Re: Sick TG501 Main 1Mhz ref not running.
These are straight TTL ICs.? The logic 1 level is roughly 4 volts or so.? All that a logic 1 needs to do is back bias an (equivalent) input diode.? Look at DTL logic (old!) to find an equivalent circuit, and then start replacing the input diodes with (typically) a multiple emitter transistor for a nand gate.
The 16 ma for a chip is also not too out of line, in my experience.
What I'd be looking for would be either slow switching times at the chip outputs or significantly lower 1 output voltages, or higher than normal 0 output levels.
Should two TTL outputs be shorted (that are not open collector), bad output levels are to be expected even from good chips.
Note:? the output high driver of a TTL chip is effectively an emitter follower with the collector and base resistor going to VCC.? There's a limit to what the transistor can pull up, so the 1 output is rated at about 400 ua source, and the standard TTL output (a saturating transistor to ground) is typically 16 ma. Since the output sinking transistor is driven (more or less) by the full VCC through an effective resistor, it gets plenty of base drive.
Harvey
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On 12/4/2021 9:40 AM, Zentronics42@... wrote: Shaun,
Just tried to order the Tauntek but the boards are sold out. I was informed that there will be a delay in getting new boards so. But no worries I am on the waiting list. I will take a closer look at the drum switch. I would imagine it is a cam switch or something in the IC's that the cam is switching. I tested U330 but totally unloaded the single IC is drawing about 16 ma which seems a touch high to me. And when I wire a gate to get a logic level flip the (high) output is only 4Vdc on some of the gates and this is with the IC out of the unit on a breadboard. So it cant get to 5V totally unloaded. VCC is 5.2 to match the TG 5V rail. This is why I am thinking the IC is marginal. Though I could also be asking to much from an IC of this vintage.
Zen
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Shaun M
Sent: Saturday, December 4, 2021 9:23 AM
To: [email protected]
Subject: Re: [TekScopes] Sick TG501 Main 1Mhz ref not running.
Zen,
I had a similar problem (double time marks) on a TG501 unit several months ago. It turned out that one finger of the drum switch assembly was not opening when it should have due to mechanical damage. I found the problem using the switch matrix in the SM which allowed me to figure out the proper position of each switch finger. The matrix is located on the “Display and Switch Details” page of the schematic section in the SM.
On the subject of vintage IC testing: The Tauntek tester lets you see pin voltages and overall current for a given chip as well as the usual logic testing.
Shaun M
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When the sweep quit working in my 465 it was Capacitor C1220 in the Horizontal Amp section that shorted to ground. I replaced this capacitor with an Aluminum Electrolytic, (it was a wet Tantalum), and scope has been working fine since then. I read a Service Notice somewhere that recommended replacing this Cap in units below a certain serial number series but can't remember the numbers. Apparently this cap is known for failures in certain old scopes. I would check it for short.
David
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Re: Sick TG501 Main 1Mhz ref not running.
Shaun,
Just tried to order the Tauntek but the boards are sold out. I was informed that there will be a delay in getting new boards so. But no worries I am on the waiting list. I will take a closer look at the drum switch. I would imagine it is a cam switch or something in the IC's that the cam is switching. I tested U330 but totally unloaded the single IC is drawing about 16 ma which seems a touch high to me. And when I wire a gate to get a logic level flip the (high) output is only 4Vdc on some of the gates and this is with the IC out of the unit on a breadboard. So it cant get to 5V totally unloaded. VCC is 5.2 to match the TG 5V rail. This is why I am thinking the IC is marginal. Though I could also be asking to much from an IC of this vintage.
Zen
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Shaun M Sent: Saturday, December 4, 2021 9:23 AM To: [email protected]Subject: Re: [TekScopes] Sick TG501 Main 1Mhz ref not running. Zen, I had a similar problem (double time marks) on a TG501 unit several months ago. It turned out that one finger of the drum switch assembly was not opening when it should have due to mechanical damage. I found the problem using the switch matrix in the SM which allowed me to figure out the proper position of each switch finger. The matrix is located on the “Display and Switch Details” page of the schematic section in the SM. On the subject of vintage IC testing: The Tauntek tester lets you see pin voltages and overall current for a given chip as well as the usual logic testing. Shaun M
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Re: Sick TG501 Main 1Mhz ref not running.
Zen,
I had a similar problem (double time marks) on a TG501 unit several months ago. It turned out that one finger of the drum switch assembly was not opening when it should have due to mechanical damage. I found the problem using the switch matrix in the SM which allowed me to figure out the proper position of each switch finger. The matrix is located on the “Display and Switch Details” page of the schematic section in the SM.
On the subject of vintage IC testing: The Tauntek tester lets you see pin voltages and overall current for a given chip as well as the usual logic testing.
Shaun M
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Inexpensive pozidrive screwdriver option
Saw tools discussed again, opened a new thread for easy search. A great starter screw driver starter set is Vessel 220W.Made in japan, includes both pozidrive and JIS. These have been a go-to for Japanese motorcycle owners for years.
Can be found on your favorite e-retailer or auction site for less than $20.
Craig
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Re: Sick TG501 Main 1Mhz ref not running.
This will be an extended troubleshooting experience. However one I asked for when I offered to help. I am running in to several marginal ICs in this unit. So I have a few IC testers on the way, I think I am going to need them. I am currently focused on U330, U300, and U235 in the switch circuit. With an external clock I can get the unit to behave enough to get good time marks out of it. However the frequency is no where near correct. And only 3 positions of the dial even look correct. All the other positions of the dial result in double time marks. I can post a picture if it will make more sense. I will also have a part 1 video out soon. The time marks look normal at 2us 1us and .5us everything else is doubled up and has time marks on top of slower time marks.
Variable timing seems to work as it should. And with an external clock now gives me readouts instead of 0.4 and not moving. So making some headway but still a ways to go before I get this back up to running.
Zen
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Jared Cabot via groups.io Sent: Saturday, December 4, 2021 2:03 AM To: [email protected]Subject: Re: [TekScopes] Sick TG501 Main 1Mhz ref not running. On Sat, Dec 4, 2021 at 08:34 AM, Dave Peterson wrote:
BTW, my homemade FR4 trimmer has set up nicely. I'm going to wait
another day before trying it out on C515. I am looking forward to
using it on the 2ns and 1ns Filter caps. I feel I've already tuned
them well, but this all seems to require repeated fine tuning.
On my TG501A I went through the adjustment process about 4 times before I had it nailed right down. A number of the adjustments interact with each other so a couple passes will get everything playing nicely with each other.
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FS (Canada) : TDS340A for parts
Hi,
I'm trying to get rid of a TDS 340A that "mostly works", except for the following :
- bad attenuator on CH 2, causing SPC and calibration errors
- bad DS1644 (NVRAM) battery, causing more errors
Otherwise, display is sharp, CH1 works fine, etc. Also has option 14 (RS232 and GPIB).
I'd like to get 80$ for it (includes free shipping anywhere in Canada)
Will consider offers, or selling separate parts.
I also have some photos and details on (uscan)-tektronix-tds-340a-with-dead-ch2/msg3581608/
Email / PM me if interested !
Thanks,
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Re: Sick TG501 Main 1Mhz ref not running.
On Sat, Dec 4, 2021 at 08:34 AM, Dave Peterson wrote:
BTW, my homemade FR4 trimmer has set up nicely. I'm going to wait another day
before trying it out on C515. I am looking forward to using it on the 2ns and
1ns Filter caps. I feel I've already tuned them well, but this all seems to
require repeated fine tuning.
On my TG501A I went through the adjustment process about 4 times before I had it nailed right down. A number of the adjustments interact with each other so a couple passes will get everything playing nicely with each other.
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Re: TG501 2ns & 1ns operation
On Fri, Dec 3, 2021 at 06:15 AM, Jared Cabot wrote:
the little metal tip was changing the capacitance just enough to alter the
rather touchy adjustments.
Well given the permittivity of metals, and the conductivity of steel, I'm thinking the de-tuning is more of an induced effect... and especially given the permittivity of ceramics... and for me the plastic tuning sticks (of with I have many... are good... or home-made ones, as described. There's always a 'better' mouse trap... especially if it catches the same number of mice as a much cheaper one... but, makes somebody more money. -- Roy Thistle
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Re: Sick TG501 Main 1Mhz ref not running.
I was going to suggest Leo’s GPSDO but you figured that out before I got ‘round to typing. I know that the desire for high precision/high accuracy can be an obsession! For calibrating scopes, something less elaborate more than suffices. Even the cheapest CPU clock oscillators are good to 200ppm. You’ll never see that error on a scope. But high accuracy clocks are now available for a song. I have a rubidium standard, and although I don’t do any work requiring 10ppb accuracy, the fact that I have one caused me to check every frequency counter and every frequency source I own and tweak out whatever errors could be tweaked out. Ridiculous! But fun.
Enjoy the Quest For the Last Digit!
— Cheers
Tom
Sent from my iThing, so please forgive typos and brevity.
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On Dec 3, 2021, at 3:35 PM, Dave Peterson via groups.io <davidpinsf@...> wrote:
? Thanks Jeff,
Michael pointed me to the appropriate section of the SM (RTFM Dave). I see there is an oscillator available on eBay. Not sure I feel the need to spend another $50 on eBay just today. I just bought an S-53 to enable viewing 1GHz signals. It was an impulse buy, sure, but this has been on my mind. And now I feel the need to have that capability. So I need to pace my spending. (Why start now!?)
Another intriguing possibility I've found in the SM is the possibility of using an external clock. So it seems I could pipe the Leo Bodnar GPSDO directly into the TG501. Now there's some time mark stability and accuracy! It should be easy to add a BNC to the back of a TM50x.
BTW, my homemade FR4 trimmer has set up nicely. I'm going to wait another day before trying it out on C515. I am looking forward to using it on the 2ns and 1ns Filter caps. I feel I've already tuned them well, but this all seems to require repeated fine tuning. And hopefully with the S-53 I'll be able to observe the 1ns signal at full BW (this will go in a 7S12 with S-6 sampler which is working quite well with my now working S-52).
Dave
On Friday, December 3, 2021, 03:21:58 PM PST, Jeff Dutky <jeff.dutky@...> wrote:
Dave,
I had thought that I had seen a video by either Jared Cabot (NFM) or Zen (Zenwizard) showing the addition of Option 01 to a TG 501, but I can't seem to find it now. I may have been thinking of Jared's video about adding a similar option to a DC503A.
The TG 501 Option 01 seems to consist of basically two components: U50 (a 7490 TTL decade counter) and Y50 (a 5MHz crystal oscillator, possibly ovenized?). The part numbers for Y50 are either Electronic Research Co. EROS-600-TK-9 (SN below B034510) or Bliley Electric Co. T15B141 (SN B034510 and above). I imagine that any 5 MHz TXCO or OCXO can be made to work, with effort.
The service manual has this to say about Option 1:
The TG 501 Option 01 is equipped with a temperature-compensated, 5 MHz crystal oscillator for a highly stable and precise internal clock. U50 provides countdown circuitry for the 5 MHz crystal.
Remove U100 and disconnect pin 3 of U350 before using external clocks. To disconnect pin 3 remove U350, bend pin 3 out then insert U350 back in tcurciut board.
The main circuit board jumpers that must be installed for Option 01 are: J3 and J7 (see. Fig. 5-2 for jumper location).
-- Jeff Dutky
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Re: Sick TG501 Main 1Mhz ref not running.
Thanks Jeff,
Michael pointed me to the appropriate section of the SM (RTFM Dave). I see there is an oscillator available on eBay. Not sure I feel the need to spend another $50 on eBay just today. I just bought an S-53 to enable viewing 1GHz signals. It was an impulse buy, sure, but this has been on my mind. And now I feel the need to have that capability. So I need to pace my spending. (Why start now!?)
Another intriguing possibility I've found in the SM is the possibility of using an external clock. So it seems I could pipe the Leo Bodnar GPSDO directly into the TG501. Now there's some time mark stability and accuracy! It should be easy to add a BNC to the back of a TM50x.
BTW, my homemade FR4 trimmer has set up nicely. I'm going to wait another day before trying it out on C515. I am looking forward to using it on the 2ns and 1ns Filter caps. I feel I've already tuned them well, but this all seems to require repeated fine tuning. And hopefully with the S-53 I'll be able to observe the 1ns signal at full BW (this will go in a 7S12 with S-6 sampler which is working quite well with my now working S-52).
Dave
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On Friday, December 3, 2021, 03:21:58 PM PST, Jeff Dutky <jeff.dutky@...> wrote:
Dave,
I had thought that I had seen a video by either Jared Cabot (NFM) or Zen (Zenwizard) showing the addition of Option 01 to a TG 501, but I can't seem to find it now. I may have been thinking of Jared's video about adding a similar option to a DC503A.
The TG 501 Option 01 seems to consist of basically two components: U50 (a 7490 TTL decade counter) and Y50 (a 5MHz crystal oscillator, possibly ovenized?). The part numbers for Y50 are either Electronic Research Co. EROS-600-TK-9 (SN below B034510) or Bliley Electric Co. T15B141 (SN B034510 and above). I imagine that any 5 MHz TXCO or OCXO can be made to work, with effort.
The service manual has this to say about Option 1:
The TG 501 Option 01 is equipped with a temperature-compensated, 5 MHz crystal oscillator for a highly stable and precise internal clock. U50 provides countdown circuitry for the 5 MHz crystal.
Remove U100 and disconnect pin 3 of U350 before using external clocks. To disconnect pin 3 remove U350, bend pin 3 out then insert U350 back in tcurciut board.
The main circuit board jumpers that must be installed for Option 01 are: J3 and J7 (see. Fig. 5-2 for jumper location).
-- Jeff Dutky
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Re: Sick TG501 Main 1Mhz ref not running.
Dave,
I had thought that I had seen a video by either Jared Cabot (NFM) or Zen (Zenwizard) showing the addition of Option 01 to a TG 501, but I can't seem to find it now. I may have been thinking of Jared's video about adding a similar option to a DC503A.
The TG 501 Option 01 seems to consist of basically two components: U50 (a 7490 TTL decade counter) and Y50 (a 5MHz crystal oscillator, possibly ovenized?). The part numbers for Y50 are either Electronic Research Co. EROS-600-TK-9 (SN below B034510) or Bliley Electric Co. T15B141 (SN B034510 and above). I imagine that any 5 MHz TXCO or OCXO can be made to work, with effort.
The service manual has this to say about Option 1:
The TG 501 Option 01 is equipped with a temperature-compensated, 5 MHz crystal oscillator for a highly stable and precise internal clock. U50 provides countdown circuitry for the 5 MHz crystal.
Remove U100 and disconnect pin 3 of U350 before using external clocks. To disconnect pin 3 remove U350, bend pin 3 out then insert U350 back in tcurciut board.
The main circuit board jumpers that must be installed for Option 01 are: J3 and J7 (see. Fig. 5-2 for jumper location).
-- Jeff Dutky
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Re: TG501 2ns & 1ns operation
If it comes to precision and ceramic tools for electronics I have always been fond of "Bernstein", a company based at Remscheid, Germany. Never cheap but well made. Somewhat bigger tools? I do prefer HAZET, again based at Remscheid. I have been fixing old cars for over 40 years now and some spanners have been in use from the first day up to now. And for coarse jobs I'd suggest "Ridgid" from Ridge tool company, Elyria, Ohio.
Not all the fine tools are European made! But well, I am old fashioned and really avoid buying from Asia as far as possible.
Regards, Joe
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Re: Sick TG501 Main 1Mhz ref not running.
On Mon, Nov 29, 2021 at 11:39 AM, Michael W. Lynch wrote:
Zen,
I converted all of my TG501s over to "Option 1" Units with the 5Mhz
Oscillator. This might be a solution as well.
--
Michael Lynch
Dardanelle, AR
Michael, I'd like to consider making this conversion. My TG501 timing is doing fine with its 1MHz oscillator, but my finicky nature would like to achieve the +/- 5x10^-7 option 1 seems to give. I would think this would directly bear on the accuracy of the 1ns timing marks? Do you have something of a BOM for the conversion? Feel free to reply off list if you prefer. Thanks, Dave
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Re: TG501 2ns & 1ns operation
Jared Cabot wrote:
(I also have cheap ebay ceramic screwdrivers that work great)
I said that they got the job done. I would not say that the "work great." The set I have was $13 (US) for 8 pieces, but several of the shafts are not straight in the plastic handle, and the swivels on the back do not turn smoothly, so you can't really use them like you would a proper jeweler's screwdriver. The work, but not great. I will have to invest in some quality Japanese tools, but the Vessel screwdrivers cost more for a single screwdriver than I paid for all eight cheap Chinese ones. -- Jeff Dutky
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Re: TG501 2ns & 1ns operation
On Fri, Dec 3, 2021 at 11:44 AM, Jared Cabot wrote:
Even when I was living in Australia, I would seek out Japanese and German
tools.
When working on Japanese motorcycles, a set of JIS screwdrivers is a must,
they have parallel flutes (like a Pozidriv minus the extra little flutes
between the larger ones), so if you try to use a Philips driver with its
tapered flutes, you'll very quickly damage or destroy the screws.
I only buy tools from Germany, Japan, USA and Taiwan (ROC), (in no particular order). I have Snap-On tools that are in excess of 50 years old and still being used daily. Tools from China, India and Pakistan (among others) are at the very bottom of my list, except where I know that the tool will only be used once, is to be modified or needs to be disposable. -- Michael Lynch Dardanelle, AR
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non-conductive tools (was: TG501 2ns & 1ns operation)
I found a seller that combines shipping, so the total for three ceramic drivers was $5.10
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Re: TG501 2ns & 1ns operation
On Sat, Dec 4, 2021 at 12:05 AM, Michael W. Lynch wrote: Jared,
I was able to find these two brands on AMAZON. Vessel makes a great set of JIS
Screwdrivers as well, invaluable when working on Japanese equipment. I also
found some very high quality, German made Pozi-Drive screwdrivers there. As a
professional motorcycle mechanic, I was exposed early on to high quality
Japanese tools. HONDA used many KOWA SEIKI brand tools. I have owned and
used these for 40+ years.
There is definitely a difference in the quality of the Japanese tools.
--
Michael Lynch
Dardanelle, AR
I'm lucky in this regard that I live in Japan, so obtaining Japanese tools is somewhat unavoidable. :) Even when I was living in Australia, I would seek out Japanese and German tools. When working on Japanese motorcycles, a set of JIS screwdrivers is a must, they have parallel flutes (like a Pozidriv minus the extra little flutes between the larger ones), so if you try to use a Philips driver with its tapered flutes, you'll very quickly damage or destroy the screws. On Sat, Dec 4, 2021 at 12:40 AM, Dave Peterson wrote: Jared,
So does your TG501A have a small amount of 500MHz signal on MARKER OUT in 1ns
mode?
Here is what I see, just random noise and junk. I guess Tek engineers assumed users wouldn't care much what was on the unused outputs when the others were in use maybe?
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Re: TG501 2ns & 1ns operation
On Fri, Dec 3, 2021 at 04:40 PM, Dave Peterson wrote:
I've been looking them up. I like the ceramic solutions, but am disappointed
that they tend to be the stubby type that don't have a lot of reach. I'm
currently fashioning an FR4 tip for the trimmer I made out of a hard
toothbrush handle.
I like my trimming screwdrivers as stubby as possible, because of their small rotational elasticity. It helps overcome the trimmer's friction, providing higher precision control. A ceramic stem works much better than materials like plastic and even FR4. Raymond
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Re: TG501 2ns & 1ns operation
Jared,
Thanks for the pics. I suspect at some point I'll pick up a modern DSO that can handle frequencies above 500MHz, just so I can capture such signals.
The "signal" that was causing me concern was the MARKER OUT output in 1ns mode. I know that the 1ns signal is on the "1ns ONLY" output. The question in my mind that I was trying to understand was what was MARKER OUT supposed to do while in 1ns mode? It seemed that the 2ns output might remain on the MARKER OUT. Raymond corrected my understanding pointing out that K450 shuts off the 2ns Filter output from MARKER OUT, which unloads it enabling a somewhat larger 1ns ONLY output. But in 2ns mode, there is still a fair level out on 1ns ONLY. I was a bit concerned about the low 1ns level, but I knew I was in BW limit territory. Feedback from the group reinforces that suspicion.
So does your TG501A have a small amount of 500MHz signal on MARKER OUT in 1ns mode?
Regarding trimmer tools: I'm sure you're all well aware of the variety of trimmer pots, caps, and inductors we encounter in Tek equipment. Not only are there a variety of cross sections (philips, flat, torx, hex, ...) there are also a variety of depths and diameters to contend with. This is why I'm trying homemade solutions first. I'm perfectly happy to spend a little, or even a lot, for a tool that works. I have, and have had, a number of trimmers that work well in some situations and not others. Have we all had the situation where you can't get the trimmer through the access hole in the cover plate? Or the pot/cap is just out of reach? It surprises me how many available trimmers have a small shaft that would fit through a small access hole, but have hardly any length so the pot/cap remains just out of reach of the tool. Alternatively there are long slender trimmers that are too weak to turn old frozen pots/caps because of their thin plastic construction. But if one uses metal there's shorting risk and/or capacitive impact.
I do appreciate the recommendations. I've been looking them up. I like the ceramic solutions, but am disappointed that they tend to be the stubby type that don't have a lot of reach. I'm currently fashioning an FR4 tip for the trimmer I made out of a hard toothbrush handle. The epoxy is setting as we speak. I tried the shaped tip on C515 to see if it could stand up to the torque required. Worked like a charm. Now I need to test my craftsmanship. I suspect I'll make a few types, and based on what works I'll buy something online once I know the dimensions I need.
Thanks all!Dave
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On Friday, December 3, 2021, 06:15:09 AM PST, Jared Cabot via groups.io <jaredcabot@...> wrote:
Both Vessel and Engineer brands are very good Japanese brands I have a bunch of tools from both brands. You can find them everywhere here in Japan, not sure about other countries though..
For reference, here is the output on my somewhat adjusted TG501A measured on my 1GHz TDS784C scope.
1ns -
2ns -
5ns -
Marker Output @ 0.1us -
+Trig Output @ 0.1us -
I found that my usual plastic adjustment screwdriver with the little metal tip would affect the adjustments for the 2ns and 1ns trimmer capacitors, making accurate adjustment almost impossible.
I guess the little metal tip was changing the capacitance just enough to alter the rather touchy adjustments. Switching to a ceramic screwdriver made it a breeze (I also have cheap ebay ceramic screwdrivers that work great).
Also, I found that putting the side cover on made a small impact to the output amplitude, probably due to the close proximity of the grounded cover plate to the trimmer capacitors.
Luckily the cover plate on the TG501A is a perforated style, so I could juuussstt squeeze the screwdriver in through the holes (sometimes at an angle) with the cover plate in place to tweak the trimmer pots for the best output.
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Shaun M
Jared Cabot
Dave Peterson
Joe
Michael W. Lynch
Raymond Domp Frank