Re: Is my Tek 468 beyond repair?
The 74HCT112 is only guaranteed for 24MHz clock. The 74S112 is rated for 80MHz minimum. The 74F112 is rated for 100MHz min.
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of John Sent: Monday, September 21, 2020 11:30 AM To: [email protected]Subject: Re: [TekScopes] Is my Tek 468 beyond repair? To test, connect pin 14 to +5, pin-7 to ground and pin 8 is the output. Pin 1 is no connect. tgerbic, ok, I think I get this now. There are only 4 actual pins, but their positions are mapped onto a 14 pin DIL package? So far corners would be 1, 7, 8 and 14 as indicated? You are correct that pin 7 is connected to ground. It isn't very visible but a continuity test confirms it. So there is a very easy albeit brutal sounding way of dealing with removing DIL type chips: I tried the de-soldering gun and solder sucker but this only removed solder from the top of the joint leaving the hole clogged. Similar problem with the IC pins. From one side the hole looked clean but the other side was still firmly soldered in place. Basically there is no chance of removing any DIL device from this board without a specialised DIL de-soldering tool or snipping pins so removal is going to be destructive and any replacement will have to go into a socket. With the crystal, the problem is that there is no access to the pins so the only way I could test was in situ by cutting the output pin track and soldering 3 short wires to the pins in question. Unfortunately this resulted in no output from the crystal. My copy of the manual has U128 and U230 as 74S122 (not LS122), my memory says that most LS devices are rated to around 40MHz which is why I suggested HCT as a possible alternative. Roger is quite correct. The ICs are 74S112. Earlier I had mistakenly stated 74LS112 but I had mis-read the diagram. Using 74HCT112's sounds like a good idea Incidentally, why are the two caps on the 5V rail such specific values? They are marked Sprague 637D 540¦ÌF 25VDC and 672D 390¦ÌF 0-15VDC but no indication of tolerence. I couldn't find any data on these, but would 680¦ÌF and 470¦ÌF 105deg be suitable replacements? I am just putting together an order to RS. Seems to work out cheaper than ordering individual bits from eBay. Also the 74LS112 is considerably cheaper than the 74HCT112 which I can only get on eBay.
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Re: Looking for TM503B manual
Thanks for the info!
I've seen a couple versions of the TM503 too, even what looked like a TM5003 of sorts with no markings or real part number, it appeared to be a part of a 'pre-built' unit that was never designed to be used with normal TM modules.
It may have been the same as the one you played with in your link..
Jared.
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On Mon, Sep 21, 2020 at 06:24 AM, Dennis Tillman W7pF wrote:
Hi Jared,
Congratulations on finding a TM503B. "B" versions of a product are uncommon
for Tek to make. They are an indication that the product sold very well. Tek
was also convinced it would continue to sell well. There were two main reasons
to create a "B" version of a product.
1) To update it to meet current market requirements such as new electrical
standards, safety standards, international environmental standards (such as
being free of lead or mercury), energy efficiency goals, etc.
2) To reduce manufacturing costs, reduce parts count, reduce assembly time,
improve product performance, improve product reliability, reduce the total
cost of ownership for the customer, etc.
I have seen enough different TM503s that I am certain Tek made many versions
of the TM503. I posted a 4 page paper on a TM503 that I came across that had
every indication of being a very late model TM503 judging from how simplified
Tek's production engineers redesigned it for quick assembly and low
manufacturing cost.
This particular TM503 was unusual for many reasons:
* There were no markings on indicating what it was but you could tell
immediately that it was a TM503 by looking at it.
* It had GPIB connectors for each slot like a TM5003 would have.
* The power supply was a conventional transformer and filter caps analog
design, and not a switching power supply like the TM5003 has.
* It produced higher TM5xx DC voltages than the TM5003 and TM5006. TM500x
voltages are lower than the TM5xx unregulated voltages because TM500x voltages
are regulated by the switching supply they use.
You may find something that applies to your TM503B in the unusual TM503 I
found and modified. It is at:
/g/TekScopes/files/Modification%20of%20an%20Unusual%20Three%20Wide%20TM%20Mainframe%20into%20an%20ordinary%20TM503/Unusual%20Three%20Wide%20TM%20Mainframe.pdf.
You may have to paste that link back together to use it.
Alternatively you can simply do a search for
Unusual TM503
in the TekScopes files section and find it that way.
Dennis Tillman W7pF
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Re: Is my Tek 468 beyond repair?
John,
540uF and 390uF sound like 'preferred values' as in resistor values. As far as I know there is no reason for any great precision on the values of reservoir and smoothing capacitors, too small and they don't do the job, too large and they are expensive, take up more space and stress the rectifier diodes on switch on. Quite commonly large value electrolytics will be toleranced at -20% +50%. (or at least they were in my younger days).
The 74LS112 spec sheet quotes maximum clock frequencies of 25MHz or 30MHz depending on the loading of the outputs. It is going to be decidedly marginal at 50MHz.
Regards,
Roger
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Re: Is my Tek 468 beyond repair?
To test, connect pin 14 to +5, pin-7 to ground and pin 8 is the output. Pin 1 is no connect. tgerbic, ok, I think I get this now. There are only 4 actual pins, but their positions are mapped onto a 14 pin DIL package? So far corners would be 1, 7, 8 and 14 as indicated? You are correct that pin 7 is connected to ground. It isn't very visible but a continuity test confirms it. So there is a very easy albeit brutal sounding way of dealing with removing DIL type chips: I tried the de-soldering gun and solder sucker but this only removed solder from the top of the joint leaving the hole clogged. Similar problem with the IC pins. From one side the hole looked clean but the other side was still firmly soldered in place. Basically there is no chance of removing any DIL device from this board without a specialised DIL de-soldering tool or snipping pins so removal is going to be destructive and any replacement will have to go into a socket. With the crystal, the problem is that there is no access to the pins so the only way I could test was in situ by cutting the output pin track and soldering 3 short wires to the pins in question. Unfortunately this resulted in no output from the crystal. My copy of the manual has U128 and U230 as 74S122 (not LS122), my memory says that most LS devices are rated to around 40MHz which is why I suggested HCT as a possible alternative. Roger is quite correct. The ICs are 74S112. Earlier I had mistakenly stated 74LS112 but I had mis-read the diagram. Using 74HCT112's sounds like a good idea Incidentally, why are the two caps on the 5V rail such specific values? They are marked Sprague 637D 540¦ÌF 25VDC and 672D 390¦ÌF 0-15VDC but no indication of tolerence. I couldn't find any data on these, but would 680¦ÌF and 470¦ÌF 105deg be suitable replacements? I am just putting together an order to RS. Seems to work out cheaper than ordering individual bits from eBay. Also the 74LS112 is considerably cheaper than the 74HCT112 which I can only get on eBay.
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Re: Please help with TDS340A
Comments Interleaved: On 9/21/2020 7:04 AM, James wrote: Thanks again Harvey.
I took the scope apart and pulled out the display module. Praise be, it's through hole components! It also appears that the HV section and horizontal deflection parts are all on this module. Pretty much have to be.? The monitor is pretty much a standard VGA monitor (I'd think) and needs the usual assortment of HV section, Horizontal and Vertical drivers (for the yoke), and a video driver. Following on I have a couple of further dumb questions:
The CRT has a white connector at the end, I presume it works like a valve base and I just gently pull it away from the CRT pins? That would be right.? Make sure that you are pulling only on the socket, and not the pin holder/base of the tube as well.? I'd be tempted to try to very gently rock it back and forth in case the pins are somehow stuck.? It should be keyed, either by a keyway in the plastic base or, if like a 7 or 9 pin valve, pin spacing Any advice/tips on doing this?
The service manual is full of obsolete part numbers for the electrolytics, with no datasheets easily obtainable. The caps are a mixture of 35-160V types from Nichicon and similar and all look fine but as yet unmeasured. It's probably easier to just pull them out and replace them, there's only a handful. I'd? do a little probing of the power inputs with another scope (I think you said you had one) to look for that 30 KHz waveform. That might tell you which to replace.? Alternatively, you can (assuming it's a 15 volt line), tack a 100 to 1000 uf 25 volt capacitor across that at the input to the monitor and see what that does or doesn't do. Another possibility is that if there's a shield around the HV (that's HT for you) transformer, then see if the screws are tight. Do I need particular spec capacitors or am I likely to be ok if replacing 105C +50-20% types with others that meet this spec (and obviously the same or higher working voltage)?
The parts list distinguishes CAP;FXD;ALUM from CAP;FXD;ELECTLT. Are these all aluminium electrolytics or is there some other difference I am unaware of? They all look like electrolytics! I suspect that they're all standard aluminum electrolytics, since this is mostly consumer level off-the-shelf electronics in the display.? I'd go for 105 degree C capacitors (typically you'd be getting 85 or 105, 105 lasts longer at higher temperatures, and even at lower ones), working voltage equal to or up to 50% more (that's arbitrary, but a slightly larger working voltage is better).? Do not use a 15 volt or 16 volt rated capacitor on a 15 volt line, just not enough headroom. and for the actual value, most electrolytics are about -20% + 100% in tolerance, so putting a 150 uf capacitor in place of a 100 uf capacitor should be fine.? If you think it's part of a signal chain, as in a filter for a particular frequency, or something doing timing, then go for the same value. Many thanks as ever in advance.
Not a problem.? Check out some of the other repair threads some time to see some general "what do I put in its place?" advice. Not sure if anyone ever collected this and put it somewhere. Harvey
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Re: 2235 Repair having no power
I don't have a 2235 manual on hand but this sounds very similar to my case with the T948 main inverter transformer (120-1348-03) used in the 2213A that had failed, in my case on a scope I fixed about 10 years ago. Once I replaced that transformer with one taken from a scrap board, everything came back to life. So these sometimes do indeed fail, although apparently not very often. I never did any testing to the failed one, so no idea what really went wrong. Wish I could offer more insight but that's it for now.
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Re: 2235 Repair having no power
On Mon, Sep 21, 2020 at 02:47 PM, satbeginner wrote:
Now I need to find another transformer for my 2235, preferably in the EU,
120-1601-01 or similar (2213, 2215, 2215A, ...)
Hi Leo, I have a 2215 wreck (very incomplete) with a transformer, will have to check. I also have a 2235 with a defective primary switcher. Never tried to repair. Contact me if interested. Raymond
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Re: Please help with TDS340A
Harvey is the BEST!!! I need him to download his brain and email me a copy
of it! Thanks Harvey for helping everyone here!!!
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On Mon, Sep 21, 2020 at 6:05 AM James <james@...> wrote: Thanks again Harvey.
I took the scope apart and pulled out the display module. Praise be, it's
through hole components! It also appears that the HV section and horizontal
deflection parts are all on this module. Following on I have a couple of
further dumb questions:
The CRT has a white connector at the end, I presume it works like a valve
base and I just gently pull it away from the CRT pins? Any advice/tips on
doing this?
The service manual is full of obsolete part numbers for the electrolytics,
with no datasheets easily obtainable. The caps are a mixture of 35-160V
types from Nichicon and similar and all look fine but as yet unmeasured.
It's probably easier to just pull them out and replace them, there's only a
handful. Do I need particular spec capacitors or am I likely to be ok if
replacing 105C +50-20% types with others that meet this spec (and obviously
the same or higher working voltage)?
The parts list distinguishes CAP;FXD;ALUM from CAP;FXD;ELECTLT. Are these
all aluminium electrolytics or is there some other difference I am unaware
of? They all look like electrolytics!
Many thanks as ever in advance.
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2235 Repair having no power
Hi all, I am fighting with a 2235 PS. I previously repaired several 2213 and 2215A's, and it "always" was the primary switcher, but this time.... I removed the Power FET to apply a external 43VDC to see if the scope would work, but no, it looked like a full short, the secondary switcher would not work at all. I disconnected all secondary diodes from transformer 120-1601-01 , still the same. I disconnected the 2kV wire and disconnected the two filament wires, still full short, no switching in the secondary switcher. I checked all components in the secondary switcher circuit, all OK. I removed the transformer 120-1601-01 (PITA!) and temporarily replaced the two primary windings in the secondary switcher circuit with two 24 Ohm 5W resistors, and behold, the secondary switcher is working! So, is my transformer dead? The weird thing is, I applied a 400mV 50kHz sine to one of the primary windings, and all secondary windings give a voltage which looks like OK with respect to what is to be expected?? My thoughts were: if the input is roughly 40V switched, I know roughly what to expect, so if I use a similar, but lower voltage from a generator, I could check the individual outputs? I still do not know if the transformer is dead or not, but when I connect the two primary windings it will not switch at all. So to test further, I did the following first: I did a "ringing test" on the transformer. Basically you apply a fast rise and fall square wave to (one of) the primary winding(s) and measure using a scope the output of one of the secondary windings at the moment of the Rising flank. More info on this "ringing test" can be found here: Here are some pictures I took: /g/TekScopes/album?id=254000In the mentioned album you see the result of the TekTronix transformer and the result of an other transformer I got from a switched mode power supply. When there is (hardly) any "ringing" that means there is a shorted winding, or at least a heavily loaded winding. But since these transformers are now both out-of-circuit, there should be no load. However, the TekTronix transformer is showing hardly any ringing, so somewhere in there is a short.... :-( Now I need to find another transformer for my 2235, preferably in the EU, 120-1601-01 or similar (2213, 2215, 2215A, ...) Saludos, stay safe, Leo
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Re: Please help with TDS340A
Personally I'd use neutral cure silicone. Hot glue gun glue is a pain to remove when you need to.
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of James Sent: 21 September 2020 12:07 To: [email protected]Subject: Re: [TekScopes] Please help with TDS340A ...Also what do you recommend to glue the electrolytics to each other and/or the board. They currently are mostly stuck; do I use hot glue or silicone and if so which grade is suitable?
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Re: Please help with TDS340A
...Also what do you recommend to glue the electrolytics to each other and/or the board. They currently are mostly stuck; do I use hot glue or silicone and if so which grade is suitable?
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Re: Please help with TDS340A
Thanks again Harvey.
I took the scope apart and pulled out the display module. Praise be, it's through hole components! It also appears that the HV section and horizontal deflection parts are all on this module. Following on I have a couple of further dumb questions:
The CRT has a white connector at the end, I presume it works like a valve base and I just gently pull it away from the CRT pins? Any advice/tips on doing this?
The service manual is full of obsolete part numbers for the electrolytics, with no datasheets easily obtainable. The caps are a mixture of 35-160V types from Nichicon and similar and all look fine but as yet unmeasured. It's probably easier to just pull them out and replace them, there's only a handful. Do I need particular spec capacitors or am I likely to be ok if replacing 105C +50-20% types with others that meet this spec (and obviously the same or higher working voltage)?
The parts list distinguishes CAP;FXD;ALUM from CAP;FXD;ELECTLT. Are these all aluminium electrolytics or is there some other difference I am unaware of? They all look like electrolytics!
Many thanks as ever in advance.
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Re: Which programmer to use to read/write dallas DS1486?
On Mon, Sep 21, 2020 at 08:31 AM, tgerbic wrote:
The info in the datasheet is probably not clear because "you should not need
to know this". Based on looking at this and other family datasheets it seems
as if the difference between the W and non-W version is the power fail voltage
level. Both chips seem to be ok with 6V on any pin so I suspect they both work
on 5V but the W version should not be used in a 5V environment because of the
power fail level being so low. This is just a guess from looking at the
datasheets so it is your choice to try it. I would probably pop it into my
Xeltek or Unisite and program it that way but if I did not have either, I
would try programming as a 5V part.
Alternately, if you are worried, you could try the Arduino driving SRAM method
I mentioned to Rogerio on this thread. In that case you could drive it at
3.3V.
I ran into a similar won't work problem with one of my HP 16xx logic analyzers
and its LAN interface. Turns out if the MAC address is not programmed in Flash
(battery died in a timekeeping device), the LAN interface will not come up at
all. I just programmed in a typical value for an HP device (random MAC) and it
came right up. Guess this is the same as your problem.
Hi Tony, Thanks for your comments. 5 V seemed to be OK for the DS1742W because the data sheet made no distinction between the 3.3 V and 5 V version re. Vcc max. and the idea that the difference in Vpf did not indicate any other differences in the chip. That was until I saw the data sheet of newer devices, where a Vcc max of 4.6 V is specified for the 3.3 V part. Could all be the reason you mentioned but I have no spare DS1742W in case it dies and can't easily get one, although alternatives exist. That's the main reason for being so careful and hesitant. I decided to connect/cloak my DS1742W as a DS1750W, although the latter is much larger but it's supported in my programmer (TL866II Plus). Connecting the DS1742W seems quite easy, with most pins straight through and just two wiring changes. I'll keep your hint re. an Arduino in mind. ISTR a similar problem with HP's 16702A/B LA's. Raymond
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Re: TDS6604 Acquisition Board Replacement
Hi Charlie,
I tried running SPC but it looks like the Acquisition board I have purchased is faulty. SPC fails and channels 3 and 4 are unstable beyond 2.5GS/s.
I might re-visit the original Acq. board - it has one faulty trigger chip which only affects channels 3 and 4.
Apparently the Tek # 156-8278-00 chips are unobtainium.
Regards,
- Guy
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Re: Which programmer to use to read/write dallas DS1486?
Raymond,
The info in the datasheet is probably not clear because "you should not need to know this". Based on looking at this and other family datasheets it seems as if the difference between the W and non-W version is the power fail voltage level. Both chips seem to be ok with 6V on any pin so I suspect they both work on 5V but the W version should not be used in a 5V environment because of the power fail level being so low. This is just a guess from looking at the datasheets so it is your choice to try it. I would probably pop it into my Xeltek or Unisite and program it that way but if I did not have either, I would try programming as a 5V part.
Alternately, if you are worried, you could try the Arduino driving SRAM method I mentioned to Rogerio on this thread. In that case you could drive it at 3.3V.
I ran into a similar won't work problem with one of my HP 16xx logic analyzers and its LAN interface. Turns out if the MAC address is not programmed in Flash (battery died in a timekeeping device), the LAN interface will not come up at all. I just programmed in a typical value for an HP device (random MAC) and it came right up. Guess this is the same as your problem.
Regards
Tony
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Re: Is my Tek 468 beyond repair? Trap and Kernel test procedure
Hi Tony
Thank you very much for your guidance.
I have been looking for an image of SERVICE ROM for about 5 years without success. It is unbelievable that nobody in the group has this file. After all, TEK 468 was very popular in the world. I have the image files for the 2 ROM's but unfortunately I don't have the image file for the SERVICE ROM.
All power supply are OK with voltages according to the specifications in the manual. The ripples are also OK.
I'll start with where you suggested.
Regards
Heitor
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On Monday, September 21, 2020, 02:02:39 AM GMT-3, tgerbic <tgerbic@...> wrote:
Heitor,
POST 3000 indicates that the acquisition RAM has failures.? The fact that the testing took place indicates the processor, address bus, data bus and ROM should be ok.? The next step would be to use the Service ROM to run some tests, especially on the acquisition RAM. No one seems to be able to product a copy of the service RAM so using the manual's troubleshooting by Service ROM is not going to work.? Additionally the manual is focused on using a signature analyzer for much of the testing.? Most people don't have one, and I assume you don't either.? They were popular back in the 80s but you don't see them today. So, I think the way forward is to use a more general troubleshooting process.
Acquisition RAM is on the A18 board so I suggest you start on the "Partial A18 Memory Board Schematic" ACQUISITION MEMORY<14>. The upper right shows the RAM and the address/data decoders. I would start looking there. Perhaps focus your logic analyzer on one of the chips and see where the test stops when the POST 3000 comes up.? Could be a bad RAM chip(s).? Since both scopes show a POST 3000 error, it could be the RAMs going bad.? I would find it hard to believe you would have identical logic failures on both scopes.
I assume you have checked the digital supply voltages, especially for high ripple voltage.? There are two +5V power supply systems, one for the microprocessor section at the back of the scope and a second one on the A15 board which powers digital logic in the rest of the scope.? Make sure you rock any ICs that are in sockets to make sure they are making contact in the crummy TI sockets.? I would avoid touching the A/D converter chip as it is big and if you break it, it might be very hard to find a replacement.
In any case this should get you started.
Regards
Tony
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Re: Which programmer to use to read/write dallas DS1486?
Rogerio,
The Xeltek 610P will also program these. I suspect any programmer that can program a 128K battery backed RAM chip, and can be set to start at 0E hex, should be able to program the chip.
You could take a different out-of-the-box approach and attach the chip to an Arduino, wire it as a 128K static RAM chip and write to it skipping the first 14 bytes (0D hex) used by the timekeeping circuit. Might be faster and cheaper than buying a programmer just to burn a flash. Just remember to skip the first 14 bytes as they are used by the timekeeping circuit. 0E hex and higher is RAM. I suspect the data you need to program in is much less than the 128K. You only need to wire up as much RAM address as needed to cover the data you need to program. Pull the rest of the address lines down. Take a look at the data and see how much there is and if there is a serial number or MAC address at the start of the data file. You might just need to add a serial number to get the scope back up.
Regards
Tony
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Re: Is my Tek 468 beyond repair? Trap and Kernel test procedure
Heitor,
POST 3000 indicates that the acquisition RAM has failures. The fact that the testing took place indicates the processor, address bus, data bus and ROM should be ok. The next step would be to use the Service ROM to run some tests, especially on the acquisition RAM. No one seems to be able to product a copy of the service RAM so using the manual's troubleshooting by Service ROM is not going to work. Additionally the manual is focused on using a signature analyzer for much of the testing. Most people don't have one, and I assume you don't either. They were popular back in the 80s but you don't see them today. So, I think the way forward is to use a more general troubleshooting process.
Acquisition RAM is on the A18 board so I suggest you start on the "Partial A18 Memory Board Schematic" ACQUISITION MEMORY<14>. The upper right shows the RAM and the address/data decoders. I would start looking there. Perhaps focus your logic analyzer on one of the chips and see where the test stops when the POST 3000 comes up. Could be a bad RAM chip(s). Since both scopes show a POST 3000 error, it could be the RAMs going bad. I would find it hard to believe you would have identical logic failures on both scopes.
I assume you have checked the digital supply voltages, especially for high ripple voltage. There are two +5V power supply systems, one for the microprocessor section at the back of the scope and a second one on the A15 board which powers digital logic in the rest of the scope. Make sure you rock any ICs that are in sockets to make sure they are making contact in the crummy TI sockets. I would avoid touching the A/D converter chip as it is big and if you break it, it might be very hard to find a replacement.
In any case this should get you started.
Regards
Tony
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Re: Looking for TM503B manual
Hi Jared,
To change the line voltage on the TM503B simply pop out the bright grey plastic piece that is part of the line selector/power switch/power connector assembly on the back. (The piece that shows 240 (V) in the little window on the left side)
Greetings,
Gregor
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-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Jared Cabot via groups.io Sent: Sunday, September 20, 2020 3:50 AM To: [email protected]Subject: [TekScopes] Looking for TM503B manual I'm poking away at my TM503B and wondering if anyone has a manual for this mainframe? I've found the TM503 manual, but no B version yet. Failing that, does anyone know how to set the line voltage, and what Option 2 is? Thanks!
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Re: 585A -- time base A linearity
Did some poking around today. Deoxit didn't change anything. I noted, however, that the linearity issue is definitely temp related. It starts out in spec, then drifts out as the instrument warms up. I reckon this probably points right at the timing capacitors (which appear to be hidden behind the adjustable trimmers). No idea how to get to them short of considerable disassembly. Any suggestions on a modern replacement cap?
Sean
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Jared Cabot
Raymond Domp Frank
satbeginner
David C. Partridge