Re: TDS460A Will not turn on?
- This link has some tips on TDS 460 power supply repair. You may find them useful.
- This is a tutorial on SMPS repair. Though not related to TDS460, this is a general information on SMPS repair.
Warm Regards,
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Re: TDS460A Will not turn on?
Thank you Michael.
In my experience, usually 2 things that affect the SMPS are, the "bootstrap" or startup pulse generation or the output feedback loop i.e. optocoupler - "Control pulse".
Warm Regards,
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Re: Why does the DC509 have a GHz indicator?
Thanks for the info, Greg!
-Dave
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On Saturday, August 17, 2019, 12:52:08 PM PDT, Greg Muir via Groups.Io <big_sky_explorer@...> wrote:
Dave,
One small caveat regarding the addition of the DP501 if you ever consider picking one up.? Making it work properly with the DC509 requires addition of interconnections between the DP501 and DC509 which is usually accomplished through adding a mating jumpered D connector to the interface connector (option 02 somewhat rarely found) on the rear of the TM50x power module (mainframe).? The DP501 is a divide-by-16 prescaler meaning that any signal passed through it in the prescale mode is divided by 16 instead of a ¡°normal¡± decade factor.? Tek came up with a somewhat unusual idea where they alter the DC509 clocking to make it work with the unusual divided signal from the DP501 to display a normal count.
If you do not possess a TM50x power module with the D interface connector on the rear you will have to go in and add a few jumpers to the backplane.? The interconnection arrangement between the two modules is called out in the DP501 manual.? I keep a internally modified TM502 for this purpose.
Since the DP501 is only useful between 100 MHz and 1.3 GHz, it possesses a front panel button to allow you to bypass the prescaling function at lower frequencies to allow the DC509 to operate in its normal mode.? This changes the counter back to its normal clocking as well as keeps you from having to juggle cables between the two when looking at those lower frequencies.
Greg
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Re: SC502 Scope -20v Supply at -28v and Won¡¯t Adjust
Thanks for the help Bruce. Pins 2 and 3 of the op amp are about 3 volts apart. The pass transistor appears to have a short between collector and emitter. I¡¯m going to order a replacement. Should I look into anything else as a possible cause?
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Does anyone know the official part number for the cover used on the Tektronix 492/496 Spectrum Analyser?
Gary
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Re: TDS460A Will not turn on?
Steve,
Excellent Information. As you can probably tell, I am quite the novice, especially when it comes to SMPS operation. My limited knowledge of SMPS told me that they must be "loaded" in order to come on. I read that in the manual and in my mind, I was thinking to do exactly what you described. However, I was also very unsure that this was the proper solution. I am very reluctant to experiment with a potentially repairable power supply. I think the 1 amp load needs to be on pin #20, if memory serves me correctly. Thank you for your valuable input. As I have stated, I do not want to make things worse by doing the wrong thing.
--
Michael Lynch
Dardanelle, AR
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Re: TDS460A Will not turn on?
Ravi,
Certainly. I will post in the PHOTOS Section shortly. I have Tried to get some good photos for your reference. Feel free to contact me off list with any questions.
Sincerely,
--
Michael Lynch
Dardanelle, AR
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Re: 11801C and the T1331 error: lost factory TB calibration data.
Hi, Reg.I am so envious of the 11000 series toys, er I mean tools, you have!? For now, I will have to be content with my 7000 series sampling gear including two S-4 heads.? Not that easy to even get a stable trace on the screen.? But, at a few hundred dollars, the price is right these days.?I agree with you that this is a golden age for test equipment acquisition.? ?May it continue for posterity!Enjoy!Jim Ford?Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: "Reginald Beardsley via Groups.Io" <pulaskite@...> Date: 8/17/19 5:40 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] 11801C and the T1331 error: lost factory TB calibration data. very interesting information.? Thanks.The 11801 series has what has to be the worst FW anyone has ever written for a scope as you will shortly experience first hand.? But they really are *fantastic* despite that.? Just watch out for the bugs.? If I execute the wrong sequence of operations I get a 1-2 order of magnitude error in the times on my 11801.IIRC they will interpolate to 200 femtoseconds.? Even at coax velocity of 2e8 m/s, that's so small a distance as to be rather "challenging".? As in measuring 40 microns "challenging".Without a detailed theory of operation, schematics, etc, it is nearly impossible to divine what Tek was doing.? I'd love to know.?? The circuitry is so fast, that even 30 years later, Keysight can just barely beat the rise time of the 11801 calibrator.I've got 2x SD-22,? 4x SD-26 and a nice crisp 11801, with another 11801 and SD-26 for parts in CA and an SD-24 in transit.? Honest, all I need now is just *one* SD-32 ;-)Prepare to be amazed.?? With an SD-24 or SD-26 & the calibrator, you can test RF connectors to 20 GHz as fast as you can connect and disconnect them.Have Fun!Reg
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Re: 11801C and the T1331 error: lost factory TB calibration data.
very interesting information. Thanks.
The 11801 series has what has to be the worst FW anyone has ever written for a scope as you will shortly experience first hand. But they really are *fantastic* despite that. Just watch out for the bugs. If I execute the wrong sequence of operations I get a 1-2 order of magnitude error in the times on my 11801.
IIRC they will interpolate to 200 femtoseconds. Even at coax velocity of 2e8 m/s, that's so small a distance as to be rather "challenging". As in measuring 40 microns "challenging".
Without a detailed theory of operation, schematics, etc, it is nearly impossible to divine what Tek was doing. I'd love to know. The circuitry is so fast, that even 30 years later, Keysight can just barely beat the rise time of the 11801 calibrator.
I've got 2x SD-22, 4x SD-26 and a nice crisp 11801, with another 11801 and SD-26 for parts in CA and an SD-24 in transit. Honest, all I need now is just *one* SD-32 ;-)
Prepare to be amazed. With an SD-24 or SD-26 & the calibrator, you can test RF connectors to 20 GHz as fast as you can connect and disconnect them.
Have Fun!
Reg
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Re: SC502 Scope -20v Supply at -28v and Won¡¯t Adjust
Start by checking the voltages at U930 pins 2 and 3.
These should be about +6.9V and equal.
Then work towards the series pass transistor.
Note voltages on a printout of the circuit schematic for the low voltage power supplies.
Bruce
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On 18 August 2019 at 11:15 dcane4@... wrote:
Hello.
I recently acquired an SC502 for my TM503. It¡¯s working, but in the course of running through the checks in the manual I found that the -20v supply is at -28v, and turning the -20v adjustment pot has no effect. The pot checks okay. The two tantalums in the -20v supply are not shorted; I haven¡¯t tested them beyond that. Any suggestions on which components to focus on would be greatly appreciated. Thanks. Dave
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SC502 Scope -20v Supply at -28v and Won¡¯t Adjust
Hello.
I recently acquired an SC502 for my TM503. It¡¯s working, but in the course of running through the checks in the manual I found that the -20v supply is at -28v, and turning the -20v adjustment pot has no effect. The pot checks okay. The two tantalums in the -20v supply are not shorted; I haven¡¯t tested them beyond that. Any suggestions on which components to focus on would be greatly appreciated. Thanks. Dave
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Re: 2467B focus/astigmatism anomaly...
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Re: 2467B focus/astigmatism anomaly...
On Sat, Aug 17, 2019 at 03:14 PM, Chuck Harris wrote:
My thought is the only way a new astigmatism voltage for optimal focus can be
required is if the beam current has changed between the gun's anode #1 and the
astigmatism lens. If you can believe the stacking of the electrodes shown in
the schematic, the focus lens comes before the astigmatism, and after the
anode #1.
And, it is the toughest to meter, as it is 1.4KV roughly, and about 15M
resistance.
I didn't give Q4432 much thought... perhaps I should, as it would shift the
focus
electrode voltage quite nicely... It is an MPSA94, which is about as you
surmised,
VCBO and VCEO = 400V
The beam current definitely changes each time between turning intensity down and up again, as the case describes. Although I can understand a jittery/jumping Q4432 role, is there a reason *not* to suspect C4403 leakage? You *did* find a broken Q4402 earlier, didn't you? And where/how does the intensity down/then up scenario cause Q4432 to make its jump, since normally there's (virtually) no (change in) current in the focus electrode circuit? Still sitting on my earlier post... Raymond
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Re: Why does the DC509 have a GHz indicator?
Dave,
One small caveat regarding the addition of the DP501 if you ever consider picking one up. Making it work properly with the DC509 requires addition of interconnections between the DP501 and DC509 which is usually accomplished through adding a mating jumpered D connector to the interface connector (option 02 somewhat rarely found) on the rear of the TM50x power module (mainframe). The DP501 is a divide-by-16 prescaler meaning that any signal passed through it in the prescale mode is divided by 16 instead of a ¡°normal¡± decade factor. Tek came up with a somewhat unusual idea where they alter the DC509 clocking to make it work with the unusual divided signal from the DP501 to display a normal count.
If you do not possess a TM50x power module with the D interface connector on the rear you will have to go in and add a few jumpers to the backplane. The interconnection arrangement between the two modules is called out in the DP501 manual. I keep a internally modified TM502 for this purpose.
Since the DP501 is only useful between 100 MHz and 1.3 GHz, it possesses a front panel button to allow you to bypass the prescaling function at lower frequencies to allow the DC509 to operate in its normal mode. This changes the counter back to its normal clocking as well as keeps you from having to juggle cables between the two when looking at those lower frequencies.
Greg
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Re: Need Help Troubleshooting Tektronix PS280
Power supply design is a series of tradeoffs.? It may be that size and cost (for a heatsink, let alone other things) suggested using a common design with a tapped transformer.
About the worst case for a linear supply is a very low output voltage at the maximum current.? The pass transistor is getting rid of the difference as heat.? This design would certainly fix that.
A switching regulator would work reasonably well, but has more noise, more complexity and the like.? If you were going to do a massive enough power supply, it might be better to have a switching pre-regulator, then a linear regulator to make the output behave.? I may have seen a design like this with an SCR bridge feeding a linear regulator.
Harvey
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On 8/17/2019 2:48 PM, daven9ooq via Groups.Io wrote: Many Thanks to all who have replied, My wife is off work for the next 3days ,so I probably won't be able to get much more done until then??From the sound of it seems like it's worth fixing? ,I did recap both variable supplies the 5volt fixed supply Was working so left it alone.
I used good quality Nichicon throughout ,off hand I forgot the series, using a? ebay cheap transistor \ component tester I found the esr of the smaller electrolytics? worse than the larger ones around 1ohm on the 4.7 uf 50 volt , and about the same for the 47uf ,the 470's didn't look that grate either didn't check the main filter as too big for the zif socket on my tester.
Since I'm working one handed and it was pretty difficult to get the board out? so I replaced everything , Don't want to do it again 6months down the line, also want something I can depend on.
?I have plenty of 50-60 + year old Tek equipment with Sprague electrolytics that still work , That said + the tons of? bad PS280's on ebay don't speak well of the Tiawan capacitors I did take the time to look up the company Jamicon.
My wife is Asisn ,so I have nothing against Asian except cheep coppies of good stuff. That said there has long been a need in this contry for good affordable test equipment.
So I can and do appreciate the need to keep a tight budget on stuff, the overall quality of the PS280 isn't bad? but I have a Astron VS50M? a 37 Amp 50 surge it is slightly adjustable .it uses a LM723 regulator and 8-2N3771 RCA pass transistors it has current limiting and most Hams in the Group can speak to thequality of it,? when you have a 4thousand dollar radio hooked up to it you need a good quality supply!
It seems to me the multi tap relay switching is? helpfull but maybe? unnecessary as one single heatsinked 2N3055 is good up to15 amps!I don't know enough about the heat dissapation to say for sure.
Also the constant voltage/ current switching is only a gimick as it a function of settings not selectable by user togeather they over complicate what should be a straightforward supply! And could save money.
But that is just my thinking, I could be wrong!
Thanks guys for the insights!
At this point I think everything is basically working but there are a lot of adjustments to do and you need a slew of load resistors to do.?Some I have some I have on order, others I need to find and order.
Thanks again!Dave n9ooq
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Re: Need Help Troubleshooting Tektronix PS280
Many Thanks to all who have replied, My wife is off work for the next 3days ,so I probably won't be able to get much more done until then??From the sound of it seems like it's worth fixing? ,I did recap both variable supplies the 5volt fixed supply Was working so left it alone.
I used good quality Nichicon throughout ,off hand I forgot the series, using a? ebay cheap transistor \ component tester I found the esr of the smaller electrolytics? worse than the larger ones around 1ohm on the 4.7 uf 50 volt , and about the same for the 47uf ,the 470's didn't look that grate either didn't check the main filter as too big for the zif socket on my tester.
Since I'm working one handed and it was pretty difficult to get the board out? so I replaced everything , Don't want to do it again 6months down the line, also want something I can depend on.
?I have plenty of 50-60 + year old Tek equipment with Sprague electrolytics that still work , That said + the tons of? bad PS280's on ebay don't speak well of the Tiawan capacitors I did take the time to look up the company Jamicon.
My wife is Asisn ,so I have nothing against Asian except cheep coppies of good stuff. That said there has long been a need in this contry for good affordable test equipment.
So I can and do appreciate the need to keep a tight budget on stuff, the overall quality of the PS280 isn't bad? but I have a Astron VS50M? a 37 Amp 50 surge it is slightly adjustable .it uses a LM723 regulator and 8-2N3771 RCA pass transistors it has current limiting and most Hams in the Group can speak to thequality of it,? when you have a 4thousand dollar radio hooked up to it you need a good quality supply!
It seems to me the multi tap relay switching is? helpfull but maybe? unnecessary as one single heatsinked 2N3055 is good up to15 amps!I don't know enough about the heat dissapation to say for sure.
Also the constant voltage/ current switching is only a gimick as it a function of settings not selectable by user togeather they over complicate what should be a straightforward supply! And could save money.?
But that is just my thinking, I could be wrong!
Thanks guys for the insights!
At this point I think everything is basically working but there are a lot of adjustments to do and you need a slew of load resistors to do.?Some I have some I have on order, others I need to find and order.
Thanks again!Dave n9ooq
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Re: General Radio 874 Connector, inner conductor "bendies"
The GR 1232A Tuned Amplifier and Null Detector has an 874 connector at the input. It receives audio signals from diode mixer/detectors used in RF measurement systems that mostly had 874 connectors.
Roy sends.
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On Aug 17, 2019, at 11:56 AM, Dale H. Cook <bridgewaterma@...> wrote:
On 8/17/2019 11:40 AM, Roy Thistle wrote:
I don't recall seeing any of them using the 874... probably because they are AF, or RF units? 874 connectors were pretty much universally used on GR RF instruments manufactured after 1948.
--
Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
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Re: 465B Fan repair help needed
A couple of years ago I got a 465 and a 465B.? The 465 worked but had no fan.? The 465B had no CRT but a good fan so I moved the fan over and all has been well since.
I really don't recall what I had to do but the two fans weren't identical.? There was a board that had to be transferred as well, as I recall, but mechanically the mounting was the same.
So perhaps you can pick up a 465 and use the fan from that one.
It occurred to me to swap the 465 and the 465B carcass for that digital unit I am hoping you get for me.? It works great except the intensity varies sometimes and needs readjustment.
Bob K6DDX
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On Saturday, August 17, 2019, 11:11:35 AM PDT, Robert Simpson via Groups.Io <go_boating_fast@...> wrote:
Working on a 465B and noticed the fan doesn't rotate. With? the rear cover removed, the blade seems to turn easily. I got the impeller off, but it looks like the A1 board needs to be removed to get at the fan motor and control board. Is that the right way to go about trying to fix the fan?
Also, I found the message from Walter about an alternate fan replacement if it comes to that.
Bob
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465B Fan repair help needed
Working on a 465B and noticed the fan doesn't rotate. With the rear cover removed, the blade seems to turn easily. I got the impeller off, but it looks like the A1 board needs to be removed to get at the fan motor and control board. Is that the right way to go about trying to fix the fan?
Also, I found the message from Walter about an alternate fan replacement if it comes to that.
Bob
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Re: Why does the DC509 have a GHz indicator?
That makes sense; the prescaler is barely mentioned in the manual- that's why I missed it.
-Dave
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On Saturday, August 17, 2019, 12:40:16 AM PDT, Dave Casey <polara413@...> wrote: It has a GHz indicator because it can count (and read out) up to 1.3 GHz when used in concert with the DP501 prescaler. Dave Casey On Sat, Aug 17, 2019 at 2:32 AM Dave Seiter <d.seiter@...> wrote: Since the DC509 is spec'd at 135MHz, and apparently tops out around
200+MHz, why does it have a GHz indicator?? I've skimmed the manual and
don't see a reason for it.? Maybe I've been up for too long and am missing
something obvious?? Does this counter have any known issues to watch out
for?
-Dave
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Gary Robert Bosworth
Mlynch001
Raymond Domp Frank