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Re: Power supply problem with Tek 2220
Tan Chor Ming
开云体育Hi Francis, You are spot on. ?There is no stupid question. ? After I downloaded the 2230 (as directed by Tom) and compared with the 2220/2230. Immediately, I notice the difference.? The 2220/2230 has a thermal shutdown board which is not present in the 2235. So, for my 2220 it is an indication that the thermal shutdown is working.? I believe it is at working at the correct temperature because shutdown always happen when the chassis is burning hot (can hold for a 4 to 5 sec before it burns) I will try to do a test to disconnect the shutdown and see it the shutdown happens again, just to locate the cause. ? Comparison between 2220 and 2235 PS ???????????????????????????? ??2220??????????????????????? 2235????????????????? Comments -5V supply ??????????????Yes???????????? ????????????No R907????????????????????? ??549 ohm????????????????? 357 ohm??? ????????Current rating on +43V for 2220 is about 30% higher Thermal shutdown?? ??Yes??????????????????????? No? ? Rgds, Chor Ming From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Francis
Sent: Monday, January 23, 2012 4:41 AM To: TekScopes@... Subject: [TekScopes] Re: Power supply problem with Tek 2220 ? ? Hi, |
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Re: Tekscopes at the Computer History Museum
Brad Thompson
On 1/22/2012 8:29 PM, Thomas Miller wrote:
I worked at Bendix Communications Division from '66 to '71. Even had myHello, Tom and the group-- IIRC, the 8080 was introduced in 1974; the 4004 was introduced in 1971. In the early 1960s, I worked as a co-op student at a company that manufactured magnetic-core logic (nonvolatile, radiation-resistant, very low power consumption). Four bits per cubic inch. 73-- Brad AA1IP |
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Re: Tekscopes at the Computer History Museum
开云体育I worked at Bendix Communications Division from '66 to '71. Even had my own
545 Tek scope. They were the days. DTL had just arrived and a lot of military
systems were just being converted to the pure digital domain. It was around 1971
that the 8080 came out and the world was about to really change.
?
Regards.
Tom
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Re: Tek 7k plug-in prices rising...
G. K.
China has finally re-valued its currency! From: Aaron
To: TekScopes@... Sent: Sunday, January 22, 2012 4:44 PM Subject: [TekScopes] Re: Tek 7k plug-in prices rising...
?
> > Have you seen the BIN price for this?
> > Item 270788500453 > Perhaps that's in HK $ ?? They just forgot to put the decimal point in when typing the price. If you check the sales history, they sold one unit for almost exactly 1/100 of the price in that listing. I wonder what the listing fee was for that ad... Aaron |
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Re: Tekscopes at the Computer History Museum
I defer to your superior knowledge of the history of computers, Steve, but I think you contradicted yourself. During the Civil war the new battefield howitzers didn't have the help of digital computers to aim them. What was learned and the mathematics developed for ever more complex artillery aiming schemes, as an example, laid the groundwork for which digital technology later took over and refined the job. Sir Isacc Newton didn't have an Apple ;-)
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Arden While analog computers made some amazing advances for their day, I disagree with the comment that they laid the groundwork for modern digital computers. The early designs of digital computers did not leverage anything from analog computers, and took totally independent paths. Probably the only connection is that one of the early digital computers – ENIAC, was designed for the purpose of computing trajectory tables for large field artillery – a similar task the Nike flight path computer performed. The latter provided correction information in real time, while ENIAC actually computed tables of numbers that were published in field manuals. |
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Re: Need Manual for Type W, SN 4560 & 5336
Bernd and Egge,
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I was aware of the change from Nuvistors to FETs in the 1A1, but didn't know a similar thing had happened to the Type W. If you are able to find the mod kit, would you mind scanning the modified schematic? I'm a complete beginner to electronics and chase enough dead ends even when I have a full manual in front of me. With incomplete schematics I find myself second-guessing everything. :-( I checked eBay and Dave's(ArtekMedia) site but didn't see any manuals for SN >7000, although I sent an inquiry to the eBay listings that didn't show a part number or SN range for the manual. What does PWB stand for, as mentioned in Egge's post below this? Aaron --- In TekScopes@..., "Egge Siert" <eggeja@...> wrote:
It seems that you have two Type W's with the FET-Frontend and the PWB for these. With SN 7000 and above this was standard. For this late versions a new Manual was printed. FET-Frontends (less drift) were used in late Type 1A1's (I don't for sure also 1A2's) and the 1A7A (which has the same circuit as the later 7A22). |
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Re: Total beginner with newly acquired 475 with issues
Hi "newbarrie"'
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There is far more expertise on this forum than mine but here are some points to get started with, but not specific to the 475: Scopes (and all electronics) that have been sitting around unused for a long time develop not only visible "verdigris" but invisible oxidation and corrosion effects. Wherever two metals are mechanically opposed to pass an electric current is where you will find problems. Apply an electrical contact cleaner that contains a lubricating protectant (I recommend MG Chemicals Super Contact Cleaner) to all connectors, unseat and reseat them at least a couple of times. Plug-in intgrated circuits can also be a problem but leave them to a later level of diagnostics. With switches be a little more careful where you apply the contact cleaner, keep it only to the contacts as well as you can. You can apply cleaner with an artist's brush in tight spaces. Rotate switches several times to restore functioning. Check for loose hardware, tight screws and nuts are required at some points to insure good grounding. You may be surprised at the results you get by performing this procedure. Next, before attempting to do further diagnositics, get a service manual and make it a reading project until you have a good sense of what the scope is all about electronically and how to perform diagnostics and calibration. When you are ready to dig into the cause of particular failures here's the place to get help. Arden ......I also have acquired through the ubiquitous Ebay a half dead Tek 475 scope to play with. ...... |
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Re: Force DSA-602 to proceed past 11A34-induced POST error?
It looks like David and Javier were right and this plugin was just missing some sort of calibration constant, fixed by running EA on a good DSA 602 mainframe.
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I have now been using it for one week, in various 11k mainframes, with no trouble at all. Thanks again guys! Aaron --- In TekScopes@..., David <davidwhess@...> wrote:
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Re: Tek 7k plug-in prices rising... 7L13/7L14
If the only thing wrong with the 7L13 is a broken knob, then I think $1k
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is a reasonable price. Microwave spectrum analyzers are always expensive. Though a 7L13 or 7L14 is on the low-end of the frequency range, it might be OK for many people, without the $3k . . $5k . . . expense of getting something with a higher frequency range. One potential advantage of the 7L13/14 is that the schematics are available and there is no power supply or display electronics to worry about. I think more modern or similar vintage but more capable spectrum analyzers which are not 7000 series plugins would have a lot more electronics to go wrong, including power supplies, firmware-based microprocessor stuff, CRT displays etc. I recently bought a 7L14, in the 2.5GHz version (without a 1.8GHz LPF and input limiter) for $650 or so. I knew it had problems, and I fixed some of them - multiple dead tantalum capacitors. I now suspect its input mixer needs its diodes replacing, since its sensitivity was very low, and there needs to be quite a lot of work to make the displayed frequency match what the device was actually responding to. At present it is not responding to any signal. Now I know more about these devices, I realize I need the 1.8GHz LPF, but fortunately MiniCircuits make one which should work OK - and the cost is under $50. I have now acquired three of John Griessen's <john@...> excellent 7000 series extender kits: so I will be able to work on this beast. Its not for everyone, but I liken this introduction to microwave electronics to buying my first vehicle - a clapped out 1961 VW Kombi van - and the years of learning experiences as I rebuilt various engines, always imperfectly, and successfully refurbished the gearbox and many other parts. It can't be ruled out that I am crazy too, but I only bid this because someone else was ready to bid a little lower. One fellow in Western Australia has a 7L14 (1.8GHz version) with the TR502 tracking generator - bought on the understanding it was fully working for ~$1.5k. That seems reasonable to me, but it turns out that it is lacking sensitivity and so probably in need of diode replacement in the input mixer, plus potentially other faults. - Robin Magnus wrote: The winning bid for this one leaves me stunning. It comes with no |
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Re: Tek 7k plug-in prices rising...
Have you seen the BIN price for this? Perhaps that's in HK $ ??They just forgot to put the decimal point in when typing the price. If you check the sales history, they sold one unit for almost exactly 1/100 of the price in that listing. I wonder what the listing fee was for that ad... Aaron |
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Re: Tekscopes at the Computer History Museum
In 1967 I worked at Bendix Aerospace and saw this F4 autopilot on the floor
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of one of the factories. I believe Bendix designed it. It is indeed an electromechanical monster. I always wondered how they figured it out it. It must have been a nightmare with all those layers of rods, gears, actuators, and servos. All the autopilots I worked on at Bendix were analog computers. Fortunately when I started there all the new designs use the new uA709 IC OpAmps. That was a revolutionary leap in technology. But before I could fully appreciate the beauty of OpAmps everything changed again. 2 years later autopilots were being designed with digital logic. The Concorde autopilot used DTL. Then they started building B52 subsystems with ROM lookup tables. I used to have to blow out diodes in those tiny ROM packages one bit at a time. They were exciting times to be in electronics. Dennis -----Original Message-----
From: phorphile, Sunday, January 22, 2012 9:22 AM In the Navy in '65 I was treated to a visit inside an F4 Phantom simulator trailor. That was one big analog electromechanical maise on wheels. Analog computers laid the ground work for digital to take off from. ......They have heard of analog computers, sort of, but they're treatedlike the redheaded stepchild. ....... |
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Re: Tek 7k plug-in prices rising...
Richard Solomon
Perhaps that's in HK $ ??
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73, Dick, W1KSZ On Sun, Jan 22, 2012 at 5:05 PM, J. L. Trantham <jltran@...> wrote:
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Re: Tek 7k plug-in prices rising...
开云体育Have you seen the BIN price for this? ? Item? 270788500453 ? Joe ? -----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of HP Sent: Sunday, January 22, 2012 5:51 PM To: TekScopes@... Subject: [TekScopes] Re: Tek 7k plug-in prices rising... ? ?
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Re: Tek 7k plug-in prices rising...
Magnus, don't worry, maybe the prices in the past was to low ???
just found: 7L14 Spectrum Analyzer: ONLY $1,499! (SOLD!) from a US used electronic seller So, they expect more, keep your eyes open ;-) Peter ==============================0 Hello,Magnus |
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Tek 7k plug-in prices rising...
Hello,
The winning bid for this one leaves me stunning. It comes with no warranty and has a broken knob as per the item description... ?I have no disbelief in the 7L13 spectrum analyser's quality and capabilities. And I am aware that these are offered rarely - but... The buyer was willing to pay 1 grand USD as you US chaps might put it. See ? Cheers, Magnus |
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Re: 7603 no trace
David Miles
开云体育On 22/01/2012 02:34, jtjewell83 wrote:?-67.6V 71.8V ( no sign of cracked solder pads.) R860 = 12KOhms ( with R860 in place on pcb ) +69V with ref to ground. I must thank you for your persistent help so far Jimmy, very explicit instructions that are very easy to follow! re cap ripple testing, do I put scope probes only on the cap pins of each individual cap to test each cap? Thanks. David. ps. I have found what looks like a mistake in the service manual A11 low voltage regulator board,I think that R860 and R866 are mixed up. I have ignored the print out and concentrated on looking at the colour codes to find the correct resistor.
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Re: 7603 no trace
Good Day,
Quote: - I'm thinking Q872 and the other 2 transistors are OK.? There's just not quite enough base current to turn on Q872, and the others.? The collector of Q860 is only 2 volts.? It should be about 52V when things are normal (+50V supply + drops of 3 transistors' B-E junctions). Ah, yes - of course - you are raising a good point here Jimmy.? Plus some small drop across R875, of course. Too obvious. I should not try to understand voltage readings and schematics when it's getting late.... David, simply follow Jimmy's advice.? As your - 50V DC voltage reads off, you also might want to check if Q908 is on and Q909 is off during operation. See the description on page 4-30. By the way: I have just seen that Tektronix has followed their own, good tradition and they have use sockets for all small transistors on the 7603's A11 Low Level Regulator board hardware. That should make any potential replacement work or tests easy, if necessary. Cheers, Magnus |
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Total beginner with newly acquired 475 with issues
I am reviving an interest in electronics I had in my youth, my day job is a race car engineer, and I need to get a better grasp of electronics as cars and engine become ever more complex in their management and control strategies. I have bought a bit of basic test gear, as well as stuff I have had for a long time. I now have a working Philips PM3380B analogue / digital scope, a 150 meg USB scope, some basic voltage measurement gear and a basic signal gen. I also have acquired through the ubiquitous Ebay a half dead Tek 475 scope to play with. it cost not a lot and was a surprise win on a bid I put in and forgot about. The abridged story is below:
Right, I picked the 475 up this evening and have had a word with the seller and a quick look inside it. It was stored under far from ideal conditions for some years in an old building undergoing restoration. It has slight signs of this damp on one board, some of the metal canned transistors have the very first signs of green verdigris / corrosion on their cases, very very minor, mind you. One of the vertical side boards has very minor corrosion on some of the ground foil near a vent on the case, but the tracks still appear fine, it's very localised and would clean off I am sure. When the scope was purchased five years ago it worked fine save for the second channel losing the display if turned up to what he described as 2 megs?? Below this ?? it worked fine, and channel one worked fine in all respects. After coming out of storage and being put in a warm dry environment the problems were apparent with which it was sold. It will focus quite well, in the centre of the pot. The dot almost appears to be two very short lines one above the other though, hard to say. Intensity needs to be in the last tenth of clockwise rotation to get any display to show. Horizontal control needs to be fully clockwise to bring the dot to the centre of the screen, a 1/4 or so turn anti clockwise and the dot is off the left of the screen. Beam finder creates a very bright bigger dot, with a lot of illumination on the phosphor around this dot. The vertical control fully clockwise has the dot off the top of the screen, fully anti clock has it a maximum of a 1/4 of the way down. Fiddling with the control will make the display occasionally flash below the vertical half way point instantaneously, as if noise in the pot is doing it. Randomly probing a few of the voltage test points which have their expected voltages shown on the main board give sensible readings, what the ripple is like I have no idea. There's a point marked "5 V unreg" on the main board, this is showing 62.9 volts. Others are within 0.01 volts of the stamped values on a reasonable hand held DMM, referenced to ground tags on the main board. Fan works, three or so of the panel switch plastics are broken, Bezel of main front panel has some corrosion, fascia is so so, but perfectly legible and usable. Would you recommend I attempt more diagnostics, or is the above enough to condemn it as a source of spares only? Thanks. I can post photos. I would like to fix it as it would be my first attempt at fixing anything electrical of any complexity, and very different from working on new automotive engine and chassis control systems. I don't NEED this to work, it won't change my life it it's a white elephant, but I know I'd get a buzz if someone were willing to treat me like a normal Joe passenger who ends up in the cockpit of a plane when the pilot has a seizure and needs talking into landing the thing, however inelegantly ;) All I have are a 150 meg dual channel USB scope, a PM3380B 100 meg dual channel Fluke analogue / digital scope, a bench and a hand DVM, a signal gen that goes only to 1 meg. I have some soldering gear anyone with a true interest in PCB work would probably laugh at, but I don't mind buying a cheap fairly basic soldering un-soldering station, I have fancied something better for years. If I blow it up (further...) I will be annoyed, but would put it down to experience. |
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Re: Tekscopes at the Computer History Museum
--- In TekScopes@..., "phosphorphile" <gumbear@...> wrote:
Another interesting example of analog computer technology was the flight path computer for Nike missiles. The Nike was an early anti-missile system. These were closed loop systems which used radar readings of incoming missiles and the Nike after it was launched. An analog computer computed the trajectory of both and sent information to a telemetry uplink to change the steering vane positions on the missile. This was designed in the early 1960's, and amazingly it actually worked in tests. You can see an example not to far from the Computer history museum in the park directly north of the golden gate bridge – do a Google search to learn more. While analog computers made some amazing advances for their day, I disagree with the comment that they laid the groundwork for modern digital computers. The early designs of digital computers did not leverage anything from analog computers, and took totally independent paths. Probably the only connection is that one of the early digital computers – ENIAC, was designed for the purpose of computing trajectory tables for large field artillery – a similar task the Nike flight path computer performed. The latter provided correction information in real time, while ENIAC actually computed tables of numbers that were published in field manuals. ENIAC had a couple of oscilloscopes stationed near its bays to assist in troubleshooting failed tubes. Some say they were Tek scopes, but I don't think the timing works. ENIAC became fully operational in February 1946 – before Tektronix was founded. - Steve |
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