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WTD: 7704A Power Supply
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Lynn Lewis
I'm going to be doing some 7704A power supply troubleshooting this evening
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myself. If you'll tell me everything you know about your problem, I'll keep it in mind while I'm working (or while its fresh on my mind, anyway). Maybe we'll get lucky. -----Original Message-----
From: w1ksz [mailto:w1ksz@...] Sent: Wednesday, January 16, 2002 5:23 PM To: TekScopes@... Subject: [TekScopes] WTD: 7704A Power Supply I have a very clean 7704A with a sick Power Supply. Anyone have one they will part with ? Thanks, Dick, W1KSZ Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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My 2 cents:
Sounds like you're so close now to having it fixed, I would think you'd want to take the last steps. You've narrowed it down to cracked or missing backplane connector shells. This is definitely why slot one is dead, and my guess is you also have one shell fractured in slot 3. My recollection is that these contact tensioning covers are nylon, snap fit into place, and become yellow and brittle over time. I would try to get replacements from anyone currently selling Tek parts: Sphere Research, Surplus Sales, Deane Kidd, plus the couple guys who keep showing up on ebay with new Tek parts. I can't recollect the names off hand--one is local here in Aloha OR I think and the other is in Canada. When the latter puts parts up on ebay, he puts up a couple dozen at a time so you can't miss him. I find them with my daily search for "Tektronix new". Only if that didn't pan out, would I scrap the mainframe (unless there is more wrong than I know). I remember I had a 7704A while at Tek many moons ago and the readout shimmied a bit on that also (and it was near new at the time). I wonder if that isn't a normal trait. I also remember having to replace those nylon shells a few times back then. Good luck either way, Don |
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Lynn Lewis
Okay, guys. Here's the deal. I have the 7704A working but I need some
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advice. Slot 1 is unusable and slot 3 is unreliable. All the switches and controls have been cleaned and work smoothly. All the panel lights work. Go here to see the scope: Is there a way to repair the slots? I can either try to repair them or else I can break the scope down into parts and sell the parts. Dick already wants a power supply. Does anyone else need any boards? Except for the slots, you can see that the scope works. The readouts have a slight ripple so there's probably a weak filter cap somewhere but it's not bad and it doesn't show up on the trace. I would be happier with a more focused trace but it's not as bad as it appears in the photos. Fix it? Or, break it down? What do you think? -----Original Message-----
From: w1ksz [mailto:w1ksz@...] Sent: Wednesday, January 16, 2002 5:23 PM To: TekScopes@... Subject: [TekScopes] WTD: 7704A Power Supply I have a very clean 7704A with a sick Power Supply. Anyone have one they will part with ? Thanks, Dick, W1KSZ Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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"....It is a long time since I used a 4-bay Tek scope, but I recall that the
readout vibrated up and down a little too (it was either a 7704 or a 7904 - I forget which now)...." Craig --------------- It seems the on screen readout, while a brilliant feature, is never quite perfect. For instance, the character focus and/or astig never seems to be quite sharp, and it varies depending on screen location in some models. Part of the wonderful character of the scopes I suppose. Don |
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Craig Sawyers
I remember I had a 7704A while at Tek many moons ago and theFunny you should mention that. It is a long time since I used a 4-bay Tek scope, but I recall that the readout vibrated up and down a little too (it was either a 7704 or a 7904 - I forget which now). I think that was what surprised me with the 7603 I recently bought - the readout is rock solid. Craig |
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Lynn Lewis
Don, that sounds like some very good advice. I'll look for replacements for
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awhile before I disassemble it. By the way, guys, I'm going to sell it either way, whole or in parts, so if someone has the slot covers and needs a scope to use them on, give me a ring. -----Original Message-----
From: donlcramer@... [mailto:donlcramer@...] Sent: Friday, January 18, 2002 1:43 AM To: TekScopes@... Subject: Re: [TekScopes] WTD: 7704A Power Supply My 2 cents: Sounds like you're so close now to having it fixed, I would think you'd want to take the last steps. You've narrowed it down to cracked or missing backplane connector shells. This is definitely why slot one is dead, and my guess is you also have one shell fractured in slot 3. My recollection is that these contact tensioning covers are nylon, snap fit into place, and become yellow and brittle over time. I would try to get replacements from anyone currently selling Tek parts: Sphere Research, Surplus Sales, Deane Kidd, plus the couple guys who keep showing up on ebay with new Tek parts. I can't recollect the names off hand--one is local here in Aloha OR I think and the other is in Canada. When the latter puts parts up on ebay, he puts up a couple dozen at a time so you can't miss him. I find them with my daily search for "Tektronix new". Only if that didn't pan out, would I scrap the mainframe (unless there is more wrong than I know). I remember I had a 7704A while at Tek many moons ago and the readout shimmied a bit on that also (and it was near new at the time). I wonder if that isn't a normal trait. I also remember having to replace those nylon shells a few times back then. Good luck either way, Don Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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Don Black
Hi,
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I recently bought a 7504A mainframe with a note saying that it's electrically perfect but has some loose contacts on the contact strips for the plugin modules. I haven't had time to do anything more than plug it in and see that it does have a trace (the only plugin I have is a 7A12 I already had that seems to work on one channel. I'll have to find some vertical and sweep plugins for it. Does anyone have a schematic for a 7A12 they could scan and email to me please). I do have the mainframe manual. I haven't looked inside but the connector problem sounds like the 7704A's. does mine use the same type of connector and is it just a typical edge connector or a "special"? Thanks, Don Black. donlcramer@... wrote: My 2 cents: |
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As far as I know (which doesn't go very far), all the 7K scopes used the same
connector system. I've never seen one with a conventional PCB connector for instance. A trait I like about the 7K backplane connectors is they allow easy/smooth plugin insertion and withdrawal. An obvious thing to try first is one of the DeOxit products. This has been mentioned before and I must say I've had great luck with the stuff, usually on the cheap (tin) platings. Maybe this is less helpful with the gold/gold plate that Tek used on the 7K contacts. Don |
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Craig Sawyers
An obvious thing to try first is one of the DeOxit products.Caig also make a product called Pro-Gold that is specifically formulated for gold plated contacts. Craig |
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jcastanton
Lynn,
I have a 7704A in good shape except that it has a weak tube. If you decide to part out your 7704A and it has a good tube, I would be interested. --- In TekScopes@y..., "Lynn Lewis" <mrzuzu@j...> wrote: Okay, guys. Here's the deal. I have the 7704A working but I needsome advice. Slot 1 is unusable and slot 3 is unreliable. All theswitches and controls have been cleaned and work smoothly. All the panel lightswork. Go here to see the scope:or else I can break the scope down into parts and sell the parts. Dickalready wants a power supply. Does anyone else need any boards? Except for theslots, you can see that the scope works. The readouts have a slight ripple sothere's probably a weak filter cap somewhere but it's not bad and itdoesn't show up on the trace. I would be happier with a more focused trace but it'snot as bad asone they will part with ?Service. |
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Stan or Patricia Griffiths
This is also partly due to poor focus in 7K CRT's in general since they use the
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mesh screen technology . . . The typical "spot size" of a 7K CRT is several times larger than that of a 453, 547, or 585A for example. Stan w7ni@... donlcramer@... wrote: "....It is a long time since I used a 4-bay Tek scope, but I recall that the |
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Lynn Lewis
I'll keep you in mind. It may yet come to that.
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-----Original Message-----
From: jcastanton [mailto:jstanton@...] Sent: Saturday, January 19, 2002 3:04 PM To: TekScopes@... Subject: [TekScopes] Re: WTD: 7704A Power Supply Lynn, I have a 7704A in good shape except that it has a weak tube. If you decide to part out your 7704A and it has a good tube, I would be interested. --- In TekScopes@y..., "Lynn Lewis" <mrzuzu@j...> wrote: > Okay, guys. Here's the deal. I have the 7704A working but I need some > advice. Slot 1 is unusable and slot 3 is unreliable. All the switches and > controls have been cleaned and work smoothly. All the panel lights work. > Go here to see the scope: > > > Is there a way to repair the slots? I can either try to repair them or else > I can break the scope down into parts and sell the parts. Dick already wants > a power supply. Does anyone else need any boards? Except for the slots, you > can see that the scope works. The readouts have a slight ripple so there's > probably a weak filter cap somewhere but it's not bad and it doesn't show up > on the trace. I would be happier with a more focused trace but it's not as > bad as > it appears in the photos. > > Fix it? Or, break it down? What do you think? > > > > > > > > -----Original Message----- > From: w1ksz [mailto:w1ksz@t...] > Sent: Wednesday, January 16, 2002 5:23 PM > To: TekScopes@y... > Subject: [TekScopes] WTD: 7704A Power Supply > > > I have a very clean 7704A with a sick Power Supply. Anyone have one > they will part with ? > > Thanks, Dick, W1KSZ > > > Yahoo! Groups Sponsor > ADVERTISEMENT > > > > > To unsubscribe from this group, send an email to: > TekScopes-unsubscribe@y... > > > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. > > > > Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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Lynn Lewis
I'm glad you said that before I started trying to "fix" the focus on my
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7704A. I really was thinking about it. I did, by the way, find a backplane that is being shipped to me so that I can attempt to repair the plugin connectors. -----Original Message-----
From: Stan or Patricia Griffiths [mailto:w7ni@...] Sent: Saturday, January 19, 2002 5:36 PM To: TekScopes@... Subject: Re: [TekScopes] WTD: 7704A Power Supply This is also partly due to poor focus in 7K CRT's in general since they use the mesh screen technology . . . The typical "spot size" of a 7K CRT is several times larger than that of a 453, 547, or 585A for example. Stan w7ni@... donlcramer@... wrote: > "....It is a long time since I used a 4-bay Tek scope, but I recall that the > readout vibrated up and down a little too (it was either a 7704 or a 7904 - I > forget which now)...." > > Craig > --------------- > It seems the on screen readout, while a brilliant feature, is never quite > perfect. For instance, the character focus and/or astig never seems to be > quite sharp, and it varies depending on screen location in some models. Part > of the wonderful character of the scopes I suppose. > > Don > > > > > To unsubscribe from this group, send an email to: > TekScopes-unsubscribe@... > > > > Your use of Yahoo! Groups is subject to Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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Hello Lyn,
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A couple of years ago I bought a 7904 and it turned out that one of those slot connector bodies was completely missing. Fortunately, all (needed) pins were undamaged so I could slide the plug in; of course, the slot did not work. I bought replacement connector body from Tektronix and price was not unreasonable as one would expect, if I remember it correctly, the price was around $5 per piece. The body just slides over pins (a care not to bend pins is very helpful). With new body, pins got proper tension and the same slot worked. You might want to try Tek spare parts. Bear in mind that not all people working there are the same, some of those ladies were going way out of their way to help out, while some others told me very curtly that instrument is no longer supported; in both cases the query was for 7904 parts. What I meant with 'going way out way.' was using listings that were either off line or just plane hard copy listings. I wander if Walter (of Sphere) would be willing to trash a scope backplane to extract connector bodies. That backplane would have to be burned up badly or cracked to make it a viable business. If I remember it right, body slides on easily but that is one way process, removing the body would damage pins. ----- Original Message -----
From: "Lynn Lewis" <mrzuzu@...> To: <TekScopes@...> Sent: Friday, January 18, 2002 4:12 AM Subject: RE: [TekScopes] WTD: 7704A Power Supply Don, that sounds like some very good advice. I'll look for replacementsfor awhile before I disassemble it. By the way, guys, I'm going to sell ita scope to use them on, give me a ring.and myis that these contact tensioning covers are nylon, snap fit into place, andfrom anyone currently selling Tek parts: Sphere Research, Surplus Sales,Deane Kidd, plus the couple guys who keep showing up on ebay with new Tekparts. Ithink andup a |
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