Wanted: Manual for OT502 E/O Converter TM500 Module
Hi,
I just picked up an OT502 E/O Converter TM500 Module in a mainframe of assorted modules, and am looking for a user/service manual for it. There doesn't seem to be much online..
If anyone has a copy, paper or digital, please let me know!
Thanks,
Jared
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TEK 494 Spec'y BAND SWITCHING PROBLEM HELP
Hi Everyone,
My 494 is stuck in the higher bands (will not switch to 0 to 1.8ghz band)
The feed to the S11 and S12 band select relays is stuck on 31v .No change in polarity when you
operate the band select push button switches on the front panel.
Display shows correct change in bands.
I assume the front panel processor drives the relays and changes polarity but i can't find the interface from
?the processor logic levels to the 31v voltage to drive the relays.
Probably right in front of me but can't find it.
Any help greatly appreciated from you TEK experts
(I am using the PDF's ,of the 494, from the net .......do not have a physical book, so my old eyes are struggling)
Best Regards
George
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Re: #tektronix475 No Beam, HV Test point @ -500V - 600V DC
#tektronix475
Search this forum, and Tekscopes and EEVblog for rebuilds.
Try Qservice in Greece for the part.
Believe its X3 not X6.
Jon
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Re: #tektronix475 No Beam, HV Test point @ -500V - 600V DC
#tektronix475
I decided to just deal with the disassembly to confirm if the HV Multiplier was the issue or not. After de-soldering it, the -2450 test point arced to the probe as soon as I got it close to it so seems like its where it should be and the issue was in fact the multiplier.
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Was really hoping this wouldn't be the case and that'd it be something easy to replace like a cap, but what can you do?
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Looking for a replacement doesn't seem to get me anywhere, any available are all sold out and even then they seem to appear pretty sporadically anyways. I'm not opposed to try constructing a new one or modifying a different replacement to work.
?
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Also, I'm a bit confused what the actual multiplication level is. Most posts I've seen say its 3x but there's also some conflicting answers saying 6x, and the service manual I have been using doesn't say either way.
?
Best Regards,
Jaden
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Re: Software for the TDS500-600-700 series scopes uploaded!
Dear all,
Is it possible to use it as a replacement for the 2.2' disk used with the tektool app?
I have tried two drives and several disks attempting to save the calibration constants of my TDS784D and TDS684A scopes without success.
Thanks
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Re: #tektronix475 No Beam, HV Test point @ -500V - 600V DC
#tektronix475
Hi.
Assuming you have the user/service manual.? (A very good learning
aid!)? Follow the "theory of operation" section relating to the
CRT section, and also follow the performance check routines,
relating the the PSU in general, and CRT section.
The circuit diagrams have typical voltages and waveforms
documented for most parts of the system.? Those manuals are almost
a college course in analogue electronics, they are so well
written.
But you will need some other test equipment.? A multimeter at the
very least, and ideally another 'scope.
Is there HF activity around the HV transformer?? (A "Blocking
Oscillator")? You should easily pickup signs of that whistling
away if it is working, using an insulated 'scope probe and another
'scope (if you have one.)?? Else, a small portable AM radio will
indicate if the HV system is even oscillating.? (The harmonics of
the waveforms will easily be heard!)
If not, check the power transistor that drives it, and it's
biasing/regulating companions.
Look closely too, at any Tantalum Bead capacitors related to the
HV regulator.? If one has a tiny shiny blob of what looks like
solder stuck to it, replace it on sight.?? They can (and often do)
fail short cct, the tiny blob of metal is a clue!
Take care removing them.? Best cut the leads as close to the body
of the cap as you can, and then de-solder and remove each
remaining lead one at a time.? NOTE!? Plated Through holes are
used, take care not to pull out the through hole plating!
One other not uncommon problem with many of the 400 series of
that era, is the CRT PDA voltage multiplier goes bad.?
Transformers independently going bad too are not unknown.? One
time, there was someone who could rewind the things, but I think
they have moved on from that.
Often the DC Input fuse to the HV section blows as a result from
either of the above, but not always.?? Try removing the HF AC feed
from the HV transformer to the multiplier, and see if the Cathode
voltage is then some -2kV or so.
Other points of failure can be the various DC Restorer diodes
(used for the CRT Grid.)
But, most such failures usually result in the fuse blowing, or
total loss of intensity control (FULL brightness all the time!)?
Hint, always turn the Intensity control to minimum, and the Focus
to one extreme or the other, that should prevent any damage to the
CRT screen, if/when you get the HV section working again.
Make sure the fuse too is actually the correct value.? It is not
unknown either, for people to fit a higher rated fuse "just to
check" things, resulting in what could have been an easy fix,
turning into something of a chore.
Though you may perhaps in time, find a NOS part, or a pull from a
dead 'scope (for other reasons) part, it is worth knowing that it
is not impossible to construct a new multiplier, but with care and
attention regarding the voltages involved.
There's a lot of good help on this list, so stick with it.
If you've not got a manual, Artek Media can help, and very good
quality they are too.
All the best.
Dave G8KBV (Ex Tek UK, from back-in-the-day, when 475's and 465's
were current products.)
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Re: #tektronix475 No Beam, HV Test point @ -500V - 600V DC
#tektronix475
usual 475 fail is HV transformer , HV mult caps, high Ohm divider res.
See many threads on Tekscopes as well as Tekscopes 2 and EEV blog for 465/475 HV transformer rebuild.
Not trivial.
Bon chance,
Jon
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#tektronix475 No Beam, HV Test point @ -500V - 600V DC
#tektronix475
Hi all, I recently acquired a Tektronix 475 oscilloscope. I've been looking to get an analog scope for a while and was really excited to finally pick one up. It was sold as working, but seller wasn't familiar enough with these to realize the display did not work. I'd like to try and fix it, and already got a partial refund for it. It does power on and indicator lights work, and all the controls appear to work as well, but the HV circuit appears to have some sort of problem and I'd really appreciate some guidance in repairing it. There also isn't any CRT noise or glow from the filament.
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Checking the power rails, all are pretty much spot on, aside from the -2450V point which instead fluctuates quite a bit but reads from about -550V on average. I've already checked the caps around it (C1318, C1374, C1316, C1317) and all are fine, as well as the 1.5A fuse which is also intact. I've inspected for any cracked solder joints to the best of my ability but there's nothing obvious and I already went ahead and re-flowed the few that looked a bit suspicious, but its made no difference.
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From what I could find it seems like the next step would be check if its the multiplier, but I'd like to avoid taking it apart enough to do this if possible and replacing it doesn't really seem that viable regardless. Does anyone have some advice for anything else it might be or things to check? If there's any measurements you'd like that would help please let me know.
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Best Regards,
Jaden
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Help to find Disk "271X Flatness Tests"
Dear All, is there someone so kind to help me by sending the content of the disk "271X Flatness Tests" for a tek 2715 CATV SA?
Thank you very much in advance
Pietro
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WTT/WTB Tektronix 7904a service manual
Hello all: Am Seeking a Tektronix scope 7904A service manual, Original printed version
The usual online, PDF , Artech repro etc are not suitable.
For museum use, by non profit.
Location in USA, (or France) we can arrange for shipping....
Open to offers, or swaps, have a LOT of TEK/HP/GenRad manulas and some TEK origial probes....
Please send a PM if you have one to spare...
MANY THANKS
Jon
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Software for the TDS500-600-700 series scopes uploaded!
Some of this (that which isn't technologically obsolete anyway) seems to be rather sought after, so here it is. I bought a CD from a seller on ebay to add to the few apps I already had, so I'll release it for free to give back to the community.
I have installed and tested it all on my TDS784D and TDS794D, but check the included readme files for specific compatibility with your scope. You will also need the HD HDD option to install these.
Installation is simply a matter of copying the file structure in the zipped file directly to your scope's HDD. Check that readme for details. :)
If anyone finds any missing softwares, documentation, different versions, or anything else at all, please do upload it to the linked folder and let me know so I can check it, update the archive and make it available for easy use by anyone. :)
I'm particularly interested in a non-Demo version of the Power Analysis software (TDSPWR1) and the Communications Pulse Measurements software (TDSCPM1), also any documentation on the Optical Eye Pattern Measurements software (TDSEYE1)
Regards,
Jared.
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Re: Tek 575 HV transformer
For the record, rewinding without repotting does not guarantee failure, or at least not immediate failure.? I rewound my 453 in 2015.? Layer winding with retrace, tape between layers, painting the end gaps (while winding) and the entire item (when finished)
with Corona Dope.? Today in 2024 the transformer is as good as it was in 2015.
Dave Wise
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Sorry, a 576 is what i'm looking for. I managed to find a silicone-potted one on ebay. Thanks for the help anyway!?
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Re: Tek 575 HV transformer
Sorry, a 576 is what i'm looking for. I managed to find a silicone-potted one on ebay. Thanks for the help anyway!?
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Re: Tek 575 HV transformer
Are you looking for a 575 HV transformer as the title states, or a 576 transformer as your message states??
If it¡¯s for a 575, I may have one if they¡¯re the same as a 532, which uses the same CRT.?
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Re: Tek 575 HV transformer
Alex fine to hear from East Europe. Bravo for your initiative. HV trsf: NO replacements avail (that was years ago) The dead HV need to be disassembled, rewind, repot. Takes days, needs special materilas, and experince. Suggest to see threads, TekWiki, and here , EEVblog , [email protected], (not 2) on TEK CRT scopes, 575/6/7 HV trsf rewinding. Bon Chance Jon
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Hey Guys!?
Just a short introduction 'bout me. I'm a Romanian who caught the Tek bug. I managed to score a 556 (which i've gotten almost fully working) a 576(fully working) and a 7104. Fixed a bunch more 400 series scopes and other tek equipment. One of my professors in uni, who's also a dear friend, is a longstanding fan of the 576 and got himself one which is a bit of a lemon, sadly. Bunch of missing panels, dead collector supply knob (managed to fix it with 3D printing, the mechanical assembly at least, but the knobs are still missing) super duper dead caps etc and a slightly burnt in tube.?
Tackling the problems one at a time, I've ordered caps and parts but I also want to get a hold of two high voltage transformers. The one in his unit seems to be almost dead and mine's the rubber potted one and I'd love to change it.
I've read on tekwiki that an industrious user of this forum ordered a bunch of newly made ones. Could anyone point me in the right direction? I'm, of course, willing to pay a fair price + shipping for two units (along with a keg of beer).
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Lovely meeting y'all and wishing you the all the best,
Alex from Romania?
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Re: 2465B Input attenuator
Hello Chuck and all....
Yes, the odd/even suffixes for CH 1/2 are indeed identical except for the 3 conductor cable that connects the BNC probe ID ring and 50 Ohm overload thermistor sensor to the main board A1 in 3 pin connector. You could modify one for the other but it's not trivial.
The stiff and thick sleeves on that cable are in the way if you remove the CH1 attenuator. The front panel aluminum casting has a threaded boss it hits. Use EXTREME care if you remove or replace an Attenuator!!! The ceramic thick film plate is suseptible to hairline cracks or breaking.
Meanwhile, I have found an old version of CH 1, for 2445, I will report back in a month.
Have an absolutely fantastic day
Jon
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Re: 2465B Input attenuator
To make the wires that control the attenuator's
relays lay nicer, they made a left and right hand
attenuator. The only difference, as I recall, is
which hole they ran the wires through.
-Chuck Harris
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On Tue, 05 Nov 2024 22:47:51 -0800 "ed breya" <eb@...> wrote: I can't help you on this, but I have to wonder. Are you saying that
the front-end attenuators for channels one and two are different from
each other? I'd think they should be identical. If not, why would
they need to be different?
Ed
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Re: 2465B Input attenuator
IIRC it¡¯s just a matter of which side the cable that drives the relays is fed out of the attenuator module ¨C you can rearrange that to suite either channel. ?
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From: [email protected] <[email protected]> On Behalf Of ed breya
Sent: 06 November 2024 06:48
To: [email protected]
Subject: Re: [TekScopes2] 2465B Input attenuator? I can't help you on this, but I have to wonder. Are you saying that the front-end attenuators for channels one and two are different from each other? I'd think they should be identical. If not, why would they need to be different?
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Re: 2465B Input attenuator
I can't help you on this, but I have to wonder. Are you saying that the front-end attenuators for channels one and two are different from each other? I'd think they should be identical. If not, why would they need to be different?
?
Ed
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Jared Cabot
Froggie the Gremlin
Eric Boyle
David C. Partridge