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7B53A Schematic Question
In the manual for the 7B53A/7B53AN, the #2 schematic for the Main Trigger Generator (for SN B209999 & Below on page 124 of the version of that manual I'm viewing) shows a small rotated rectangle labeled E376 across the output of U350D. I've not found references to that symbol nor have I seen this before. Could someone please fill me in on what that represents?
Thanks, Barry - N4BUQ |
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Re: Looking for fasteners in EU
You linked to the black one which only goes up to 16mm. It doesn't
matter. It proves nothing. The fact that some fly by night corner shop in China doesn't have a specific screw doesn't mean someone else won't have them. I posted here because people are helpful here, so take a hint from others and stop being negative. On Mon, Nov 1, 2021 at 12:10 AM snapdiode via groups.io <snapdiode@...> wrote:
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Re: tek 2215 trace position issues
The usual rule for fault finding is 'first check all low voltage DC supplies for correct voltage and ripple'. Particularly relevant in this case!
It is not clear why you have two spots. Are you displaying Ch1, Ch2 or both? What input do you have to the active channel? What have you selected for the horizontal display options? Where are the spots on the screen? Regards, Roger |
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Re: 7B92 with no repeating sweep
Mark,
Thanks for the rundown. I have not tried again to address the TIME/DIV issues on the new 7B92, concentrating instead on diagnosing the old 7B92 by swapping boards (I will get to the new 7B92 in due course, so your advice is invaluable. Also, the trigger lamp on the old 7B92 may also need to be replaced, so good advice all around). I've also gotten some encouragement from Dave Peterson for disassembling and maintaining Tek cam switches, including a wonderful set of photographs of disassembled cam switches from (I believe) a 465. It looks much more doable than the dire warnings in the Tek service manuals would lead you to believe. I swapped the sweep and main trigger boards between the two 7B92s and I think I found out the following things: 1. swapping the sweep boards makes no difference in the behavior of either unit, which rules out the sweep board, and any of its components as faulty. 2. swapping the main trigger boards between the two units did not fix the old 7B92, but it did make the new 7B92 unable to get a stable trigger on a signal, which means that the main trigger board from the old 7B92 has a fault, but it is not the fault that is causing the lack of free running sweep in the old unit. With these two conclusions in hand I proceeded to examine components on the main interface board that were directly related to the sweep IC: Q102, Q104, Q106, Q108, Q144, Q146, and Q148. All of those checked out as "good" on my cheap Chinese component checker, but while I was doing that I noticed two more bits of damage to the main interface board: R238 had one leg sheared off at the solder pad, and CR205 was blown open. I reattached the left of R238 at the pad easily, but I'm having trouble finding a proper replacement for CR205. The Tek part number is 152-0322-00, which maps to an HP part number of 5082-2672 and a JEDEC number of ND4973. The CDPC indicates (on page 12-4, 2nd row) that it is a "General Purpose, 15V" Schottky diode with a maximum junction capacitance of 1.2 pF. For most of the specs it looks like I can use a 1N4148 as a substitute, but the maximum junction capacitance on the 1N4148 is specced as 4 pF (yes, it's a maximum value, I know, so the typical may be much lower, and may in fact meet the Tek spec for CR205). It occurs to me that the same Schottky diodes that I am using for the 7S14 samplers may work here too. CR205 is in the AUX Z-AXIS signal chain. It occurs to me that if the Z-axis signal were clamped in the "off" state then I might see something that looks like a lack of free running sweep (because the beam is always blanked). Also, why is it always a Z-axis fault with me? -- Jeff Dutky |
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Re: Curve Tracer CRTs
Roy,
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I will have to respectfully disagree with the statement that the 57X units have been replaced and usurped. However to establish my personal bias I will have to admin that I have more than one of the 57X units in both types I have a couple 576¡¯s and a few 577¡¯s. Despite having to do major overhalls and calibrations. Even going so far as to get the calibration fixture. 067-0599-00. I can say that these units have been an incredibly addition to my lab and I wish that everyone especially students have access to them and knowledge as to how to use them. I have even made a few videos on the topic of rebuilding and tuning these for the channel. Having a Vc up to 1600 Vdc and a current capacity of 200 amps is incredibly useful for testing power silicon especially power silicon in HV application that tends to only about ? way fail like in the case of my fluke 5200A There was a power transistor that went some what leaky and was over loading the -190V supply. Also my 577 was instrumental in repairing and testing my 284¡¯s as it was used to test the tunnel diode that was an irreplaceable part so I was skittish about even testing it on a 57X. The current modern equivalent from Tek/Keithly is a transistor characterizer and those concise of a special computer with 4 built in SMU¡¯s and a starting price tag non-upgraded at $26,000. Even a single SMU at the LOW end new in the 24XX series will run you $6,000 at the high end it is $10,000. To test 3 pin devices you need 2 of those and a computer to script it. In my mind there is not anything that is a ¡°modern¡± equivalent as the current SMU¡¯s top out at 1100 VDC. Don¡¯t get me wrong I have some SMU¡¯s on the acquisition list for the lab but the price is steep. And in the lab I also have a 178 for the 577 and a 176 for the 576. I have not repaired and tested the 176 quite yet. But this turns them in to incredibly capable units even measuring currents as low as 2na/div up to 200 A/div I find my self using the 577 more often but this is to save the tubes on the 576¡¯s till I need them. I would also love to add the 570 to the lab but owners are holding on to those tightly right now. I would not even mind having to rebuild one but I will see what time will tell. I have no personal experience with the 3xx series but from a bench space perspective I will stick with the 57X even given the weight. Zen -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Roy Thistle Sent: Monday, November 1, 2021 4:53 PM To: [email protected] Subject: Re: [TekScopes] Curve Tracer CRTs On Sun, Oct 31, 2021 at 11:17 AM, Andy Warner wrote: Well... given the prices that some people pay for these... and unless its on one end of a chain... and sometimes on the bottom of the pond (just cause you can afford it)... I just don't see why, if it isn't for the analog display. (Perhaps not the unit's own CRT... but, a CRT never the less.) Getting/designing a "device" to generate a set of I-V curves (especially in a box the size of the 57x big boys) isn't rocket science, anymore. Probably however, I'm missing something... because I know people who have them holding down the basement floor... and are working on finding the perfect transistors?... to get that "perfect" audio experience. Others covet them, I reckon, for speculation. I remember there were some of the 57x series, in the graduate lab(s)... and the students in the groups working on BJTs didn't even know what they were. -- Roy Thistle |
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Re: Replacement 7000 Plugin Guides
Albert,
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I had been looking at it with the side cover removed; however, I just went out and turned the scope on its left side and that gave me a slightly better view. While it's a bit hard to see, I can now see that H?kan is indeed correct and that protrusion does not give an initial lift like I thought. Apologies. I'm not really sure why this one plugin is being difficult; however, given that the plastic guide on it is broken like it is, then perhaps it's just an overall slight misalignment. As I say, none of the other plugins exhibit this problem. If anything, it would help if the bottom plastic guide rails were raised a mm or two so that the slanted guide surfaces would not have as much work to do but I don't want to modify the scope that way so, for now, I'll chalk this up to the broken plastic guide on the back of the plugin. Thanks, Barry - N4BUQ ----- Original Message -----
From: "Albert Otten" <aodiversen@...> Barry, |
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Re: Replacement 7000 Plugin Guides
Barry,
H?kan already mentioned that the protruding part with the 4 holes plays no role at all (in positioning of the rear of the plugin). When you push the plugin into the scope the rear of the plugin gets lifted and then vertically centered by the protruding vertical ribs at both sides of the PCB edge. It's easy to see what happens when you take the right side panel away and insert the plugin into the A slot. Bottom and top of the vertical ribs should eventually fit closely, without any vertical play (judge by eye). When it's not a defect of the plugin ribs It could be that the small bottom guide notch at the scope's interface connector has broken away. Inside the scope the top level of the long bottom guide rails should lie about 1 mm above the bottom level of the holes in the slot's vertical metal rear plate. Albert |
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Re: Curve Tracer CRTs
walter shawlee
Keith,
I don't have access to the 531 CRTs specs, so hard to say how good a fit it might be into the 575, BUT I suspect the vertical deflection will be clipped by the physical plates, and that it will need too much accelerator voltage. the 5CAP1 is interesting, I see it is an internal Tek tube with a helical accelerator, might run fine. it is more like the original tek 575 tube in that it has neck deflection, so that is possibly a big plus for you. the 5BCP1 is magnetic, I can't see any way to make that work. I still like the 5ADP1 as a possible more universal fix since there are a lot of them around, I don't think I have ever seen a live 5CAP1. I can send you a 5ADP1 if you can cover the shipping. all the best, walter |
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Re: Curve Tracer CRTs
On Sun, Oct 31, 2021 at 04:43 PM, Bob Rosenbloom wrote:
Interesting video. I'd say, they are sure putting lipstick on the pig with that fancy GUI they have coded up. I'd reckon 90% of the fiddly work went into knocking the bugs out of that. The rest of it hardware-wise and given a working 576... while there might be a few design traps...it appears it's relatively straight forward. Sampling relatively slow high voltage signals, and sending them out over a serial bus isn't rocket science anymore, either. -- Roy Thistle |
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Re: tek 2215 trace position issues
well the replacement transistors are fitted,i now hove the trace for want of a better word adjustable but now have no sweep,did i mention i put the scope down on a pice of coiled solder wire,it shorted sommat on the main board as sommat smoked,pulled the plug but to late i think!,cant see any signs of anything beeing fried tho,all i get now is 2 dots on the screen,as if in xy mode,any ideas where to start,seems i fixed one issue and created a bucket load more,teach me to keep my bench clean!! tia
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Re: Curve Tracer CRTs
On Sun, Oct 31, 2021 at 11:17 AM, Andy Warner wrote:
Well... given the prices that some people pay for these... and unless its on one end of a chain... and sometimes on the bottom of the pond (just cause you can afford it)... I just don't see why, if it isn't for the analog display. (Perhaps not the unit's own CRT... but, a CRT never the less.) Getting/designing a "device" to generate a set of I-V curves (especially in a box the size of the 57x big boys) isn't rocket science, anymore. Probably however, I'm missing something... because I know people who have them holding down the basement floor... and are working on finding the perfect transistors?... to get that "perfect" audio experience. Others covet them, I reckon, for speculation. I remember there were some of the 57x series, in the graduate lab(s)... and the students in the groups working on BJTs didn't even know what they were. -- Roy Thistle |
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Re: Replacement 7000 Plugin Guides
Albert,
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I looked again at two of my plugins - this badly broken one and an intact one. The one without that upper protrusion is quite difficult to push into the back socket due to it being slightly lower when the two parts first meet. It helps a lot if I lift the rear of the plugin slightly just to get the mating surfaces to meet on the slanted surfaces. I can push hard and force that alignment to occur, but it's not a very smooth action. The one that does have that upper protrusion lifts itself just slightly and allows those slanted surfaces to mate better and the plugin then can be pushed in normally. Dunno. Maybe it's my mainframe that's the problem. Thanks, Barry - N4BUQ ----- Original Message -----
From: "Albert Otten" <aodiversen@...> Barry, |
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Re: Replacement 7000 Plugin Guides
If I'm not mistaken, that protruding part provides an initial "lift" so that the rest of the aligning surfaces can start correctly. I'm pretty sure this one wasn't purposefully cut off but was more likely broken from being dropped. It's a pretty jagged, broken area on this one but, who knows how or why it got that way.
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Thanks, Barry - N4BUQ ----- Original Message -----
From: "zenith5106 via groups.io" <hahi@...> On Mon, Nov 1, 2021 at 03:07 PM, n4buq wrote:That doesn't has any purpose in most 7k plugins. |
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Re: Replacement 7000 Plugin Guides
On Mon, Nov 1, 2021 at 03:07 PM, n4buq wrote:
That doesn't has any purpose in most 7k plugins. Chances are that it was deliberately cut off since that's what had to be done for the plugin to fit and work in an 11000 mainframe. /H?kan |
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Re: Replacement 7000 Plugin Guides
Barry,
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I¡¯ll get back to you with what I have. Steve On Mon, Nov 1, 2021 at 10:07 n4buq <n4buq@...> wrote:
Hi Steve, |
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Re: Curve Tracer CRTs
Hi Walter,
Yes, I've had similar thoughts, especially around the 575. As some folks here know, I'm doing a fairly thorough restoration/update on a circa 1962 Tek 575. Phase 1: At this point my 575 is working pretty well. It makes curves that seem to be reasonably accurate, within the limits of the technology. Phase 2: I am now working my way through the very many factory mods and upgrades as collected here; Lordy, but there are a lot of factory upgrades on the 575! Phase 3: A=B CRT comparison. I currently have a "correct" CRT for my 575, as well as a good 5BCP1 taken from a 531/535 series. My intention going forward is to complete all the appropriate factory mods and upgrades, then do the most careful calibration I can do with the correct CRT installed - and THEN swap in the 531/535 type CRT and check operation. I want to see how different things really are when a 5BCP1 is installed in a correctly calibrated, fully modded and functional 575 that is set up for a 5CAP1. I've already had both types of CRT in there, and with the requisite pin 8/9 jumper installed, the 531/535 CRT at least works and shows a display. I now want to see if it is a direct swap into a correctly modded and calibrated device. (excepting the requisite pin 8/9 jumper, of course) I know this is kind of a brute-force approach, but unfortunately I'm not as smart as the other guys and gals in this group, so I have to do it the dumb old "A=B" way. :-) Hope to report something by the end of the year... Keith coolblueglow |
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Re: Grease for the VOLTS/DIV and the SEC/DIV Controls on TDS Series 310, 320, 340, 350, 382, 420, 430
I've been using MG Chemicals Carbon Conductive Grease for over 30 years now...It's black with carbon and lasts a very very long time.
I learned about it while working in production for fibre-optic lottery terminals where the static would build up due to the nylon rollers, rubber drive rings and metal rollers and metal frames of the pickup assembly that pulled lottery tickets through so they could be read... I know MG Chemicals is still around as I use a lot of their products, such as contact cleaners etc... 73...Jordan VE6ZT |
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Re: Replacement 7000 Plugin Guides
Hi Steve,
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Yes, those are what I'm looking for. One of mine is completely missing the upper oblong-ish part with the four small holes and, without that, I have to reach in and guide the board in until the other aligning pieces can take over. I have one or two others where the small "clips" that help hold the board are broken but that's not quite as much of a problem. If you have one to spare, I'd really appreciate it. If you have more, I could maybe use one or two more but don't want to be greedy. I got a working 7A26 from eBay and, while it was packed very well, it appears to have taken fall somewhere and it cracked that guide. I think I can glue that one, though, so it isn't that much of a problem. I really appreciate that! Thanks, Barry - N4BUQ ----- Original Message -----
From: "stevenhorii" <sonodocsch@...> Barry, |
G?ran Krusell
zenith5106
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