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Re: Tektronix 2445 - trace doesn't go to the left edge.
Chuck Harris
Does the readout display in the proper position?
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-Chuck Harris machineguy59 via Groups.Io wrote: There is an adjustment on the mainboard that "centers" the horizontal display. It may also effect the readout, moving everything as a whole. These are usually adjusted during calibration. It concerns me that yours seems to have drifted. That drift may indicate other problems with the calibration of the scope. |
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Re: AVR Scope Clock
I hadn't seen those! I still like the clock, though. That benefits the VintageTEK Museum so I might pick one up anyway. Thanks!
John ________________________________ From: [email protected] <[email protected]> on behalf of Dave Brown <davebr@...> Sent: Wednesday, November 28, 2018 9:32 PM To: [email protected] Subject: Re: [TekScopes] AVR Scope Clock You don't want no stinking clock! You want to play tennis on your oscilloscope! Dave |
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Re: Tektronix 2445 - trace doesn't go to the left edge.
There is an adjustment on the mainboard that "centers" the horizontal display.? It may also effect the readout, moving everything as a whole.? These are usually adjusted during calibration.? It concerns me that yours seems to have drifted.? That drift may indicate other problems with the calibration of the scope.
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On ?Wednesday?, ?November? ?28?, ?2018? ?05?:?27?:?26? ?PM? ?CST, Mattis Lind <mattislind@...> wrote:
I have this nice tektronix 2445. It works quite well, but it has one small annoyance. The trace doesn't go to left edge, regardless of setting of position knob. Is this something that can be corrected? /Mattis |
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Re: AVR Scope Clock
Thank you Raymond...
I did try emailing the dutchtronix email address but didn't see the southhollandtrading.com site. Looks like the same guy. I sent an email to that address, as well, and will try giving that number a call, as well. Thanks for the help! John ________________________________ From: [email protected] <[email protected]> on behalf of Raymond Domp Frank <hewpatek@...> Sent: Wednesday, November 28, 2018 6:07 PM To: [email protected] Subject: Re: [TekScopes] AVR Scope Clock John, Have you tried mailing jdr@... (apparently, yes) or andyr@...? The southhollandtrading.com website shows a phone number: (503) 410-9850. I have one of their clockd, I like it and no, it"s not for sale... Raymond |
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Re: MSO 3012 input resistors / schematic attenuator board
On Wed, 28 Nov 2018 01:15:41 -0800, you wrote:
Hello Tek fanatics!Some scopes have a lower bandwidth 1 meghohm input impedance, with a 10 megohm probe they're fine as a 10:1 divider. With a direct 1:1 probe, they're also fine, but voltage limited by the ratings of the plugin/input. For higher bandwidth, some scopes have a 50 ohm input. Allows direct connection to a 50 ohm system, or 10:1 with a 500 ohm probe. That's often a resistor switched in. For some 7000 series plugins, that's a system that has 50 ohm everything, they have (sometimes!) protection built in. why? The 50 ohm inputs generally have a maximum of about 2-3 volts input. The 50 ohm resistor has a limited power dissipation. Guess what someone did with your scope? switched on the 50 ohms (or left it on), used a 1:1 probe or a direct connection, and applied the voltage.... Harvey
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Re: Schematics for TDS744A ?
Hey David,
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if you look at H?kan's site <>, you'll find schematics for the TDS544A, which is probably the nearest you'll get. I also happen to know that the Tek Vintage museum have scanned vol 3 of the TDS544A Technical Reference Manual, which is about 100 pages mostly of block diagrams and schematics, strangely no component layouts though. I believe this'll eventually appear on TekWiki. Aside from that, there's the TDS520B Component Service Manual provided by Tek, and Artek Manuals has the full TDS520 service manual. I seem to remember cross-checking the Tek-supplied service manuals for the acquisition board part numbers, and I seem to remember that the acquisition boards are indeed shared between the 5/700 models. Siggi On Wed, Nov 28, 2018 at 6:42 PM David Slipper <softfoot@...> wrote:
Has anyone found a source of these, in electronic format would be best ?? |
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FW: MSO3000-DPO3000-Digital-Phosphor-Oscilloscopes-Service-Manual_0.pdf
Hi Arnold,
Hope this gets to you. This is not the schematic, however it is the service manual [very slim version]. From the picture, you have ONLY one 50 ohm resistor in series with the INPUT; that looks like an SMT resistor with a very low pulse power spec., or low voltage rating. If the scope was used with probe and AC INPUT, only high voltage or pulse power would have opened the resistor, not DC voltage. Do you know what type of equipment your friend was troubleshooting? I have only used crowbar circuits on High Energy circuits, so that the voltage, current, or energy is disabled BEFORE any damage can happen to components or circuitry. //John KC1GJE |
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Re: MSO 3012 input resistors / schematic attenuator board
Hi Albert,
Yes indeed, it seems the 50 ohm is always in series with the 1M input. But I also think the 75 and 50 ohm impedance corrections are just set in parallel with the 1Mohm input directly on the BNC input when turned on. So the measuring circuit stays the same.. And I agree that the protection circuit is just behind those roasted 50 ohm resistors. Since the scope works well again, that protection circuit is at least not short circuited. But I wonder if it has survived and if it will still protect my scope when things go wrong. I can't find any other roasted components... So it might be okay... |
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Re: AVR Scope Clock
Yes, but that still doesn't mean I can order from there, nor does it mean it ships to the US.
Mostly I was curious if anyone here was familiar with the dutchtronix guy and knew about those kits or where to get one. I'd even be interested in a used one. John ________________________________ From: [email protected] <[email protected]> on behalf of Jack <goldmort@...> Sent: Wednesday, November 28, 2018 2:45 PM To: [email protected] Subject: Re: [TekScopes] AVR Scope Clock HI Google's Internet translator makes translation easy. -- Jack |
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Re: AVR Scope Clock
Thanks Dennis. I found that site earlier too but it's no longer available.
john ________________________________ From: [email protected] <[email protected]> on behalf of Dennis Tillman W7PF <dennis@...> Sent: Wednesday, November 28, 2018 3:56 PM To: [email protected] Subject: Re: [TekScopes] AVR Scope Clock Hi John, You might try this site Dennis Tillman W7PF -----Original Message----- -- Dennis Tillman W7PF TekScopes Moderator |
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Re: AVR Scope Clock
Hi John,
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You might try this site Dennis Tillman W7PF -----Original Message----- -- Dennis Tillman W7PF TekScopes Moderator |
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Re: MSO 3012 input resistors / schematic attenuator board
Hi Arnold,
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At a Dutch forum you mentioned an important finding I think. With "open" 50R resistor and scope set at 1M, 75R and 50R respectively, the DC input resistance appeared to be Infinity, 75R and 50R. With repaired 50R resistor the first figure was 1M. So I guess the 50R resistor is only used in the 1M input stream, with some kind of protection immediately after that resistor. The protection shorts to ground and the resistor gets roasted. Albert On Wed, Nov 28, 2018 at 04:48 PM, <arnoldniemeier@...> wrote:
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Re: MSO 3012 input resistors / schematic attenuator board
Hi Jack,
Thanks for your reply! I think you mean a circuit outside the scope here? This can help to protect the scope indeed. I wished I had that on the scope before it was damaged ;-) But I want to know what circuit Tek uses inside the scope to protect their circuits. I think the rest of my scope survived because of a protection in the scope. But I want to be sure this protection is still in tact. There is a bit quite common info on the website of Tek: |
Raymond Domp Frank
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