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Rogerio O <rodd414@...> added the album Tek 577 unable to display more than 5 steps: The waveform at TP305 is fine, but when I turn the knob to increase the number of step s, the maximum I can get is 5. I have attached the schematics so anybody willing to help does not have to look up for them.

The power supply in my TDS684A has decided to go into hiccup mode. Researching the topic, I keep finding schematics and advice only for the TDS520 and similar. Does anyone have or know where I can find a schematic for the actual TDS684A power supply? Or for that matter, experience of the most common failure modes/device failures? And, it seems folks are capable of running these supplies stand alone on the bench - which connector/pins need to be shorted/or grounded as would be provided by the front panel power button to get the supply to turn on? Thanks! Reinhard Metz n49ex@...

The following photos have been uploaded to the DM502 Switch pack album of the [email protected] group. Switch Pack.JPG Switch Actuator.JPG By: Zentronics42@...

I have an issue with the switch pack on a DM502A I will be uploading pictures. here in a few. I am servicing the meter and the switch actuator spit its self out of the front of the meter. I am curious as this is a 3 position double sided switch but it looks like it is only populated with 4 of the 6 switching elements. Does any one know how this go back tougher? photos will be posted soon. At this point I am 99% sure the switching elements did not get eaten by the lab.

Hi folks, I was performing the CAL08 procedure as suggested in other trend to fix a four rows of dots that are showing on the screen. First, I could not adjust grid bias trimpot (R1878) because the spot was MUCH MORE brighter than the line of dots for the entire pot range. The the display flickered and the dot became a lot less brighter but still brigter that the dots, but I decide to move on. When I started the geometry adjustment moving R4350, the scope rebooted and the vertical position controls for all the channels are not working The scope is able to display the calibration signal, but it is high "up" for CH1 and CH2. Just in case I checked the voltages at J119 and they are all fine. I went to the troubleshooting chart but it is very "vague" to me. It says " if the problem happens on the four channels the problem can be: 1- channel switch 2- delay line 3- Vert Output Amplifier 4- Hybrid Power Suplies I do not have enough knowledge to proceed. Any suggestions? Thanks to all, Roger

A word to the wise. I know how we all religiously terminate our 50 Ohm cables with a 50 Ohm load...... don't we.....???? Well sometimes we forget, or are just doing a quicky check and fail to use, or notice, the termination (if it's not already internal to the target equipment). As I just discovered, by chance, that is a no-no for the marker output of the TG501..... if you do not terminate in 50 Ohms (or whatever), you don't get an output at all, or at least just a very tiny one! This had me chasing around the TG for a couple hours trying to find a fault that didn't exist. I couldn't get any marker through the diode gate before the BNC. The diodes tested good and there were no shorts to ground to be found. Plenty of pulse amplitude up-stream of the gate but nothing (well less than 50mV) arriving at the BNC socket. Something made me put a 50 Ohm term on the socket/cable and hey presto a full amplitude pulse got delivered into the target module. Summary; the TG501 will output "nothing" without a 50 Ohm term somewhere on it's output socket. I didn't find anything in the manual that specifically said that would be the case, only the obvious "... use a 50 Ohm cable and termination"; obviously good practice, but missing out the critical "MUST USE" about termination. The trigger output does not seem to have the same criticality; it delivers regardless of termination.

Hi all, I think Tektronix and Keithley are part of the same group, so I thought appropriate to post here. I searched for a Keithley group, but don't seem to find one. Is there no such thing? Are Keithley posts fair game here because of affiliation? Radu.

A new chat has been created: Looking for chuck harris for some help on ps280 By: mystic96 <clbarber1@...> View/Join This Chat Do not reply to this message to post to the chat. You can participate in chats only through the group's website.

I saw this listing on Craigslist. It looks like a custom-built 545B, 546, or 547. Maybe something a Tek employee built in the spare time? It appears to be working, and it’s a bit of an interesting oddity. Is this actually in anybody’s back yard? Could somebody save it from the tube vultures? https://rochester.craigslist.org/ele/d/scottsville-large-dual-trace/7538354343.html — Jeff Dutky

I have a ps280 I need some help with, completed recap, new op amps, new transistors including pass, new diodes including zeners. Rails are good, +/- 15 & +/- 24. Master side works well. Slave side goes to max as soon as voltage control is turned even a small amount. I have noticed relays on slave side both turn on if voltage control is even turned a very small amount. Oh fuses are good and transformer secondaries are good(even swapped them with master side same issue). Tried swapping relays, no help. When I got it 5vdc was dead, got that working, just battling this slave side. I found a youtube where pot was defective I even swapped those. Running out of ideas. And of course schematic in manual is no where close.

New member here. I posted this incorrectly my first time since I put the comments with the pictures. My screenshot pictures are at this link: /g/TekScopes2/album?id=278262 I'm looking for help with my first scope repair. My 465 recently failed. Worked fine one day and not so much the next. With no input signal I no longer have a clean trace but rather some type of spurious image is present as shown in the No Signal Screreen picture. Using the position controls I can adjust that signal "ghost image" horizontally but not vertically. The 9KHz signal originates near the center of the screen, expands and then rebounds from the left side of the screen, eventually compressing and exiting on the right side of the screen. There is also a blip trace out to the right of the 9KHz signal that does not vary with the input frequency or amplitude. The 9KHz signal can be adjusted horizontally but not vertically. All symptoms are identical on the A and B channels. I've tested the power supply low voltages as: Design Actual 110 104.5 5 4.99 55 54.91 22 17.89 15 12.92 -8 -7.95 I'm currently troubleshooting the low voltage power supply but I don't think the spurious image would necessarily originate there. Does the fact I can adjust the spurious image as well as the 9KHz signal horizontally but not vertically indicate a problem in the vertical amplifier section? Any guidance will be appreciated!

I have a THS730A that I bought used a several years ago. It seemed to work well at the time, but now has been sitting in its case for a few years. I put in a new battery and found that the backlight is VERY dim, so it is of course very difficult to read the screen. Has anyone else repaired screen issues for this unit or other THS7xx? Is this likely to the CCFL lamp, or the inverter that drives it? I have found 'replacement screens' on eBay for US$140 to US$180, but I cannot tell if these include the CCFL lamp or the inverter. My guess is that the lamp is included, because the photos show two white wires with no connector on them. Thanks Steve

Many requests for one of these, so I got this one running, and posted it to the stuff page in the scope section: https://www.sphere.bc.ca/test/stuffday.html#scopes Very nice cosmetic condition, hopefully it will make somebody happy. This is big and heavy, so a pick up here in Kelowna is a lot better than shipping. hope everybody has a good weekend, walter (walter2 -at- sphere.bc.ca) sphere research corp.

Started this thread because it was being discussed in another topic that really wasn't the place to do so. I know there was a split, I was in tekscopes at the time, but I have totally forgotten it happened. Can someone remind me why there are both groups? I subscribe to both and it does get confusing. I get good advice from both. My confusion is usually that I don't notice which group I'm reading a digest from, reply online, then don't see the response because I'm looking in the other group. No flamewar invite here, just some rational info, please.

The following photos have been uploaded to the SG 502 Repair album of the [email protected] group. bulb.JPG SG502 LED.JPG By: Radu Bogdan Dicher <vondicher@...>

Radu Bogdan Dicher <vondicher@...> added the album SG 502 Repair

Recently my 7633 HV stopped putting out HV and obviously lost the trace. I received a replacement HV supply and have installed it to restores the scope to operation. I am still curious as to the failure mechanism. I am checking to old HV transformer and believe the HV winding is shorted. The HV winding is 1200 turns of #37 wire and is tapped at about 512 turns to provide a lower voltage. I have removed the XFMR from the board and testing these two windings the measurements seem to indicate a problem. #37 wire has a resistance of about 532.1 m ohms per foot. Common to end tap of the coil (1200 turns) tests about 157 Ohms. Common to first (center) tap (512 turns) tests @ 104 Ohms. Here is the strange part, and I don’t understand why I get this measurement. Measuring from the end tap to the center tap (686 turns) I get 261 ohms. How can 686 turns have a higher resistance than 1200 turns of the same wire? Am I misunderstanding what is going on? Shouldn’t that partial set of windings measure somewhat less than the entire end to end measurements? Or does this indicate that this is a failure mode. Education and/or enlightenment is much appreciated! -- Michael Lynch Dardanelle, AR

Rogerio O <rodd414@...> added the album 2465B strange display: The horizontal dotted liea are not affected by INTENSITY, but the do respond to REDOUT INTENSITY

I have 2 vectorscopes/waveform monitors, one 1740 not an A made around 1988 and one 1760 made around 1998. Both units exibit the same problem, weak display. I did some quick tests and all voltages look good and functions I know how to use seem to work. Most likley these both have weak tubes but I need to be positive any help on what to test next? The 1760 manual is on tekwiki and I have the 1740 manual on order. I do not have a tube checker or a HV probe of 1G resistance at this time. -- Jeffeelcr

I could get a a couple of these cheap locally, (one for parts), except they are not super repairable...and they are huge. Anyone like their function? Skip to 11801 or CSA803? John