Re: [volt-nuts] Some questions to zeners (1N823-1N829)
On 28/01/2013 22:47, Andreas Jahn wrote: After a run in phase of nearly 1 year the ageing of ADC #13 stabilized. Currently I compare ADC13 nearly every day with 3 heated references (1 LM399 = LM_2 and 2 LTZ1000A = LTZ_1/2). The last half year the ageing is about 0.5 to 1.5 ppm for 6 months compared to the heated references. See picture ADC13_longterm: X-Axis is day Y-Axis left is drift in ppm with red = LM399#2, green = LTZ1000A #1, blue = LTZ1000A #2 Y-axis right is temperature in degree celsius of the temperature sensor near ADC13 reference. By the way: up to now I could not measure any effect which is related to thermocouples. Ok my temperature step noise is still too high. And probably I am using the wrong connectors in my tests: cheap D-Sub connectors where a metal shield is equalizing the temperature of 2 relative close neighboured contacts. With best regards Andreas Andreas, Very interesting results - thanks for sharing your painstaking work. Hope you don't mind me asking a few questions though: How are you dealing with the issue of drift in the thermocouple measurements (including the cold junction compensation)? Do you calibrate it periodically? Thermocouples aren't noted for high stability - but presumably at room temperature its perhaps not much of an issue. Do you know what temperature the LTZ1000 references are operating at, and how long have they been operated for - ie. have they been aged prior to starting the long term test? (Presumably the answer to that is the fact that you are showing results from day 460 onwards?) Have you any insight into how stable the ADC's reference (AD586LJ) is? I.E. Have you made any occasional or periodic measurements with other calibrated instruments during the long term test or is it the long term test results themselves which leads you to state: After a run in phase of nearly 1 year the ageing of ADC #13 stabilized.? Thanks, Tony H ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 7081 AC buffer *again*
House standard should be pretty close as it's a Trimble Thunderbolt GPS. However, I don't *think* that is the culprit as thjis is just close to 10MHz, rather than spot on. So yes, oscillation is likely. Regards, David Partridge -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of J. L. Trantham Sent: 30 January 2013 04:15 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] 7081 AC buffer *again* Is it possible that it is, somehow, 'picking up interference' from your 'house standard'? How close to 10.000 000 000 MHz is it? 100 mV P-P is fairly substantial. Otherwise, is it oscillating? Good luck. Joe ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] 7081 AC buffer *again*
Ed, thank you, that pencil trick is one I don't know. One of the problems with being self taught. Mind you, if it is FB round the op-amp, then anywhere in the FB loop might well show as a culprit :( Regards, David Partridge -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Ed Breya Sent: 30 January 2013 04:57 To: volt-nuts@febo.com Subject: Re: [volt-nuts] 7081 AC buffer *again* I agree with JL - it's either picking up an available frequency, or making its own. Oscillation can happen with transistors, especially any common-base amplifiers or emitter followers that don't have enough degeneration - but that is usually in the VHF range. For MHz-type oscillations, look for opamp loops that went unstable for some reason - bad grounds or bypassing can do it. An old trick for VHF is to poke around with the tip of a wood-sheathed lead pencil - the partially-conductive graphite core and the lossy wooden capacitance to an even lossier hand would sometimes damp oscillations and point directly to the problem, so to speak. For lower frequency you need brute force - try a small screwdriver, a meter probe lead, or tweezers held in the hand, and just poke around on various nodes, without shorting anything out. If that's not enough, a small RC series damper - say 1000 pF and a few hundred ohms - with a clip lead to ground should show some results. All you're looking for is some effect - it should either reduce or aggravate the problem when you are around the problem circuit. You will naturally be injecting all kinds of line frequency and RF interference into any high-Z circuits, so ignore that and just look for the effects at the target frequency. Ed ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7071 beeping about twice a second (J. L.Trantham)
Bill, I'm looking at power supply problems right now ... the three 47uF capacitors (C56 - C58) in the 40V supply were all very ill (two had huge series resistance and measured as about 20uF, and the other one was a 10M resistor). It is remarkable that the 40V supply was even partially functional. Massive ripple on that supply for at least 10 seconds after power on. I'm currently waiting for the post to deliver the replacement caps. Regards, David Partridge -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Bill Ezell Sent: 29 January 2013 21:51 To: volt-nuts@febo.com Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second (J. L.Trantham) On 01/28/2013 12:00 PM, David C. Partridge david.partri...@perdrix.co.uk wrote: I've got a problem with a 7071 which is beeping at me about twice a second, and also flashes the COMPUTE and DIG FILT LEDs on the front panel at the same rate. I can't find anything in any versions of my service or operating manuals that correspond to that failure. I suspect you have a significant failure in the earthy-side processor board. You replaced your ROMs at one point, didn't you? I'd try swapping in a new set just to be sure one didn't die. Otherwise, you've probably got some difficult diagnosing to do. Can you get anything over the RS-232 link? -- Bill Ezell They said 'Windows or better' so I used Linux. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7071 beeping about twice a second (J.L.Trantham)
Ho-hum, it wasn't the capacitors :( Dave -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C. Partridge Sent: 30 January 2013 10:36 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second (J.L.Trantham) Bill, I'm looking at power supply problems right now ... the three 47uF capacitors (C56 - C58) in the 40V supply were all very ill (two had huge series resistance and measured as about 20uF, and the other one was a 10M resistor). It is remarkable that the 40V supply was even partially functional. Massive ripple on that supply for at least 10 seconds after power on. I'm currently waiting for the post to deliver the replacement caps. Regards, David Partridge -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Bill Ezell Sent: 29 January 2013 21:51 To: volt-nuts@febo.com Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second (J. L.Trantham) On 01/28/2013 12:00 PM, David C. Partridge david.partri...@perdrix.co.uk wrote: I've got a problem with a 7071 which is beeping at me about twice a second, and also flashes the COMPUTE and DIG FILT LEDs on the front panel at the same rate. I can't find anything in any versions of my service or operating manuals that correspond to that failure. I suspect you have a significant failure in the earthy-side processor board. You replaced your ROMs at one point, didn't you? I'd try swapping in a new set just to be sure one didn't die. Otherwise, you've probably got some difficult diagnosing to do. Can you get anything over the RS-232 link? -- Bill Ezell They said 'Windows or better' so I used Linux. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7071 beeping about twice a second
Further information: Shorting pins 5 and 6 of PL2 causes the same symptoms, as does pressing and holding the DIG FILT key on another meter. The odd thing is though that an ohms test between 5 and 6 of keyboard is OC - which does not make sense to me? Dave -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C. Partridge Sent: 30 January 2013 17:15 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second Joe, Looks like you win the prize for remote diagnosis! Disconnecting PL2 which goes to the keyboard, and it all comes up nicely. What I can do about that though I am not at all sure ... :( Dave -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of J. L. Trantham Sent: 29 January 2013 03:14 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second I wonder if it might mean multiple 'stuck' buttons on the front panel. Any way to check that? Perhaps disconnecting the front panel and reconnecting? Perhaps making measurements on the front panel itself? Good luck. Joe ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7071 beeping about twice a second
And just to make a monkeys uncle out me, it just started working after reconnecting the keyboard for the nth time. Confused ... You bet, especially as I cannot now provoke the fault (except by holding down the DIG-FILT key or shorting pins 5 and 6). Dave -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C. Partridge Sent: 30 January 2013 17:49 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second Further information: Shorting pins 5 and 6 of PL2 causes the same symptoms, as does pressing and holding the DIG FILT key on another meter. The odd thing is though that an ohms test between 5 and 6 of keyboard is OC - which does not make sense to me? Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7071 beeping about twice a second
Joe, Looks like you win the prize for remote diagnosis! Disconnecting PL2 which goes to the keyboard, and it all comes up nicely. What I can do about that though I am not at all sure ... That is a remarkable catch. You can disassemble the front panel quite easily. It could be as simple as a bad bypass cap, an intermittent short, or, yes, a sticky switch. If the last, you do have a bit of problem. It might be possible to just work it a bit and get it to unstick. I don't remember the construction of the switches, but I have a vague recollection that the flexible silk-screen button is separate from the actual switch. If so, you can probably find something that will work. Note also that there are a number of ICs on the front panel PCB. You could have a bad IC. If, for example, interrupt is being continually asserted, that could certainly keep the self-test from completing. (happened to me on a 7061) -- Bill Ezell They said 'Windows or better' so I used Linux. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7071 beeping about twice a second
All the stuff on the PCB and the PCB itself are only used for the display. The keyboard is completely independent and is completely stupid (just a row/column arrangement of switches inside the front panel which are connected to PL2). The front panel and keys are AFAIK a sealed unit with no possibility for repair. Regards, David Partridge -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of Bill Ezell Sent: 30 January 2013 22:59 To: volt-nuts@febo.com Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second Joe, Looks like you win the prize for remote diagnosis! Disconnecting PL2 which goes to the keyboard, and it all comes up nicely. What I can do about that though I am not at all sure ... That is a remarkable catch. You can disassemble the front panel quite easily. It could be as simple as a bad bypass cap, an intermittent short, or, yes, a sticky switch. If the last, you do have a bit of problem. It might be possible to just work it a bit and get it to unstick. I don't remember the construction of the switches, but I have a vague recollection that the flexible silk-screen button is separate from the actual switch. If so, you can probably find something that will work. Note also that there are a number of ICs on the front panel PCB. You could have a bad IC. If, for example, interrupt is being continually asserted, that could certainly keep the self-test from completing. (happened to me on a 7061) -- Bill Ezell They said 'Windows or better' so I used Linux. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
Re: [volt-nuts] Solartron 7071 beeping about twice a second
One other thing. I presume that when you push the 'DIG-FILT' key, pin 5 and 6 are 'shorted' when measured on the key board connector. I think this is what you are saying but just want to make sure. If so, then I would conclude that there is a piece of conductive 'FOD' loose in the keyboard or the key was stuck. You might want to connect your 'beeping' DMM to indicate a short to pins 5 and 6 from the keyboard then shake the keyboard to see if it will 'beep' when you get it in the proper position. If an occasional beep occurs, then I would try to open the keyboard and clean the connectors. Joe -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of J. L. Trantham Sent: Wednesday, January 30, 2013 1:50 PM To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second I wonder if you have a small piece of 'FOD' floating around in the front panel contacts? I have never taken a front panel for one of these apart but would suspect there would be a way to separate the buttons from their contacts and perhaps clean them. If you could do the disassembly in a clean plastic tub then carefully inspect for any small 'pieces' that might fall out, it might explain what the problem was. Glad you are making progress. Joe -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C. Partridge Sent: Wednesday, January 30, 2013 12:53 PM To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second And just to make a monkeys uncle out me, it just started working after reconnecting the keyboard for the nth time. Confused ... You bet, especially as I cannot now provoke the fault (except by holding down the DIG-FILT key or shorting pins 5 and 6). Dave -Original Message- From: volt-nuts-boun...@febo.com [mailto:volt-nuts-boun...@febo.com] On Behalf Of David C. Partridge Sent: 30 January 2013 17:49 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] Solartron 7071 beeping about twice a second Further information: Shorting pins 5 and 6 of PL2 causes the same symptoms, as does pressing and holding the DIG FILT key on another meter. The odd thing is though that an ohms test between 5 and 6 of keyboard is OC - which does not make sense to me? Dave ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. ___ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
