I have the same problem with a 2221a. This video saves me hours and hours of troubleshooting. Thank you for the time and effort to figure this all out. Many troubleshooters will find this helpful. Should be a very popular video. Great job !
The switches are high-frequency, low-signal, low-noise, gold-plated, low-capacitance, miracle switches, because standard rotary switches just aren't good enough. If you ever encounter them again, remember that they deserve huge amounts of care and consideration! Clean with the recommended solvent; no fingerprints all over them creating leakage and such. If my brother were still with us, he'd say "Slow down and think more carefully about what could go wrong, and what you're doing." I'm still learning that lesson myself!
Never add solder to those gold plated pads and keep clean from fingerprints, those have high frequency going through them and the gold plating is absolutely necessary for attenuator to work correctly. Any change to those attenuator will require likely a calibration/performance check. So best not to mess with them if not needed. Now of course you can skip steps but best if calibrating to go though all steps. Plus don’t use contact cleaner to clean them just rubbing alcohol only and clean only when contacts are down to avoid bending them. The other issue notice is the two contacts you cut off to fix the broken off ones are used for the AC DC GND coupling switch. That why there is a separate small cam assembly for it. You need to buy a new attenuator assembly to fix it completely. I worked on many of these oscilloscopes over the years and know them well. Yes I screwed up as well and learned lessons early on. We all make mistakes. I see you realized the mistake on the cut off contracts strip off coupling later on in the video my apologies.
Great video.. I have a Telinstruments TI5252 25mhz scope...I have an issue with ch1 as I cannot centre the trace, at the bottom of the screen is where the trace is at its highest, however the trace on channel 2 can be centred and moved up and down no problem.. Any suggestions ? Much appreciated
Man, i just really love how this is such a naturally service video with all the "I wish i did that first" hahaha Congrats man, really loved your videos! Will subscribe xD
I just bought a 2213A from ebay, but was delivered a 2213. Did I get ripped off? What is the difference, I'm not having any luck locating anything on google.
@@larrybud Never use contact cleaner on these attenuator assemblies. Service Manual also states that only isopropyl alcoholc must be used. is all that needed and clean with contacts in down position to avoid bending them. Been using isopropyl alcohol for years and use a syringe and drop on each of the contacts and never had issues with them being flaky and even years later still works as good after cleaning them. Of course exercising the switches and using the scope keep them clean.
The 1st physical "fork" contact is on the far left of the schematic. The contact they label as #1, is actually the second physical contact. That is why it is 6th and 9th as you count the physical contacts.
good video I'm having the same problems, but I'm having real trouble removing the attenuator board. I removed all the knobs,screws, de-soldered the B&C connector resistors. the attenuated board is now very loose but will not move back from the front fascia panel because of the AC/DC Grd switches can anybody tell me how I disengage these switches from the attenuator board without having to remove all the front fascia panel . Any help would be greatly appreciated.
Jiri, The red knobs marked with "CAL" are to allow for continuous adjustments between the discrete, calibrated values determined by the volts/division and seconds/division switches. You can think of these "CAL" knobs as fine tune adjustments, while the main switches are used for rough adjustments.
I have the same problem with a 2221a. This video saves me hours and hours of troubleshooting. Thank you for the time and effort to figure this all out. Many troubleshooters will find this helpful. Should be a very popular video. Great job !
The switches are high-frequency, low-signal, low-noise, gold-plated, low-capacitance, miracle switches, because standard rotary switches just aren't good enough. If you ever encounter them again, remember that they deserve huge amounts of care and consideration! Clean with the recommended solvent; no fingerprints all over them creating leakage and such.
If my brother were still with us, he'd say "Slow down and think more carefully about what could go wrong, and what you're doing." I'm still learning that lesson myself!
Lesson learned in many aspects of these two videos. Do the fix right from the start.
The serviceable nature of this Tek is amazing. Thumbs up sir. Great repair.
Your tenacity is astounding. Inspirational to watch you progress through a maze of possibilities to a successful finish!!!
Outstanding job. I really like how you include your errors in the troubleshooting also. Thanks for filming this repair!
Great Job, Well done on you staying with it!
Never add solder to those gold plated pads and keep clean from fingerprints, those have high frequency going through them and the gold plating is absolutely necessary for attenuator to work correctly. Any change to those attenuator will require likely a calibration/performance check. So best not to mess with them if not needed. Now of course you can skip steps but best if calibrating to go though all steps. Plus don’t use contact cleaner to clean them just rubbing alcohol only and clean only when contacts are down to avoid bending them.
The other issue notice is the two contacts you cut off to fix the broken off ones are used for the AC DC GND coupling switch. That why there is a separate small cam assembly for it. You need to buy a new attenuator assembly to fix it completely. I worked on many of these oscilloscopes over the years and know them well. Yes I screwed up as well and learned lessons early on. We all make mistakes.
I see you realized the mistake on the cut off contracts strip off coupling later on in the video my apologies.
I have a 2215 that I'm working on. Great video!
Great video.. I have a Telinstruments TI5252 25mhz scope...I have an issue with ch1 as I cannot centre the trace, at the bottom of the screen is where the trace is at its highest, however the trace on channel 2 can be centred and moved up and down no problem..
Any suggestions ?
Much appreciated
Great work and very informative!
Good Job!
Man, i just really love how this is such a naturally service video with all the "I wish i did that first" hahaha
Congrats man, really loved your videos! Will subscribe xD
Fantastic ! Fantastic !
I just bought a 2213A from ebay, but was delivered a 2213. Did I get ripped off? What is the difference, I'm not having any luck locating anything on google.
Excellent! Works fine.
Now wondering if it might have been simply debris under the contact strip?? Maybe blowing it out with compressed air could have done the job?
Yeah, I can't believe the first thing you don't do in any of the old electronics is to douse the thing with contact cleaner/lube.
@@larrybud Never use contact cleaner on these attenuator assemblies. Service Manual also states that only isopropyl alcoholc must be used. is all that needed and clean with contacts in down position to avoid bending them.
Been using isopropyl alcohol for years and use a syringe and drop on each of the contacts and never had issues with them being flaky and even years later still works as good after cleaning them. Of course exercising the switches and using the scope keep them clean.
@@thetechgenie7374 What negative impact can contact cleaner do?
The 1st physical "fork" contact is on the far left of the schematic. The contact they label as #1, is actually the second physical contact. That is why it is 6th and 9th as you count the physical contacts.
I have a 2213A. Any utility in getting the OEM Tek 6122 probe? Just to keep it original.
👌👌👌
good video I'm having the same problems, but I'm having real trouble removing the attenuator board. I removed all the knobs,screws, de-soldered the B&C connector resistors. the attenuated board is now very loose but will not move back from the front fascia panel because of the AC/DC Grd switches can anybody tell me how I disengage these switches from the attenuator board without having to remove all the front fascia panel . Any help would be greatly appreciated.
well done
Dumb question probably, sorry, but do You know about the red "zoom" knobs marked with "CAL" and arrow?
Jiri,
The red knobs marked with "CAL" are to allow for continuous adjustments between the discrete, calibrated values determined by the volts/division and seconds/division switches. You can think of these "CAL" knobs as fine tune adjustments, while the main switches are used for rough adjustments.
(Apparently wasn't aware of w140.com, the TekWiki!)