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.
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
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 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.
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
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.)
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.
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
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)?
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.
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/hpUFRhHChttps://github.com/peekpt/tekcaps
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
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.
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
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
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
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
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.
