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Hi Everyone, My TEK 494 is displaying signs of faulty Eproms (I think) This is an early 494 (No A or AP) just plain 494 All the files on the net are for later models I suspect The eproms include 1600-2366-04, 1600-2367-04 (on the labels) etc Any feedback greatly appreciated (probably my favorite piece of Tek gear) Very hard to get help down here in Sydney, Australia for this kind of instrument) Regards George Livanes

Due to a bad combination of serious illness and old age, we will be closing our Sphere business at year end. We will do our best to provide good service up to the end, but responses and page updates will be slower. All our curated parts collections (Tek, HP, Fluke plus fans, semiconductors and passive parts) are for sale, all offers are welcome. Please contact Susan at Susan Shawlee <susan@...> we have many items not on line, and coming by to see for yourself is really the best plan. tons of parts are free, plus two out buildings full of free gear. help your self. PLUS a huge shelf full of Tek and HP manuals, take all you want. sorry, we just don't have the resources to ship you this free stuff, it has to be picked up. Our thanks to the dozens of customers that have already come by in person to help us clear out parts and equipment, we really appreciate the effort you made on our behalf with this difficult problem. We have really enjoyed operating Sphere, and I hope it has been a useful tool for you to keep your test gear up and running. best regards, walter & susan -- Walter Shawlee 2 Sphere Research Corp. 3394 Sunnyside Rd. West Kelowna, BC, V1Z 2V4 CANADA Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca +We're all in one boat, no matter how it looks to you. (WS2) +All you need is love. (John Lennon) +But, that doesn't mean other things don't come in handy. (WS2) +Nature is trying very hard to make us succeed, but nature does not depend on us. We are not the only experiment. (R. Buckminster Fuller)

Hi all, Have been working on a TDS430A that had an SRAM problem, now fixed. Passes self test ok. But now three of the front panel pots have stopped working; the multi-function, vertical position and trigger level. The horizontal position works ok. All three had been working fine and am not sure now if they all failed at the same time or not, though I don't think so. I've tried a bit of contact cleaner to see if it was just dirty pots, but this has made no difference. Anybody else come across this issue and got any suggestions for what might be the reason? Thanks, Ralph

Hi, Due to other interests I came across this https://www.youtube.com/watch?v=DX6ipBe3WGQ video today. I was initially very sceptical that it would end well. However, to my very amateur eyes, it didn't end too badly. There has been some commenting on the video suggesting the 'scratching' was not an optimum procedure. I would be interested to hear what others here have to say. And perhaps we could even add some suggestions to the comments on the video to improve the outcome for the 2445. Brian.

I am looking for a working Earthy Logic board from a Solartron 7071 or 7081. That's the PCB on the top deck left side. The Guildline 9578 is also a valid donor as they are just a rebadge. Can anyone help? I burnt more hours than I care to think of on this board and someone else had at it for 8 months on and off. We both failed to get it working. I know it is that board as the meter works if I install one from another meter If you do have one you are prepared to part with please contact me off-list Thank you , David

I am testing several 556's that will be for sale and one has a lower beam that behaves badly with different plugins installed, so the gain in the mainframe is the problem. I can vary the position of a square wave from the cal out up and down with either the lower or upper CRT zone and time base, but on the lower beam the height of the square wave decreases as I position it toward the bottom of the CRT face. I'm going to start reading the manual soon today, but wonder if this is a common thing with an explanation like, "has to be in the last amp before driving the CRT pins", or "Can be the CRT internally damaged...". When driving the upper beam on the upper CRT zone, height of the square wave stays constant all the way until part of it is off screen.

My 465M would not trigger a few months ago so I found a used trigger board and installed it and it worked fine. I haven't used it since then, and today, it won't trigger again just like before. It has been stored in my humidity/temperature controlled shop so I am not sure how this can happen so any ideas would be appreciated. Thanks, Larry

I noticed this a few weeks ago, that after about 10-15 minutes I see an occasional horizontal jitter that lasts just for about half to 1 second, and then does not happen again until about another 30 or 60 seconds, sometimes more, sometimes less (no constant rhythm). I confirmed this issue to be in the scope by also sending the same signal to another scope. There is no vibration or physical movement present that could mechanically affect the scope while in use, so I suspect this might be related to a defective cap, perhaps in the sweep section. Or a bad solder joint somewhere? I had not powered up the scope for a few weeks, so kind of forgot about the issue, but while recently using it again was reminded. Before tearing into this intermittent issue, wanted to ask if anyone with a 224x (or 2252) scope, or in general, has seen anything similar to this, and any suggestions of where to start.

I have two power supplies for the 2445b and they both need new caps. I know a few years ago there were cap kits that included all the key caps to replace in the supply. My particular issue is with the AC High voltage section as the trace takes about 10 min to finally appear. I have done some due diligence on the web looking but to no avail. This is a great scope and I really want to freshen it up. Any leads to cap kits ? Or even a list of critical caps that have been replaced in the past would help. Thanks in advance.

Background: I was chasing a sweep issue with generous help from people here when R908 caught fire, taking out CR908 and R909. Found Q908 bad. So...replaced all the above along with Q9070. U930 seemed to have survived the fire as the output transistor showed the same emitter-collector resistance as a new replacement, so I took a chance on not replacing it. For good measure, I replaced U975, the high voltage module. Lifted and checked diodes and filter caps in the 8.6, 5.2, 30 and 100 volt supplies. All checked good with a Simpson 260 (that's how old I am). Turned it on for a smoke check (for real in this particular case). -/+8.6v came up and adjusted nicely, but... +4.76v at W968 (5.5 norm) +93.5v at W954 (100 norm) +28.2v at W956 (30 norm) Beam find worked normally, bright and center, so I surmise I'm getting HV okay. Trace shows as two dim dots with posn control almost full right, focus control seems to work, but intensity control has no effect. So... Opened W968, 954 & 956 to unload the 5.2, 30 and 100 volt lines. ±8.6 still good. +5.2v came up to normal. +100 and +30v still read low with no load. So there seems to be trouble in the 100/30 volt supply. I know this is getting tedious, but I would appreciate any helpful suggestions.

Thanks tto all the people who have helped with my PS problems. I've done some research and come up with some cross references to some of the arcane part numbers in the Tek parts list. Q908, 930 is a 2N2907A CR908 is a 1N4152 Q9070 crosses to an IRF720, and is available U930 is a TL94CN and is available CR967,70 are 1N5817s Q938 is a 2N5087 and is available Q944 & Q928 can probably be subbed with 2N5551s, but I haven't tried it yet. CR946,7/CR956-963 are fast switching diodes and the problem is that they were put in a TO-92 case and all the subs I come up with are Schottky diodes in much larger cases. The NTE 587, 574series have thick steel leads and come in a TO-41 case. Attaching whisker leads to adapt to the thru-hole mounts may be the best option. If anyone has found subs for Q946 & 947, please let us know. For the moment, I think an AF audio power amp ought work.

Dug out my 2215A after 2 year storage to fix a tape recorder and the horizontal sweep begins with a bright point of light, or a vertical line when a vertical signal is present. Both traces the same, vaveforms display correctly but I think the sweep is short. Ramp signals present on L&R sweep pins on CRT, but not having another scope, I can't tell much about the quality. Based on the principle that 90% of anything is having seen it before, does anyone have a good suggestion before I start tearing into an unfamiliar circuit and doing the monk-work?

Hi, On my 7704A which I bought decades ago non working: When plugged, on the regulator board A32: TP+7 +7,28V TP+54 +54,4V TP+17 +17,00V TP-17 -16,98V TP-54 -54,16V Outputs of the regulators on P32: -15V -1.2 +5V +0.1 +15 +0.4 +50 +52.6 -50 -53.6 +5 lights +4.5 I found on the -50V an opened resistor R134 which explains the opened loop and -53.6 out. Explains also the +50 over referenced on -50. Then I found short circuits. For +15V I tracked to C83 on A20 (main interface) and for -15V to C98 on A43 (H amp) Next move, I still have the short on +5 and I'll run the regs unconnected to A20 but on some resistors. And I'll have to replace the faulty caps and even the non faulty I suppose. As usual, comments, critics etc. welcome, Renaud F5ZR

Hi everybody and thanks for having me here. I also post on TekScopes but don't see why I could not here as well. Just me for the context: Retired EE, analog and RF mostly, built my first scope when 18, long ago! Measuring equipment: Fluke multimeter and PM3382 scope. I own a 7704A and a 7904 both in need of serious attention. Two 7A26, 7A19, 7B53AN & 7B87. All this not working since decades and never used by myself. 7704A, no plug-ins: When plugged, a 20mm spot. Intensity not working. Reduced by turning CW R 4135. As I didn't want obviously to burn the CRT, all my following measurements done one by one unplugging each time. We are in 230V mains here and C3016 get 156V, C3017 153V. When I cut the mains the 309V slows down very slowly. I consider that fine. Will give the inverter more attention later probably. Apart from A32 which on top collected decades of dust, A30 and A31 as well as mains caps etc. look very clean, visual control could not find anything obviously bad. Nothing leaking or burned. ON A32: TP+7 +7,28V TP+54 +54,4V TP+17 +17,00V TP-17 -16,98V TP-54 -54,16V As I have +50, -50 -even very out of tolerance- and +5 lights, I understand that the inverter is working, ok maybe incorrectly. I know that the main regulator is -50 from the 9V zener reference. Then all the others take that -50 as a reference. So inverter fine. -50 regulator wrong. A32: Diode and cap on Q130A good as were res and all others around. Q115, 137 141 good. Q139 (power) untested but my money's on it beeing ok. But R134 (divider from -50V sens) opened. It's a 32.4k I changed for two series res totaling 32,37K. Of course it explains why the -50 went to -54 with a loop open. Q1: Just a thought then: R32140 (470 ohms), between -50 and -50 sens is no use when A32 is connected to A20 because short circuited by the bridge on A20 between P20G -50 and P20H -50 sens. I would guess that R140 is used to have the loop working when P32G&H are disconnected from A20. In short may I try A32 disconnected from A20? Q2: Now I didn't dare fire it (litterally maybe). Rather I disconnected P32 H&G (to A20) and found shorts from A20 only Q2:for +15V and -15V. If not mistaken, from A20 they only reach A33 and the plug-ins. The shorts stayed as I disconnected A33 and I have no plug-ins so I will have to look on A20. I will need help there because C2081/C2085 are not the easiest to reach. Any help gratefully appreciated, Renaud F5ZR

Hi all, I've just been "tipped" by a good friend the 7A29 has a very delicate input switch - mechanically, the rollers need some lubrication to perform well and last. I appreciate the heads up, as the switch feels fragile and particularly sticky, so I'm sure I was heading head first into permanent damage. I searched the archives (not very deeply, yet) but I didn't find good direction on this yet. Has anyone done this work and have some good recommendations? What lube to use, where to lube, what not to do, some steps maybe, etc. Thank you, Radu.

Dear all, I happened to destroy this knob while trying to fit it in. It broke in dozen of pieces so it is impossible for me even try to glue the pieces together to allow me to draw a sketch for 3D printing. So I am asking the forum for a sketch, since it seems this knob has been an unobtainium part since a looong time ago. Thanks to all. Roger

Hi all, I have a 7k plugin I thought I successfully repaired the pulling mechanism (the finger pull knob broke from the plastic insert that is attached to the spring, and I epoxy glued it together, but if failed quite quickly). I removed the two plugins to the left and right of this stuck one, but I don't see to be able to pull it out if I grab it by the sides. Can anyone share any experience on this, please? Thank you, Radu.

Hi all, It's been a while. I hope everyone's doing just great! I lucked into a 7104 for the princely sum of $20 ($40 added a couple of 7A19s and a 7B92A came "free," all basically functional as I've seen home). Go swap meets!! Still exploring it and assessing functionality, but so far so good. One thing I'll need to look into is the power light bulb. I think the part number is DS308, and may be a 5V bulb. I can't really confirm this from the SM - has anyone looked at this recently, and can confirm? I think replacing it involves separating the display unit from the base (involving some "kickstand?...") - if anyone can shed any light on the process I'd appreciate it. Thank you, Radu.

Hello, Im new to this group. I am also fairly new to Tek Scopes. I have recently aquired a Tek 2430 Digital Scope, with a fault. On switch on the self test comes up and all items pass. However there is a warning of Un Cal. So trying the self Cal, a Running display appears but goes no further. The system appears to hang at this stage. No traces on either channel , but on screen displays are there. Going through the various menus all seems correct. Any direction on this please? Best Regards Paul

He passed away over Easter. His wife (Linda) is fulfilling orders but they do have some IT issues … Cheers, David Please click here to support DeepSkyStacker development