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Re: OT UNI-T UT81B or ? ( ~ $300 ) meter size scope
Bert, take a look at a Attn ADS1102CAL. Yes, it's Chinese (like a LOT of other mfgs today). I have one and absolutely love it. It sits atop my 2465A. I have 18 other scopes from a small Leader to a big (LeCroy). Can't beat the Atten, IMHO. Liked the quality so much I have since purchased some of their other equipment.
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3 yr warranty besides...... ron N4UE -----Original Message----- From: Bert Haskins To: TekScopes Sent: Tue, Oct 16, 2012 7:17 pm Subject: [TekScopes] OT UNI-T UT81B or ? ( ~ $300 ) meter size scope
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My mobility has slipped ( kinda much ) and I just can't toss around
my favorite Tek scopes like in the better days. Since most of the Tek/Fluke scope-meters are considered to be non-repairable anyway, is there anyone on the list that has used something like the UIN-T with reasonable results or there another good choice. The $300 is just sort of a arbitrary price point. (1) This will be backed up by several other really nice instruments. (2) Most of my scope usage is just on, check something, off. (3) Most is under 250K Thanks, ? Bert |
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Re: AN/USM-125 Scope Woes
开云体育Where are you located? What model is the AN/USM-125? Do you have the
service manual?
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Sounds like it might just have a bad power supply capacitor. You'll get
some bad karma if you through it in a dumpster.
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Maybe someone on the list lives close to you and has the skills to repair
it.
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Regards,
Tom
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OT UNI-T UT81B or ? ( ~ $300 ) meter size scope
开云体育My mobility has slipped ( kinda much ) and I just can't toss aroundmy favorite Tek scopes like in the better days. Since most of the Tek/Fluke scope-meters are considered to be non-repairable anyway, is there anyone on the list that has used something like the UIN-T with reasonable results or there another good choice. The $300 is just sort of a arbitrary price point. (1) This will be backed up by several other really nice instruments. (2) Most of my scope usage is just on, check something, off. (3) Most is under 250K Thanks, ? Bert |
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AN/USM-125 Scope Woes
I have an AN/USM-125 that has always (as long as I have owned it) had issues with vertical stability. I used to be able to clean or re-seat the vertical module and it would stabilize. This time, in the process of performing the ritual, the chan 1 and 2 traces could not be positioned below the zero line on the graticule, and any input signal appeared to compress with an adjustment in vertical positioning. Now, the trace has disappeared and the +90 volt supply appears dead (at +11 volts). I do not have the guts or the tools to dig into troubleshooting the HV circuitry. Can anyone shed some light on this before the scope hits the dumpster?
Thanks in advance, Dan |
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Re: 2465A Calibration question
开云体育Hello Tom,I thought that was one of those Tek products with cheap TI sockets. Tek continued to use those sockets long after computer industry abandoned them. Miroslav Pokorni On 10/16/2012 2:28 PM, Tom Miller wrote: ? |
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Re: 2465A Calibration question
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Hello Miroslav,
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The original ram was soldered in. I installed a 28 pin milled pin, low
profile socket and the new ram. I did not try to check the old ram as I clipped
all the pins close to the package and removed each pin one by one.
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Re: 7B92 No Auto trigger
On Tue, 16 Oct 2012 19:29:35 -0000, "baltimora86" <acuffe@...>
wrote: I borrowed a 10 mA 152-0140-01 tunnel diode from my 7B52, and I think I've confirmed that the only problem is the tunnel diode. Delayed triggering appears to work properly now (although I have to tweak the TD bias when switching between runs after delay, and delayed sweep triggerable). I hope that's due to my temporary TD substitution (8pF instead of 2pF).It took me until last night to make some good 11x17 printouts from the 7B92 schematics I cleaned up so I could follow you. I will add them in their own section to my 3 ring binder of instruments that I do not have. If I was dealing with a Tektronix unobtanium tunnel diode, I would track down some cheaper East Block replacements and alter the circuit biasing if necessary. I do not know the original source so I have copied the Tektronix tunnel diode summery worksheet into my 7B92 directory. Maybe that will help: |
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Re: 2465A Calibration question
开云体育Did you try to put old? RAM back in? Those large sockets, like one used for RAM are of poor quality and over time contacts corrode and loose connection. I saw that in 7D01; socket was 16 or 18 pin, but still bad TI type and after replacing a RAM analyzer's display worked correctly and when old RAM was returned it still worked, so that looked to me as poor contact which was fixed by cycling IC.Miroslav Pokorni On 10/16/2012 12:54 PM, Tom Miller wrote: ? |
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Re: 7B92 No Auto trigger
Albert
Good that you found the cause Andy! I think the bias re-adjustment won't be necessary any more after you adjust all 3 pots in that section.
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Albert I borrowed a 10 mA 152-0140-01 tunnel diode from my 7B52, and I think I've confirmed that the only problem is the tunnel diode. Delayed triggering appears to work properly now (although I have to tweak the TD bias when switching between runs after delay, and delayed sweep triggerable). I hope that's due to my temporary TD substitution (8pF instead of 2pF). |
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Re: 2465A Calibration question
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That was it. Changed the ram and it calibrated on the first pass. It was a
D4464C 8Kx8 ram.
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Thanks,
Tom
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Re: 7B92 No Auto trigger
I borrowed a 10 mA 152-0140-01 tunnel diode from my 7B52, and I think I've confirmed that the only problem is the tunnel diode. Delayed triggering appears to work properly now (although I have to tweak the TD bias when switching between runs after delay, and delayed sweep triggerable). I hope that's due to my temporary TD substitution (8pF instead of 2pF).
I guess I'm in the market for a 152-0177-02 tunnel diode or two. The closest I can find is a 152-0177-01 for $20. To sum it up, I think what happened was that CR950 shorted and was killing the sweep gate which caused the CRT to be blanked while in auto mode. When I attempted to manually pull up the sweep gate, it must have changed CR950 from a short to an open. I initially missed the fact the CR950 was open because it tests good wile in circuit, and I didn't pay close attention to the DC voltages when I was looking at the signal across it. Thanks to everyone who took the time to help me. You saved me from countless hours of frustration. |
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Re: 7B92 No Auto trigger
Albert
Hi Andy,
Please see below. Albert If I adjust R364 (delay TD pickoff bias) to maximum resistance, I do get a healthy square wave at TP365, and the low to high transition time is controlled by the delay time multiplier knob. There still no response on screen. This seems to indicate that CR364 is being over biased from something.No, CR354 is OK now. I can trace the signal from TP365 as far as Q422 where is disappears. I've checked all the transistors around Q422, but nothing else yet. It seems like something is upsetting the bias on Q422, Q426, or Q424. The pulse should at least be present at TP421, which is directly connected to TP365. Check that the delayed sweep is present at TP462. Set the delayed sweep 2 or 3 steps faster than the delaying sweep. Then at the end of the delayed sweep (= end of intensified portion), the level at TP462 remains high until end of trace (unless you have Delay so large that the delayed sweep didn't finish before end of trace). Check that TP489 (Sweep gate) is high (+5 V) only during the intensified portion.
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Re: 7B92 No Auto trigger
After some more thinking, and re-reading the supplemental circuit description, I realized that my previous line of thinking was a dead end. CR950 is what should be triggering the delayed sweep, so I rechecked the signal there. At first glance it looked fine, but I noticed there was over a volt across CR950. Since the voltage on CR950 is always above the threshold to trigger the delayed sweep, I assume it's causing it to run immediately.
I removed CR950 from the circuit, and confirmed that it's open. I don't think I have a suitable replacement on hand, but I might have something that will work for testing. |
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Re: 7B92 No Auto trigger
Hi Albert,
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Here's what I'm seeing in intensified mode when triggering from TP408. TP365 has a brief pulse down to 0 V at the start of the sawtooth ramp at TP408, then immediately goes up to about 570 mV. TP365 does go a few mV higher after the end of the delay period, but it's only a few mV. If I adjust R364 (delay TD pickoff bias) to maximum resistance, I do get a healthy square wave at TP365, and the low to high transition time is controlled by the delay time multiplier knob. There still no response on screen. This seems to indicate that CR364 is being over biased from something. I can trace the signal from TP365 as far as Q422 where is disappears. I've checked all the transistors around Q422, but nothing else yet. It seems like something is upsetting the bias on Q422, Q426, or Q424. The auto trigger problem seemed to come from around Q422 as well, so I might be getting close. Thanks Andy --- In TekScopes@..., "Albert" <aodiversen@...> wrote:
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Re: 2445A Calibration question
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Hi Bob,
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Yeah, I am kinda thinking the same. It did have a dead battery when I got
it.
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Also, I said it was a 2445A but it is a 2465A but that doesn't matter for
this problem. Same A5 board I think.
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Thanks,
Tom
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Re: 2445A Calibration question
Bob Koller
I think you have a bad RAM chip. From: tmillermdems To: TekScopes@... Sent: Monday, October 15, 2012 9:48 PM Subject: [TekScopes] 2445A Calibration question
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I am getting a Test 04 Fail 01 error on a 2445A scope and I have been through the cal proceedure four times. I keep getting the error but when I exit out of the self test, every thing works fine.
Going through the calibration has no issues, no limit errors, etc. Is there anyway to tell what is causing the fail? The manual says the Fail01 is a parity error with the calibration data. Is there any way to tell where this error is? I know that one can examine the ram contents. Is there anything that clues on into what the data should be? Thanks, Tom |
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Re: Screwdriver for Pozidriv (Pozi) Screws used by Tek
Paul Kraemer
开云体育I was amazed, after looking for the proper screwdrivers,
finding these bits were available as part of a set that cost about $5 dollars in
the local store. I bought the set and it includes a nice handle for running the
bits.
Yes, we do live in a wonderful country and are often
ignorant about the?resources available to others
Paul
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Re: Screwdriver for Pozidriv (Pozi) Screws used by Tek
开云体育Hi Paul, I have bought many of those “sets” over the years and never found a Pozi bit. They may be a recent addition to the sets as the manufacturers of these sets seem to be competing over how many new bits each can include that the others don’t have. The sets seem to grow more elaborate every year as each vendor tries to outdo the competition by adding more oddball bits to their sets. Dennis ? From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Paul Kraemer Pozidrive screwdriver tips are available in most DIY stores like Lowes, Home Depot, Menards, Harbor Freight etc.---if you know where to look for them. They are included in many of the multi bit sets, the ones that have assortment of phillips, square, torx, plain---all those. Phillips are marked P1etc and pozidrive are PZ1 etc. They are there, just hiding. Paul K0UYA
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Re: Screwdriver for Pozidriv (Pozi) Screws used by Tek
Yes. I meant hardware store in the USA. And Yes! I know about and respect
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that we are just one country among many nations around the world. I consider myself fortunate that I live in a unique place within a mile of Microsoft. Because they have brought in people from all over the world to help write their software and to internationalize it I am in a multicultural microcosm where I am sometimes the only American in the supermarket. It is fascinating to see so many different costumes and hear so many languages spoken in the aisles. That microcosm is situated in a myopic bubble world called the USA where most people take it for granted that they, and their country, are the only ones that matter. When they think "foreign country", if they think at all, what comes to mind is Canada and Mexico. Most of them don't realize, or don't care (which is worse!) the other 180+ countries even exist. Recently they have been rudely awakened to the ugly fact that just about everything they now wear, buy, and own is made in China. Americans have fought metrification for at least the past 50 years (since I was first introduced to its elegant simplicity in high school) kicking and screaming all the way. They prefer the comfort of teaspoons, tablespoons, ounces, cups, pints, quarts, gallons etc. when they cook. I defy anyone to tell me how many teaspoons are in a quart. To me it is mindboggling how confusing the English system is. I hold onto a glimmer of hope. While Americans were sleeping their quart soda bottles were replaced with 2 liter bottles. They don't seem to have noticed. Everything they buy in a liquor store comes measured in liters but as long as the bottles look the same size as what they are used to they don't realize they have been fooled into accepting those 'socialist' metric liters. What's worse, to accommodate their fear of metrification we are now mixing the systems together. For instance marijuana is smuggled in kilogram bundles ('keys') but they buy it by the ounce. Cocaine is bought by the gram. At least every hippie knows how many grams are in an ounce. American's cars come with metric bolts but the metric socket sets they use are designed to slip into their 1/4" ratchet drives. I gave up long ago advocating for the metric system in the US. It was always met with ignorance, closed minds, and worse, anger. Every time I still bring up the metric system I am reminded, painfully, that "half the people I know are below average". Sometimes I think most of the below average people live near me. Dennis PS No doubt I'm going to hear about this! -----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf Of fred Sent: Tuesday, October 16, 2012 12:54 AM To be specific. I think you mean, hardware store in the USA. There is a wild outside the US, we use strange things like metric instead of Inch, Celcius instead of Fahrenheit ect. And so there are many tools a " standard over here but as rare as metric in the US. In Holland and as far a I know a big part of Europe, you can buy them everywhere. Even sub 5 euro sets from food-supermarktets like Lidl or Aldi have them included. ( most times a screwdriver with exchangsble bits) i think I have somewhere around ( including bits) 20-30 pozidriv's. Almost all woodscrews here are pozidriv. Also most "parkers" , the selfcutting screws for use in metal. Bolts not with a hex wrench head are almost always Philips but in modern stuf more often torque or Hex. Fred --- In TekScopes@..., "Dennis Tillman" <dennis@...> wrote:
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Re: Screwdriver for Pozidriv (Pozi) Screws used by Tek
Paul Kraemer
开云体育Pozidrive screwdriver tips are available in most DIY
stores like Lowes, Home Depot, Menards, Harbor Freight etc.---if you know where
to look for them. They are included in many of the multi bit sets, the ones that
have assortment of phillips, square, torx, plain---all those.
Phillips are marked P1etc and pozidrive are PZ1
etc.
They are there, just hiding.
Paul K0UYA
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David Hess