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Re: 21A and 22A for 555
Stan or Patricia Griffiths
Its going to be a couple of months before I get all the stuff here. I am
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depending on you to remind me of this need you have for the 21A and 22A. Did you say the early version would be OK or do you want only the later ones? Stan w7ni@... morriso2002@... wrote: --- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:I will keep my eyes open for some plugins for you. I just enlargedmycollection by an addtional 350 instruments (to a total of about1100) so Imight just have some by the time I get all that stuff transported tomy shop |
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follow up on jitter in RM31a
Hello
Thanks for the tips. I found a replacement cap from a 545A "hangar queen". Now the RM31a works great and no jitter. The cap in question was leaky, thus causing the ripple. Oh and the 475 motor is on it's way. I've been having email problems so I am slow to respond. Have a great day and may your fans run smoothly and your filters be clean. Windsor |
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Re: 21A and 22A for 555
--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:
I will keep my eyes open for some plugins for you. I just enlargedmy collection by an addtional 350 instruments (to a total of about1100) so I might just have some by the time I get all that stuff transported tomy shop Amazing!! Thanks you very much, I would be very grateful if you could find me a 21A/22A set. Morris |
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46X series front cover
Does anyone know where to get a decent front cover? I would like to
take one to some of the plastic molding firms and see what it would cost to make up maybe 100 or so. This part seems to be the first casualty when the scope was new and now they want an arm and a leg for them. Maybe some one has already done this and can set me straight if the cost is too high? Thanks, Mike |
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Re: Adventure in tracing down jitter
Hi Windsor
Your Email address no longer works. I hope you have sent the tek 475 fan. Let me know. Richard --- In TekScopes@y..., mongteen@e... wrote: Hello,Thanks Dean :) There is a slight horz. jitter about 2mm worth. So I checkthe right deflection pin and see jitter. So I go about measuring andvery low sweep speeds. I connect my 7704a to the right deflection pinset the coupling to AC and volia I found that the jitter is 120 Hertz.So I measured the 500 V supply and found ripple of about 1 volt PP. SoI added a small cap to help filter out the ripple and the jitter isto the trap of seeing that everything else worked OK and assumed the PS |
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Re: Adventure in tracing down jitter
--- In TekScopes@y..., Don Black <jeans@n...> wrote:
If it's got selenium rectifiers they may be getting weak, notsupplying enough voltage or the regulators to work. Replace them with silicondiodes with added series resistors to compensate for the higher efficiencyof the silicon diodes.Even the Selenium Rectifiers aro OK (at this time), REPLACE them! Often they fail suddenly with a short and not in any case the fuse(s) blown fast enough to prevent damage to the transformerwinding(s)!!! Seen those often enough... (not only in Scopes) Jorgen dj0ud |
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Re: Adventure in tracing down jitter
Stan or Patricia Griffiths
If you have identified the bad filter cap, I probably have a good salvaged
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replacement that you can have for a few bucks. Let me know. Stan w7ni@... mongteen@... wrote: Hello, |
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Re: 21A and 22A for 555
Stan or Patricia Griffiths
Mixing 21,22,21A, 22A. Let me say I don't know of any reason why you
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couldn't do it but I have never tried it . . . I will keep my eyes open for some plugins for you. I just enlarged my collection by an addtional 350 instruments (to a total of about 1100) so I might just have some by the time I get all that stuff transported to my shop . . . Stan w7ni@... morriso2002@... wrote: --- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:morriso2002@y... wrote:There was an extensive modification to the 21A and 22A tunnel diodetriggers |
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Re: 21A and 22A for 555
--- In TekScopes@y..., Stan or Patricia Griffiths <w7ni@e...> wrote:
morriso2002@y... wrote: There was an extensive modification to the 21A and 22A tunnel diodetriggers <snip> I would stay away fromthose unless they have had Mod Kit 040-0417-00 installed.Hi Stan, Thanks for the advice. The only 21A/22A I have ever seen, which belongs to a friend, has the later version triggers. These timebase plugins are not easy to find and I suspect "beggars will have to be choosers" if a pair ever turns up. Mind you, the 21/22 works very nicely indeed. Incidentally do you know if it is possible to mix a 21 and 22A or 21A and 22 in the one mainframe? Morris |
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Re: 21A and 22A for 555
Stan or Patricia Griffiths
morriso2002@... wrote:
Timebase plugins however are not so easy to find - in fact if anyoneHi Morris, There was an extensive modification to the 21A and 22A tunnel diode triggers at SN 11000. 21A and 22A timebases have the older tunnel diode trigger circuitry in them from SN 7000 to SN 10999. I would stay away from those unless they have had Mod Kit 040-0417-00 installed. The kit is very complex and includes a double sided circuit board and lots of hard to find parts so it would be almost impossible to try to put this kit together from scratch. The early TD triggers were very unstable and I can remember being very frustrated trying to get them adjusted so they would continue to operate reliably. They way to tell if the mod has been installed or not is too look in the timebase in question on the top of the chassis and just behind the front panel about an inch to see of the etched circuit board is installed there. The early 21A and 22A timebases had a couple of short rows of the small notch ceramic strips installed there with the early TD trigger circuits installed on them. Stan w7ni@... |
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Re: Adventure in tracing down jitter
Don Black
Hi Windsor,
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You seem to have found the source of the jitter however I think you're working around the fundamental problem with your small bypass capacitor. Check the regulated power supply, perhaps the main filter capacitors are weak, allowing too much ripple before the regulator or the regulator tubes could be weak and saturating, passing the ripple. If it's got selenium rectifiers they may be getting weak, not supplying enough voltage or the regulators to work. Replace them with silicon diodes with added series resistors to compensate for the higher efficiency of the silicon diodes. Your bypass capacitors might be a cheap way of working around the problem but be prepared for it to get worse and you'll have to look further. Don Black. PS check the mains voltage settings match the local supply, if it's set for a higher voltage than your local supply so the set's not getting enough supply voltage that could cause it to drop out of regulation. mongteen@... wrote: Hello, |
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Adventure in tracing down jitter
Hello,
I have a RM31a that has a 54x CRT that works reasonably well. Thanks Dean :) There is a slight horz. jitter about 2mm worth. So I check the left deflection pin and see that there was no jitter. I check the right deflection pin and see jitter. So I go about measuring and changing tubes associated with the right deflection pin. Then I sleep on it for a while. It occured to me to check for jitter at very low sweep speeds. I connect my 7704a to the right deflection pin set the coupling to AC and volia I found that the jitter is 120 Hertz. So I measured the 500 V supply and found ripple of about 1 volt PP. So I added a small cap to help filter out the ripple and the jitter is gone! The moral of the story is that alway check the PS first! I fell in to the trap of seeing that everything else worked OK and assumed the PS was OK. Windsor |
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8233/E55L
Greetings;
I am trying to understand the failure mode of one of these in a 3A6. Both cathode tabs are melted and the 47^ screen resistor is smoked. With great trepidation, I replaced the defective tube after checking the asssociated 6DJ8s, xistors, and diodes. The replacement held and the screen resistor stayed cool. However, there is a DC imbalance on both traces that the controls won't comp. I suspected possible filament-cathode leakage in the otherwise fresh looking dead tube. No way to check for that now. I definitely don't want to risk a presently good 8233/E55L. Any ideas on the probable failure mode? Thanx in advance; Steve P.S., Hi Stan, nice to find you again. Great Resource! |
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Re: Tektronix 500 Series Scope Plug-In
Phil (VA3UX)
At 01:11 AM 5/31/2001 +0000, morriso2002@... wrote:
--- In TekScopes@y..., "Phil (VA3UX)" <phil@v...> wrote:Finding a non-blank plug-in for a 555 is tough enough,The 555 will take quite a wide range of vertical plugins including the Sorry Morris. It was the 21A/22A timebase plug-ins I was referring to in my comment, rather than the vertical plug-ins. Timebase plugins however are not so easy to find - in fact if anyoneI *might* be coming into some of these shortly. If I do I'll let you know. Phil Morris |
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Re: Tektronix 500 Series Scope Plug-In
--- In TekScopes@y..., "Phil (VA3UX)" <phil@v...> wrote:
Finding a non-blank plug-in for a 555 is tough enough,The 555 will take quite a wide range of vertical plugins including the 53/54 series, the letter series and the 1- series. With some of them (such as the 1A4) you have to be careful that the timebase plugins have been appropriately modified to remove DC bias from one of the pins which could otherwise damage the plugin (I have details if anyone needs them). Timebase plugins however are not so easy to find - in fact if anyone has a spare 21A/22A combo for disposal I would be happy to give them a good home here in Melbourne Australia :-) Morris |
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Re: Tektronix 500 Series Scope Plug-In
Phil (VA3UX)
At 11:12 AM 5/30/2001 +1000, Andrew Campbell wrote:
Hi All,Finding a non-blank plug-in for a 555 is tough enough, let alone a blank one. I've never seen one Andrew but I'll keep my eyes open during flea market hunts. Stan G. and Deane Kidd are the only other potential sources I can think of at the moment. Phil Regards, |
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Support for Tektronix TDS Oscilloscopes
Andrew Campbell
Hi All,
Does anyone know of a company or business that may be able to supply boards for the Tektronix TDS model oscilloscope. They could be boards that have been pulled from non-repairable instruments. Tektronix has recently removed from their "Long Term Support Program" a variety of early model TDS oscilloscopes. In particular I am interested in obtaining TDS540 Acquisition Boards and TDS540 Processor Boards. I have recently tried Verizon (GTE) and they won't part with boards, they want me to send in the instrument for them to survey. Not a good option from Sydney, Australia. Best Regards, Andrew |
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Re: Tektronix 500 Series Scope Plug-In
--- In TekScopes@y..., "Andrew Campbell" <service@c...> wrote:
Could anyone tell me where I could find a "blank" vertical plug-inmodule for a Tek 555 series scope?I would be surprised if a kit is still around. When I wanted to build a custom plugin I butchered an old type 80. The dimensions are the same and the plug just has to be reversed. I'm sure there are plenty of junker plugins around at hamfests etc. morris |
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