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Re: SMB Adaptor (again)
The SMB-BNC cables I ordered from Amazon arrived and they do fit my DC505, but they are very tight, almost impossible to disconnect using just my fingers. Where/are the outputs on the DC505 infrequently used?
The specific cables that I bought (KNARCO) seem to be out of stock now, but I see another (even less expensive) listing from LIVISN. The odd company names (and the price) make me suspect that these are Chinese sellers, but I have no proof of that. The cables I ordered came somewhat inexplicably triple bagged: first a small bubble wrap bag, enclosed in a sealed anti-static bag, and finally in a blue and white ziplock bag. -- Jeff Dutky |
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Re: TDS544A with strange display
#photo-notice
Thanks Siggi; your conclusion is matching mine. I'll go the board and make some real measurements (till now, mostly in my mind - with some few exceptions).
TT |
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Re: TM500 Board Set- 3D printed plastic face plate
Did anyone in Europe (or better UK) get the inner front panel 3D printed? If so did you have to get more than one printed? If so I'd be interested to buy one of them? If no-one has spares what material is recommended for 3d printing and what units should I use for the STL file?
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Thanks David---- -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Jared Cabot via groups.io Sent: 17 February 2021 15:31 To: [email protected] Subject: Re: [TekScopes] TM500 Board Set- 3D printed plastic face plate Ok, I've corrected the dimensions in the manual now. The PCB's were made from the latest revision, but I pulled the dimensions from the 3D files just before that final tweak. The manual has been updated with the correct dimension, so f you download v1.5, it should all match up now. |
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Re: 485 super weak brightness control
So..... I changed following diodes for BAV21 and there was no change to the
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behaviour. CR1651 CR1646 CR1664 CR1666 CR1660 CR1656 CR1652 No intensity control and no grid bias control. I was desperate but then I noticed there's another one hiding covered by a cap CR1663 and that was the one!! Now I have nice sharp trace and working intensity control! I need to calibrate it, I can get good image but as soon as I change either of the intensity controls it gets blurry. Now with the HV supply sorted I can progress further with the list of problems Vertical amp Channel 1 is in top condition all LEDs working lightbulb working Vertical amp channel 2 has the 1x LED gone and lightbulb gone. Otherwise cleaning brought it back to 100% working order. Horizontal A sweep Works flawlessly from 5second to about 10uS. From 5uS the image starts ever so slightly moving to the right but I still get enough to fill the full screen when I use the horizontal position control because there is a reserve, at 10nS I pretty much run out of the reserve. I can still center it to have full 10 divisions but there is no reserve at all. The 5 2 and 1nS settings are not working at all. Horizontal B sweep. I don't get any B sweep from 5s to 20ms then I get good B sweep for 10mS to 0.2uS 0.1uS to 10nS is showing only first 4 divisions from the left 5 2 and 1 ns is working correctly. The delay time position potenciometer is not in best shape, it gets stuck quite often and needs to be wiggled about to move it further. The latching is somehow damaged. Power supply fan. Is quite picky, it sometimes runs and sometimes it does not. On Wed, 17 Mar 2021, 19:17 Ozan, <ozan_g@...> wrote:
Trust me it's the phones auto correct turning opamp into obama :)I know I was just kidding. I also had my share of funny auto correct |
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Re: Tek 2230 psu story (work in progress)
Pitpat
Update, the new t948 has arrived but not before i managed to burst another componet, a zener diode this time (1N475A) 6.2 voltage reference in the inverter section seems to be the only fault this time but since im at it ill replace all the electrolitic caps with some new good low esr ones. BTW the fail (open not shorted) of the said diode seems to result in a similar cycle of the one induced by the crowbar circuit (witch it was removed on my scope) but with the neon spark-gaps that do not operate.
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Re: PS 5010 troubleshooting (no negative, erratical display)
Hi Steve,
thanks for your insights. I did understand what you said about the front/rear switch, but I could not altogether follow what you said about the voltage and current ramps. In particular, the error-condition (i.e. erratical blinking of pos and neg supply), when present, was permanent. It only disappeared once I got a certain amount of current flowing. And finally it turned out it was related somehow to the hi/lo switch. Realigning the supplies was straightforward and easy to do... well designed, as I said. Currently I have two PS5004 precision supplies in the frame. Both turned out OK, so I started the alignment. But theres a weird thing, something I've never seen before: a corse and fine alignment pot that is realigned several times on later steps! Usually a pot is aligned and you don't touch it anymore. Do you know anything about that module, too? cheers Martin |
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Re: Message from your fearless (foolish?) leader
Hi Dennis,
Please add my best wishes to Marian for her speedy and complete recovery. Was happy to hear that she finally got the much needed and delayed hip replacement. I'm sure the outcome will eventually be very good, but sorry for the pain she has to endure in the meantime, and the extra duties you have to take on. I know how busy you were already. You have both been such gracious hosts every time I've been to your place over the years. (Guess George and I won't be returning any more to tune at Westminster Chapel, as he's finally totally retired.) Hopefully things will be getting back to normal soon! All the best, Tom G. |
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Re: Type 111 Pretrigger Pulse Generator
From Tim P (UK)
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Hi; This is the mod to supply double pulse output. See Hakan's page I think it was used to set up the loop gain on samplers. Tim On Thu, 18 Mar 2021 at 03:16, Sean Turner <[email protected]> wrote:
Hey all, |
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Re: PS 5010 troubleshooting (no negative, erratical display)
Hello Martin,
I designed the analog circuitry in the PS5010, although that was nearly 45 years ago¡ The front/rear switch not only selects the output terminals, but the remote sense inputs for voltage regulation as well. So if the switch is intermittent, you many have one of the sense inputs open, which would explain the lack of regulation. The power supply goes through voltage and current ramps when the output is cycled to protect the relay from damage in fault conditions. The loop balance monitors are not monitored during this ramp cycle. I have found those switches commonly used in TM500/5000 and 5100 series remain reliable if operated in a very clean environment, but have problems when there is dust in the air. They are not sealed, and lubricated with grease. Dust will get into the grease and make its way into the contact surface, which causes them to become intermittent. Also, the grease cakes up when it gets dirty, making the switch spring return not operational. Steve |
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Type 111 Pretrigger Pulse Generator
Hey all,
I was wondering if anyone knows of any factory mods that were done on the Type 111? I have an example that has a significant divergence from the schematic in the manual, namely around the fixed increment control. It's a little circuit mounted on an aluminum tab with a small ceramic strip on the inside and three socketed transistors on the outside, and there is a pot installed instead of the switch. I can't discern that this control has any effect on anything, and it is definitely not present in any scan of the manual or any pictures of the internals of other Type 111s. Furthermore, it is factory quality assembly work, so I'm assuming it's either factory or someone who was really careful. I put three photos of the circuit here (/g/TekScopes/album?id=261991). I annoted one of them to show the four places where the mystery circuit is wired into the main PCB. Thanks! Sean Sean |
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Re: Free 547 and plug ins (pick up in Boston area)
Hi again all--the 547 and plug ins have found a new home. Thanks! --Chris
On Wed, Mar 17, 2021 at 8:38 AM Christopher Galbraith < christopher.galbraith@...> wrote: Hi folks, |
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Restore CD for TLA714
Sandra Carroll
Hi,
I just finished repairing a TLA714 LA which had a Bad HD. Installed Windows 2000 and got TLA software from XDEV. LA was perfectly fine otherwise. I am looking for anyone who has a copy of the TLA714 Restore CD with the OS and TLA software whos either willing to provide a ISO of the CD or I'll purchase from you if you prefer? I've got an original Doc CD coming but just don't have the restore CD TIA to anyone who can help Sandra |
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Re: Alert for 519 owners - The significance of the Gold GR Connectors
I don't have a 519, but I figured some of the members would :)
There are several listings for 125 ohm GR (search for "GR874" but most sellers don't know the difference between 125 and 50 ohm connectors). 174325617026 363163812256 222979950687 223426804340 161839191197 333654464808 Unfortunately, I think someone got the adapters Dennis is referring to (don't see them listed). Better luck next time! |
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Re: TDS544A with strange display
#photo-notice
Hey TT,
I groused through the block diagram and the schematics a bit more, and here's my hypothesis for how the VGA and the LCS interfaces relate. This is pure speculation, but I think everything below fits the facts that you've observed, the TLC34075 datasheet and the schematic. U2011 (on diagram <24>) gets the VGA timing and 5 bits per pixel data from U2101. It buffers up a batch of 4 VGA pixels, and then writes them to the VRAM (U400 et al on diagram <23>). The TLC34075 reads pixel data from the VRAM 4 pixels at a time, where each pixel is padded out to 8 bits by a zero bit and the two LCS_CSEL0/1 lines. The line scan frequency of the TLC34075 is exactly three times the line scan frequency of the VGA interface, and it displays each VGA line three times in rapid succession, once for each color in RGB (in some order). Padding the pixel data with the LCS_CSEL1/0 lines allows the TLC34075 to pick out the appropriate part of the palette for the current primary color of the pixel displayed, against the LCD shutter selected for the current replay of the VGA line. Now a good question might be why 5 bits per pixel, and I don't know the answer to that. One way to cut it might be 3 bits of color, one bit of intensity, and 1 bit of (text?) overlay. This could again be shoehorned into providing the display we observe through the right palette data. This might help narrowing down why your intensity modulation seems to be pixel clocked. If you look at the ordering of the data lines into and out of the VRAM, you'll see that they get interleaved into the pixel inputs on the TLC4075. I don't know why this is, but maybe you need to be focusing on the address and data lines for the VRAM. It might be as simple as a high-resistance or floating VRAM data line, possibly an "intensity" bit. Happy hunting, Siggi On Wed, Mar 17, 2021 at 5:20 PM durechenew via groups.io <durechenew= [email protected]> wrote: Last few days I just read everything in manual from start to end, |
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Re: Alert for 519 owners - The significance of the Gold GR Connectors
Dennis,
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Is there a link to this listing? I am certainly interested. I actually have two of the boxes (actually, mine are walnut, according to the label on the bottom) and am only missing one or two of the impedance matching adapters. The second one I found local to me, and while the box is unfortunately in poor shape, it contains a total of TEN brand new reeds for the calibration step generator! Sean On Wed, Mar 17, 2021 at 10:19 AM, Dennis Tillman W7pF wrote:
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Re: Help: unreadable listing from: 42W-4281-1 Measurement Variety. An Engineering Challenge Featuring the 7854
Hi Max,
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We (TekScopes) are incredibly fortunate to benefit from the tireless work of Kurt Rosenfeld who has created and maintained the most astounding collection of information about Tektronix instruments. Whenever you are looking for documentation on Tek products ALWAYS go to the TekWiki at Dennis Tillman W7pF -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of unclebanjoman Sent: Tuesday, March 16, 2021 11:43 AM To: [email protected] Subject: Re: [TekScopes] Help: unreadable listing from: 42W-4281-1 Measurement Variety. An Engineering Challenge Featuring the 7854 Oh yess!!! Thank you folks! The scan you pointed on tekwiki is definitely more, more readable! Thank you again, Max -- Dennis Tillman W7pF TekScopes Moderator |
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Re: TDS544A with strange display
#photo-notice
Last few days I just read everything in manual from start to end, sometimes backwards, to try to understand as good as possible how this scope works (CPU and display board).
Siggi was right about signal on Ch4 having some issues. Three new clips in Dropbox (name starts with 3., then 4. and 5.; all after CLEAR MENU pressed): The first one shows scope screen; Ch1 and Ch4 on display, no input signal on any channel; on Vertical, button Ch1 pressed and Ch1 light ON; nothing unusual (disregard fuzziness, it's angle of camera) The second one shows scope screen; Ch1 and Ch4 on display, no input signal on any channel; on Vertical, button Ch4 pressed and Ch4 light ON; some vectors on Ch4 show in red; if I switch to dots (in Display), some dots will show red. The third one shows VGA monitor screen; Ch1 and Ch4 on display, no input signal on any channel; on Vertical, button Ch4 pressed and Ch4 light ON; same information as above but on VGA monitor - no red vectors (not obvious, but to naked eye Ch4 is blue on VGA too). Previous idea stays (that everything is correct, up to the point where information is split between VGA path and Video path). Not ready to make assumptions, I'll wait a little, so the stuff settles in my mind; it seems everyday is clearer, but still some way to go... TT |
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Re: 485 super weak brightness control
Trust me it's the phones auto correct turning opamp into obama :)I know I was just kidding. I also had my share of funny auto correct stories. I think I had the timebase measurements AC coupled and there was no changeThe goal is to find if sweep trigger is not coming (no gate) or sweep trigger comes but sweep doesn't happen. DC levels are important to understand the state of the sweep circuit. At the end most likely it will be a dirty switch. You can make a good guess which one by looking sheet <10> and see which switches only change in the last three settings. However, we can also pinpoint which one by electrical debug. BAV21 looks OK as a replacement, it has better specs in some areas. The swing at the restorer input is ~ 100Vpp max, so the diodes in the grid bias area will not see more than 200V. Close to max spec but could be a good initial debug step. If others see a problem please chime in. Ozan |
David C. Partridge
Martin
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