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Re: Tek DM44
EB4APL
Jordan,
I have the service manual in pdf. It???s about 12 Mb. It is a hi quality scan that I downloaded some time ago, I don???t rememeber the source so I can???t give them the due credit, sorry. If your mailbox is able to cope with a 12 Mb file, I can send it directly to you. Regards, Ignacio ................................................................................................................................................... Jordan Kersten wrote: Anyone got a manual for a DM44? Owners and/or service. ~Jordan~ |
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Re: 067-0587-02 (was Calibrating a 7704A)
d.seiter@... escribi???:
Does anyone know if the -02 has an achillies heel of any kind, Mmmm... let me see... yes, the exoticc elastomeric switch! Well, it has also quite a lot of exotic hybrids :)like maybe the strange elastomeric switch? Regards, Javier -- ------------------------------------------------------------------------ Javier Herrero EMAIL: jherrero@... HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17A FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: |
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Re: 067-0587-02 (was Calibrating a 7704A)
Craig Sawyers
Does anyone know if the -02 has an achillies heel of anyOne of my two was DOA through this. Inside the switch ("do not open" says the manual. Ha!), the cunningly shaped elastomer had a tear in it, and was failing to operate two of the contacts. A bit of careful use of superglue later, and it has not missed a beat in four years. Craig |
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Re: 7603 filter caps
Craig Sawyers
TheDeane is quite right. Think about it this way - when the bridge diode turns on, the capacitor charges up through the secondary resistance of the power transformer and the reflected primary resistance, plus the series resistance of the bridge diode. For high voltages that is generally many tens of ohms. Even then, the effect of an ESR even equal to the charging resistance is pretty minimal - the charging time simply doubles. The effect on discharge when the diode is turned off and the capacitor is supplying current to the circuit is even less dependent on ESR, since the current is less than during the charging cycle (by roughly the charge/discharge duty cycle). The main significance of ESR, or an ESR that is rising as the years pass, is that the capacitor runs hotter - since the ESR is a real dissipative component. Look at a modern cap's spec sheet - say a good power electrolytic from RIFA - and you will see the main consideration for reducing ESR to the milliohm level in high value low voltage electrolytics is entirely to do with power dissipation and maximum operating temperature. The effect on ripple is mininmal. The main failure mode for Tek electrolytics, as we have discussed many times on the forum, is the Sprague twist-lock caps. The failure mode is that the internal negative tab connection corrodes through inside the can just where it goes into the can crimp - so the capacitance falls to zero, more or less instantly. Then you can see the ripple for sure! Craig |
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Re: 7603 filter caps
I wouldn't say that the ESR meter is "required", but it sure makes life easier! Plus, it's a cool kit to build (if you happen to go that route...;-))
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-Dave -------------- Original message ----------------------
From: "Stefan Trethan" <stefan_trethan@...> That may be so, but when repairing relatively modern equipment with many |
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067-0587-02 (was Calibrating a 7704A)
I decided to pull out my 067-0587-0x's and realized that I'd never tried the -02. Of course, I find it has problems, like the gain steps aren't there. I only have the manual for the -02, but I assume the basic operation is the same for both. Since the -02 can be used for "all 7000 mainframes", trying it in a 7704A shouldn't make any difference.
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Does anyone know if the -02 has an achillies heel of any kind, like maybe the strange elastomeric switch? Is the -01 manual out there anywhere? -Dave -------------- Original message ----------------------
From: "Craig Sawyers" <c.sawyers@...> I was just wondering if a Tek 067-0587-01 calibration fixture isThe key thing about the cal fixture is that it calibrates the mainframe |
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Re: 7603 filter caps
Stefan Trethan
That may be so, but when repairing relatively modern equipment with many
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many caps that need to have low ESR for the circuit to work (e.g. switching voltage converters) it is absolutely great to be able to test all caps in circuit in a matter of seconds. Sure, one could add a good cap in parallel and try the circuit, but that takes much longer. OTOH i have no need for it when designing new equipment (power supplies). But for industrial gear of say 5-10 years or more and consumer gear of 2 years of more the electrolytic cap has been the primary failure for me. I have repaired a OS254P-U (which is very similar to a 7603) and found one major fault with the esr meter, so i'd say it's definitely been useful there. Sure i could have found the fault some other way. ST On Wed, Oct 1, 2008 at 6:39 PM, DEANE KIDD <dektyr@...> wrote:
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Re: Calibrating a 7704A
This reminds me that I need to do a "group cal" on all my gear. I have both fixtures, but I just never get around to it. The individual scopes are all cal'd, but when I start swapping plugins, I sometimes forget what goes where. Maybe when it starts raining... I have been seeing both fixtures fairly regularly, so they shouldn't be too hard to find at a good price (at least in the SF bay area).
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-Dave -------------- Original message ----------------------
From: "Craig Sawyers" <c.sawyers@...> I was just wondering if a Tek 067-0587-01 calibration fixture isThe key thing about the cal fixture is that it calibrates the mainframe |
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Re: Tek 465B blurry CRT.
Bernice Loui
Hello,
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There was also an entire batch/lot of problem 465B crts from back in the day. One of the problems was spot size and ability to focus. Many were replaced under warranty by Tek. I remember looking a quite a few 465Bs with this problem at a local cal lab. Bernice ~~~~~~~~~~~~~~~~~~ --- On Wed, 10/1/08, Jordan Kersten <jordankersten@...> wrote:
From: Jordan Kersten <jordankersten@...> Subject: [TekScopes] Tek 465B blurry CRT. To: TekScopes@... Date: Wednesday, October 1, 2008, 10:39 PM My 465b won't focus quite as clear as it should. Doesn't matter where I adjust the focus or astig control. It looks like there is a ghost image of whatever I am measuring. So the trace/waveform becomes larger/wider than it should. I don't think it is physical damage inside the CRT because the "out of focus" is uniform and does not change at all when you change the trace position. ~Jordan~ |
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Tek 465B Blurry CRT - Photo
Jordan Kersten
I posted a photo of the blurr to my album. You can't see it well in the pic, but it looks much worse and fuzzy/blurry in real life. It looks like it is focusing right, there just seems to me a shadow always beside the trace.
Here is the album link: ~Jordan~ |
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Re: 7603 filter caps
tom jobe
Hello Scott,
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Thanks for posting the link to the Anatek ESR comparison page. I have both the EVB from Portugal, and the CapAnalyzer 88A that are on the Anatek comparison page. The EVB is another modern version of the famous Bob Parker design, and it is my favorite everyday ESR meter. It is a very durable unit, as I have not been able to kill it yet, and I have done some very dumb things to it! It does not care about polarity, and it just works. I bought it directly from the fellow in Portugal who builds it, and he was a treat to deal with. I just followed the link on the Anatek ESR page to the EVB web site, and it still is just $79 $ US delivered, which is 56 Euros. This is not a kit, it is a finished ESR meter that you put a 9V battery in and use. The CapAnalyzer 88A is a full featured very nice ESR meter, but you will have at least $200 US in it by the time it arrives. The downside to the 88A is that it has a nice set of tweezers permanently attached (Pomona brand on my 88A) but that limits what you can check, as the tweezer only open up a little. The EVB does not come with any leads, so you supply (or make) some test leads, and then you can check anything with two separate leads that can be very far apart. The 88A also requires that you have the polarity correct. Working on this old equipment without an ESR meter of some kind, is very foolish in my opinion. Bad electrolytic capacitors are the number one failure in much of this old gear, and the ESR meter will identify the bad caps in a few seconds. tom jobe... ----- Original Message -----
From: "Scott McGrath" <mcgrath@...> To: "Paul Kraemer" <elespe@...>; "Tek Scopes" <TekScopes@...> Sent: Wednesday, October 01, 2008 12:40 PM Subject: Re: [TekScopes] 7603 filter caps
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Re: Tek 465B blurry CRT.
Dino Papas
Take a look at:
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where there are procedures that try to address this problem for both the 465 and 475 scopes. When I had a 475 I did this procedure and it helped a little but did not solve the problem....graduated to a 2440A, but I do miss the nice sharp trace of an good analog scope! Dino KL0S On 1Oct2008, at 6:39 PM, Jordan Kersten wrote:
My 465b won't focus quite as clear as it should. Doesn't matter |
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Re: Calibrating a 7704A
Craig Sawyers
I was just wondering if a Tek 067-0587-01 calibration fixture isThe key thing about the cal fixture is that it calibrates the mainframe independent of plug ins. So you adjust horizontal and vertical gains, and trim up the rise time of both vertical and horizontal channels. It probably won't surprise you that I have one, and two of the faster 067-0587-02 too (for 7904/7904A/7104/7912 cal). I certainly would not part with mine - they don't get a whole lot of use, but when you need one it is good to have the right tool to hand. Craig |
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Tek 465B blurry CRT.
Jordan Kersten
My 465b won't focus quite as clear as it should. Doesn't matter where I adjust the focus or astig control. It looks like there is a ghost image of whatever I am measuring. So the trace/waveform becomes larger/wider than it should. I don't think it is physical damage inside the CRT because the "out of focus" is uniform and does not change at all when you change the trace position.
~Jordan~ |
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Re: 7603 filter caps
Scott McGrath
See this web page
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- There is what is known as the 'Bob Parker' design this is a cheap accurate ESR meter upon which countless commercial implementations have been built upon. I use the BLUE meter myself it is more than accurate enough for service work. But read the information and decide for yourself Paul Kraemer wrote: ESR meter |
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Re: 7603 filter caps
Scott McGrath
Using higher Voltage/Capacitance ratings usually is not a problem especially since many of the old can type electrolytics were rated -20/+40% of nominal rating.
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Higher voltage is usually ok as long as the voltage differential is not extreme anything less than 3:1 is probably ok more than that and the capacitor will not work effciently Pay attention to temperature ratings and a ESR meter would be a good investment - Scott Robert Simpson wrote: Hi folks, Thanks for all the tips in this forum. I am just stating to work on a used 7603 with three plug-ins (7A18A, 7D15, 7B70) I acquired cheap as a second scope with a 442 I got also got cheap (neither working, both for $50, 442 now works) Thanks for the article on washing scopes as the 7603 really needed it. With the plug-ins removed so they could be washed separately, I used the siphon spray wand for my air hose with a bucket of water with dish soap (avoiding the front panel). Rinsed it off with the garden hose, blew it mostly dry with the air hose, and then let it sit in the sun all afternoon. Then let it sit inside overnight. |
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7603 filter caps
Hi folks,
Thanks for all the tips in this forum. I am just stating to work on a used 7603 with three plug-ins (7A18A, 7D15, 7B70) I acquired cheap as a second scope with a 442 I got also got cheap (neither working, both for $50, 442 now works) Thanks for the article on washing scopes as the 7603 really needed it. With the plug-ins removed so they could be washed separately, I used the siphon spray wand for my air hose with a bucket of water with dish soap (avoiding the front panel). Rinsed it off with the garden hose, blew it mostly dry with the air hose, and then let it sit in the sun all afternoon. Then let it sit inside overnight. It now turns on. And with no plug-ins installed gets a spot beam in the center using the beam finder button. Most of the voltages are within spec except for +5 which is 4.4V. All voltages except 130V have too much ripple; I am guessing filter cap problems. So, since exact replacement caps are hard to find and incredibly expensive, I am thinking of using substitutes. For example, in place of the 1800uf 75V caps I could get 2000uf 100V caps. Would slightly larger specs work being they are used as filter caps? |
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File - Posting Rules
Please edit any posts/replies to the list to
minimize quoted material to that required for continuity. Please do not send personal replies to the list. List replies go to the original sender by default. If you want to also reply to the list, use Reply-to-all (or whatever it's called in your mailer), or manually add the TekScopes address. Do this if your reply would be of interest to the list. Otherwise, just reply to the sender. Those congesting the list with with either of the above may have posting rights revoked. Only by following these simple rules will we have a "clean" archive. They also reduce inbox clutter, make digests much nicer to read, improve searches, and reduce the chance of having old messages deleted. To post to the group, mail to: TekScopes@... I occasionally get emails meant for the group mistakenly sent to TekScopes-owner@...! I just delete these, so please watch where you're sending... If you post or have posted to the Photos section, please make sure your files are fairly small (<100K). See the bottom of this message for further instructions. If you do not wish to belong to TekScopes, you may unsubscribe by sending an email to TekScopes-unsubscribe@... You may also visit the Yahoo web site to modify your subscription: Check out the files, links, and photos sections, and remember, you can search the group's archives from its home page, or when reading messages. The group's home is at: Regards, Michael Dunn Listowner, TekScopes Keeping Photos Small: There's no point uploading large images to the photos section, as Yahoo severely limits the size and quality that others can view them at. I reserve the right to delete oversize files without warning. Therefore: I would ask anyone who has uploaded large (>100K) files (you can see file sizes by selecting list instead of thumbnail view) to either: 1. Delete the full-sized version via Yahoo by first viewing it. There is then a link (top-center) that allows deletion. 2. Replace it with a reduced-size version. 3. Delete it. |
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Re: 7603 filter caps
DEANE KIDD
Hi All:
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The CRT's in the modern Tek scopes all have a problem with poor focus as compared to the the focus with the tubes as used in the 547, 546,545, 581,585, 561, 564 series of scopes. As the need for higher bandwidth became the norm much work was done to improve the CRT performance, but nothing seemed to help and a decision was made to add an element beyond the defection plates which is incorporated in all of the CRT's of modern design. This element is a doomed mesh screen thru which the beam is guided on its way to the phosphor. This allows the tube to have much lower deflection plate voltages which is required by the solid state amplifiers. There is a price to pay for this improved performance. Since the beam is guided thru the deflection system and then accellerated thru the doomed mesh, the beam is defocused and there are no other means of refocusing the beam and it appears defocused on the screen and this is the focusing problem that many of you are complaining about. This is the price we pay to have the gain/bandwidth of the modern oscilloscope. With the advent of flat-panel displays this problem is less apparent and the constant improvement in display technology is making it less of a problem. I started at Tek in August of '49 and retired in June of '91 and was on hand as these problems were addressed and decisions made. Deane E. Kidd ps: Add it all up and I have been around a long time. The ESR meter that everyone seems to believe is required piece of test gear in the service kit was never heard of until mid '90s when electrolytic caps of high values and low voltages became the norm. I have never used an ESR meter and my normal capacitors were 80 - 120 MFD at 350 - 450 volts. Deane ----- Original Message -----
From: tom jobe To: Paul Kraemer ; Tek Scopes ; Scott McGrath Sent: Wednesday, October 01, 2008 4:37 PM Subject: Re: [TekScopes] 7603 filter caps Hello Scott, Thanks for posting the link to the Anatek ESR comparison page. I have both the EVB from Portugal, and the CapAnalyzer 88A that are on the Anatek comparison page. The EVB is another modern version of the famous Bob Parker design, and it is my favorite everyday ESR meter. It is a very durable unit, as I have not been able to kill it yet, and I have done some very dumb things to it! It does not care about polarity, and it just works. I bought it directly from the fellow in Portugal who builds it, and he was a treat to deal with. I just followed the link on the Anatek ESR page to the EVB web site, and it still is just $79 $ US delivered, which is 56 Euros. This is not a kit, it is a finished ESR meter that you put a 9V battery in and use. The CapAnalyzer 88A is a full featured very nice ESR meter, but you will have at least $200 US in it by the time it arrives. The downside to the 88A is that it has a nice set of tweezers permanently attached (Pomona brand on my 88A) but that limits what you can check, as the tweezer only open up a little. The EVB does not come with any leads, so you supply (or make) some test leads, and then you can check anything with two separate leads that can be very far apart. The 88A also requires that you have the polarity correct. Working on this old equipment without an ESR meter of some kind, is very foolish in my opinion. Bad electrolytic capacitors are the number one failure in much of this old gear, and the ESR meter will identify the bad caps in a few seconds. tom jobe... ----- Original Message ----- From: "Scott McGrath" <mcgrath@...> To: "Paul Kraemer" <elespe@...>; "Tek Scopes" <TekScopes@...> Sent: Wednesday, October 01, 2008 12:40 PM Subject: Re: [TekScopes] 7603 filter caps > > See this web page > > > > - There is what is known as the 'Bob Parker' design this is a cheap > accurate ESR meter upon which countless commercial implementations have > been built upon. I use the BLUE meter myself it is more than accurate > enough for service work. > > But read the information and decide for yourself > > Paul Kraemer wrote: > > ESR meter > > Do you have a recommendation? Works well, cost effective. > > Thanks > > Paul > > > > ----- Original Message ----- > > *From:* Scott McGrath <mailto:mcgrath@...> > > *To:* go_boating_fast@... <mailto:go_boating_fast@...> > > *Cc:* Tek Scopes <mailto:TekScopes@...> > > *Sent:* Wednesday, October 01, 2008 1:24 PM > > *Subject:* Re: [TekScopes] 7603 filter caps > > > > Using higher Voltage/Capacitance ratings usually is not a problem > > especially since many of the old can type electrolytics were rated > > -20/+40% of nominal rating. > > > > Higher voltage is usually ok as long as the voltage differential > > is not > > extreme anything less than 3:1 is probably ok more than that and the > > capacitor will not work effciently > > > > Pay attention to temperature ratings and a ESR meter would be a good > > investment > > > > - Scott > > > > Robert Simpson wrote: > > > Hi folks, > > > Thanks for all the tips in this forum. I am just stating to work > > on a used 7603 with three plug-ins (7A18A, 7D15, 7B70) I acquired > > cheap as a second scope with a 442 I got also got cheap (neither > > working, both for $50, 442 now works) > > > Thanks for the article on washing scopes as the 7603 really > > needed it. With the plug-ins removed so they could be washed > > separately, I used the siphon spray wand for my air hose with a > > bucket of water with dish soap (avoiding the front panel). Rinsed > > it off with the garden hose, blew it mostly dry with the air hose, > > and then let it sit in the sun all afternoon. Then let it sit > > inside overnight. > > > > > > It now turns on. And with no plug-ins installed gets a spot beam > > in the center using the beam finder button. Most of the voltages > > are within spec except for +5 which is 4.4V. All voltages except > > 130V have too much ripple; I am guessing filter cap problems. > > > > > > So, since exact replacement caps are hard to find and incredibly > > expensive, I am thinking of using substitutes. For example, in > > place of the 1800uf 75V caps I could get 2000uf 100V caps. Would > > slightly larger specs work being they are used as filter caps? > > > > > > > > > > > > > > > > > > > > > ------------------------------------ > > > > > > Yahoo! Groups Links > > > > > > > > > > > > > > > > > > ------------------------------------ > > Yahoo! Groups Links > > > ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG - Version: 8.0.173 / Virus Database: 270.7.5/1702 - Release Date: 10/1/2008 9:05 AM |
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