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Re: Need Help With Tek 453 Weird Problem
On Tue, Apr 5, 2022 at 07:18 AM, diyguitarist wrote:
I did notice that if I put the HorizontalAfter latest fixes is above behavior still there? When the switch is in between nothing is connected to horizontal amplifier. If you are seeing a dot in when switch is in between the issue is before horizontal amplifier. EXT HORIZ amplifier (sheet <10>) only has +12V and -12V supplies. -12V transformer is shared with the HV oscillator, HV oscillator might be coupling. I see that you already checked but you may want to double check the ripple on all the supplies, especially +75V, +12V and -12V, with a scope in AC coupled mode. Note that ripple spec is 2mVpp. C937 on sheet <16>, C1142 and C1151 on sheet <13> could be bad if there is ripple on -12V. Other possibility is sharing noisy equipment on the same power strip, check the scope in another room in another power outlet. Ozan |
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Re: Need Help With Tek 453 Weird Problem
I checked one of my 453s that is above 20,000. The TP voltages in the schematic are right. Check the transistors and diodes in that area. The 3,3mfd condenser could be bad. I have had ones with high ESR I replaced with Nichicon ULD type. R473, R674 and R483 I raised to 1 and 2W respectively. Yours could be high in resistance. The originals are 1/2W carbons. The tunnel diode will be good if you can get a signal to trigger.
The trace problems you describe sound like the astig and geometry(?) need adjusting. Mark |
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Re: Dogbone Capacitors
I have seen them in HP gear too, and I've mainly seen them referred to as 'dogbone' capacitors when referred to specifically.
Unless you specifically want them for an original appearance in a restoration, I suspect that modern MLCC capacitors are generally going to be far better performance-wise. Jared. |
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Re: Need Help With Tek 453 Weird Problem
UPDATE: I have looked at basically every circuit in the scope at this point. I have suspected that maybe there is an oscillation problem somewhere and even made a "snooping loop" as described in this Tektronix document but haven't found anything conclusive (I think).
So I can not find anything wrong other than two test points that seem to be backwards from the schematic. They are in the A Trigger Generator, test points TP485 & TP494. Having all of the scope controls set per Page 1 of the manual schematics, TP485 should be +12.5V and measures -0.32V & TP494 should be -0.98V and it measures +11.42V. These are almost exactly opposite of the schematic. Is there is a mistake on the schematic or do I have a legitimate problem here? This strange problem does definitely seem to be somehow related to the sweep, so I imagine it's more likely I have problem than the schematic being wrong. Interestingly, the snooping loop detects some activity in this same area and nowhere else except for the Z Axis PCB, where there is an oscillator for the CRT HV supply. However, if the problem is with A Trigger circuit, and if A & B sweep is grounded in Ext Horiz mode, then how can I possibly be getting this fuzzy halo around the waveform in X-Y mode? This is what confuses me. Additionally, I did notice one other interesting thing: Although I cannot get just a dot in Ext Horiz mode (I get a dot with an 1/8" line extending horizontally in both directions, about 1/4" total), I can get a beautifully round one in A & B sweep modes using the Norm Trigger setting with no input, if I turn the intensity up enough and move the dot into view with the Horizontal Position control. Not sure what I should looking at here... I'm used to working with positive only voltages and a ground. Any suggestions? |
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Re: 2432 calibration battery?
I have always had a good experience with Alex. I don't see how anyone could "fake" a 2465 Oscilloscope. The hardware is so unique.
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Yes, there are ways to enable additional Bandwidth for some models, Tektronix built them that way. I don't see that as a problem, the capability is already there, nothing needs to be "faked". Just my opinion, of course. Ross -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Jim Ford Sent: Thursday, April 21, 2022 1:09 PM To: [email protected] Subject: Re: [TekScopes] 2432 calibration battery? Ross, Alex Schonfeld has a bad reputation for selling fake 2465's. I don't think many people in this group would have anything to do with him. Just FYI.Jim FordSent from my T-Mobile 4G LTE Device -------- Original message --------From: si_emi_01 <wellington@...> Date: 4/21/22 9:28 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 2432 calibration battery? Yes, it does.It is located on the A12 Processor Board. It is a 3.5V 1.6AH Lithium Thionyl Chloride Battery. The Generic Part Number is: LTC-16P-CO-F-S. The only one I can see on Mouser is the LTC-16M version which they are out of stock until 5/23/2022. The 2465 Series uses a LTC-7P Battery that is 700mAH. The Batteries come in two flavors. One that is just a Battery, the other has a built-in 1.6k Resistor with a Series 1N5817 Schottky Diode (this is to prevent shorting and reverse Charging of the Battery in parallel configurations). The LTC-16P doesn't appear to have that feature.There is a procedure that can be performed that will preserve your RAM contents if the Battery isn't dead and you want to be pro-active. I would imagine it is probably paralleling the SRAM with an external supply greater than the 3.5V limited by a series Resistor while you change the old Battery. Just guessing here, you would have to make sure it is safe.Alex Schonfeld repairs and calibrates Tektronix Oscilloscopes. I had him calibrate my 2465B a few years ago after I replaced the Battery in mine. He does good work. Maybe he can help you.Depending on the Serial Number of your Oscilloscope, some Processor Boards use an integrated NVRAM (Battery Backed-up SRAM). The 2440 Processor uses a Dallas DS1230AB part that includes an SRAM and Back-up Battery in the same package. It can be replaced with later version NVRAM or FRAM chips. I don't know if they did that with the 2432 Oscilloscope. Maybe someone else on the List can provide that information. The TekWiki only one Service Manual on their site and it shows the Battery version.Ross-----Original Message-----From: [email protected] <[email protected]> On Behalf Of Bert HaskinsSent: Thursday, April 21, 2022 9:33 AMTo: TekScopes@...: [TekScopes] 2432 calibration battery?Does this scope have calibration data stored in battery backed ram?I have one of these in absolutely pristine condition that I hardly ever use.Thanks, Bert |
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Re: 2432 calibration battery?
Ross, Alex Schonfeld has a bad reputation for selling fake 2465's.? I don't think many people in this group would have anything to do with him.? Just FYI.Jim FordSent from my T-Mobile 4G LTE Device
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-------- Original message --------From: si_emi_01 <wellington@...> Date: 4/21/22 9:28 AM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 2432 calibration battery? Yes, it does.It is located on the A12 Processor Board. It is a 3.5V 1.6AH Lithium Thionyl Chloride Battery. The Generic Part Number is: LTC-16P-CO-F-S. The only one I can see on Mouser is the LTC-16M version which they are out of stock until 5/23/2022. The 2465 Series uses a LTC-7P Battery that is 700mAH. The Batteries come in two flavors. One that is just a Battery, the other has a built-in 1.6k Resistor with a Series 1N5817 Schottky Diode (this is to prevent shorting and reverse Charging of the Battery in parallel configurations). The LTC-16P doesn't appear to have that feature.There is a procedure that can be performed that will preserve your RAM contents if the Battery isn't dead and you want to be pro-active. I would imagine it is probably paralleling the SRAM with an external supply greater than the 3.5V limited by a series Resistor while you change the old Battery. Just guessing here, you would have to make sure it is safe.Alex Schonfeld repairs and calibrates Tektronix Oscilloscopes. I had him calibrate my 2465B a few years ago after I replaced the Battery in mine. He does good work. Maybe he can help you.Depending on the Serial Number of your Oscilloscope, some Processor Boards use an integrated NVRAM (Battery Backed-up SRAM). The 2440 Processor uses a Dallas DS1230AB part that includes an SRAM and Back-up Battery in the same package. It can be replaced with later version NVRAM or FRAM chips. I don't know if they did that with the 2432 Oscilloscope. Maybe someone else on the List can provide that information. The TekWiki only one Service Manual on their site and it shows the Battery version.Ross-----Original Message-----From: [email protected] <[email protected]> On Behalf Of Bert HaskinsSent: Thursday, April 21, 2022 9:33 AMTo: TekScopes@...: [TekScopes] 2432 calibration battery?Does this scope have calibration data stored in battery backed ram?I have one of these in absolutely pristine condition that I hardly ever use.Thanks,?? Bert
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Re: Thinking on CRT restorations for double peaking tubes.
Looked up Glyptal. I would suggest the red 1201. I am thinking that is the
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original formulation. On Thu, Apr 21, 2022, 1:15 PM JRN <ir25@...> wrote:
Dave, |
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Re: 2465 Calibration
Also correct. Thanks for pointing that out.
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Ross -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Mark Litwack Sent: Thursday, April 21, 2022 8:01 AM To: [email protected] Subject: Re: [TekScopes] 2465 Calibration Just a minor point of detail... The 2445 and 2465 (not A or B version) scopes don't have a battery. They have a GI ER1400 EAROM which is an early version of EEPROM. The ER1400 datasheet claims 10 year data storage. The EAROM in my 2465 is 38+ years old and hasn't lost anything yet (although I have backed it up). -mark On Wed, Apr 20, 2022 at 07:30 PM, si_emi_01 wrote: ...
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Re: DM501A Input Leakage Source
Hi Roman,
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Just for grins, what happens if you touch the input terminal of the plug-in while in dc volts mode? Don't touch ground the ground terminal at all -- just be an antenna. If the reading rises, try connecting a capacitor (say, some nanofarads) across the input terminals of that plug-in. A small amount of line noise pickup can be aliased down to dc by dual-slope converters. This test will tell you whether that's happening here. Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 On 4/21/2022 06:24, romeo987 wrote:
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Re: 2432 calibration battery?
Yes, it does.
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It is located on the A12 Processor Board. It is a 3.5V 1.6AH Lithium Thionyl Chloride Battery. The Generic Part Number is: LTC-16P-CO-F-S. The only one I can see on Mouser is the LTC-16M version which they are out of stock until 5/23/2022. The 2465 Series uses a LTC-7P Battery that is 700mAH. The Batteries come in two flavors. One that is just a Battery, the other has a built-in 1.6k Resistor with a Series 1N5817 Schottky Diode (this is to prevent shorting and reverse Charging of the Battery in parallel configurations). The LTC-16P doesn't appear to have that feature. There is a procedure that can be performed that will preserve your RAM contents if the Battery isn't dead and you want to be pro-active. I would imagine it is probably paralleling the SRAM with an external supply greater than the 3.5V limited by a series Resistor while you change the old Battery. Just guessing here, you would have to make sure it is safe. Alex Schonfeld repairs and calibrates Tektronix Oscilloscopes. I had him calibrate my 2465B a few years ago after I replaced the Battery in mine. He does good work. Maybe he can help you. Depending on the Serial Number of your Oscilloscope, some Processor Boards use an integrated NVRAM (Battery Backed-up SRAM). The 2440 Processor uses a Dallas DS1230AB part that includes an SRAM and Back-up Battery in the same package. It can be replaced with later version NVRAM or FRAM chips. I don't know if they did that with the 2432 Oscilloscope. Maybe someone else on the List can provide that information. The TekWiki only one Service Manual on their site and it shows the Battery version. Ross -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Bert Haskins Sent: Thursday, April 21, 2022 9:33 AM To: [email protected] Subject: [TekScopes] 2432 calibration battery? Does this scope have calibration data stored in battery backed ram? I have one of these in absolutely pristine condition that I hardly ever use. Thanks, Bert |
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Re: 2465 Calibration
Just a minor point of detail... The 2445 and 2465 (not A or B version) scopes don't have a battery. They have a GI ER1400 EAROM which is an early version of EEPROM.
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The ER1400 datasheet claims 10 year data storage. The EAROM in my 2465 is 38+ years old and hasn't lost anything yet (although I have backed it up). -mark On Wed, Apr 20, 2022 at 07:30 PM, si_emi_01 wrote:
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Re: DM501A Input Leakage Source
Greg,
Thanks for your response. I realize that this leakage does not affect the utility of the meter one whit. I am just trying to improve what I have, because I can. Academic, of course, but interesting. I am just a retired old bloke who loves to play. Not particularly interested in measuring fA and pV, but only in making my two instances of this meter as good as they can be. And I am intrigued that you appear to be in a lab that has 70¡¯s vintage 501As alongside Fluke 8588s. Says a bit for the longevity of this Tek stuff. I guess that¡¯s why we love to play with it! Just out of curiosity, what sort of offset do you see on yours on 200mV DC range, OC input? Is it always positive? Roman |
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Re: DM501A Input Leakage Source
Tom,
Thanks for your input. I do note that you are very generous with your advice on this board - as are many others. I really appreciate it. In this case, I think your first and third points are well made. As to the second, that is almost certainly true of a normal scope amplifier input, but in this case there are no such devices ¡°left¡± of the A/D chip itself, which I have absolved by test as the cause. Roman |
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Re: DM501A Input Leakage Source
Gudjon,
Thanks for your input. I have seen this, but it doesn¡¯t actually address switch removal :-(. But do those long plastic actuators unclip easily from the switch itself? Looks like it might be a plastic part just itching to be broken unless one does it just right! Roman |
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Re: Thinking on CRT restorations for double peaking tubes.
Thanks for this Dave. I need to roll this around a bit and understand how to hook everything up but it sounds like everything can be done here in the lab. Just need to understand where the grounds go and how all the references work out. To keep heater and cathode near the same potential.
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Zen -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Dave Brown Sent: Thursday, April 21, 2022 1:20 AM To: [email protected] Subject: Re: [TekScopes] Thinking on CRT restorations for double peaking tubes. I am passing this on from an ex-CRT engineer I know at the museum. - Dave 1. Increase the nominal 6.3V heater to 8V at least, possibly 10V if the cathode current is very weak 2. Keep heater and cathode very near the same potential 3. Apply AC voltage to the control grid, up to +6V Max. compared to cathode 4. Set the first anode at +100 to 150V to collect the electrons 5. Limit reactivation time to ~10 minutes; 20 minutes Max. Here¡¯s a 2015 note from Thomas Electronics where they recommend operation with cathode current for 24 hours: Normal CRT operation with cathode current is always good, especially in storage tubes where the flood gun electrons can form an ion pump. Mesh storage CRTs at Tektronix (in the 7613, 7623, etc.) had the best vacuum levels measured. Re: Potential leaks in glass-to-metal seals. Glyptal can be applied to the cracked glass, or before straightening badly bent pins. |
Jared Cabot
diyguitarist
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