msg681691

[timb]

I recently acquired 4 Tek 7000 series scopes (with plugins), a pair of 7603s and a pair of 7613s. The idea is to repair/restore these in my spare time, so updates might be slow.

Starting with a 7603 and the first unit I check is 100% dead. Others who have repaired these have replaced the main filter caps in these scopes. I figured that is a good place to start before checking the regulator board.

Rather than replace the original Mallory electros with NOS ones I elected to use modern equivalents. Most (if not all) modern electros are snap-in PCB mounting using 10mm spaced leads. The original caps had 4 leads around the perimeter with a 5th leg in the middle. Over lunch one day I came up with a neat answer to this square peg/round hole dilemma.


The original cap is on the right, replacement with adapter on the left. PCB was made by iTead (US$1 per board) and the mounting pins are from Harwin (p/n H2101-01).

Very clever solution, but one question: Do all four of the ground pins actually need to be connected from the cap to the board? The only reason I can see for that is if Tek used the caps to hook separate ground runs together.

I've replaced a lot of these caps on TM 500 power modules. On these four pin caps, the three inner pins have 10mm lead spacing, so I simply replaced them with new snap in style caps with that spacing, only using two of the holes on the board.

On the TM 500, the front side of the board connects all four ground pins together with a solid plane, while they do route off independently on the back side.







Bonus Picture: 30 Years, Twice the Capacitance, Half the Size!




Sent from my Tablet

[dave_k]

Very clever solution, but one question: Do all four of the ground pins actually need to be connected from the cap to the board? The only reason I can see for that is if Tek used the caps to hook separate ground runs together.

.. and that is exactly what is happening on the rectifier board in the 76x3 scope. The cap is used to bridge 2 parts of a ground plane together so that a track may run underneath. I have seen other repairs where wire links were installed to make the bridge. I think the PCB solution looks neater   

[timb]

Very clever solution, but one question: Do all four of the ground pins actually need to be connected from the cap to the board? The only reason I can see for that is if Tek used the caps to hook separate ground runs together.

.. and that is exactly what is happening on the rectifier board in the 76x3 scope. The cap is used to bridge 2 parts of a ground plane together so that a track may run underneath. I have seen other repairs where wire links were installed to make the bridge. I think the PCB solution looks neater 

Ah hah, gotcha! I figured that must be what's going on; just wanted to make sure. Does look a ton nicer!

You know, I recently opened a small triple output HP power supply from 1984. It used smaller diameter versions on those 4-terminal caps, only they were 5-terminal! Two positive and three common ground terminals; they were actually two separate capacitors in one can!  (One was a 1000uF/300uF, for example.)

They also used the three ground terminals to bridge two ground planes. I was actually going to make up little adapter boards just like yours; only they would have allowed you to put two capacitors on them. (In the end, all the caps tested fine, so I figured it was more trouble than it's worth.)

I think I'll have some of your PCBs made up though as they're cheap enough and it seems like I'm always fixing a TM500 series mainframe! (It's a better solution than just wedging a two lead snap in cap down. I just did a TM501 last week, and there wasn't quite enough horizontal clearance for the new cap. This would have been the ideal solution.)

What kind of pins are those you have on the bottom of the boards? They don't look like standard headers to me.




Sent from my Smartphone

[krivx]

What kind of pins are those you have on the bottom of the boards? They don't look like standard headers to me.

Yeah, I'm also curious about this. I want to make some boards to plug into vacuum tube sockets and these look close...

[Tothwolf]

What kind of pins are those you have on the bottom of the boards? They don't look like standard headers to me.

To me they looked like they might be feed-thru turret terminals with the head clipped off.

http://www.keyelco.com/category.cfm/Terminals-Turret-Rivet-Types/Feed-Thru-Terminals/p/512/id/759

[krivx]

The original cap is on the right, replacement with adapter on the left. PCB was made by iTead (US$1 per board) and the mounting pins are from Harwin (p/n H2101-01).

I should have paid more attention...

[dom0]

One plug-in I commend highly is the 7A13. It's incredibly useful for many things, and allows insanely accurate measurements, even in comparison to top-of-the-line digital scopes.

A storage mainframe (e.g. 7623) is pretty neat to have, because the various storage modes, mainly FAST and VAR PERSIST, allow to filter noise very effectively. This is especially handy for low-level measurements e.g. with a 7A22.

(Maybe we should make a thread for general 7000 series discussion? On the other hand this might drive prices up even further )

[DC912]

I recently purchased a 7633 storage scope and would appreciate some guidance on getting the vertical placement of the readouts on the screen adjusted.

The location of the upper readouts are fine.  The lower readouts need to be raised up towards the top of the screen because the bottom half of the characters are not visible.  Will a row adjustment on the readout board take care of that, or is there something else that ought to be adjusted?

Thanks.

[dom0]

Colum and row match adjust the analog level used to index the ROMs, if the characters are displayed properly these are already correct.

Take a look at R2291 (vertical separation). If you can't get a good display, check for drifted resistors in the vicinity of U2284.

[MarkL]

One plug-in I commend highly is the 7A13. It's incredibly useful for many things, and allows insanely accurate measurements, even in comparison to top-of-the-line digital scopes.

A storage mainframe (e.g. 7623) is pretty neat to have, because the various storage modes, mainly FAST and VAR PERSIST, allow to filter noise very effectively. This is especially handy for low-level measurements e.g. with a 7A22.

(Maybe we should make a thread for general 7000 series discussion? On the other hand this might drive prices up even further )

Too late.  Prices on 7A13 plugins just jumped 20%.

Let's hope Dave doesn't mention them in a video.

[timb]

The original cap is on the right, replacement with adapter on the left. PCB was made by iTead (US$1 per board) and the mounting pins are from Harwin (p/n H2101-01).

I should have paid more attention...

Whoops. Serves me right for posting while half asleep!

OP, can you post the Gerbers somewhere? I know you said you'd make them available, but I didn't see a link or anything.


Sent from my Tablet

[dave_k]

I posted them earlier in this thread. 

https://www.eevblog.com/forum/testgear/tektronix-76037613-repairs/msg804009/#msg804009

[MickM]

see reply # 12 for the two zips

[miguelvp]

One plug-in I commend highly is the 7A13. It's incredibly useful for many things, and allows insanely accurate measurements, even in comparison to top-of-the-line digital scopes.

A storage mainframe (e.g. 7623) is pretty neat to have, because the various storage modes, mainly FAST and VAR PERSIST, allow to filter noise very effectively. This is especially handy for low-level measurements e.g. with a 7A22.

(Maybe we should make a thread for general 7000 series discussion? On the other hand this might drive prices up even further )

Too late.  Prices on 7A13 plugins just jumped 20%.

Let's hope Dave doesn't mention them in a video.

I'm glad I was able to get mine earlier this year, $36 for all three shipped. The one on the left is really an 7A11 but the pull tab was missing so I used a broken single channel plug-in as the donor for the pull tab.

[timb]

I posted them earlier in this thread. 

https://www.eevblog.com/forum/testgear/tektronix-76037613-repairs/msg804009/#msg804009

Sorry, I think my Tapatalk app is eating posts. I just looked at the thread on the website and saw your original post that talks about bridging the ground planes, has the pin part number and post 12 with the links. So basically every one of my posts in this thread is redundant.

I'm not illiterate, I swear!


Sent from my Tablet

[AF6LJ]

This is great work.

[dan3460]

Thanks Dave, I think I place the order correctly, we'll see what I order when it arrives.

[scopeman]

Dave,

This is ingenuous! Tek Aficionado and legendary analog guru  Jim Williams would have been impressed!

7K series are great scopes!

They are dirt cheap for what they are at hamfests these days.

All the best.

Sam
W3OHM
Owner/Moderator of the LeCroy_Owners_Group on Yahoo! Groups

[scopeman]

Okay .. I'll post them here

Dave,

When I try and load these Gerbers in Gerbv or Sprint I either can not get the drill file to line up or the layers do not contain traces. I don't know what is happening here. Any chance you could also post the original CAD system files and perhaps the drill file in standard 2.4 Excelon trailing format?

Thanks,

Sam

[scopeman]

Okay .. I'll post them here

Dave,

When I try and load these Gerbers in Gerbv or Sprint I either can not get the drill file to line up or the layers do not contain traces. I don't know what is happening here. Any chance you could also post the original CAD system files and perhaps the drill file in standard 2.4 Excelon trailing format?

Dave,

I may have figured this out by using a couple of CAD systems. I have one board done in SprintLayout 6.0 and will post the Sprint and Gerber files probably tomorrow (it's probably near 1 am now). If you post the original files it might be easier.

Thanks,

Sam


Thanks,

Sam

[dave_k]

The next item of work on the first 7603 scope is cleaning up the horizontal output PCB.
It is looking rather crusty and dirty. 


Particularly around the output drive transistors.


After removing all components, the amount of crud left behind is visible. Some repair work has been done to this board in the past with solder that left behind lots of ugly flux.


A combination of careful solder removal with wick and copious cleaning with IPA has made a significant improvement. Despite the scorch marks on the board not one track has lifted. This is a very well made PCB!


Now I am half-way through reloading the board. The wipe-contact IC socket was replaced with a machine pin version. 4 out-of-tolerance resistors and 1 capacitor have been replaced so far..

[AF6LJ]

This looks good, this has become one of my favorite threads.

[dave_k]

Rebuild of horizontal amp is complete 


Compare the finished board ...


.. to what it originally looked like.


Components rejected for being out of tolerance or damaged.


Next on the agenda is to remove the HV power supply for re-capping.

[dom0]

Soon you'll be making repairs as elaborately as Ralf does..did them (www.amplifier.cd) :-)

[Radio Tech]

Very good job on this. Cannot wait to see more.
 

[SeanB]

You replaced a silver mica capacitor with a ceramic one, I would not do that, the ceramic cap is very poor as against the silver mica, which I onlyt see fail as open circuit or blown apart from overvoltage.

As well space the hot resistors off the board a little so you can have airflow around them, and they do not contact the board and scorch it.

[AF6LJ]

You replaced a silver mica capacitor with a ceramic one, I would not do that, the ceramic cap is very poor as against the silver mica, which I onlyt see fail as open circuit or blown apart from overvoltage.

As well space the hot resistors off the board a little so you can have airflow around them, and they do not contact the board and scorch it.

Generally speaking I would agree, the SM is most likely more stable, I would trust the ceramic to be of the proper voltage but may not age as well as the SM cap.

[dave_k]

You replaced a silver mica capacitor with a ceramic one, I would not do that, the ceramic cap is very poor as against the silver mica, which I only see fail as open circuit or blown apart from overvoltage.

As well space the hot resistors off the board a little so you can have airflow around them, and they do not contact the board and scorch it.

Generally speaking I would agree, the SM is most likely more stable, I would trust the ceramic to be of the proper voltage but may not age as well as the SM cap.

You're be referring to C584, which forms a thermal compensation network along with series resistor R584. The original part specified is a 330pF 500V ceramic tubular cap. The silver mica cap was the wrong value (680pF) and I can only assume fitted in desperation during a previous repair attempt.
I am satisfied in this application the replacement capacitor will be adequate.

[AF6LJ]

You replaced a silver mica capacitor with a ceramic one, I would not do that, the ceramic cap is very poor as against the silver mica, which I only see fail as open circuit or blown apart from overvoltage.

As well space the hot resistors off the board a little so you can have airflow around them, and they do not contact the board and scorch it.

Generally speaking I would agree, the SM is most likely more stable, I would trust the ceramic to be of the proper voltage but may not age as well as the SM cap.

You're be referring to C584, which forms a thermal compensation network along with series resistor R584. The original part specified is a 330pF 500V ceramic tubular cap. The silver mica cap was the wrong value (680pF) and I can only assume fitted in desperation during a previous repair attempt.
I am satisfied in this application the replacement capacitor will be adequate.

Cool, good to know...

[PedroDaGr8]

Rebuild of horizontal amp is complete 



.. to what it originally looked like.


Compare the finished board ...
Components rejected for being out of tolerance or damaged.


Next on the agenda is to remove the HV power supply for re-capping.

It looks like the variable component in the center changed orientation. Not sure if that matters or not, just something I noticed.

[Radio Tech]

It looks like the variable component in the center changed orientation. Not sure if that matters or not, just something I noticed.

I notice that the ceramic trimmer was turned also, but figured he going to properly align everything when done. Perhaps he cleaned it by turning.

[dave_k]

It looks like the variable component in the center changed orientation. Not sure if that matters or not, just something I noticed.

I notice that the ceramic trimmer was turned also, but figured he going to properly align everything when done. Perhaps he cleaned it by turning.

Bingo 

[3roomlab]

this 7xxx scopes are just WOW !!!
http://www.tek.com/Measurement/Support/scopes/faq/history.html

[dom0]

And their weight and size is WOW too!

[liquibyte]

And their weight and size is WOW too!

Yes, they are.  I now have a working R7603 and I can tell those that don't know that they weigh around 50 pounds or so and are unwieldy to boot.  We're talking just over 17 inches wide by over 24 inches length if you include the handles and bits poking out and about 5 1/4 inches thick.  I don't have a proper rack to put this thing in so I'm going to make up a custom job with wheels more than likely.

[jh15]

Nice to see some recent stuff on the 7000 series. I am about to pull apart my 7834  and another couple storage mainframes (one a 5000 series). It is working fine, (the others neeed work). Even has unbroken calibration void stickers on it from M.I.T.  Maybe Limor Fried of Adafruit touched it while she was there

Want to troubleshoot these in front of hackerspace members.

A 7000 series thread would be nice.

For other countries info, M.I T. is Massachusetts Institute of Technology a little tech college

[vk6zgo]

And their weight and size is WOW too!

Nah! they are featherweight compared to a 524AD!

[cncjerry]

I have two 7603s, one an R model.  Be careful cleaning the buttons as I have one that the lettering came off with just water.

[Martin.M]

Soon you'll be making repairs as elaborately as Ralf does..did them (www.amplifier.cd) :-)

The community from Ralf is RIP, there is no life since a long time. Very sad !
My  (www.wellenkino.de) is actually the last castle for Tek enthusiasts here in germany.
We are 120 people now, worldwide.

greetings
Martin

[dave_k]

UPDATE: So not much has been happening lately due to holidays, but recently I acquired another 7603 mainframe, and it is in much better condition than the one I originally began repairing.
Work has started on fixing the power supply section first, but I am waiting on the delivery of some parts from overseas.

I shall post some more pics next week

[dave_k]

Update: work on the 2nd 7603 I have is progressing well.

Refurbishing the power supply and regulator board is complete. The rectifier board received a new batch of electrolytic caps (on their nice adapter boards). The rectifier for +/-15v rail was faulty (CR811) and replaced. Also CR820/821 was replaced with modern equivalents (1N5625GP). Most of the carbon comp resistors were a little high. They are there to discharge the electrolytic caps, so I left them as is.





The main interface was removed and given an overhaul of electrolytic caps, plus a cleaning of sockets and pin connectors.



Finally the regulator board was carefully inspected. 6 out of tolerance resistors were replaced, and R952 was upgraded to a 1W metal film resistor (in line with changes to later production units). the original 0.5W resistor dissipated a little heat, and was beginning to discolor the PCB.



Tested on the bench, the -50v rail measured -49.9 prior to adjustment. Not bad for a 38 year old piece of gear. I will assess ripple performance later when work on this mainframe is complete. (Note that the ICs are removed from the logic and trigger/vertical boards - I did not want a faulty regulator to damage them!)



Initial results look good




Pile of rejects. 

[AF6LJ]

Looking really good.
Makes me want to go out and get one of those.
It would be a fun project and have a first class scope when it was all done.

[tautech]

Update: work on the 2nd 7603 I have is progressing well.

Refurbishing the power supply and regulator board is complete. The rectifier board received a new batch of electrolytic caps (on their nice adapter boards). The rectifier for +/-15v rail was faulty (CR811) and replaced. Also CR820/821 was replaced with modern equivalents (1N5625GP).

The solder joint, top layer CR821 looks a little crusty to me. 

[dave_k]

I'll have a look next time that module is removed... pretty sure it's just a bit of funk on top of the solder.

[jh15]

One plug-in I commend highly is the 7A13. It's incredibly useful for many things, and allows insanely accurate measurements, even in comparison to top-of-the-line digital scopes.

A storage mainframe (e.g. 7623) is pretty neat to have, because the various storage modes, mainly FAST and VAR PERSIST, allow to filter noise very effectively. This is especially handy for low-level measurements e.g. with a 7A22.

(Maybe we should make a thread for general 7000 series discussion? On the other hand this might drive prices up even further )

Too late.  Prices on 7A13 plugins just jumped 20%.

Let's hope Dave doesn't mention them in a video.

I'm glad I was able to get mine earlier this year, $36 for all three shipped. The one on the left is really an 7A11 but the pull tab was missing so I used a broken single channel plug-in as the donor for the pull tab.

Miguelvp, can you immediately open your 7a13, remove the large gears and cast molds or make drawings? They all break and are made of the purest unobtainium. I would like to fix my 7a13 with broken gears. Maybe 3d print?

Otherwise, I was thinking of connecting switches or relays to the rotary switch.

[miguelvp]

Maybe a small MCU and a small OLED screen?
I know they made them later with graphical displays, maybe you can find how the digital display is wired and do a mod.

But I'll give it a try if I find time to do the molds. I will also look at the links I have regarding old Tek parts from my bookmarks.

Edit: In the meantime the following site mentions that using an external voltimeter to monitor the  comparison voltage

http://w140.com/tekwiki/wiki/7A13

Edit2: both technical reference manuals for the early and later models with schematics can be found here:
http://bama.edebris.com/manuals/tek/7a13/

[fatbeard]

Hello, I'm new to this forum. I design RFID readers for a living, and have been interested in electronics virtually all my life.
I found it via the Yahoo Tek forums, and am more than a little interested since I have aquired quite a collection of Tek 7k series equipment (from which a lot is not working quite right, or not at all).
The remote possibility of obtaining the bevel gears for the early 7A13 has me on the edge of my seat... I'll be following this thread closely.

[dave_k]

I reckon the Chris from the ClickSpring channel on YouTube would be able to turn some out. What that guy can do with a lathe is incredible!

[robrenz]

I have two 7603s, one an R model.  Be careful cleaning the buttons as I have one that the lettering came off with just water.

A fix for that situation here in reply #5 in my 7603 restore thread

[jmsc_02]

Thanks for the gerbers (and the thread... just wow). I'll give them a good use

[jh15]

I almost added that yes, you can monitor the voltage from the panel jack, but you cannot switch the voltage ranges.

FYI, I can take out the plug-in and turn my wafer switch with needle nose pliers. If one usually stays within a voltage range for their needs consider that.

Then use the multiturn pot and panel jack voltage readings.

i have access to metal lathes, 3d prnters, and Bridgeport MDI milling machine, just not skilled enough to do it yet.

[dave_k]

I had a question from a forum member about the pin spacing of the smaller cap adapter board.

Here are the details:

[guido]

 

Thanks for making these available. I'm running a 7603 with 7A13/7A22/7B53 and a 7623A with 7L5+TG. I am not doing a complete overhaul like you, but changing the caps was needed.

I also have some spare mainframes, one also with a recapped supply. So when one fails i just swap and repair later 

[dave_k]

Looks very neat 

[Uselesss]

Hello Guys,

I'm trying to repair an 7613, I have changed all the Powercaps (thanks for this nice boards) but my scope is stille broken, as you see on the Picture.

The points (I think they are the Overlay informations) change number an posistion according to trigger an Amp. Setings.
The Test generator works fine.

What should I do now?
best regads from Gemany.

[tautech]

Hello Guys,

I'm trying to repair an 7613, I have changed all the Powercaps (thanks for this nice boards) but my scope is stille broken, as you see on the Picture.

The points (I think they are the Overlay informations) change number an posistion according to trigger an Amp. Setings.
The Test generator works fine.

What should I do now?
best regads from Gemany.

Welcome to the forum.

You don't say what documentation you have. 
This one is handy along with the Service manual:
http://www.sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

[Uselesss]

 tautech Thank you for your fast reply until now I just had the service manual, I think the troubleshooting guide will help me allot.

Do you(or someone else) have an clue for the actual problem? How can I test the readout Unit?.
An vertical horizontal deflection ?

Best regards

[tautech]

tautech Thank you for your fast reply until now I just had the service manual, I think the troubleshooting guide will help me allot.

Do you(or someone else) have an clue for the actual problem? How can I test the readout Unit?.
An vertical horizontal deflection ?

Best regards

I'm not overly familiar with the 7k series but just looking at the pic you posted the dual pot for intensity also controls Readout, does it not? The outer knob is in the Off position.

There's a good # of members with these scopes, give it a day or so and others will come to your rescue. 

[Uselesss]

Theater is why I'm posting here.

You're right with the internsety Poti, but this doesn't affect the result ??.

EDIT:

I managed to get the Scope working . But the Readout Signal is still mesedup. I will follow the debug instructions in the service Manual to find the resaon for this behavior.
Do you have an clue what reason this could have?

best regards

[wine+dine]

It's hard to tell from one picture and no description of the state & conditions.

Did you first check and align the vertical amplifier independently of the readout?  Unplug the readout Y cable at the V amp and go through the alignment checklist.

Next I would put the readout into diagnostic (there's a transistor you pull out, see manual) so it shows digits in all locations, as in http://w140.com/tekwiki/wiki/File:7000-readout-diagnostic.jpg.  Then use another scope to check that the readout board X and Y outputs make sense - the stuff is DC coupled into the Y amplifier so it can mess up a lot if the levels are off.
Take it from there and let us know how it goes.

Just for ideas, the readout on my 7904 failed a while ago and it turned out it wasn't dead but just some 20-30 Div off screen (I "found" the readout display by unplugging the blanking signal and shifting the V amp offset around).  Culprit was an emitter resistor (in the readout blanking IIRC), value was nominal but the stage would never turn off anyway - probably the transistors had higher beta than what was designed in in 1970.

There's also a description of a "cute" readout error and its repair at http://www.amplifier.cd/Test_Equipment/Tektronix/Tektronix_7000_series_mainframe/rep-und-kal-7603/Reparaturbericht%20TEKTRONIX%207603.htm that might give you an idea.

(Oh and before you do any of the above, please double-check that ALL supplies are nominal both in DC and ripple.)

[wine+dine]

I just looked it up, the transistor to pull for the diagnostic display is Q2225.  Also check/replace the tantalum caps on the readout board, for example in one case C2115/2117/2119 caused me some grief.

[Uselesss]

Hello wine+dine thank you for the input.

I removed Q2225 and the result is showed in the picture. On Every possible location an dot appears.
I checked the X and Y Signals from the read  out-ROM to the Format Generator Signals are present.
I checked all Voltages the look god (measured on test points against Chassis GND).
Is it necessary to use Tantalum Caps, or could I use low ESR Electrolytic Caps as well?

On the Picture https://www.dropbox.com/s/kt68a9ihquj5l1g/readout_mit_werten.png?dl=0 I wrote down my measurements in the maintenance Mode.

Thanks for the Help best regards

[wine+dine]

Looks like things are OK from the character position signals all the way to the CRT, but the per-character X and Y signals are missing or much too small. 

Since both X and Y are affected, which are generated in the analog character ROMs by steering emitter currents (see http://w140.com/tekwiki/wiki/7000_series_readout_system), I'd suspect the driving side. 

Do you see a triangle signal at TP2129?  At pin 16 of U2126? Does turning R2128 have any effect? Are the ROMs being strobed (Pins 9 U227x)?

[David Hess]

I removed Q2225 and the result is showed in the picture. On Every possible location an dot appears.

Good, that is roughly what is suppose to happen although it should be displaying zeros rather than dots.

Is it necessary to use Tantalum Caps, or could I use low ESR Electrolytic Caps as well?

I doubt the tantalum capacitors are the problem but low ESR aluminum electrolytic capacitors will work fine.  Use 2 to 4 times the capacitance to get the same ESR.

[peekpt]

I happen to have a partially working  tek 7603 to restore in my lab.
I will start with the Pwr Supply, so caps need to get tossed out.

I pick @dave_k adaptors idea and made a multi adaptor instead of two.
I want to ask you if you can review it before I order the pcbs. Thank you in advance.
Feel free to use the design. It's ready to upload to any pcb maker.


https://oshpark.com/shared_projects/hpUFRhHC

https://github.com/peekpt/tekcaps

[danmc]

stupid question... Got any good tips for getting those big cans off the board?  It's been 25 years since I touched anything other than surface mount. 

I like the adapter boards.  Very slick.

My other question is if you had to desolder the transformer to get that board out.  My 7613 went belly up last time I turned it on.  Looks like I have a shorted diode and one of the caps is shorted.  I figure the others can't be far behind and  I might as well recap the whole board while I have it apart. 

Thanks
-Dan

[danmc]

Have you ordered those dual adapter boards?  I just cloned your github repo and looked at the gerbers.  I have two questions

1)  Why is the Tektronix logo (pretty by the way) on the soldermask layer?  I would have expected it to be in silk?

2)  The bottom copper looks kind of weird.  There aren't thermal reliefs on the 4 outside pads (where the pins to connect to the Tektronix board would go) but the ground circle isn't exactly unbroken either. 

I've not picked which caps to buy yet and checked pin out and drill sizes.

[peekpt]

1) It will be shinny this way    golden if you order from oshpark
2)Not thermal relief was an option since some of pads are jumpers and drive a lot of current. The bigger pads are for the pins, you can get triangular or square shape. 10mm apart for the capacitor's pins, some have an extra pin

[peekpt]

stupid question... Got any good tips for getting those big cans off the board?  It's been 25 years since I touched anything other than surface mount. 

I like the adapter boards.  Very slick.

My other question is if you had to desolder the transformer to get that board out.  My 7613 went belly up last time I turned it on.  Looks like I have a shorted diode and one of the caps is shorted.  I figure the others can't be far behind and  I might as well recap the whole board while I have it apart. 

Thanks
-Dan

this is yet on my todo lis  :-[t, but if you unsolder transformer it will be easier to work, not a big deal if you have a good practice

[WastelandTek]

Hey folks,

These little adapter boards are brilliant!  I am working on a couple of 5000 series scopes and some other D10 chassis and these are just the thing.

I got KiCad on and I can look at all the (6?) art layers.  I got the Harwin pins in my Mouser cart.

I know I am being dense here...I can't figure out how to use iTead.  I figured out the answers to the questions under "Small batches 2 Layer PCB".  Got the 1.6mm board thickness from the Harwin pin spec.  Guessed default on most.  Guessing 3.8 cm size from the little text files in the zip...is that right?

So I got 20 of these in my shopping cart ready to check out

 Small batches 2 Layer PCB

PCB Qty
    20pcs
PCB Color
    Green
PCB Thickness
    1.6mm
Surface Finish
    HASL
Copper Thickness
    1oz
Panelized PCBs
    1
PCB Width
    3.8
PCB Length
    3.8


but I can't figure out where to upload all the .G** files. 

I know I am being stupid here, but what am I missing??


edit/ disregard, I found the other thread https://www.eevblog.com/forum/repair/making-dave_k's-capacitor-adapters-at-osh-park/ and that process is very user friendly indeed  /edit

[WastelandTek]

looks like someone is monetizing the capboard idea

http://www.ebay.com/itm/Capacitor-Adapter-3-4-Square-Tek-Tektronix-TM501-Power-Supply-Recap-x1-/272740191627?hash=item3f80950d8b:g:RGwAAOSwwvZZVDa0

[mikepukmel]

Update: oops, sorry, just found that you had posted the files, thanks!!! 


Hi Dave,  This is a fairly old thread,  hoping you still check for posts from time to time.   Im not much of an electronics guy, learning.  I like to build and work on guitar amps.    I got a Tek 7613, from a friend that was saved from a spring cleaning effort (was headed for the dumpster).     Took a few weeks to get up the courage to power it  up,  but it started OK, no smoke or sparks and I get a trace (could roughly measure a 60hz test tone).      I started reading around, and it seems that most real tech's replace most the electrolytic filter caps, esp on the power supply board, like you did in your unit. 

Any chance you still have the ITEAD files to make those cool adapter boards, and wouldn't mind posting them? 

Also, in general, I read around other threads, and looks like you guys really go through and replace lots of components, out of tolerance resistors, and other caps.    How do you determine that a component is out of tolerance?    I didn't think you could measure values in circuit, i.e. you'd have to remove the part to figure out if it was bad or not.

Thanks!
Mike

[jh15]

Just don't go nuts. Look at posts for your unit.  If you can grab another scope or meter and look at ripple limits in the power supply. High quality capacitors can last a long time.

Shotgunning capacitors in an antique radio might be good, but in test equipment you might not do well if you are not an expert.

Haven't had it happen to me, but tantalum caps were the bees knees when I was into repairing tek, fluke, hp, wavetek sound technology, and all the broadcast equipment of yesteryear.  Guess I'll consider replacing the tants in my stuff.

Even scarier, is the fragility of multi-layer capacitors as Dave has shown.

Oh well it fits in with the planned appleescence one puts most or their money into besides a house or retirement.

[mikepukmel]

Hi All,   Its been a long time since anyone has posted on this thread.  In case anyone is watching: 

A friend gave me a throw away TEK 7613 that has been sitting in his closet at home since about 1990.  it powers, displays a trace,  seems fairly stable.   

I found this thread after a long search on what to replace in these great old scopes.     

Found the link above,

https://www.ebay.com/itm/Capacitor-Adapter-Tek-Tektronix-7000-Series-Recap-6-square-1-triangle-adapter/272799971348?_trkparms=aid%3D1110002%26algo%3DSPLICE.SOI%26ao%3D1%26asc%3D225074%26meid%3D1a6579e933b2414b97a29fee05aa89d9%26pid%3D100008%26rk%3D2%26rkt%3D2%26mehot%3Dag%26sd%3D272740191627%26itm%3D272799971348%26pmt%3D1%26noa%3D0%26pg%3D2047675&_trksid=p2047675.c100008.m2219


but the seller has several different listings.     I haven't had this unit apart yet, does anyone know if the kt above is the right one for this 7613 ps? 

Also, anyone happen to have a parts list for replacement ps caps?

Thanks,
Mike

[mikepukmel]

Thanks JH, will do.