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They seem specialized so maybe a factory setting? They do not fit Bell system "phone jacks".

I'm contemplating getting rid of my 547 with rewound HV transformer and about 25 plugins, including 1S1s and 1S2s. I do not wish to ship, so what would the local interest be in Montreal?

Is the 2465A Service Manual Rev. October 1988 available for free anywhere? Thanks George

can the 1A1 dual pre-amp be used with a 561a scope?

Given a million years I would have never thought these were so hard to track down. I have the PM403 for the 6502. I'm looking for others, primarily the PM406 and PM407 for the 6800/6809. If you have one or more, *PLEASE* get in touch. Buying them would be great, but if you don't want to part with them you could still be of great help by providing PCB photos and dumps of the EPROMs. I will, of course, be happy to reciprocate. The goal here is, in part, to determine the extent to which these pods can be reconfigured for the other processors. Thanks much. Jonathan

I have the opportunity to grab, likely very affordably, an 11401 and/or a DSA 602A (the latter coming with a couple of 11A34a and one 11A72 plugs), and I've never - yet - considered getting a digitizing scopes, which I'm not very familiar with. One feature I am aware of is outstanding risetime performance. But I'd appreciate a bit of education on if/why I'd need one of those at my bench. Where my main scope is an HP 54522A which may soon be replaced with a TDS754D (which I hope to upgrade to 784D), a 7104 analog, a 7704A, 453A, etc. Thank you! Radu.

victor.silva <daejon1@...> added the photo album 2465x RIFA madness : RIFA Caps blowing up does occur, even on 120VAC.

OK gang! I changed the Subject to better reflect what we are doing. To test the concept, I took the 256, 16 bit words read from a 2465B using the EXER 02 function, and filled them into a blank Dallas DS1225Y NVRAM at addresses 0x1E00 - 0x1FFF. I replaced the FRAM in the 2465B with the newly programmed DS1225Y NVRAM, and turned the scope on.... ....DRUM ROLL..... It booted up normally, all calibration intact, with no indication that I did anything unusual. Torpedoes loaded full speed ahead, we got this thing! -Chuck Harris

The following photos have been uploaded to the TDS754D - repair images photo album of the [email protected] group. 05192024 Error Log.jpg Replaced ICs.jpg By: Radu Bogdan Dicher <vondicher@...>

I am using the vertical signal output (back panel) on a 7623A. It seems to have a 2:1 attenuator. I am measuring the output with a 1 meg input on another scope and find I get 1/2 the signal going into the 7623A vertical input. I haven't seen this specified in the online manual I use. This won't be a problem as long as it does it for all the inputs I select on the vertical plug-in. I will use Ch1, Ch1, and Add. Is this attenuation normal and specified?

All I can find online is the Operations manual for the LA-501. I have both early and late versions needing a look at, and schematics would be most helpful. Going to be a bit of work since they are loaded with those awful TI sockets.

Dear all, I bought a 7904 at the famous website as "not powering up". After reseating al the hamonica connectors, to my surprise it powered up, i could move the trace up/down and left right to "some extent", but I could not focus the trace which was abou 2mm thick at best. I started the troubleshooting by measuring the power supply voltages and ripple (with a Fluke 87 in AC mode) at the Z axis board test points The voltages seemed good as one can see below, but I am not sure about the ripple. header----- voltage (V)----- ripple (mV) -50 -50.01 1.3 -15 -14.83 1.6 +5 5.02 0.3 +15 14.69 0.6 +50 50.0 1.3 +130 129.3 16.0 HV test point (expected -2960V) measured -2784V While making these measurements I heard some clicking noise which seemed to come from the HEPS. The display flickered and after the fourth or fifth click the trace disappeared and the display has an uniform glow. The brightness control has no effect and the focus can change the brightness a little bit. I am a hobbyist and have a VERY basic understanding of HV / CRT circuits but I have read in other posts that some brightness problems seem to be connected with the autofocus/restorerer capacitors and diodes so there is a Mouser order on the way. Is this the correct way to go? Any other tests I could (or should) perform while I am waiting the order to arrive? Thanks to all, Roger PS. the blue harmonica connector of the Z axis board (near the voltage test points) is falling appart. I have already read about them in this forum but I can't remember of any solution for this What is the best way to fix it? Thank again

Hi folks, I decided to create a new thread with with question so other (as inexperienced as I am) may benefit from the answers. While trying to find why my 7904 was showing a blurry trace, I heard a tick and now there is no trace anymore, just a glow. Checking the Voltages at the Z axis test point I found that +15V and +5V were down. So I decided to remove the power supply to isolate the problem; is the Regulator boad broken or something outside is drawing too much current? In order to test the HEPS out of the scope I built a dummy load as suggested here (https://w140.com/tekwiki/images/8/84/Dennis_Tillman_7104-7854_SMPS_Dummy_Load.pdf). In this article, it seems that there is just one flat cable to be connected to the regulator board at P1482 ( voltage output to mainframe) However, there is a voltage feedback from the mainframe that arrives at P1483 (sense voltage return). Can I test the HEPS with just the loads connected? I vaguely remember seing another dummy load where voltage sense signals were derived connecting each voltage rail point at the load back to the corresponding voltage sense input using a second flat cable. Is it required? Thank you.

I recently got a 453 that needed some work that I got going good but it’s missing the rear cover plate. It’s the early version that takes the separate power cord. If anyone has a parts unit with a good rear plate that they’d like to sell please pm me.

Hello everyone, I am selling my trusty TM503. It’s the first generation, very early 1970s, and I have modified it with the IEC line input module and it has had all 3 caps replaced with brand new Spragues in 2007. You’ll find it rather unique I think. Good pictures (I hope) included with the listing - I recommend having a look, as you may be surprised. No reserve, bids start at $1, whoever wins gets it. https://www.ebay.com/itm/166739885570 Cheers, Kuba

I have a manual for "P6021 current probe and termination" free for anyone who might want it. A few stamps would be appreciated. Chuck Pilgrim

Hi all, I got a bunch of defective DM501As to have fun with. We'll see... ;) The first of these displays non-sensical data, and per troubleshooting tree (FIG 8-5), I've: Diagnosed the PS rails - they are reasonably close U1601-15 has no reaction to anything at the input at all (0.000V). I maintained the same GND to measure as I had for the rails. Q1435 has the waveform enclosed in a following email at the base U1603-8 has a pretty distorted waveform (it seems to me), which I'm not sure could be because of scope loading (I'm using a 10X probe). Shall I become suspicious of Q1435? The troubleshooting tree is pretty confusing, as that box doesn't have clear Y/Ns... (not clear what the "No" out means, and what would a "Yes" mean also). Thank you for your input. Radu.

Dear all, While troubleshooting the 7904 I recently bought I stumbled upon its serial number B092402! The service manual I am using lists the early units as B260000. I am working on the horizontal amplifier and the board number last two digits is a blank rectangle of metal. The layout corresponds to the one presented in the service manual for the B260000& Up (rev Nov 1983). I have not checked the other boards (yet). Is this a "pre-production" unit? Any special concer I might have while trying to restore this instrument?

In performing a much overdue calibration of my beloved 547, S/N 81xx, I found that the rise time was between 12.5 & 16 nS, rather than the specified 7.93 nS. It was while calibrating the 1A1 plug-in that I was able to confirm, once I was at the 24th Step (Check Upper Bandwidth Limit (Both Channels)) with the 191 that the bandwidth of the whole systems was closer to 22 MHz for the -3 dB point. A disappointment but not a surprise. What would be a good starting point to track down the cause of this limited bandwidth? I have a nice, flat square wave after having adjusted the Vertical Amp HF via the signal from the 067-0521-00. (To get close to the specified rise time, I would have had to leave a 1 cm overshoot at the beginning of the top of the square wave. The output card of the 1A1 (S/N 26,xxx) is also adjusted for a flat square wave, as generated by the Fast Rise portion of the terminated 106.) While using the Calibration instructions from the more modern TekWiki 547 manual, I did see some substantial changes in the Vertical Amplifier, such as the addition of two potentiometers, R1091 and R1077, as well as some small capacitors, starting with S/N 10730. (My manual is for a 547 with a S/N 3xxx and, of course, had never heard of these adjustments.) These additions were represented as adjustments for the rise time, especially R1091. Other than Dave Wise’s helpful information about the failing Sprague 160P capacitors and the substitutes for unobtainable 2N2207, I did not find much else on this topic other than his suggestion to move the leads of the 170 nS delay line, which I did and which had no effect at all. I would add that checking the 191 bandwidth result with another, unmolested 1A1 and a 1A4 provided the same, dismal result on the 547. I then checked the 191 output against a nearby 453, which had a -3 dB point of around 55 MHz. I did use the 50 ohm terminator in all cases.