Acqusition board available, cheap
I have a surplus acquisition board, P/N 679-4774-02 (from the label) or
G9F-2841-00 (from the top copper layer). It was, as far as I know,
working when pulled out of its host TDS520. The 'scope itself sustained
mechanical damage in shipping, though its electronics were not affected.
Anyone interested? How does $30 and free shipping within the USA sound?
Thanks much.
--
---
Bruce Lane, ARS KC7GR
kyrrin (at) bluefeathertech dot com
"Quando Omni Flunkus Moritati" (Red Green)
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Re: 2465B Replace Aluminum Electrolytics with Tantalum
I don't share your disdain for tantalum electrolytic capacitors.? Their dramatic failure modes to happen when they are operated near their rated voltage.? For this reason, I de-rate their voltage application by more than 4:1.? That seems pretty safe by most accounts.? Also, I chose capacitors with an ESR equivalent or less than the aluminum capacitors they replaced (smaller ones were available at higher ESR).? I know nothing of the "ethics" of tantalum capacitors or their vendors. ?
On the other hand, I know that SMD aluminum electrolytic capacitors are known to leak electrolyte onto the PCB.? Newer ones may not do it so often, but they do it.? When they do, they nearly always destroy portions of the board.? Tantalum electrolytic capacitors do not leak.? I considered ceramic capacitors but their capacitance values are voltage sensitive and that dictates significant voltage derating for them too.
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On ?Sunday?, ?August? ?12?, ?2018? ?02?:?20?:?50? ?PM? ?CDT, Hawker <rick@...> wrote:
So you replaced parts who's current main failure mode is less capacitance with a part who's known normal failure modes are burns up in flames taking out the PCB or short circuit taking out the parts before? And we won't even touch on the questionable ethics of Tantalum. I have NEVER seen a quality electrolytic made after the mid 1990s leak unless it was over temperatured or over voltaged. I'm pretty sure that is a bygone problem.
Doesn't seem like a smart move to me.? A modern LOW ESR 5k hour 105C electrolytic should be far Superior to Tantalum with the ESR going 2-4 octaves higher with a safer part.? You could possibly use a X7R or X5R MLCC for even lower ESR that goes 10 octaves longer and reliability but some of those older circuits are not ceramic stable and X7R/X5R are micro-phonic, where other options are not.
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Re: 2465B Replace Aluminum Electrolytics with Tantalum
So you replaced parts who's current main failure mode is less capacitance with a part who's known normal failure modes are burns up in flames taking out the PCB or short circuit taking out the parts before? And we won't even touch on the questionable ethics of Tantalum. I have NEVER seen a quality electrolytic made after the mid 1990s leak unless it was over temperatured or over voltaged. I'm pretty sure that is a bygone problem.
Doesn't seem like a smart move to me. A modern LOW ESR 5k hour 105C electrolytic should be far Superior to Tantalum with the ESR going 2-4 octaves higher with a safer part. You could possibly use a X7R or X5R MLCC for even lower ESR that goes 10 octaves longer and reliability but some of those older circuits are not ceramic stable and X7R/X5R are micro-phonic, where other options are not.
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DM501A AC range calibration
Howdy all.
Was trying to calibrate a DM501A this weekend. DC volts calibrated with no issues however AC volts and dBmV did not.
In both cases I ran out of pot room just a tad before I had it in agreement with my Fluke 289 meter that I used for reference.
I'm debating if I should just not worry about it. It is such an old meter.
Any idea what is the normal reason they don't reach calibration range? I used a 500Hz signal to calibrate but I saw no difference at 100Hz or 1KHz so I don't think the issue is around there.
I'm wondering how deep I'll have to go to fix this one. It looks like dBmV doesn't have enough resolution to be useful so I'm not so worried about that.
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Re: 2465B Replace Aluminum Electrolytics with Tantalum
On 8/11/2018 4:28 PM, machineguy59 via Groups.Io wrote: See this photo album /g/TekScopes/album?id=66462 for my recent repairs on a 2465B. This 2465B had modest corrosion on the A5 board from leaking aluminum electrolytic capacitors. On this board the pads for C2222 and C2520 were partially eaten away and R2013 itself had failed completely (R2013 pads were OK). A few cycles of applying flux, hot air heating, then wash with PCB cleaner and the board was ready for repair. But I wanted a repair that did not suffer the same fate as the OEM assembly.
Todays aluminum electrolytic capacitors have more robust seals than the ones Tek had available in the 1990's. Also, hand soldering the capacitors to the board avoids severely heating the capacitor seals as happens with wave soldering systems. Still, electrolytic capacitors always eventually fail anelectrolyticd often leak electrolyte onto the PCB. Tantalum electrolytics do not have this failure mode, at least not often, because they are made different. So I resolved to replace the four aluminum electrolytic capacitors with SMD tantalum electrolytic capacitors. I understand that Tektronix did something like that with certain 2465B scopes manufactured in Guernsey, UK (see here /g/TekScopes/photo/12841/0?p=Name,,,20,1,0,0 ).
So I elongated one pad of each mounting for C2011, C2113, C2331, and C2965. This was simple to do. Each of these capacitors have a through hole or trace on one pad that can be cleaned and a copper foil strip can be soldered to elongate that pad by 1 to 2 mm (I was neat, not precise). This allowed me to hand solder 2917 package size SMD capacitors. I chose electrolytic
and an ESR of less than 1 Ohm in each case. The result is working very well. I will try to report back in 30 years on how the reliability turned out.
That 30 years might not be so far off. Has anyone on this list ever seen one of these solid Ecaps ever "wear" out? I often replace aluminum electrolytics with the solid SMD parts. I have yet to see one of these fail in service. -Bert
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On Sat, 11 Aug 2018 20:31:33 -0700, you wrote: All the lights ought to come on, then the power up sequence starts. You should hear relays clicking, and you should see different lights on the front panel. If not, then you have a possible power supply problem, or a possible processor problem. There are diagnostic modes that you should be able to use to check out the processor. However, another possibility is that the display has failed. If so, then you can plug in a computer display to the scope and you should be able to see something. I'd do that first, then check power supply voltages, then check the processor, etc. Harvey On Sat, Aug 11, 2018 at 8:27 PM Thomas Dodge <tdodge2404@...> wrote:
Hi,
My name is Tom, and I haven't sent any emails in a while. I just bought a
Tektronix TDS 648A scope. I plugged it in for the first time, and all the
lights come on, but no intensity at all. Does anyone know how to approach
this issue? Thanks a lot.
Tom
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FYI: Tektronix 7S12+S6+S52+S53+S54 TDR/Sampler - Outstanding Condition!
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Re: scanned: 545B and 561 Instrument Reference Books
A big THANX for all the effort !
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On Sat, Aug 11, 2018 at 8:27 PM Thomas Dodge <tdodge2404@...> wrote: Hi,
My name is Tom, and I haven't sent any emails in a while. I just bought a
Tektronix TDS 648A scope. I plugged it in for the first time, and all the
lights come on, but no intensity at all. Does anyone know how to approach
this issue? Thanks a lot.
Tom
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do you have anything points that you think will help in this process ?? Things to pay attention to. Only to be careful with the high voltage and the complex reassembly process. My replacement transformers were layer wound but the originals are pie (universal) wound. Chuck Harris on this group has wound beautifully made replacements for the 547 transformer that is similar but not identical. I don't know if he might be able to do a pair of 556 trannies. Good luck! Morris
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Re: SG 504 leveled sine wave generator.
Took the chance to recal. the unit using better precision gear than specified in the manual.
Improved the 6Mhz reference accuracy to -0.06dBm vs -0.12dBm with the R270 & R280 amplitude adjustments. Given the several connections from the new SMA leveling heads (adapters & 10dB attenuator to an N type power head). I'd guess the 0.06dBm loss is to be expected at 6Mhz.
All reference power levels are about spot on from 1Vpp thru 5Vpp now with the 6Mhz freq. Sometimes a little glitch helps u improve your instrument!
At the frequencies 245Mhz to 700Mhz I am seeing at most a 0.15dBm loss at 4Vpp thru those connectors, sometimes a bit less (freq dependent). The new Leveling head stub tuning offsets/negates the connector loss (by compensating upward) at the hi end of the range (1Ghz). So from about 700 Khz to 1Ghz the connector losses steadily diminish to nil.
8D
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Re: 2465B Replace Aluminum Electrolytics with Tantalum
And me 108 years.? That is if my electrolyics don't leak out.
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On ?Saturday?, ?August? ?11?, ?2018? ?09?:?07?:?45? ?PM? ?CDT, Leon Robinson <leon-robinson@...> wrote: Lets see that would make me 107 Years Young. Sounds like you did a good job.?Leon Robinson ?? K5JLR Political Correctness is a Political Disease. ? ? ? From: machineguy59 via Groups.Io <machineguy59@...> To: [email protected] Sent: Saturday, August 11, 2018 3:28 PM Subject: [TekScopes] 2465B Replace Aluminum Electrolytics with Tantalum ? See this photo album /g/TekScopes/album?id=66462 for my recent repairs on a 2465B.? This 2465B had modest corrosion on the A5 board from leaking aluminum electrolytic capacitors.? On this board the pads for C2222 and C2520 were partially eaten away and R2013 itself had failed completely (R2013 pads were OK).? A few cycles of applying flux, hot air heating, then wash with PCB cleaner and the board was ready for repair.? But I wanted a repair that did not suffer the same fate as the OEM assembly. Todays aluminum electrolytic capacitors have more robust seals than the ones Tek had available in the 1990's.? Also, hand soldering the capacitors to the board avoids severely heating the capacitor seals as happens with wave soldering systems.? Still, electrolytic capacitors always eventually fail and often leak electrolyte onto the PCB.? Tantalum electrolytics do not have this failure mode, at least not often, because they are made different.? So I resolved to replace the four aluminum electrolytic capacitors with SMD tantalum electrolytic capacitors.? I understand that Tektronix did something like that with certain 2465B scopes manufactured in Guernsey, UK (see here /g/TekScopes/photo/12841/0?p=Name,,,20,1,0,0 ). So I elongated one pad of each mounting for C2011, C2113, C2331, and C2965.? This was simple to do.? Each of these capacitors have a through hole or trace on one pad that can be cleaned and a copper foil strip can be soldered to elongate that pad by 1 to 2 mm (I was neat, not precise).? This allowed me to hand solder 2917 package size SMD capacitors.? I chose 4:1 or better voltage derating and an ESR of less than 1 Ohm in each case.? The result is working very well.? I will try to report back in 30 years on how the reliability turned out.
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SG 504 leveled sine wave generator.
Hi y'all:
Was doing some calibrations on some precision, stub tuned (+/- 0.10dBm @ 4Vpp, full range) leveling heads over the past couple of weeks for the EBAY sale listing that I put up occasionally when I have time.
The SG-504 plugin started to behave a bit wonky on the Hi band and I would have to change bands and power up and down a lot to get it to stabilize for a few mins.
Finally got out the extender cable and spent an hour on it checking around (hot/cold air/ tapping etc). Eventually managed to locate the problem as the Hi band current trimmer near the card edge connector. The wiper was intermittent.
Just an FYI if u see such behaviour in your units.
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Re: 2465B Replace Aluminum Electrolytics with Tantalum
Lets see that would make me 107 Years Young. Sounds like you did a good job.?Leon Robinson ?? K5JLR Political Correctness is a Political Disease. From: machineguy59 via Groups.Io <machineguy59@...> To: [email protected] Sent: Saturday, August 11, 2018 3:28 PM Subject: [TekScopes] 2465B Replace Aluminum Electrolytics with Tantalum See this photo album /g/TekScopes/album?id=66462 for my recent repairs on a 2465B.? This 2465B had modest corrosion on the A5 board from leaking aluminum electrolytic capacitors.? On this board the pads for C2222 and C2520 were partially eaten away and R2013 itself had failed completely (R2013 pads were OK).? A few cycles of applying flux, hot air heating, then wash with PCB cleaner and the board was ready for repair.? But I wanted a repair that did not suffer the same fate as the OEM assembly. Todays aluminum electrolytic capacitors have more robust seals than the ones Tek had available in the 1990's.? Also, hand soldering the capacitors to the board avoids severely heating the capacitor seals as happens with wave soldering systems.? Still, electrolytic capacitors always eventually fail and often leak electrolyte onto the PCB.? Tantalum electrolytics do not have this failure mode, at least not often, because they are made different.? So I resolved to replace the four aluminum electrolytic capacitors with SMD tantalum electrolytic capacitors.? I understand that Tektronix did something like that with certain 2465B scopes manufactured in Guernsey, UK (see here /g/TekScopes/photo/12841/0?p=Name,,,20,1,0,0 ). So I elongated one pad of each mounting for C2011, C2113, C2331, and C2965.? This was simple to do.? Each of these capacitors have a through hole or trace on one pad that can be cleaned and a copper foil strip can be soldered to elongate that pad by 1 to 2 mm (I was neat, not precise).? This allowed me to hand solder 2917 package size SMD capacitors.? I chose 4:1 or better voltage derating and an ESR of less than 1 Ohm in each case.? The result is working very well.? I will try to report back in 30 years on how the reliability turned out.
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2465B Replace Aluminum Electrolytics with Tantalum
See this photo album /g/TekScopes/album?id=66462 for my recent repairs on a 2465B. This 2465B had modest corrosion on the A5 board from leaking aluminum electrolytic capacitors. On this board the pads for C2222 and C2520 were partially eaten away and R2013 itself had failed completely (R2013 pads were OK). A few cycles of applying flux, hot air heating, then wash with PCB cleaner and the board was ready for repair. But I wanted a repair that did not suffer the same fate as the OEM assembly. Todays aluminum electrolytic capacitors have more robust seals than the ones Tek had available in the 1990's. Also, hand soldering the capacitors to the board avoids severely heating the capacitor seals as happens with wave soldering systems. Still, electrolytic capacitors always eventually fail and often leak electrolyte onto the PCB. Tantalum electrolytics do not have this failure mode, at least not often, because they are made different. So I resolved to replace the four aluminum electrolytic capacitors with SMD tantalum electrolytic capacitors. I understand that Tektronix did something like that with certain 2465B scopes manufactured in Guernsey, UK (see here /g/TekScopes/photo/12841/0?p=Name,,,20,1,0,0 ). So I elongated one pad of each mounting for C2011, C2113, C2331, and C2965. This was simple to do. Each of these capacitors have a through hole or trace on one pad that can be cleaned and a copper foil strip can be soldered to elongate that pad by 1 to 2 mm (I was neat, not precise). This allowed me to hand solder 2917 package size SMD capacitors. I chose 4:1 or better voltage derating and an ESR of less than 1 Ohm in each case. The result is working very well. I will try to report back in 30 years on how the reliability turned out.
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On Sat, Aug 11, 2018 at 05:29 PM, tom jobe wrote:
Hi Leo,
Yesterday I found the Fluke thermocouple and did some tests on a 2215A.
First I disconnected the optional fan, then let the scope run with two
traces like you did.
The temperature of the Mosfet Q9070 ceramic heat sink piece stabilized
at 54.0 degrees C in a 29.5 degree room.
I removed Q9070 and discovered it was a TP3N40 Mosfet that I doubt was
original, The only datasheet I found for it suggested that it was a 3
Amp part rated at 400 volts with an RDS(on) of 3.3 Ohms.
The Mosfet replacement I have used for years on 22xx's is the common
IRF840, so I put one of them in for Q9070.? According to the datasheet,
this is an 8 Amp 500 Volt part with an RDS(on) of 0.75 Ohms.
Later in the day, the 2215A stabilized with a temperature of 56.5
degrees in a 30 degree room.
Maybe I did not wait long enough the first time, because the results
were not quite what I expected?
In any case, I consider this 2215A to be functioning normally so this
range of Mosfet temperatures must be what we should expect to see.
I also believe that this 2215A has all of the standard component values
you would expect it to have for R909 etc.
tom jobe...
Hi Tom, I think we both see about the same temperatures, when I did my measurements it was around 32-33 degree Celsius in the room and mine ended at 59 Celsius (I really need aircon in there!!). The higher R-on FET does give a slightly higher temperature, but only like 2-3 degrees, so I think I'll wait for the fan to put in and call it a day. I like the 2215A for having the nice things like delayed timebase, and being light as well, in the future this will be my carry-on scope. That way I can leave the 2465B's and my TDS540B at home... :-) Thanks for filling in the blanks, Un saludo, Leo
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Hi Leo,
Yesterday I found the Fluke thermocouple and did some tests on a 2215A.
First I disconnected the optional fan, then let the scope run with two traces like you did.
The temperature of the Mosfet Q9070 ceramic heat sink piece stabilized at 54.0 degrees C in a 29.5 degree room.
I removed Q9070 and discovered it was a TP3N40 Mosfet that I doubt was original, The only datasheet I found for it suggested that it was a 3 Amp part rated at 400 volts with an RDS(on) of 3.3 Ohms.
The Mosfet replacement I have used for years on 22xx's is the common IRF840, so I put one of them in for Q9070.? According to the datasheet, this is an 8 Amp 500 Volt part with an RDS(on) of 0.75 Ohms.
Later in the day, the 2215A stabilized with a temperature of 56.5 degrees in a 30 degree room.
Maybe I did not wait long enough the first time, because the results were not quite what I expected?
In any case, I consider this 2215A to be functioning normally so this range of Mosfet temperatures must be what we should expect to see.
I also believe that this 2215A has all of the standard component values you would expect it to have for R909 etc.
tom jobe...
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On 8/10/2018 10:14 AM, satbeginner wrote: Hi all,
Hi Tom,
I tested for temperature this afternoon again, after I performed a full calibration on the scope.
So, the scope had been running for several hours when I did this measurement.
I used a 80-TK Fluke surface temperature probe, holding it flush with the small heatsink just next to the FET, that was the hottest spot I found.
At that point in time the scope was just running with both traces visible, where trace A was showing the "calibration" signal.
Hello Ed,
in the end I consider my modification of the PS minimal, I used a lower ON-resistance FET (better, but maybe a slightly higher "switch-on" current?), and I reduced the Gate series resistor, where Tek in some models removed it even completely. (maybe the faster current pulse is not filtered as it should be, so maybe some may be injected into the grid?)
In my humble opinion is adding a fan also in the category minimal, again, because Tek used several FAN configurations in basically the same Power Supply.
Hola Vincent,
I think even the 2-or 3-wire PC fans have electronics inside.
Usually these fans are brushless, so they need some form of rotating magnetic field, and this is generated by a cheap and simple oscillator and coil driving circuit.
Some information can be found here:
I added some pictures of the temperature taking in the album: /g/TekScopes/album?id=64919
Un saludo,
Leo
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Thanks for the info morrios , do you have anything points that you think will help in this process ??? Things to pay attention to.?
On Sat, Aug 11, 2018 at 5:22 AM, Morris Odell<vilgotch@...> wrote: I have uploaded scans of the hv transformer drawings to a folder in the Photos area called (not surprisingly) "556 high voltage transformers".
Good luck!
Morrios
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Re: scanned: 545B and 561 Instrument Reference Books
I don't currently have Instrument Reference Books for any instruments later than the early 1960s. If I find them, I will scan them and share the scans.
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On Fri, Aug 10, 2018 at 11:54 PM, <kickingypsy9@...> wrote:
hey all,i have a 464 with no crt display.front pannel lights work. i have the
service man..wow what a book ! Any comon problems causing crt not to light?
Are all the low voltages correct?
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Bruce Lane
Ancel
satbeginner