Tek 475/DM44 Newbie **got it, pics added ** - Page 1
Forum section: electronics / testgear

author: echap
author_rank: Contributor
timestamp: November 05, 2015, 06:12:34 pm
content: Hello to the group. Joined the site today. Bought my first scope the other day and been trying to learn how to use it before it gets here and I let the magic smoke out. Here's the eBay auction linkeBay auction: #371475445368So anyway, that's how I found this site. I mostly work on antique vacuum tube radios, but found a 1951 TV a few months ago that I intend to restore, so I knew I needed a scope. I guess I never needed one before this. I wanted something that I could possibly repair, so I settled on the Tek 4xx series. I think I got a pretty good deal for this at $145 shipped. That brings me to a perhaps silly question. It is coming with a bunch of probes, but I have no idea why I would need more than a couple. I guess one of them is a current probe, so that makes sense, but I am not sure what the others do. I hope you guys can help me out.Here is the list of what I am getting.· 2 Tek P6131 Probes· 1 Tektronix 13.5pF probe· 1 TEK P6105 Probe· 3.5 Ohm 013-0071-00 Probe· Red and Black Probes· Termination Probe P6021I guess the Red/Black probes are for the DM44 multimeter. What is the difference in the others.Thanks all info in advance.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: November 05, 2015, 10:34:13 pm
content: Well, if you really did get a working p6021 current probe and its termination, that is indeed a good deal, as the probe (complete with termination) alone is worth more than you paid for the whole deal. But I'm thinking you may just be getting the _termination_ and not the probe itself.http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%20P6021%20Instruction.pdfETA: I just had a close look at the original listing and I think I _do_ see the p6021 probe head in there. So let's hope it all works, you got a great deal if it does !!

author: echap
author_rank: Contributor
timestamp: November 05, 2015, 11:05:41 pm
content: wow! I don't ever get that lucky. What are some of the other probes for?

author: helius
author_rank: Super Contributor
timestamp: November 05, 2015, 11:49:29 pm
content: The 475 is high-enough bandwidth that it is not using just commodity parts, so it is not necessarily the most repairable of them all. There are custom hybrid circuits (and they are brittle, so be careful). Tek specified that all repairs be carried out with Sn62Pb36Ag2 to protect the silver plated parts.The probes you got (nice deal with all of those probes) areP6131 x2: 250 MHz (if 2m cable, bandwidth depends on length)P6105: 100 MHzP6021: 60 MHz current probeP6006 or P6007: 25 MHz probe, 10X or 100XP6053/A/B/P6054/A: hard to tell. 150 to 290 MHz.

author: AF6LJ
author_rank: Unknown
timestamp: November 06, 2015, 12:00:31 am
content: Nice Find, I do cringe when I see decent scope probes treated the way they are in that picture.

author: echap
author_rank: Contributor
timestamp: November 06, 2015, 12:12:32 am
content: Quote from: helius on November 05, 2015, 11:49:29 pmExcellent info, thanks.

author: echap
author_rank: Contributor
timestamp: November 06, 2015, 12:13:54 am
content: Quote from: AF6LJ on November 06, 2015, 12:00:31 amHow should they be stored? Are you concerned about the way the cables are wrapped? Please explain.

author: PaulAm
author_rank: Frequent Contributor
timestamp: November 06, 2015, 01:22:52 am
content: Coil loosely and store in a plastic bag. When you wrap the cable up like a line cord you risk breaking the center conductor. Probe cables are highly engineered pieces of technology, not just a piece of cheap coax.The multimeters on those scopes look really cool, but they are not all that useful. You'll still be reaching for your Fluke. The DM44 does have a temperature range and the meter gives you a digital readout of the delay time which I've always found handy. The higher bandwidth 475 is a little more involved to repair than the 465, the higher bandwidth comes with a price of more complexity, but still reasonable. Be sure to pick up a service manual.Overall, looks like a pretty good deal. I have one of those in my repair pile (but no current probe, unfortunately).

author: echap
author_rank: Contributor
timestamp: November 07, 2015, 05:54:29 pm
content: Got the scope yesterday. it works great and came with the current probe.Are the power supply caps an absolute replace?Here are some pics, excuse my bench, its a messThe probeCalibrate probe

author: alsetalokin4017
author_rank: Super Contributor
timestamp: November 07, 2015, 07:46:43 pm
content: Looks very nice, good for you! Now to set up some proper tests for that current probe (color me green with envy).As far as the caps, etc. go...:If it ain't broke... don't fix it!:(sometimes known as.... if it ain't broke, fix it until it is!)

author: tec5c
author_rank: Frequent Contributor
timestamp: November 07, 2015, 11:31:59 pm
content: Probe doesn't look properly calibrated? Did you adjust the compensation cap.?

author: Cubdriver
author_rank: Unknown
timestamp: November 08, 2015, 12:58:15 am
content: Excellent score! I just paid nearly what you did for all that for just the 6201 current probe and its associated amplifier (slightly different than the termination you have; an older version). That's a fine scope, enjoy it!-Pat

author: PaulAm
author_rank: Frequent Contributor
timestamp: November 08, 2015, 03:12:55 am
content: If the scope is working fine, then the power supply caps are almost certainly OK. The service manual has the spec on ripple; I think it's around 5-10mV but I don't remember the exact number off hand. You can check that by using another scope, or a DMM on an AC range. Don't replace them unless they go bad. It's relatively easy to damage the pcb when removing those and it's difficult (but not impossible) to replace them without taking at least the trigger board out.Nice looking scope