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Re: Tektronix TDS684A
I'm not in California, in fact, about as far away in the US as you can get from there.
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However, I've worked a bit on TDSS540 scopes, and I have a TDS640 as well. Things to know: 1) the only high voltage is in two places, inside the power supply (should be more or less shielded), and inside the monitor (should be shielded as well). Most other voltages are at the class 2 (less than 24 or so volts) level. 2) these power supplies are similar, but not as well documented as you'd like.? It sounds a bit like a power supply problem until you check all the voltages and know it isn't. 3) some scopes of the era (and type) have a known capacitor problem.? Try inspecting each capacitor on the boards (not the PS board, that's another animal) for dull looking leads or any sign of leakage.? I'd suggest that you look for threads about the TDS series which will cover various issues about some capacitors. There's a self test capability (at least in mine) on the CPU board which runs through a number of tests, with the pass/fail indication being on a 7 segment readout.? It should hang (with the right switch settings) on a failing test.? That'll give you an idea if the CPU is failing. Further than this, I can't help too much, there are people here who have done a lot more work on these than I have. Harvey On 1/11/2021 7:19 PM, Thomas Dodge wrote:
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Tektronix TDS684A
Hi,
I emailed about this before. I have a Tektronix TDS 684A scope, and it is in very good condition, and it was almost working, but now it is not. I bought it from a surplus place, and I had seen it every time I came into the place. When I took it home the first time, and powered it on, it didn't do anything. But after a while, the panel lights came on, and it did run the self test. When I powered it on recently, the panel lights power on, but no self test at all. I want to know how to fix this. I do have the manual, but I would like to work together with someone who is local in my area who is more experienced than I am. I could just send it off to be repaired, but that would be no fun for me. I have a couple other Tektronix scopes that are not working too. Does anyone know who is around my area? I am in California, in the San Gabriel Valley area in Glendora. I want to learn how to fix these when problems come up. I am well aware of the high voltage that is present here, so that's why I am asking. Any help is appreciated. Thanks very much. Thomas Dodge |
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Re: PM - Address Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Hi All!?Just today I found 4 custom assemblies here, built in TM-500 frames. One is missing the covers. They have a front panel that may be adaptables for the project. I would like 15.00 each for the ones with covers and $10 for the one without (good top & bottom rails plus the front panel. All plus postage. I can knock these down and ship flat in a flat rate box. PM me if anyone wants one.?I will try to send a pic later.?Jeff Kruth
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Re: PM - Address Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Sorry, it was not suppose to go to the group....not sure what I did ...sometimes this client does what it wants! ( it has happened before, so some button/key on the keyboard sends and I guess i hit it as I type?)
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It did go as a pm in another one so not sure what happened....I will do better/be more careful. nuf said..... ¸é±ð²Ô¨¦±ð On 1/11/21 3:25 PM, Dave Daniel wrote:
Please send these emails privately. The list doesn¡¯t need to see hundreds of random emails containing addresses. |
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Re: PM - Address Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Please send these emails privately. The list doesn¡¯t need to see hundreds of random emails containing addresses.
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DaveD On Jan 11, 2021, at 18:00, ¸é±ð²Ô¨¦±ð <k6fsb.1@...> wrote: |
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PM - Address Re: [TekScopes] I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Hi Larry-
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#17 ( after the EWs), ¸é±ð²Ô¨¦±ð Deeter 1200 Independence Rd. Mokelumne Hill, CA 95245-9632 IF you need the phone 209-293-3129 I will await the request for funds. Thank you for all your hard work and frustration. ¸é±ð²Ô¨¦±ð On 1/11/21 2:50 PM, Larry McDavid wrote:
Folks, I'm closing this group purchase at this time; no additional requests will be accepted. |
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Folks, I'm closing this group purchase at this time; no additional requests will be accepted.
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Please send me a private email with your postal mailing address; don't send this to the whole Group. If you live in the USA, include your full Zip+4 Zip code. If you don't know your full Zip code (why would you not?) you may find it here: You should find my private email address in the header of this Group email. If not, use lmcdavid at lmceng dot com. Those "l" characters are the letter, "L." Please check the list of initials shown below for your participation. I found some duplicate initials and have corrected that. ML ML ML PA SM DC HB GL MH JRe WR JT EW EW EW EW RD AW SG DS JF MU PE SN SC AAlt BHu EPa WS KT RDD PMu GM CC BHe BK LR MPe MPe MPe SA BG JK AAin PTC PD BO JG EP BL CT MD RLG CB CH DM AD JRa JRa CR PM SW JW DP DG HV BH EL TP TP LM Final pricing will follow. Larry McDavid On 12/31/2020 11:27 AM, Jared Cabot via groups.io wrote:
Hi all, --
Best wishes, Larry McDavid W6FUB Anaheim, California (SE of Los Angeles, near Disneyland) |
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Re: SC-502 transistor
One question & one observation.
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Question: Did you verify that there are no short circuits loading any of the transformers secondaries? Observation: If the transformer in determined to be bad, there's at least one SC502 being parted out on eBay. You might inquire about the availability of a good transformer for purposes of transplant. Thomas Garson Aural Technology, Ashland, OR By my calculation, the dynamic range of the universe is roughly 679dB, which is approximately 225 bits, collected at a rate 1.714287514x10^23 sps. On 1/11/21 1:23 AM, Giovanni Carboni wrote:
The final outcome is negative. Fried Q855 twice, The HV supply won't oscillate and draws a lot of current that |
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Re: New (to me) 2465 Power On State
Thanks Siggi, that did the trick. I'm glad that I did not have to open it up and set a jumper.
I was a bit worried about this scope, as I've heard sob stories about blown custom ASICs on the main board, and the dent in the case spoke to serious mishandling of the unit, but it seems to be in pretty good condition. It came with the pouch attached, but no face cover, which I gather is hard to come by, especially for a unit with the DMM option. I cut a cover from packing foam so that I could stand the unit on its face without damagin the knobs. I've downloaded the manuals (man, there are a lot of them: I've got a 2465 DMS which has almost all the options, so two manuals per option as well as the scope's operators and service manuals) and will familiarize myself with them before asking more questions. -- Jeff Dutky |
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Re: Tek 576 step generator problem
Hi Jack, my measurements. Is normal, try to put a 10 k resistor
/g/TekScopes/photo/94656/0?p=Name,,,20,1,0,0 Max voltage in current mode seems 13V aprox., above this voltage constant current mode is not working. Regards! -----Mensaje original----- De: [email protected] [mailto:[email protected]] En nombre de Jack2015 Enviado el: lunes, 11 de enero de 2021 17:44 Para: [email protected] Asunto: Re: [TekScopes] Tek 576 step generator problem Step-Amplitude: .5V (no resistor)The staircase looks ok! it's not broken trace issue. The design of step generator circuit is different between 576 and 577. In case of 577 the traces synchronize with the collector supply 4 traces per period(one trace per 90 degree). This could be seen by the timing between collector supply and staircase. </g/TekScopes/photo/255563/29?p=Created,,,100,1,0,0> </g/TekScopes/photo/255563/30?p=Created,,,100,1,0,0> Hope it helps. Jack Scanned by McAfee and confirmed virus-free. Find out more here: |
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Yes, I have your name on the list as RG; I'll change it to RLG.
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Larry On 1/10/2021 10:49 PM, momemeca wrote:
Hello Larry, --
Best wishes, Larry McDavid W6FUB Anaheim, California (SE of Los Angeles, near Disneyland) |
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Re: SC-502 transistor
The final outcome is negative. Fried Q855 twice, The HV supply won't oscillateHi Giovanni, I would be interested to try to debug and repair it. Would you be willing to ship it to France (I'll pay of course)? Thank you. Best regards, |
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Re: New (to me) 2465 Power On State
On Mon, Jan 11, 2021 at 3:25 PM Jeff Dutky <jeff.dutky@...> wrote:
Is the instrument always supposed to start up in diagnostic mode? Do II believe if you run "CYCLE ERROR CLEAR", which is "Exerciser 3" on a 2465, you'll clear the error and go directly to operating mode on startup in the future. |
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Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Folks, don't send me money for tester board sets yet! Stop it, really!
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Final pricing of the boards in the higher quantity now needed has made re-quote necessary. But, I expect the cost for the board sets to actually go down. I'll post to TekScopes and Tek500 when I have final costs. But, I gotta tell you, this is getting complicated! We now have requests for this set of circuit boards from US, Canada, Australia, UK, Spain, Germany, Ireland and Romania. I have post office postage prices only for UK and Australia; I'll spot check a few others but I hope to use just one or two average postage costs for international shipments. Larry On 12/31/2020 11:27 AM, Jared Cabot via groups.io wrote:
Hi all, --
Best wishes, Larry McDavid W6FUB Anaheim, California (SE of Los Angeles, near Disneyland) |
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New (to me) 2465 Power On State
I just got a 2465 in pretty good condition (one sharp dent in the case, a broken corner on the rear bezel, disintegrated rear cord-wrap feet, and a bent shaft on the SEC/DIV VAR knob) but after a bit of struggling, an application of pliers, and some minor metal work, it's almost as good as new. I ran through a bunch of functions, somewhat haphazardly, and checked that I could see traces on all four channels, all of which seemed to work, within the limits of my equipment and skill. The main SEC/DIV knob seems to have some trouble when setting a delayed sweep more than a few positions in advance of the main sweep, but I haven't investigated enough to really understand what's happening.
When I first got it it would show a diagonal line on the screen on power up with the messages "DIAGNOSTIC. PUSH A/B TRIG TO EXIT" and "CT TEST 81 FAIL 03 BU<F110>". When I opened it up I found a cable had been rudely disconnected from the control board (J502 which transmits some EAROM signals to the option boards). I straightened the bent pins and reconnected the cable before addressing the dented case and reassembling the unit. When it was reassembled it still showed the diagonal line on the screen, but now the message at the bottom of the screen reads "ALL 00 PASS BU<F110>". Is the instrument always supposed to start up in diagnostic mode? Do I need to do something to take it out of diagnostic mode? -- Jeff Dutky |
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7633 no high voltage -1475V on test point
I just repaired the time base 7B53A and a new problem appears.
An acrid smell came from the oscilloscope so decide to test the scope for 3 hours and the trace and readout disappeared. I measured the low voltages and are all ok but is missing the high voltage (-1475V) on the test point. Where is the problem? Fabio |
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Re: Tek 576 step generator problem
I will check it later with mine
-----Mensaje original----- De: [email protected] [mailto:[email protected]] En nombre de Dave S. Enviado el: lunes, 11 de enero de 2021 19:23 Para: [email protected] Asunto: Re: [TekScopes] Tek 576 step generator problem Hi, thanks for ur help! What about the 50uA and 100uA (.1mA) waveform with the 100k paralell? Maybe you can check it on your 577 or someone else could check it on a 576 if it looks strange aswell. Thank you! David Scanned by McAfee and confirmed virus-free. Find out more here: |
John Williams
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