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Re: Tek485 - a quick question on disabling/bypassing power supply protection
fiftythreebuick
Another approach that has served me well with this type of "ticking" power supply is to let it tick and use a storage scope to capture what's happening "during the tick" for evaluation. Sometimes you can get a good bit of info from what's happening in various places during the tick, while the scope is attempting to operate.
Good luck with it! Tom |
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Re: SG503 amplitude precision
True enough....seems to work.
Also had a recent prob with the fine freq adj...going wonky sometimes and the digital display flashing zeroes. Turned out not to be the variable capacitor at all...cleaning and reseating the rear brass 'shaft' nut to the (newly cleaned) Alum. housing made a minor improvement. It was the frequency range selector switch. Applied Yellow deoxit (low viscosity) to all contacts, exercised the rotation and all is well. SG503 frequencies working well now...even the amplitudes are solid based on my Scope (calibrated with an SG504). SG504 head calibrated to within 0.15dB. Ancel |
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Re: Pacific Measurements or Wavetek 1038 System
Hi,
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Wiltron also made a Scalar Network Analyzer (Model 640) and they used the entire Tek 5000 series mainframe for it. It looks like they used plugin chassis parts from Tek and put their own electronics in each of the 3 slots. These Wiltron 640 instruments are quite common so many of them were made using a Tek chassis. The big advantage of buying an already designed scope display, power supply, chassis, and plugin board mechanical parts, is that Wiltron can concentrate on designing the electronics. They do not need a team of mechanical engineers or a mechanical fabrication machine shop and the considerable overhead of all these machines and staff. Dennis Tillman W7PF -----Original Message----- -- Dennis Tillman W7PF TekScopes Moderator |
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Re: CRT Hood for 7000 series 'scopes?
Hi Sean,
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I stand corrected. Tek did make a simple viewing hood . The 016-0260-00 was a simple 3 sided folding viewing hood for the 577, 5000 series, and the 7000 series. I'm looking at a picture of one on page 196 of the 1975 catalog. Like the other viewing hood it is listed in the Accessories section of the Tek catalogs under Viewing Accessories (oddly enough). Viewing Accessories and Viewing Hood are both listed in the catalog's index so it should be easy to find in every catalog up until 1990. There are several variations to fit other scopes. Dennis Tillman W7PF -----Original Message----- -- -- Dennis Tillman W7PF TekScopes Moderator |
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Re: Pacific Measurements or Wavetek 1038 System
Great timing Walter.
I replied to Hans off list and even mentioned you had commented regarding the switches. I was wondering also if Gigatronics had inherited Wavetek since I read somewhere else regarding I think with the signal generators in a thread. I was also wondering if some of the line went to Wandel & Goltermann and then to Fluke per this EEVblog comment ( (1970-1990-era)-shenanigans/msg1264368/#msg1264368 ) that clearly shows a Tektronix mainframe with the 1038 system: "Meet the Pacific Measurements (later gobbled up by Wavetek, later gobbled up by Wandel & Goltermann, later gobbled up by Fluke) 1038 system, in this case configured as a dual port network analyzer." Especially the background history and connection to other manufacturers systems and Tektronix. Seems fitting timing to expose also especially with the recent passing of Rex Garrod more well known from the "Secret Life of Machines" TV series. Looking forward to more information regarding the 5114-D14? or any other "connections." Thanks in advance! |
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Re: CRT Hood for 7000 series 'scopes?
Richard Solomon
I use a piece of cardboard, rolled up to fit.
73, Dick, W1KSZ On Tue, Apr 23, 2019, 10:22 AM Dennis Tillman W7PF <dennis@...> wrote: Hi Colin, |
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Re: CRT Hood for 7000 series 'scopes?
Hi Colin,
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They aren't rare. They used to show up on Ebay all the time. They are listed in the Tek catalogs in the Accessory section. Dennis Tillman W7PF -----Original Message----- -- Dennis Tillman W7PF TekScopes Moderator |
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Re: CRT Hood for 7000 series 'scopes?
Hi Sean,
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I did send Gary Bosworth the two viewing hoods I had that are mentioned in the email link you are referring to. I do not recall ever seeing a simple shade for the 7000 series scopes. I made my own shade a long time ago out of stiff cardboard. It was primitive but it did the job. The "Batman" adjective you used seems appropriate for the shape of the viewing hood that Tek came up with. It relies on a human putting his face right on it to block out the light. It is possible with this hood to really block out all of the room light and improve your ability to see fast single shot pulses. The other viewing hood I recall is a more "conventional" rectangular 8 by 10 shape with a piece of Polaroid anti-glare filter inside it. Ideally Tek should have used circularly polaroid film for the filter to improve the contrast but I do not know if they did. As far as I know Tek never made a viewing hood based on this design for the 7000 series. Dennis Tillman W7PF -----Original Message----- -- Dennis Tillman W7PF TekScopes Moderator |
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Re: CRT Hood for 7000 series 'scopes?
Craig Sawyers
I was thinking more along the lines of the hood shownThat is probably the 016-0053-00 round hood for 5" round CRT scopes. Does something similar exist for 7000 series mainframes?There is a three sided folding one 016-0260-00, and a full light shield that you put your face against 016-0154-00 But you can look all this stuff up yourself by downloading the complete set of Tek catalogues. Craig |
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Re: Tek485 - a quick question on disabling/bypassing power supply protection
Not that specific component failures on mine will address your issue, but about 17 years ago I replaced these shorted components. (Not all in the same incident)
CR1534 killed beam C581 - 22uF killed 9v subsystem C2011 - 15uF killed everything as I remember. There are myriad little isolated power subsystems in this scope and they all have to work. I would check every single CAP node impedance on pages 14, 15 & 17 with caps larger than 0.5uF as a starting point. Many are isolated with inductors, so DC and AC measurements are in order. If your inverter won¡¯t start or continue after starting, it¡¯s a high probability there is a shorted CAP or diode. Good luck and keep us posted. KJO |
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Re: CRT Hood for 7000 series 'scopes?
Yeah, that's the one shown in the old thread. I was thinking more along the lines of the hood shown on Mr. Carlson's 565 in this video:
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Does something similar exist for 7000 series mainframes? Sean On Tue, Apr 23, 2019 at 01:39 AM, Colin Herbert wrote:
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Re: Pacific Measurements or Wavetek 1038 System
walter shawlee
1038-N10 Switches
The switches on the N10 are a huge problem because the footprint and shaft do not match anything else. I was able to buy one box of replacement switches from Gigatronics (they inherited the line from Wavetek) several years ago, but I do not know if any spares still remain there.? only a contact to the service department will reveal that. I do have a bunch of the black buttons left from the switches if any use to anyone to try and make a replacement, and one switch to serve as a model. I think the only fix is to make a tiny adaptor board to fit a more common tact switch to the wide 2 pin format, and try and find a switch shaft that can mate to the X-cross-section inside the buttons. It's possible that glue is the only answer to button attachment, which makes the whole process much clumsier to carry out. best regards, walter -- Walter Shawlee 2 Sphere Research Corp. 3394 Sunnyside Rd. West Kelowna, BC, V1Z 2V4 CANADA Phone: +1 (250-769-1834 -:- +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) |
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Re: Tek485 - a quick question on disabling/bypassing power supply protection
Thanks for the several cautions and suggestions. I did look for shorted caps as I had several tantalums go previously - but I replaced them all a couple of years ago and it had been running fine. Didn't find any obvious problems. Also pulled all the permissible combs one by one and scoped all the rails - only the -5V showed a short and it was still present after I disconnected all the peripheral -5V connections (there aren't many IIRC). I ran out of time after finding the non-inverting input on U1624 was going haywire (spiking from ca +4v to -1.2V) at exactly the same time the -5V rail showed a short - this with U3 in/HV operating. Replacing U1624 made no difference. I have a screenshot of that trace but can't work out at present how to attach a photo to this reply. I think the next step will be to check rail resistances to ground - not sure now whether I did this step thoroughly as I followed the service manual. Though I did do extensive component checking after replacing U1624 without turning up any obvious answer. Thanks again for the advice. Will report back when I get to it again.
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Re: Again a 7854 power supply beast to be repaired...
Hi Max, I checked that P83 can be left disconnected, like in many previous versions of power supplies. At the LV board there are resistors R76, R96 and R132 for this between the sense lines and the voltage output lines. Are you using a variac? I have seen strange things when I cranked up the variac untile the spms starts. Later on I applied normal line voltage immediately. Albert |
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Re: Tek485 - a quick question on disabling/bypassing power supply protection
Had similar problems years ago and the problem was those little tants going short. Rather hazy on the details now, but I remember how infuriating those power supply interlocking systems were. With supplies disconnected and unplugged and unpowered, be sure there are no shorts or low resistance paths to ground from all of the rails. (Beating the obvious though).
I vaguely remember once replacing a TO92 bjt somewhere causing power supply problems. I¡¯ll dig out my service manual to see if I made a note. I don¡¯t know how Tek did service, but even with the manual, I don¡¯t recall a means to bypass supply sequencing. KJO |
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Re: CRT Hood for 7000 series 'scopes?
Craig Sawyers
I have one of these. I got it off eBay and it seems no-one else was interested, as I got it for theListed in the 1970 catalogue (and probably others). USD 7.00 Apparently not only fits the 7000 series but also the 601, 602 and 528 Craig |
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Re: Tek485 - a quick question on disabling/bypassing power supply protection
Hi Lorenzo,
don't disable the protection, it could damage your supply. Maybe you should disconnect the -5V regulator from its load and use a lab power-supply to provide the -5V to the loaad. Set the current limit on your supply to 1 - 2A. Something will get hot... -- Best regards, Fred S. |
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Re: Tek485 - a quick question on disabling/bypassing power supply protection
If you really have a short circuit from -5V to ground (eg a failed tantalum capacitor) you don't need to power up the scope, it should be obvious with a resistance measurement. Schematic <17> shows the power distribution between boards and you can isolate boards by pulling the multi-way 'combs' that are used for interconnection.
To be sure that your diagnosis of a -5V fault is correct, and assuming that you have another double beam scope available you can look at the low voltage power rails in pairs as the power comes on and check that each is heading for its intended value before the protection cuts in. Roger |
GeorgeP
Ancel
Fred S.
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