tektronix 2215 - Page 1
Forum section: electronics / repair

author: jdragoset
author_rank: Frequent Contributor
timestamp: March 09, 2019, 02:36:19 am
content: Is anyone still trying to replace the HV multiplier on these?

author: David Hess
author_rank: Super Contributor
timestamp: March 09, 2019, 03:16:32 am
content: If you had to, it would not be difficult to make.

author: tautech
author_rank: Super Contributor
timestamp: March 09, 2019, 12:04:52 pm
content: Quote from: jdragoset on March 09, 2019, 02:36:19 amWelcome to the forum.Some good guidance here:https://www.eevblog.com/forum/repair/tektronix-465/

author: jdragoset
author_rank: Frequent Contributor
timestamp: March 10, 2019, 01:28:47 am
content: Thanks,4x stage anode, 1x stage cathode works great!8 kV, 5 mA diodes and 0.001uf 3kV caps.fits in half a pill bottle w/ 3M scotchcast 4 resin

author: jdragoset
author_rank: Frequent Contributor
timestamp: April 27, 2019, 10:01:21 pm
content: Here is the unpotted HV multiplier under test before potting.Caps are 0.001 uf, diodes are 8kv 5 ma

author: bob91343
author_rank: Super Contributor
timestamp: May 28, 2019, 05:48:29 pm
content: I have a 2215 that will not turn on. The power switch is good. There is shown on my diagram an inductor off the board which my unit does not have, rather it has an IRF820 FET. In poking around I broke the FET lead and found in my stock an IRF740. Can I sub that?More importantly, how can I get this unit working? The power line isn't getting through the off board 'inductor'. Can I just jumper those leads and make it work?All help appreciated.

author: jdragoset
author_rank: Frequent Contributor
timestamp: May 29, 2019, 12:29:37 am
content: Follow David Hess' advice to make sure you have the "current limiter" or the "pre regulator" A 19 board before making any assumptions.All my posts to-date are about an HV multiplier replacement within the easy reach of an "experienced" electronics tech. ( these are not telephones )

author: jdragoset
author_rank: Frequent Contributor
timestamp: June 05, 2019, 01:10:42 am
content: HV multiplier still workingBeen trouble shooting an internal (ch1/ch2) trigger malfunction.Only works on "both", "chop or add" and source "vert. mode".Looked at all U305/U315 open collector resistors, switch contact/diodes-everything ok.U170/U270 and U197 voltages not all correct.Find an OC transistor in U197D.Lift the three pins and put in 2n5961 as replacement for U197DSingle line on scope that position controls will not move.Insert 10k resistor in series with base terminal of 2n5961 and all internal trigger modes work correctly.Is the U197 selected by Tek for low gain?I've got two on the way but if wrong hfe, will they work?My final fix would be :1) replace U1972) increase the 2n5961 base resistor to 33k and call it a day

author: tautech
author_rank: Super Contributor
timestamp: June 05, 2019, 01:57:37 am
content: Good work.Check the X ref for U197 here:https://www.sphere.bc.ca/test/tekequiv.html

author: bob91343
author_rank: Super Contributor
timestamp: June 05, 2019, 03:20:46 am
content: Well I solved the dead 2215 issue. Now it works great except no B sweep. I thought that worked before. Has anyone worked on this part of the scope?

author: jdragoset
author_rank: Frequent Contributor
timestamp: June 07, 2019, 08:52:40 pm
content: Changed U197, all trigger and channel modes work fine.

author: bob91343
author_rank: Super Contributor
timestamp: June 07, 2019, 09:18:02 pm
content: I checked again and now it seems to work, sort of. The triggering system has me confused. If I want to measure the period of a sinusoid with the B sweep and the 10-turn pot, what is the procedure?

author: David Hess
author_rank: Super Contributor
timestamp: June 08, 2019, 04:46:21 am
content: Quote from: bob91343 on June 07, 2019, 09:18:02 pmMost of the manuals cover how to use the delayed sweep for measurements.Adjust the main sweep to display one or more cycles. Select a suitable delayed sweep. Align one edge with a spot on the graticule. Measure the difference between that edge and the next edge using the delay control with main sweep units.

author: bob91343
author_rank: Super Contributor
timestamp: June 08, 2019, 06:30:00 am
content: That's what I tried but the triggering circuit doesn't respond as I expect. First I make the B sweep faster than the A sweep and then I see an intensified portion. As I turn the 10 turn pot the display doesn't change intensity for a while and then jumps to another position.I think I have to find a way to trigger on the signal for the A sweep but not sure how to set up B sweep. Also, can I just display B sweep and watch the wave walk across as I turn the pot? Once I can do that, I can read the calibrataions and figure out what the period is.It's much easier on my 2445, especially since it has screen display of parameters.

author: David Hess
author_rank: Super Contributor
timestamp: June 08, 2019, 09:00:27 pm
content: Quote from: bob91343 on June 08, 2019, 06:30:00 amTurn the B trigger level fully clockwise to select "B sweep runs after" instead of "B sweep triggers after".

author: bob91343
author_rank: Super Contributor
timestamp: June 08, 2019, 11:20:53 pm
content: Thanks! That did it. I don't find the control layout very user friendly and the legends are both small and almost hidden in the shadows of the knobs.Add to that the fact that the unit has some issues with time calibration as well as trace intensity and focus. But for my current use, they don't pose a problem. For serious work I have the other Tektronix and the HP digital.I do appreciate you taking the time to tell me what should have been obvious but wasn't.

author: David Hess
author_rank: Super Contributor
timestamp: June 10, 2019, 04:59:49 am
content: Tektronix used that interface feature in a number of their dual delayed timebase oscilloscopes to save space on the control panel. Another one is to combine the even more obscure "B ends A" with the trigger holdoff control like on the 485.

author: jdragoset
author_rank: Frequent Contributor
timestamp: June 10, 2019, 09:49:22 pm
content: Thanks for that.It is great to know there are forum folks well versed in Tek obscurities.

author: lordvader88
author_rank: Frequent Contributor
timestamp: June 11, 2019, 10:44:05 pm
content: I hope mine breaks too ?? I have, so far I had to rig the pwr switch, some plastic part broke. The CH1 AC/GND/DC switch needs cleaning or fixing. I barely have any refenernce. Something obivios could be wrong with mine, and I wouldn't know, and I only use the basic modes

author: bob91343
author_rank: Super Contributor
timestamp: June 11, 2019, 11:35:29 pm
content: I remember when Tektronix documentation was useful. Well, I also remember when HP documentation was useful.Not to say I can't use it, but some things I'd like to see just aren't there.I had power switch problems with my 2215 but some contact spray fixed them. This was compounded by the intermittent FET that confused me as to whether it was switched on or off. That stupid switch is about as far from the panel pushbutton as they could put it. And it's buried between two boards. Anyone who gets it apart that far deserves to get it working. When I put it together I omitted some parts, shields and heat sinik and such but it works fine without them. I was worried about the heat sink but the thing runs all day long now without missing a beat so I am going to leave it. If it fails I have another one and probably will reinstall the heat sink.

author: jdragoset
author_rank: Frequent Contributor
timestamp: June 12, 2019, 12:11:07 pm
content: All the 2215 rocker switches have at least one open end accessible to a long needle oiler.These are found empty on Ebay.Use a good contact cleaner that the solvent has been allowed to evaporate (Tektronix plastics used in switches can be damaged by many solvents).Get a drop or two into the contact open end (switch in opposite position), let gravity carry the lubricant down the movable contact plate and finally tip the scope face up while working the switch to let the lube end up on all the fixed contacts.For noisy pots, a salvaged focus pot insulator will thread onto the front panel pots and allow pressure from the contact lube (De-Oxit Fader) to penetrate around the shaft, into the sliding contacts inside the pot.Similar can be done with the cal/variable pots with some disassembly of the coupling and long shaft (through the switch shaft) removal.

author: bob91343
author_rank: Super Contributor
timestamp: June 12, 2019, 04:28:51 pm
content: Trouble is, the power switch isn't like that. It's a DPDT slide switch activated by a long convoluted plastic piece, and is buried between two circuit boards near the rear of the unit. Even if you disassemble the unit enough to see the switch, you still can't reach it. So you shoot or drip solvent at it and hope enough reaches the important places as you exercise the switch.If I tried, I still couldn't make it harder to service. That unit, and perhaps others, is a real piece of work.Yet, I repaired mine and use it daily. It needs calibration and alignment but I have more important projects.

author: jdragoset
author_rank: Frequent Contributor
timestamp: June 12, 2019, 06:01:55 pm
content: It is true that Tektronix went to great lengths to keep anyone out of the HV cage, where the power switch is contained, partly because of many components carry line voltages and many more even higher DC voltages.With the outer cover removed, balance the scope on its right rear lower corner (CRT face nearly up).Looking straight down at the HV cage left side is a plastic lined aperture that some CRT socket wires come through and also a straight gravity drop to the power switch push button, toggle latch with the contacts below that, where a needle oilier could put a small amount of the fader lube.Removing the cage can be done for the most part with the Harbor security bit set, but I had to use a jeweler screw driver on the rear counter-sunk screws.

author: bob91343
author_rank: Super Contributor
timestamp: June 12, 2019, 06:21:51 pm
content: I removed some covers and shields and the heat sink. I didn't put them back but the 'scope seems fine. I saved them in a box should I work on it again.As I said, it's out of calibration but that's of minor interest. I mostly want to see my transmitted waveform; I know what frequency it is. And the amplitude is whatever the pickup loop gives it.So now I can see that I am not overdriving the rig and even see the received audio, either 'phone or CW. Perhaps if I get more into digital modes it will be useful there as well.

author: t1d
author_rank: Super Contributor
timestamp: June 14, 2019, 04:02:27 am
content: I have this unit. It was given to me. I replaced the power switch, the main 470 ohm capacitor and the main fuse. I have extras of these parts.I found the exact switch in some other kind of a mount. I disassembled it from that mount and then I could use it in the 2215. I can take the mount off of my extra, for you; see below.I made sure to get a high quality cap. I found an Ebay/USA Seller that had Panasonics. Great guy, he even proofed them for me, to be really close on Ferad. They came in a lot. I used the one closest to 470 ohms. The remainder that I have to share were spec'd at 480. I have no idea of how old they are, but mine works.The fuse is an AGC 2a/250v. I have one extra to share, but you should be able to source these, with little problem.All that said to say that if you need any of these items, we can work it out. I wasn't sure where you ended up with the switch. Yes, you have to dig in there to get to it, but it is replaceable. IIRC, I managed it, without removing the board - but, don't hold me to that... If you want anything, send me a private message. Maybe we can work a friendly trade, or you can cover my costs.