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Re: 575 restoration
On Fri, 29 Jun 2018 at 13:38 Pete Lancashire <xyzzypdx@...> wrote:
How about some picturesmentioned. John - Groups.IO doesn't have any sane searching of photo albums, so best to link the album in your messages. |
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Re: If you had $1, 000 to buy a 100 MHz scope...
I have a couple TDS754s. An 'A' and a 'D' - while I agree that the 'A' is a little slow to respond at times when doing more processor heavy work, the 'D' is very snappy and responsive.? I find little fault with it except the lack of a few newer conveniences,? like there's no "roll" mode; one must basically wait for the scope to complete a full triggering sequence to get any data on a long timebase setting. And of course the "extended" memory option (8M) is more like the basic one that's offered these days. I used to find the menu structure somewhat less than intuitive but I've grown accustomed to it nowadays and don't have trouble finding anything anymore. Personally I love the display,? it's much more vivid than an LCD to my eyes.
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Looking at modern offerings that are affordable, I might pick a Siglent 1204.? --Eric Sent from my Samsung Galaxy smartphone. -------- Original message --------From: stefan_trethan <stefan_trethan@...> Date: 6/29/18 12:37 PM (GMT-06:00) To: [email protected] Subject: Re: [TekScopes] If you had $1, 000 to buy a 100 MHz scope...
I have a TDS544 at home, which is somewhat similar to the newer TDS784D, and I really dislike the display, menu structure, and general lack of responsiveness. To me this is the point where Tek went wrong, and I have not liked any Tek scope from this point on. Often I prefer to fire up the 7d20 digitizer in a 7k mainframe, when I know it's only slow signals and I don't need 4 channels. The later TDS3000 series was extremely popular, but I just straight out hate the darn things. From that vintage on I really much prefer Lecroy, even a LC series, with LCD screen if you can get it instead od the CRT, yes, I would much prefer that over the Tek ones. I used to have a Lecroy DDA125 as my main work scope until a year or two ago, and it is _A LOT_ of scope which you may now get in the $1000 range (The DDA is the same as a LC684 only with special HDD options added). Not as repairable as old Tek (but so is new Tek). Now I have a HRO64Zi at work which I got a really good deal on when they discontinued the series, but still well outside your $1k budget. That is a fine scope, but _even less_ responsive than the TDS544 or DDA125. It needs to think and calibrate itself _all the f-ing time_. But you can so so much with it, it somewhat compensates for the lack of responsiveness. And the 12 Bit, I wouldn't want to miss that. It is not the best scope for random debug or fault finding, but for analysis when you need to get numbers out, document or compare stuff, it's great. Anyway, that's well out of price range, all I'm saying is I do miss using the old DDA125 some days. So for me the decision for a used scope in the 1k range would be easy, the DDA125 or something very similar any day. But is it really better than a modern low end scope, like a Rigol? Hard to tell. There is something those old "lab grade" scopes have that you just don't get in a low end scope. We have a Keysight 3000x at work that I use some times, and it always infuriates me when you are limited by stupid things such as not enough reference channels, or not enough math, or... Also, on that Keysight you can't switch off analog persistence (just like a Tek TDS3000) and I dislike that. Of course a new scope will have convenient modern features you just won't find on one made around the year 2000. And it will be lightweight, easy to carry around, likely work reliably without needing repair. It is the same as with a car, do you prefer a used quality car, or a cheap and cheerful new car? I don't mind old, but I do like quality. What I can say is that the new very lowest end Tek/Keysight/Lecroy are _not_ worth the money in my mind. You still pay extra for the brand, but you get nothing above and beyond say a Rigol, less actually. They try to capture that market by either re-labeling imported crappy scopes, or building their own crappy scopes to the cheapest price, but they can never beat a lesser brand with their high overheads. So the choice for me would be between a Rigol 1000Z, or something, and a DDS125, or something like it. If you can still do that thing where you buy the low end Rigol and they let you upgrade it to a higher end model, I'd be hard pressed to make a choice. Luckily, I don't have to. ST On Fri, Jun 29, 2018 at 6:45 PM, Pete Lancashire <xyzzypdx@...> wrote: I'm trying to break the habit of buying old scopes. I'm looking for |
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Re: Tek 465 no display
That's a LOT of progress Russ!
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With some more experience you might have thought already of a shorted C1549 after posts by Harvey and Fabio IIRC. One was that as good as zero output is a significant observation. The other that most tantalum caps have a series resistor so just one failing will not fully pull down the rail to zero. C1549 might be the only one *without* series resistor (I didn't check that). That -6.4 V at the -8V rail could be due to a heavy load but more likely I think a bad big cap C1562. I would start there. Note that both sides of C1562 might show ripple w.r.t. ground when -8V is out of regulation. Try to measure the difference, so the ripple (and DC) across C1562. If OK then proceed with testing for current limiter activity as explained already in some posts. Albert On Fri, Jun 29, 2018 at 10:57 am, musicamex wrote:
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Re: If you had $1, 000 to buy a 100 MHz scope...
On Fri, 29 Jun 2018 at 12:45 Pete Lancashire <xyzzypdx@...> wrote:
I'm trying to break the habit of buying old scopes. I'm looking forMy TDS784D is only turned on when I need the bandwidth or one of its features, I'll usually reach for the 2467 or the HP54622D - in that order of preference. If Rigol is under consideration, you may want to also look at the Siglents. For $1k you can get the 4 channel SDS1104X-E < > model with the 16 channel logic probe & analyzer. Alternatively you could go for the 200MHz model inside $1k. I believe Siglent throws in all manner of serial decoders, which is a nice bonus. Disclaimer: I've never used a Siglent scope, and I've not read the one thorough looking review I found < >. |
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Re: Tek 465 no display
i have the papier version for en After 25000?? ,but it conversation before mod¨¨les ,to repair power rails you need to switch through all the Book ,but ¨¤ good start is how PS operates ,then go to schematics, if you want i will make photos , John
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Envoy¨¦ depuis mon Redmi 4X Le Albert Otten <aodiversen@...>, 29 juin 2018 8:04 PM a ¨¦crit :
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Re: Tek 465 no display
On Fri, Jun 29, 2018 at 07:35 am, musicamex wrote:
Hi Russ, you mean board A9? I can send you 2 jpg's at 1200 dpi of about 6.5 MB each. Enlargeable until you have the screen almost filled with one component number. When you reply via Private I have your e-mail address and can send it as attachment. BTW the original is rather vague also. There are several "partial" board layouts in the manual at which components involved in the next schematic(s) are shown in bold while other components are vague. Bad luck that Tek didn't do so for the Power schematic. Albert |
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Re: Tek 465 no display
One step closer! C1549 looked like it might have been replaced with a mylar cap. As soon as I unsoldered one side and turned on the scope, the fan came on! So i replaced it with a 47mf 25 v electrolytic and now had a bit of a trace but way off vertical axis. Good call Albert!
The voltages now are112.5, 55.66, 15.1, 4.9 and -6.4 I see that the vertical axis is associated with the -8 rail and read the troubleshooting for vertical axis anomalies but before I go further I thought I check for advice here first. Thanks in advance, Russ |
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Re: 575 restoration
Hi John,
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Lack of shielding, maybe (RFI from HV circuit)? I think the '575 doesn't have a shield lid in the HV area, but you can try again with the bottom lid in its place. Regards, Sebastian. PS: Pete, please note that John provided pictures in the Photo files area. Pete Lancashire 10:38am #149306 How about some pictures . . . On Fri, Jun 29, 2018, 10:35 AM John <John@...> wrote:
My 575 mod 122C arrived at the weekend. It did basically work when brought up gently on a variac. I've been through most of the valves and replaced a few which were well down on emmision, including the 6AQ5 /V810. Similarly, most of the paper caps have been replaced with polyester 600V. I've just been through the cal. procedure and everything seems fine, but there is now a slight dot-pattern on the trace which I don't recall noticing when it had the "old" caps and "old" valves in place. As there doesn't appear to be any Z-mod capability, I'm wondering what might cause this? Or is it normal? I've checked the -1700V with a P6015 probe, and it looks clean. There's small amount of ripple on the +2300V anode, but only c 20V p-p. Photo album uploaded under "575 dot-pattern trace" John |
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Re: 575 restoration
How about some pictures
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On Fri, Jun 29, 2018, 10:35 AM John <John@...> wrote:
My 575 mod 122C arrived at the weekend. It did basically work when |
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Re: If you had $1, 000 to buy a 100 MHz scope...
stefan_trethan
I have a TDS544 at home, which is somewhat similar to the newer
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TDS784D, and I really dislike the display, menu structure, and general lack of responsiveness. To me this is the point where Tek went wrong, and I have not liked any Tek scope from this point on. Often I prefer to fire up the 7d20 digitizer in a 7k mainframe, when I know it's only slow signals and I don't need 4 channels. The later TDS3000 series was extremely popular, but I just straight out hate the darn things. From that vintage on I really much prefer Lecroy, even a LC series, with LCD screen if you can get it instead od the CRT, yes, I would much prefer that over the Tek ones. I used to have a Lecroy DDA125 as my main work scope until a year or two ago, and it is _A LOT_ of scope which you may now get in the $1000 range (The DDA is the same as a LC684 only with special HDD options added). Not as repairable as old Tek (but so is new Tek). Now I have a HRO64Zi at work which I got a really good deal on when they discontinued the series, but still well outside your $1k budget. That is a fine scope, but _even less_ responsive than the TDS544 or DDA125. It needs to think and calibrate itself _all the f-ing time_. But you can so so much with it, it somewhat compensates for the lack of responsiveness. And the 12 Bit, I wouldn't want to miss that. It is not the best scope for random debug or fault finding, but for analysis when you need to get numbers out, document or compare stuff, it's great. Anyway, that's well out of price range, all I'm saying is I do miss using the old DDA125 some days. So for me the decision for a used scope in the 1k range would be easy, the DDA125 or something very similar any day. But is it really better than a modern low end scope, like a Rigol? Hard to tell. There is something those old "lab grade" scopes have that you just don't get in a low end scope. We have a Keysight 3000x at work that I use some times, and it always infuriates me when you are limited by stupid things such as not enough reference channels, or not enough math, or... Also, on that Keysight you can't switch off analog persistence (just like a Tek TDS3000) and I dislike that. Of course a new scope will have convenient modern features you just won't find on one made around the year 2000. And it will be lightweight, easy to carry around, likely work reliably without needing repair. It is the same as with a car, do you prefer a used quality car, or a cheap and cheerful new car? I don't mind old, but I do like quality. What I can say is that the new very lowest end Tek/Keysight/Lecroy are _not_ worth the money in my mind. You still pay extra for the brand, but you get nothing above and beyond say a Rigol, less actually. They try to capture that market by either re-labeling imported crappy scopes, or building their own crappy scopes to the cheapest price, but they can never beat a lesser brand with their high overheads. So the choice for me would be between a Rigol 1000Z, or something, and a DDS125, or something like it. If you can still do that thing where you buy the low end Rigol and they let you upgrade it to a higher end model, I'd be hard pressed to make a choice. Luckily, I don't have to. ST On Fri, Jun 29, 2018 at 6:45 PM, Pete Lancashire <xyzzypdx@...> wrote:
I'm trying to break the habit of buying old scopes. I'm looking for |
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575 restoration
My 575 mod 122C arrived at the weekend. It did basically work when brought up gently on a variac. I've been through most of the valves and replaced a few which were well down on emmision, including the 6AQ5 /V810.
Similarly, most of the paper caps have been replaced with polyester 600V. I've just been through the cal. procedure and everything seems fine, but there is now a slight dot-pattern on the trace which I don't recall noticing when it had the "old" caps and "old" valves in place. As there doesn't appear to be any Z-mod capability, I'm wondering what might cause this? Or is it normal? I've checked the -1700V with a P6015 probe, and it looks clean. There's small amount of ripple on the +2300V anode, but only c 20V p-p. Photo album uploaded under "575 dot-pattern trace" John |
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If you had $1, 000 to buy a 100 MHz scope...
I'm trying to break the habit of buying old scopes. I'm looking for
suggestions 100 megahertz or better, 4 channels, supports a mode where multiple pulses are shown over and over again and shows Distortion errors. I would say that's the one unique thing. So what would members of this is esteamed group suggest. And older tek scope that is higher, TDS784D for example or a new Tek / keysight / Regal |
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Re: Kludging together a TDR or similar?
It's one of those things you may only use once every two years but damn
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does it make it easy. I have a 1503 as well as a 1502 and I had to find where in my attic the Romex was tapped into. I was able to locate the junction box which was hidden two within less then one foot. That paid for it many times over. The other one were at paid for itself was a broken wire restoring a r390a HF receiver I was able to locate the brake in a wire in the middle of a wiring harness to within an inch. On Fri, Jun 29, 2018, 9:13 AM Richard Solomon <dickw1ksz@...> wrote:
I picked up a working 1502 a few years |
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Re: Kludging together a TDR or similar?
Richard Solomon
I picked up a working 1502 a few years
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ago on that auction site. The batteries were shot, but I found a paper on using a resistor and a big cap to fool it into thinking it had batteries. I think I have used if less than 5 times over the years, but for the price it was a nice addition to the test equipment pile. It didn't hurt that I had an original manual for it. 73, Dick, W1KSZ On Fri, Jun 29, 2018 at 4:11 AM, Tom Gardner <tggzzz@...> wrote:
I really like 1502 (not a, b, 1503 etc), and have some I ought to sell. |
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Re: Tek 465 no display
On Thu, 28 Jun 2018 19:57:26 -0700, you wrote:
I'm so sorry that I havent kept up with all of the help here, Albert. I wasn't expecting such a willingly helpful group when i joined the group. This has been an exceptionally busy June for me. I'm recovering from recent heart surgery and seem to be falling behind on my lab repair work among other things. But i did get a bit of time [about 30 min] to follow up on some of the suggestions here. The access board layout diagram is pretty hard to read and not all that much is labeled on the actual board so it is going slower for someone used to point to point and turret board electronics. I have almost zip experience with transistors or pcb layout. But I'm determined to get this figured out.You might, for the sake of general learning, get some breadboard kits, general purpose transistors, and start breadboarding some transistor amplifiers and switches. It would give you a feel for the parts. For PCB layout, consider that you are doing the same as wiring a breadboard (the type with millions of holes). The rules, though, is that the traces cannot cross each other on the same side (otherwise they're the same trace). They must go from layer to layer through a plated through hole called a via. On dual layer boards, you have simply a top and bottom, and the vias go all the way through. On 4 layer boards, there's a top, bottom, and two inner layers. Frequently, some of the layers are reserved for power and ground. So PC boards are not all that bad. You might want to look at linear supplies and how they work. The principles between a linear regulator for tubes and transistors are identical, but the different parts will give you different voltages on the transistors (vs the tubes). Depletion mode N channel FETS are most like tubes, once you get to that point. (triodes, thank you). As in any such project, suspect the power first, then look at functional blocks. I've had 468's with high voltage resistor network problems, which will throw off the high voltage. There's a high voltage divider network that's part of the feedback from the high voltage output back to the regulator. Harvey
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Re: TDS 380 won't trigger
On Fri, 29 Jun 2018 at 00:19 Gary Appel <garyappel@...> wrote:
It's alive!Excellent - congrats on the fix. |
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Re: Dead 7603
On 06/28/2018 09:07 PM, garp66 wrote:
hi all,Which "above written description" are you talking about?? Unless you quote from the email you are replying to, we have no idea what you are talking about.? Notice how I quoted your email reply?? Now folks know who and what I'm replying to, and have the context of the conversation. Top or bottom replying is a religious discussion for another day. Mark |
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Re: Kludging together a TDR or similar?
I really like 1502 (not a, b, 1503 etc), and have some I ought to sell.
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There are two principal weaknesses other than the usual PSU caps: * the tunnel diode is relatively fragile, and can be destroyed by a DC voltage on the cable or even a static charge in the cable - hence the special shorting BNC connector. Having aid that, all 5 that I have seen are intact * the battery pack must be present before it will switch on: the PSU detects missing and uncharged batteries. All 5 that I have seen have had faulty batteries. There are ways of faking a battery, or they can be replaced by new sub-C NiCds or NiMH. With NiMH be very careful with "Chinese capacity specifications" and the trickle charging current. On 29/06/18 04:09, Pete Lancashire wrote:
Yeah if you need the short distance performance the 1502 is the only way to |
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Re: Tek 465 no display
Sorry to hear about your health problems Russ. First things first of course.
There you got me! I remember I was typing with the laptop on my knees. I had to look skew at the manual and though I even checked twice I made this mistake. Success, Albert |
John Sykes
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