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Re: FS: Tektronix DPO4104 1GHz 5GS/s 4CH
I did try to buy this item but after a signed contract and payment mostly silence.
Has anyone else paid for this item ? If so then this is a scam. Please drop me a private message to confirm. If not then this migth still be valid deal but something might have happened to 'Mark Yeager'. |
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Re: Please help with TDS340A
Hi and thanks to all, especially Harvey. I am not much further forward. I haven't gone for replacing the caps as advised by Harvey, but have managed instead to probe the power supply into the scope, and to upload a pic of what the interference looks like taken at the screen. This pulse is lessened but still present all the way around the scope. My old Trio scope shows almost nothing at all when the same probe is held against its CRT. The PSU output is clean and the trigger pulse is about 5V at the same frequency of 31.5ish kHz.
Is this info helpful to you who know so much more than I? I am out of my depth so moving very cautiously here! |
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Re: Tektronix 475A B Delayed only triggering with A Trigger Slope
I have had a problem with a couple of 475's and 475A's caused by Q904 in the A sweep circuit. This part is specified as a 151-0190-01. The base -0190 is a 2N3904, but the -01 version is a Teledyne part in a round white ceramic package with a triangular lead pattern, rather than the black plastic TO-92 of the regular 2N3904. I don't know what the selection criteria for this part are, but it is specified as being supplied by Teledyne. (There are 9 variants of the -0190 listed in Tek documentation). I have found that these tend to be lower beta than other 2N3904's, and I have had some success using the lowest-beta part I could find in this position.
-- Bob Haas |
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Re: Front cover for 2225 ?
Thanks for the info :-)
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It's a low priority "nice to have" for me too. Regards, Dave On 24/09/2020 16:51, Raymond Domp Frank wrote:
On Thu, Sep 24, 2020 at 05:47 PM, <tekscopegroup@...> wrote:I just found that have among my notes that the front cover PN 200-2520-00 fitsI mostly agree: I think that the same front cover fits all 2200 models, except the 224X and 2252 models. |
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Re: Front cover for 2225 ?
I just found that have among my notes that the front cover PN 200-2520-00 fits All 22xx models.
Was trying to verify this by looking up this number in the 2213A SM, but could not find where they list the optional accessories, on page 1-1 it only says "to refer to the Accessories page at the back of this manual", no page number given. I have manual 070-4733-00 purchased ages ago from Artek 1984, Last Rev 1988. If you look up this PN on ebay there are several covers that look correct, but are either too expensive or shipping is too high. My target was/still is finding a cover for my 2213A, but its very low priority for now, unless a very must buy crazy good deal comes along. |
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Re: Shipping Scopes
Here in my area, we have a shipping store call Go'ng Postal. I have them
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boxed in bubble wrap, 3" on all sides. Then that box is inside another box with 3" of foam or bubble wrap on all sides. He charges me anywhere from $35 to $47 each time. It seems to vary with the same instrument. Depends on his mood I guess - lol. It will cause the shipping charges to be more due to dimensional shipping weight, but it's worth it. People think you can ship them an instrument for $10. They don't realize that it costs about $50 to properly box it. Then it may be $50-$80 on top of that. I hear that if you insure for $2000, UPS take much better care of it in transportation. The boxes don't get tossed as much. Dave On Wed, Sep 23, 2020 at 10:26 AM Adam Beasley <abeasley@...> wrote:
Is there a good service to use to ship scopes? The only boxes I have |
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Re: Shipping Scopes
Adam,
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For those ini Southern California, there's a pack-and-ship company called BoxBrothers that has a number of branches in California. My experience is with the branches near Los Angeles. They have a "guaranteed" service. They line all sides of the box with 2" styrofoam and they cut it so there is little, if any, styrofoam "dust".. The item is bubble-wrapped and placed in the opening with additional bubble or styro peanuts to fill the voids. They wrap so the item will not move within the foam cube they create. I used this service multiple times - my test was shipping some optical equipment. Prisms in it were affixed with glue so my concern was that shock could break them free. The item arrived and was fine. I subsequently used their service for shipping space program surplus that I knew even taking as checked baggage on a flight home was going to be problematic - it was not at all dangerous, but on an x-ray scanner, might look to be. All of those items arrived fine. This service was expensive, but low compared with the cost of the items. I did use FedEx to ship an Apollo optical unit assembly (the sextant used in the Command Module) that belongd to a friend of mine, for auction. I wrapped the unit itself with polyethylene foam and stretch-wrapped it in place. FedEx then packed and shipped it. The auction house took photos for their catalog and it was in as good condition as when I shipped it. I had it insusred for $5000 which was a lot less than what it wound up selling for, but it meant that FedEx was going to pack it well and handle it equally well. The auction house told me the packing was similar to what BoxBrothers does - the double-walled box was completely lined with 2" of styrofoam with an extra 1" on the bottom. Before 9/11, I had won a high-resolution graphics display system on a GSA sale. This was a system made by Celco and was the imaging part of a film recorder. It was used to turn digital images into film ones for the enterainment film industry. The CRT in it was a very high-resolution one. It had a low-persistence phosphor and a spot size of around 1 micron. This was NOT a direct-view tube - basically one line was displayed at a time until the entire image had been recorded on the film. It used a precison magnetic deflection system built by Celco. If I recall correctly, the tube was made by Litton. There was no way I was going to ship that tube, so I boxed it up - "floated" in soft foam - and took it as a carry-on item. I doubut I could do that today. I got it home fine, reassembled the display part and then it sat for several years. I wanted to try to use it, but it had no cables. Celco told me the cabling could be rebuilt (these were pretty much custom systems) and they could do it for $5000. I wound up selling it to R/Greenberg Associates, the folks known for generating titles for movies. They had a system like it and wanted it for spare parts. They came to pick it up. They told me the tube worked when they tested it. From the same lot, I also won a Tek 556 dual-beam scope. I boxed that myself and shipped it (quite expensive). When it arrived home, it powered up and worked on the first try. I was worried about that dual-beam tube, it all was OK. I think that was the heaviest Tek scope I ever shipped. My packing method was similar to what I and others have described. Steve On Thu, Sep 24, 2020 at 10:36 AM Oz-in-DFW <lists@...> wrote:
Adam, |
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Re: Shipping Scopes
Adam,
None of 'pack and ship' places I've dealt with know how to deal with heavy delicate stuff. To them heavy generally seems to mean sturdy. In addition to the other sources folks have mentioned, most home centers seem to carry moving boxes these days. Lowes and Home Depot have high pressure double-wall corrugated boxes. If you pack it yourself (and I suggest you do) I would: - Double box - Use double-wall outer boxes for anything over 35 pounds - Have at least 3" cushion on all six sides between inner and outer boxes. - Put address labels on all inner boxes, and large items. Boxes get damaged and labels get stripped. Inner labels increase the chance of most of the shipment getting there. This has saved me several times. - Put an address label inside the top flap of the outside box. - Use extra padding/blocking for the front and back panels. I usually cut strips of corrugated and "S" curl them around controls or use small boxes to make sure the panels, controls, and the tube face are protected. - Pack tight. Leave no air and compress the packing as much as you can get away with without damaging the outer box. Loose packing results in a guaranteed damaged box. A box damaged in transit is not a recipe for shipping success. - Do not use "air pillows' with heavy items. If one air pillow breaks or leaks your cushion pretty much goes away. They always leak or break. Always - Tape all the way around the box in both axes on the closed sides of the box with one continuous piece of tape and overlap the ends at least 8 inches. Use real >1.5" wide shipping tape. Use good quality tape designed for shipping that is at least 2 mil thick. - While not essential, it's a good idea to seal all box flap edges. If the box deforms it is more likely to retain the all important packing material. - When in doubt, overpack. Be doubtful. Extra packing doesn't add much to shipping cost (as long as it doesn't require an oversize box.) -- Oz (in DFW) N1OZ |
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Re: Is my Tek 468 beyond repair?
However.... Something is not right here as I would say you (and us) are spending too much time analyzing and speculating on this one problem. If you have a good new oscillator and have good new FFs, the circuit should just be fixed and work as it did 30 years ago.Tony, your point is well taken and apologies for over-analyzing. It is mostly about learning and trying to understand on my part and a certain amount of confusion. However, I think I have now discovered why the crystal output was so variable. More below. I had a quick look at the DIL packaged 50MHz oscillators available from RS Online and they are all marked TTL/CMOS compatible, from where did you get yours?From an eBay seller. Please don't be insulted - you haven't switched the scope input to 50 ohms have you?Not at all. Checked just in case, but my Philips scope does warn and will not allow switching to 50¦¸ while a probe is connected to the channel. It was not set to 50¦¸. I did realise that the FC cable was still connected up and plugged in but both scope and FC were using 1M¦¸ inputs. Connecting the FC does have some effect on amplitude but not quite that much. Another long shot to try when you have the FFs and the oscillator out, ohm the trace to ground and +5 (power off) and see if there is any resistance. Should be an open circuit.I am still hoping I can get the ICs out in one piece so as to be able to make a comparison between old and new and do a "post-mortem" as I agree with the consensus that there is likely a fault with one of them. It might be worthwhile to repeat the oscillator output test with the load resistor connected to +5 rather than ground. The oscillator on my board appears to pull a high level down rather than drive a low level up to a TTL level. ... I had suggested much earlier that you try pulling pin 8 of the oscillator up through a resistor to +5 to see if it improves the clock level. Did you try that? Might try a 1K pull up with the scope monitoring the pin and see if you get a clock with a better TTL signal.I did (rather embarrasingly) find a problem with the earth lead on the scope probe which caused a much reduced signal amplitude at times. I also found that when my hand was on the scope probe this also seems to reduce signal amplitude significantly. Both of these issues, while not explaining the abscence of signals on the processor (these were also checked with an LA), did contribute the variations I was seeing while testing the crystals and the resulting confusion. Having sorted that out, I re-ran the tests on both old and new crystals, first with the 1k¦¸ resistor then with 470¦¸, 30 mins each. The new crystal has a slightly higher output (perhaps by 0.2V) without load. Both hold steady at just below 4V with a 1k¦¸ load resistor and about 3.8V with a 470k¦¸ load resistor. Neither gets warm to the touch. It seems reasonable to conclude that both crystals are good and the problem is with one of the ICs. While repeating the tests I did also try pulling up to +5V as suggested rather than pulling down to GND with a 1k¦¸ resistor but that made no difference to the amplitude of the signal. It only changes the shape of the wave very slightly. I am still waiting for the remaining parts to arrive at which point I will be able to replace the two ICs, finish re-capping (except for the large can), re-assemble and test the clock. In the meantime I have partially re-capped the board. I still need to tackle removing the two 74S112 ICs. |
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Re: Tek 571 curve tracer
I'm not so sure they are. DC leakage current is well below 100uA at 20V.
I'll check them again at 40. When I say the cans are domed, they may have been made that way as these are sealed at the bottom and don't have the usual "fault lines" in the domed end. I will also check ESR. Replacements are standing by, but I'm not convinced these were the source of the noise, especially since it's not line noise. These are all pre-regulator caps, so I'll check the smaller ones after the linear regulators to see if anything is suspicious there. Low capacitance on the output and some fast switching in the video circuits could be to blame. I should also see if the noise is in sync with the video. Dave Casey On Wed, Sep 23, 2020 at 9:43 PM Richard R. Pope <mechanic_2@...> wrote: Dave, |
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Re: Free TWD 120
Chuck Harris
Thomas,
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Snapdiode is usually pretty tolerant. I would bet that he was commenting on the spelling, and then only tongue-in-cheek. Part of surviving on these groups is learning that most folks don't mean offense when they say the things they do. And, that a whole lot of conversational clues don't make it through the channel in a text only mode. Please keep doing what you are doing. You are fine. -Chuck Harris Thomas Garson wrote: This came directly to me from snapdiode, whoever that is. |
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Re: Shipping Scopes
We get Fed Ex International flat rate boxes, 10 and 25 kg, come in packs of 10, sometimes available at Fed Ex stations.
Very sturdy double walled, and special rate if used for Fed Ex international shipment In general a double or triple wall carton is much better than single walls. Beware carrier insurance payment for loss or damage requires proof of the value, and cannot exceed the Customs Declared values Jon |
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Re: Shipping Scopes
Don't bet on the shipper doing a good packing job. I watched a UPS Store employee do a pack job on a an antique porcelain vase: Packed it in a poly bag. OK, that's good. He then placed it in the center of a box that was big enough to hold about 6 of them, fill the box to the brim with foam peanuts and tape it shut. He did not even compress the peanuts. It's also very difficult to get to watch them pack YOUR item.
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In some areas, there are independent packing specialists who will pack your shipment, taking full responsibility for safe and intact delivery. However, they charge quite a bit, so much that it often isn't worth doing. Perhaps over the "pond" Pack & Send provides such service. Thomas Garson Aural Technology, Ashland, OR By my calculation, the dynamic range of the universe is roughly 679dB, which is approximately 225 bits, collected at a rate 1.714287514x10^23 sps. On 9/23/20 12:23 PM, greenboxmaven via groups.io wrote:
I am well aware that things do go wrong. However, if Fedex or UPS pack the item, they have some incentive to do it well. |
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Re: Shipping Scopes
I purchase cardboard boxes from a local supplier that specializes in paper products and shipping supplies. There is usually one or more such companies in any moderately metropolitan area. For reference, here in all of south western Oregon, regional population is a well under 200,000. Often these companies also carry janitorial supplies and deliver.
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The cardboard boxes I use by choice are designated for heavy items. For some items shipped overseas, I use double wall. I completely line them with 1.5 to 2" polystyrene foam (because it's softer than the rigid sheets) cut from 4x8 sheets of residential insulation (from Home Depot). Faces, with any type of display and/or knobs get spacers to minimize the possibility of their damage from that side of the package getting mashed. After protecting the face, I literally roll the unit up in three layers (sometimes more if necessary) of 24" bubble wrap, which I purchase in a roll that's about 4 to 5 feet in diameter from the same place I get boxes. I use lots of Duck brand clear packing tape in the wrapping process in order to turn the bubble wrapped item into a modern plastic mummy. I use enough bubble wrap to make sure the mummy fits snugly into the foam lined box. I do charge for this. I don't make a profit on packing, but I want my time (at dock labor rates, not bench rates) and expenses covered. This is made clear up front. I have successfully shipped expensive collector grade professional and home audio equipment, some with vacuum tubes, to SE Asia, Australia, Europe and the UK as well as around the US and Canada. I have also shipped to S. America, which I no longer do because the buyers I have encountered are a PITA and the customs personnel in many countries there are completely untrustworthy. If the equipment I am shipping has vacuum tubes, I will either remove them and individually wrap each and place them inside a small box that is included within the main box, or I will custom build a unit enclosing inner cardboard box and line it with shaped soft foam that holds all tubes snugly in their sockets. I recently did that for a pair of 5 (five!) channel 56 year old recording mixers that have a street value of about $5000.00 each. I did add 1/4" plywood sheet to the inside of the cardboard walls for that package. One shipment packed thusly, in 20+ years of doing shipping, had contents so damaged as to render it junk. The fork lift tine hole in the side of the box that a flashlight could clearly show penetration of more than half way trough the steel chassis packed inside was evidence enough for the insurance adjuster to authorize a full value claim. Some times it doesn't matter how well you pack something. If the baggage handler pushes your box out of the bay door of a 747 without having a conveyor or stairs in place, it probably wont matter how well you packed it. Thomas Garson Aural Technology, Ashland, OR By my calculation, the dynamic range of the universe is roughly 679dB, which is approximately 225 bits, collected at a rate 1.714287514x10^23 sps. On 9/23/20 11:12 AM, Dave Seiter wrote:
My favorite is polyethylene foam planking,.......... |
Perdad
Charlie Conger
Bob Haas
Raymond Domp Frank
Jean-Paul