Re: 7603 CRT
cmjones01
On 31/12/2013 21:16, David wrote:
Something I noticed before on my 7603 and confirmed recently whileThis is quite a widely-reported phenomenon with CRTs. It seems very common in the vintage TV world that the CRT in an old TV will take some hours of operation to 'wake up' after having been unused for some years. I've observed it on CRTs in my workshop, too - a 2465A I bought a couple of years ago had a rather disappointing trace when I first started using it, but improved with use. I don't know whether it's about the cathode emission improving, or impurities in the vacuum (!) getting reabsorbed by the getter and electrodes as they all heat up, or what, but it's real enough. Chris
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Re: For sale DC508(a) display modules
ralflaborenz@...
Dear Paul,
First a happy new year and thanks again for the replacement display board for the DC508 counter. This works fine if I use my DC508A as a "normal" frequency counter. I just wanted to let you know that if the DC508A is modified for option 7 and used in a set-up with a 7L14/TR502 (spec.analyzer/tracking generator) for indicating the centre frequency, one needs a decimal point in front of the least significant digit for a 100 kHz resolution. This is not supported by the display board I received, however it can be implemented simply by adding another stage of the circuit you use to generate the decimal point driving signal. I did so using some bare wire, the required transistor and diode. Cheers, Ralf
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File - Posting Rules
TekScopes@...
Welcome to TekScopes.
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. Replies currently go to the list by default. 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@yahoogroups.com It is now possible to send attachments with postings. In the message, Yahoo replaces the file with a link, and they store the file on-site for a limited time. I occasionally get emails meant for the group mistakenly sent to TekScopes-owner@yahoogroups.com! I just delete these, so please watch where you're sending... Please use the archive groups listed on the home page for file uploads, as our own area is pretty much full! If you really want to put a file in our directory, contact me directly at TekScopes-owner@yahoogroups.com. If you do not wish to belong to TekScopes, you may unsubscribe by sending an email to TekScopes-unsubscribe@yahoogroups.com You may also visit the Yahoo web site to modify your subscription: http://groups.yahoo.com/mygroups 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: http://groups.yahoo.com/group/TekScopes Regards, Michael Dunn Listowner, TekScopes
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Plotters (was OT LOL)
Morris Odell
Hi all,
Does anyone still use plotters or pen recorders? I have had one for years which I originally got to plot PCB patterns on copper using an etchant resistant felt tip pen. It worked nicely until I went to toner transfer and has been sitting in the cupboard ever since. I took it out the other day and put in the recycling pile :-( It's an old Graphtec A3 size with a non-standard parallel (Centronics) interface. It has a very nifty magnetic pen selection and holding system. I had to mess around a lot with an interface converter to get it working years ago and it would be even more of a pain today. Now I have machine shop facilities to make pen adaptors but is it worth the trouble? A search on eBay for flatbed plotters shows there's not much of a market for this type of machine. XY recorders are different and might be a source of fun for the hobbyist as long as they don't need special paper. I also have a an old HP chart recorder which I did use recently to monitor a GPS controlled oscillator for several days for the hell of it, but that could just as easily be done electronically. Given that it needs special paper and the ink plumbing clogs easily I can see it going the same way..... Morris .....Of relevance to the HP group, did anyone notice Paillard is using a Just a lathe? There were little "wings" on the pens that twist-lock..... I drilled and reamed one of the little stubby felt tip pens out to wherethe regular pen was a friction fit. Not hard to do even with just hand tools.
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Re: 2564A preventive maintenance
mosaicmerc
Were ALL the traces active?
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Re: OT LOL
I'm getting really annoyed at aetoulis. I asked him a perfectly legitimate
toggle quoted messageShow quoted text
question about the other amplifier - the one with the volume control (331094423899) - and he didn't include my question along with the other four perfectly reasonable questions he was asked. The NERVE! In his answer to the second question he got he recommended against putting the amplifier in a box because the capacitance of the box would reduce the frequency response. So I asked if putting his amplifier in a purely inductive box (one made of MuMetal or Nitinol) would enhance the frequency response? Maybe I stumped him! Dennis PS Apparently someone was dumb enough to pay aetoulis $29 on Dec-23-13 16:10 for a schematic of the Pleiades Electra Only Tubes & No Other Components Headphone Amplifier (331079777606) according to aetoulis' feedback. $29 for 30 seconds of work makes me think aetoulis is definitely smarter than me. I would love to be there to see the look on the buyer's face when he/she opened the schematic for the very first time.
-----Original Message-----
From: Paul Amaranth, Sent: Tuesday, December 31, 2013 3:57 PM Now that one is a definately a ripoff. It doesn't have a volume control and he wants THAT much for it ??!! On Tue, Dec 31, 2013 at 03:18:14PM -0800, Leon Robinson wrote: Here is one with wires in it.http://www.ebay.com/itm/Battery-Tube-Only-Headphones-Amplifier-for-Sennheise r-HD-580-600-650-Beyer-DT880-/331096206110?pt=US_Pro_Audio_Amplifiers&hash=i tem4d16df2b1e -- Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@AuroraGrp.Com | Unix & Windows
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Re: 2564A preventive maintenance
af7u@...
Tom, I can't speak to specific sweep speeds, I was just doing general testing under various conditions... I remember evaluating the beam modulation that I saw at low sweep speeds, then I fed a signal from my HP 8648B and tested bandwidth at higher sweep speeds up to it's upper limit. Seems like I magnified the sweep a few times just for giggles but not for long periods. Not a very comprehensive test for certain but just twisting knobs and pushing buttons. I just got it up after fixing issues and was just checking it out when I noticed U800 not heating... I am thinking of adding additional sinking anyway... ~Michael - AF7U
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Re: OT LOL
stefan_trethan
I drilled and reamed one of the little stubby felt tip pens out to
toggle quoted messageShow quoted text
where the regular pen was a friction fit. Not hard to do even with just hand tools. ST
On Tue, Dec 31, 2013 at 4:03 PM, Daniel Koller <kaboomdk@yahoo.com> wrote:
Chuck is correct. The relevant footage is near the end of the video where he tests the tube. Link is here in case Yahoo lost it for you: http://www.youtube.com/watch?v=EzyXMEpq4qw
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Re: OT LOL
Don Black <donald_black@...>
Come on, look on the bright side.
Perhaps he can't speak English.
Happy New Year. Don Black. On 01-Jan-14 3:56 PM, Dennis Tillman wrote:
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Re: OT LOL
Damn! Everytime I think I have everything, someone has to show me something like this video to make me realize I need to live another hundred years to be able to do all the things I want to do.
toggle quoted messageShow quoted text
In addition to a very complete machine shop he appears to have a professional glassblowing laboratory, and a knowledge of electronics. Plus, he speaks French! Sigh! How I am going to explain that I need a glassblowing laboratory to my wife? Dennis PS Clearly, if he can make a vacuum tube he can adapt a pen to fit a plotter. I don't think it took him more than a minute to figure out how to do that. The only question I have is whether he thought about making the holder out of blown glass or out of machined metal. He probably could have done either.
-----Original Message-----
From: Daniel Koller, Sent: Tuesday, December 31, 2013 7:03 AM Chuck is correct. The relevant footage is near the end of the video where he tests the tube. Link is here in case Yahoo lost it for you: http://www.youtube.com/watch?v=EzyXMEpq4qw Just a lathe? There were little "wings" on the pens that twist-lock into the holders. I supposed I could start with a rectangular piece of stock and turn all but the wings. Anyone have one of these little pen adapters? Dan On Tuesday, December 31, 2013 9:21 AM, Chuck Harris <cfharris@erols.com> wrote: He is referring to the little video on the making of a triode
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Re: OT LOL
Brad Thompson <brad.thompson@...>
On 12/31/2013 6:57 PM, Paul Amaranth wrote:
Now that one is a definately a ripoff. It doesn't have a volume controlHello-- Beware of Geeks bearing grifts.... Yours for audio purity, truth in advertising, and the eternal quest for Something Better (or failing that, something more expensive). 73, and my best wishes go to all for a happy New Year-- Brad AA1IP --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com
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Re: OT LOL
Paul Amaranth
Now that one is a definately a ripoff. It doesn't have a volume control
toggle quoted messageShow quoted text
and he wants THAT much for it ??!!
On Tue, Dec 31, 2013 at 03:18:14PM -0800, Leon Robinson wrote:
Here is one with wires in it. --
Paul Amaranth, GCIH | Rochester MI, USA Aurora Group, Inc. | Security, Systems & Software paul@AuroraGrp.Com | Unix & Windows
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Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement
Phil Peri
Hi all, I pulled the FPLA and power cycled the unit a few times and I saw traces! Power cycling a couple more times but I never got a trace again. Here are some images: http://imgur.com/a/q6fOe So, intermittent issues... ! P.
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Re: OT LOL
Leon Robinson
Here is one with wires in it. http://www.ebay.com/itm/Battery-Tube-Only-Headphones-Amplifier-for-Sennheiser-HD-580-600-650-Beyer-DT880-/331096206110?pt=US_Pro_Audio_Amplifiers&hash=item4d16df2b1e Leon Robinson K5JLR Political Correctness is a Political Disease.
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7603 CRT
Something I noticed before on my 7603 and confirmed recently while working on it
is that the longer it is operating, the sharper and brighter the CRT gets even after adjusting the focus and astigmatism. It was especially dim and blurred after being in storage for years. I have never found any faults in other areas of this oscilloscope so is there some specific characteristic of the CRT which would cause this? None of my other oscilloscopes display this behavior.
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Re: Tek 7854 Doesn't Come On After EPROM ROM Replacement
Phil Peri
Hello all, Thanks for the replies! Shortly after I posted this topic the author of Modular Synthesis, Dave B., got in touch with me and has been walking me through a potential fix over email. Wher we arrive at a solution I will update everyone.
Göran: Excellent document! I will print it out and look at it but already you've stated to *remove* the FPLA, and when I tried that I get some new lights (two red LEDs: 'REMOTE ONLY' and 'ERROR') popped up! So I will look over this document more in-depth and see what I can do to get this going again. Thanks again, everyone, and I'll update everyone with my progress :) Philip.
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Re: 2564A preventive maintenance
Did you do the test under different sweep speeds and magnify? The fast
sweep times might require higher power?
Tom
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Re: 5113 calibration problem
h_posilovic@...
Hello,
Thank You all for excellent and very useful advices.
You were right; I measured HV at the test point on the CRT socket. The voltage is only 2325 V, and should be 3400 V. Then tried to raise voltage with trim-pot on the HV board, but the voltage das not react at all, stay around 2325 V. There are some soldering traces on this board; it looks like somebody already tried to repair there something. One transistor is marked with black paint. I will try to find schematics in the manual you recommended to me.
I wish You Happy New Year and a lot of good waves on your scopes.
Hrvoje.
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Re: 2564A preventive maintenance
af7u@...
<Scratching Head> My U800 is *not* getting hot... maybe warm, maybe, but definitely not hot. Unit left on for hours and temp is mildly warm to touch, touch being full finger contact across length of IC. This leads me to think one of two things. Either there is component value shifting in the related circuitry to U800 causing it to over heat, or... some other issue is afoot. I've read about proper ventilation and such, my test was done with slide cover removed. Don't get me wrong, I'm darn grateful for a cool IC, but any thoughts regarding a NON-heating U800? ~Michael _ AF7U
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Re: 7603 with power supply problems
On Tue, 31 Dec 2013 16:44:41 -0000, you wrote:
--- In TekScopes@yahoogroups.com, "Michael A. Terrell" <mike.terrell@...> wrote:In the places where Tektronix used parallel transistors without emitter ballastA series of transistors are used to increase amplification of a signal - each t ransistor has an 'amplification factor' hfe, increasing the emitter-collector current over the emitter-base (input) current. resistors and apparently without grading, I suspect the reason was to raise the current gain at high peak currents where a transistor's current gain drops. In this type of situation, parallel transistors can multiply the current gain at least 2 to 4 times without a Darlington connection. One of the claims to fame that Zetex (bought by Diodes Incorporated) has with their Super E-line of transistors is high current gain at high currents. Older transistors like the 2N4401 and 2N4403 have much lower current gain at high currents. Other companies now produce similar transistors for applications requiring high efficiency. A transistor like a ZTX690 at 1 watt would make an excellent replacement for a 2N5859 but costs 10 times more than a 2N4401.
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