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7A13 overshoot
Hi all,
I noticed my 7A13 amplitude was way down on a 70 MHz sine the other day, so figured I'd run through the calibration. I skipped the input resistance section that requires the precision DC divider, and I'm using a PG 506 fast rise for the HF compensation; it's slower than the 250 ps Type 109 the manual calls for, but easier than messing with the Type 284. Through a 20 dB attenuator and 50 ohm thru termination, the 7A13 is showing about 1 div overshoot on a 5 division step from the PG 506, and I cannot adjust that out. It's so huge that I can't even see the effect of C113/C150/C250 on the corner. A bandwidth check with SG 503 says it's ~40-45 MHz. I've tried swapping the 1-2 relays that I haven't drilled and cleaned in this 7A13 with a NOS relay, with no change. It affects + input and - input alike (unused input set to GND), which has me pretty confused, as I thought the signal paths would be independent. Anyone encountered this before or have ideas on what to look at? Just as a sanity check, I tried a spare 7A13 that I'd never even plugged in, and it does not have the overshoot problem, and rise time is respectable (did not measure bandwidth because the SG 503 crapped out and started flashing 000). thanks, Adam |
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Re: I got a working 2465B, looking for some advice.
Jay,
The resistors that are known to give problems are to Q1851, Q1852 and Q1890. Mouser part number for these are: 279-H4P150KFCA, 279-H4P180KFZA, 71-CCF60-332K-E3, 279-H4P430KFZA and (2 in series) 660-MF1/2CC2213F for R1853. For the 100meg: . See which radial leads fit in the original holes. Mark |
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Re: TEK 2465A Rebuild
On Sun, May 18, 2025 at 06:18 AM, Lawrance A. Schneider wrote:
From the Tektronix Documentation Eagle Picher LTC-7P Battery Non-Rechargeable,Rectangular, Lithium Thionyl Chloride,3.5 VDC,750mAh MFR Part #: LTC-7P RS Stock Number: 70141129 That's RS components (You have to search your country's RS Website yourself: they block links.) Note: (1) That is not a LIPO battery. (2) Replacing the battery, if done incorrectly, could lead to unintended consequences. (You can search TekScopes for the details.) -- Roy Thistle |
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Re: I got a working 2465B, looking for some advice.
Thanks. The CRT's brightness is fine. It's the focus that is soft and is most noticeable in the corners. I'll have a look at the schematic and get my bearings on where the focus resistors are and replace them and see if there's any improvement.
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On Sun, May 18, 2025 at 07:29 PM, Mark Vincent wrote:
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Re: TEK 2465A Rebuild
Luca,
You nailed it! Some things you know to redo because of age/known problems no matter if it works today or not. What works today can easily fail tomorrow. What you save today could cost more tomorrow. A way to think about this is would someone not change oil in their vehicle because it works today thinking they saved money and time saved was worth it then get mad tomorrow when the engine locks up due to too little oil. Mark |
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Re: I got a working 2465B, looking for some advice.
Jay,
You know by now to recap the piece as PM. This way, you know it is up to date and better quality condensers are installed. There are some resistors that should be increased in wattage.. Condoraudio has a great kit. There are some resistors not in his kit that should be there, yet. You can get the parts list if you want then order. It is best to mount the new condensers with a gap from the condenser to the board to allow for air flow and get a good solder joint on each side. As for the crt being weak/borderline, you can increase the heater voltage 20-30% higher for some minutes to see if that helps. This step is done without the scope being on, only a supply that is higher than 6.3V. If you have or access to a crt checker that is good to professional quality, you can check it. Crt checkers have different heater voltage selections so the previous step can be done with a checker. If weak, replace with a known good one. There are resistors in the focus circuit and a few on the high voltage board that are known to go bad to being overstressed. They are the ones from B+ to C and C to B on the collectors. Use 1W 1% types, get ones that are physically correct for 1W such as 4x10mm or so, to replace the 1/4W types. These resistors will go high/open making it look like poor focus or a weak crt. The 100meg 1/4W carbon on the high voltage board, replace! That will be way out of tolerance. Ohmite has a blue body radial type that will directly fit that is larger in wattage or you can get 1% 1/2W axial from Mouser. IF yours has a separate battery, use a Tadiran 2.4A/hr axial type. This is heavier in capacity than original and is cheaper. I had the old Dallas chip removed and a FRAM put in to eliminate the Dallas chip and battery. I had someone else do the work and programming since I am not set up to do programming. It was worth the cost in my case. Yes, replace the SMD condensers on the A5 board! Tantalums work well. You can increase the capacitance if you want. Keep the voltage the same. Make sure the A5 board does not have condenser electrolyte leakage from the originals. The noisy fan can likely be quieted by removing it then oiling it. Peel the label back to get to the rubber disc then remove the disc then oil well. Mark |
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Re: 2337 problem with A15 board
Problem solved.
HV Module U130 has defect and have to be replaced. New one is unobtainable. U130 made by me. I chose diodes 2CL77 20kV 5 mA 100Khz and 470 pF 6kV for the multiplier. The remaining diodes are also 2CL77. All capacitors are disk ceramic for 3 or 6 kV blue color. Has 13 input/output pins. They are made of brass, stuck in Teflon sleeves. So it can be soldered from the inside and outside. The HV coupling is made of Teflon. Low founding paraffin for pouring. It melts at about 70 degrees. In case of a defect, you melt it, pour it and repair it. It is great instead of epoxy resin. Measured voltages vs GND. CRT anode - 16000 CRT pin 1 - 1974 CRT pin 2 - 1974 CRT pin 3 - 2048 CRT pin 4 - 1544 CRT pin 14- 1976 |
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Re: TEK 2465A Rebuild
The "if it ain't broke, don't fix it" attitude kind of doesn't fly with these scopes anymore. I've opened three of these 24xx series scopes and each of them had their selection of either cracked RIFAs, worn out/leaking PSU caps, leaking A5 board SMD caps or the backup battery on its last legs.
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Re: Sphere's Tektronix (and HP) Component Inventory - tekandhpparts.com
Thanks Tom and Darla for helping Susan and the family to keep the inventory
of electronics available. I was a customer of Sphere Research for both slide rules and electronics for years. Whenever I bought electronics from Sphere, they would include a bag of ¡°bonus¡± parts - and it wasn¡¯t just junk. A lot of useful parts would be in those bags. I¡¯ll have a look at the website. I continue to look at the Slide Rule Universe both for information and the occasional check to see what slide rules remain. Regards, Steve Horii On Sun, May 18, 2025 at 11:23 Tom Norman via groups.io <jtnorman= [email protected]> wrote: As many may remember, Walter Shawlee II passed away September of 2023. |
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I got a working 2465B, looking for some advice.
I picked up a working 2465B locally for a decent price, at least much more decent than eBay prices. It has a lot of miles on it and has certainly been used (40k+ hours) but obviously not abused. Physically and mechanically it's is really nice shape. I also did some quick tests (horizontal and vertical) with a PG506 and TG501 and calibration still seems to be just about spot on. The scope was removed from a working environment and was was part of an equipment auction for employees of the company.
The only thing noticeable and bother me is that the CRT is soft which is not surprising given the number of hours on the unit and the fan is a bit noisy. Its serial number is >55000 and appears to have been assembled in the early 90s perhaps even 1990 since that's the newest date code I saw on the few ICs I looked at. The electrolytics on the A5 board haven't leaked and the NVRAM (1990 date code) is still working. I'd have to assume the NVRAM is living on borrowed time and needs to be replaced. I'll also need to take a look at the condition of the caps on the power supply boards and figure out if any are in need of replacement. I'd think with all the hours on this scope, a lot of the electroytics are going to be a little tired. Since I'd like to put a better CRT into the scope at some point, I'm assuming it wouldn't really matter if the calibration data is lost since it'd have to be recalibrated anyhow. I'm assuming the replacement NVRAM need to be programmed with some data before installation into the scope. Is the anyone out there willing to program one for me or any suggestions for a cheap programmer that would do the job? I read through the calibration sections of the service manual and while it looks daunting It seems doable. The only piece of equipment that I don't have is the Tunnel Diode Pulser (Tek 067-0681-01.) or the 15pf input normalizer (the normalizer looks trivial to DIY). Is there anything else I can use as a substitute for the tunnel diode pulser? or is there anyone in the NJ area that has one? I'm assuming it's be a good idea to replace the SMD electrolytic caps on the A5 pcb as well, even though they don't appear to be in bad shape. Jay |
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Re: Sphere's Tektronix (and HP) Component Inventory - tekandhpparts.com
Thank you, Tom and Darla, for taking on this monumental task!? Best wishes as you continue the Shawlee legacy.
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Jim FordLaguna Hills, California, USA On Sunday, May 18, 2025 at 10:23:57 AM CDT, Tom Norman via groups.io <jtnorman@...> wrote:
As many may remember, Walter Shawlee II passed away September of 2023.? Since that time, his wife Susan, and children, have been busying themselves with the task of liquidating much of the electronic goodness that Sphere Research had accumulated.? Susan intends to continue to make their collection of slide rules, nixie tubes and various other items available.? Additionally, she is continuing in her effort to find homes for the remaining equipment.? Please do visit Sphere¡¯s site and help. Sphere¡¯s inventory of Tektronix and HP parts has found a new home with us.? We have the beginnings of a website (tekandhpparts.com), with the intention of continuing to make these parts available to the Tek and HP enthusiast community. A bit about us: 1)? The goal of the website is to continue to make Sphere¡¯s inventory available to the people like us that enjoy collecting, repairing and making use of these amazing examples of engineering and manufacturing. 2)? A secondary goal is to ¡°pay back¡± our retirement account of the funds used to buy the parts.? It is truly secondary, and may never happen, but who knows? 3)? We are retired, have three children, farm 20 acres of grass hay, tend to cows, sheep, horses and chickens, and have FAR too many hobbies and other responsibilities to have taken on another, but here we are¡.? 4)? Our website is an amateur work in progress.? Please read the home page posts for information on the site and on our progress.? Tek items will be posted first, followed by HP and then ¡°other¡± semiconductors and who knows what else.? There is much awaiting inventorying, so if you don¡¯t see the part you are interested in, please contact us directly (tom@...) and we will let you know if we have it.? Look for announcements on the homepage as we complete the inventorying and pricing of each group of parts.? Please be patient as we get the website, inventory and pricing figured out.? Feedback is, as they say, a gift, so please share any constructive advice or suggestions for the site that you may have.? The suggestion "You should have your head examined" has already been given!? :) We can¡¯t ever hope to duplicate the knowledge that Walter possessed, but will do our best to provide you with the right parts for your project.? We look forward to getting to know our new customers, and will work hard to earn your trust.? Thank you, Tom and Darla Norman |
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Sphere's Tektronix (and HP) Component Inventory - tekandhpparts.com
As many may remember, Walter Shawlee II passed away September of 2023. Since that time, his wife Susan, and children, have been busying themselves with the task of liquidating much of the electronic goodness that Sphere Research had accumulated. Susan intends to continue to make their collection of slide rules, nixie tubes and various other items available. Additionally, she is continuing in her effort to find homes for the remaining equipment. Please do visit Sphere¡¯s site and help.
Sphere¡¯s inventory of Tektronix and HP parts has found a new home with us. We have the beginnings of a website (tekandhpparts.com), with the intention of continuing to make these parts available to the Tek and HP enthusiast community. A bit about us: 1) The goal of the website is to continue to make Sphere¡¯s inventory available to the people like us that enjoy collecting, repairing and making use of these amazing examples of engineering and manufacturing. 2) A secondary goal is to ¡°pay back¡± our retirement account of the funds used to buy the parts. It is truly secondary, and may never happen, but who knows? 3) We are retired, have three children, farm 20 acres of grass hay, tend to cows, sheep, horses and chickens, and have FAR too many hobbies and other responsibilities to have taken on another, but here we are¡. 4) Our website is an amateur work in progress. Please read the home page posts for information on the site and on our progress. Tek items will be posted first, followed by HP and then ¡°other¡± semiconductors and who knows what else. There is much awaiting inventorying, so if you don¡¯t see the part you are interested in, please contact us directly (tom@...) and we will let you know if we have it. Look for announcements on the homepage as we complete the inventorying and pricing of each group of parts. Please be patient as we get the website, inventory and pricing figured out. Feedback is, as they say, a gift, so please share any constructive advice or suggestions for the site that you may have. The suggestion "You should have your head examined" has already been given! :) We can¡¯t ever hope to duplicate the knowledge that Walter possessed, but will do our best to provide you with the right parts for your project. We look forward to getting to know our new customers, and will work hard to earn your trust. Thank you, Tom and Darla Norman |
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Want : Tek576 collector knob (366-1007-00/-01) set screw hole height
I am looking for someone to measure the height from the bottom of the knob to the center of the set screw hole. some dimensions on the qservice page. but not listed set screw height.
same knob used in 7L13 SA and some TM500 series plugins. ((366-1007-00-01)-set-screw-hole-height) |
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Re: TEK 2465A Rebuild
I have a 2465BDV and have looked at re-capping it from time to time. So
far, my "if it ain't broke, don't fix it" attitude has prevailed and, since the 'scope has worked beautifully since I had it calibrated, I haven't re-capped it. But in my travels around the web, Condor Audio has popped up as a viable source for repair kits. My take on the post in question is that it is merely a rather complete description of the author's experience and in no way meant to promote Condor Audio for business purposes. DaveD KC0WJN On Sat, May 17, 2025 at 21:14 Roy Thistle via groups.io <roy.thistle= [email protected]> wrote: Hi: |
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Re: TEK 2465A Rebuild
Hi:
I just want to say I am moderating this post. It reads like, a promotion, for a product or service. AFAIR, TekScopes hasn't allowed promotions for products or services... with the exception of long-time members who also frequently posted about Tektronix scopes, and their repairs. If you think that policy should change, please PM me, and we can discuss it. Best regards. -- Roy Thistle |
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Re: vintageTEK new debugging aid
You've got the right of it. The Windows program just asks for a block of data and then displays it. The real hard part is figuring out what name Windows gave to the COM port. I generally try to avoid programming at such a low level, but I wasn't getting the perfomance I wanted using the more user-friendly .NET programming environment. The program is no thing of beauty. I only published it to make sure that the Vintage Tek Museum wouldn't have any potential liability if some customer's Windows machine did something naughty.
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TEK 2465A Rebuild
I got a TEK 2465A for free a few weeks ago from a neighbor. The only problem it had was a severely pulsing display. It went through boot up ok and i assumed ripple from the power supply was the issue. I searched around for some guidance and several group members mentioned CondorAudio in Jerusalem sells rebuild kits for TEK 24XX series scopes. He also has a very good rebuild guide at condoraudio dot com.
The kit for my scope was only $80 + $28 shipping on Etsy (under $100 there are no tariffs) and I received it in 7 days to GA US. Included caps for all the PCB's, not just the power supply. Anyway, kudos to Yachad for making this kit available, it saved me a ton of time putting together numerous orders for high quality caps for less cost when you consider shipping from numerous supply houses. Just finished it up and the scope is working great after replacing all the ecaps & tants. Also, replaced the LIPO Keeper battery that I found from eBay for $25 that maintains the calibration. I just soldered a couple AA batteries in a battery holder to the back of the diode and resistor that the battery connects to so it didn't loose the calibration. The original battery was dated 1987 and still read full 3.5+v! But I didn't think it would last much longer. It was quite a job, but well worth the time. Thanks again Yachad! |
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Re: Tek 7J20 application use, research papers
Thank you. The papers published in Applied Optics appear to be behind a
firewall. But I see that the first paper is co-authored by Jay Pasaschoff whose textbooks on astronomy we hsed in college. DaveD KC0WJN On Sat, May 17, 2025 at 14:33 garp66 via groups.io <Bean595939= [email protected]> wrote:
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