Adventures with the Tektronix 570, 575, 576 and 577 Curve tracers

[Nashou66]

Well another addition to my gear, and I still dont know how to use most of it But I cant stop collecting this stuff.

A Tektronix 577 Curve tracer with the 177 test fixture .



Got it for half the asking price cause I argued how much it world cost to repair it. The auction add said no power and that it must be something with the switch or that it was bad.

Well on these you have to pull the switch out, so I was hoping it was only that.

Well got it today and plugged it in and nothing. So I pulled the fuse in the back and it was open yes, I had a fast blow 2 amp fuse but it requires a slow blow. Well it all I had. Well it worked and I got a few lights but I did not hear the HV come up. Hmm.

So I popped the side cover off and had a look around. And I saw one of two wet tantalums leads not soldered in and bent out towards me . WTF? ( Forgot to take a pic) So I bent the lead back towards the pad and heated up the leg and was able to solder it from the component side for now.

Top cap was the culprit.

Powered it up and that sound of the HV came up and a relay click !!

yes , I was able to find a trace with the beam finder and able to increase intensity and adjust focus. So I think the tube is ok.

Didn't do much more as I need to read the service manual which I also found NOS still in its shrink wrap !

Some more pics of the one side cover off.

So much Fun !!!

And I still have the old Type 575 that needs a little work as well.

Athanasios

 

[pac1085]

She's a beauty, nice score!! I have a nice 575 but would really like to replace it with a 576 or 577 eventually. How's the condition of the storage tube? I really want a 577 with storage, but I hear the tubes wear out pretty bad? Also, it sounds like you bought it online? Glad to hear it didn't get obliterated in shipping.

 

[Cubdriver]

Verrah niiice!!

-Pat

 

[Nashou66]

She's a beauty, nice score!! I have a nice 575 but would really like to replace it with a 576 or 577 eventually. How's the condition of the storage tube? I really want a 577 with storage, but I hear the tubes wear out pretty bad? Also, it sounds like you bought it online? Glad to hear it didn't get obliterated in shipping.

Not too sure on the tube health . But I was ab le to get the beam spot pretty bright.

I need to watch a video by one of the YouTubers again I watched last week . He went trough a bunch of things about the D2 and this D1 . Not sure how the power generators are working either. the sale came with a bag go parts that I guess some previous tech replaced .

So lots of testing and investigation for this one.

My 575 works b ut it could use tweaking as the traces have a lot of loop back.

Athanasios

 

[Nashou66]

Who ever worked on this before was FU&*^%$ HACK!!!!!

Look at this PS !!!

This is what it's suppose to look like!!!

I have a lot of work ahead of me !! I took lots of pictures, and made a map of the wires that were not on headers.

I need to start a new thread for this one.

This is where we need a Dedicated Test Equipment forum to have a place for situations like this.

So I guess the DIY forum will have to do for now.


Athanasios

 

[Cubdriver]

Jeebus!! I did better work than that in junior high school when I was jest getting started in electronics! Yike! That poor curve tracer!! I'm sure it's much happier in your hands, though you have quite the challenge in front of you.

Makes me think of one of the Ten Commandments for Electronic Technicians I learned in HS - Maketh not unauthorized modifications to equipment, and causeth thou to duly record all field changes thus made, lest thy successor tear his hair and go slowly mad as he struggles to divine what manner of creature hath made a nest in said wiring.

Some people should not be allowed near tools or a soldering iron.

-Pat

<edit - typo>

 

[Nashou66]

Jeebus!! I did better work than that in junior high school when I was jest getting started in electronics! Yike! That poor curve tracer!! I'm sure it's much happier in your hands, though you have quite the challenge in front of you.

Makes me think of one of the Ten Commandments for Electronic Technicians I learned in HS - Maketh not unauthorized modifications to equipment, and causeth thou to duly record all field changes thus made, lest thy successor tear his hair and go slowly mad as he struggles to divine what manner of creature hath made a nest in said wiring.

Some people should not be allowed near tools or a soldering iron.

-Pat

If I can't repair it as is I might try to make a new one with Eagle . But that might take months for me to design as Im not that good at it .

Ugh Wish me luck .

Nashou

 

[pac1085]

Taking a trip up to Canada on Friday to pick up these Tektronix 576 curve tracers. I've been wanting to replace my 575 for a while, when the right deal came along. I also finally managed to locate one of Dennis Tillman's Vacuum Tube Curve Tracer boards, which I will use to mod my Eico 667 and be able to plug it into my curve tracer and measure vacuum tubes. The 575 did not have Mod 122c, so it was limited to 200v collector. The 576 will fix that. The 576 comes with a working parts unit, but the parts unit has the faulty HV transformer so you can only run it for 10 mins at a time. Will be nice to have spare parts, though. I'm not sure if I'm going to keep the 575 around or sell it.



Oh, and I almost forgot, I don't mess around with speakers too much but I picked up a Dayton DATS:

Dayton Audio - DATS V3 Computer Based Audio Component Test System

DATS V3 Computer Based Audio Component Test System

www.daytonaudio.com

Pretty neat tool for the $$$. I wanted to see the impedance sweep for some speakers. May be useful when buying speakers as well, I could take it with my laptop and compare both to see if one has a bad tweeter etc, or if they are drastically different for some other reason.

 

[Nashou66]

@pac1085 Is that you that has the 575 for sale on Facebook Market place , Great price if it is !

You should put it up on Bartertown as well.

I have two more Nixie tube units coming in today , Another HP 3440A and a HP 5326 frequency counter with a DVM module

Athanasios

 

[pac1085]

@pac1085 Is that you that has the 575 for sale on Facebook Market place , Great price if it is !

You should put it up on Bartertown as well.

I have two more Nixie tube units coming in today , Another HP 3440A and a HP 5326 frequency counter with a DVM module

Athanasios

Yeah that's mine. Supposedly a guy from Buffalo wants to come check it out. I actually took the ad down for now because I picked up the 576's but I am having issues with them (still happy considering how cheap I got them for). For some reason the step generator seems to randomly give up the ghost on the one unit. Also, the 576 fits nicely on the cart intended for the 575. And the TO-3 adapters I have for sale with the 575, I'm thinking about keeping. I was looking on eBay and the TO-3 adapters with kelvin sensing for the 576 are rare and go for about $100 each. Although I should probably make my own test fixture with a heatsink for the TO-3 stuff.

I bought a 2467B from the guy while I was up there since it looked brand new and was cheap, but has issues with the A5 board. He isolated the fault to a specific chip but damaged the surface mount pads and traces pretty bad while removing it. That looks like fun... hopefully I can repair it. I wanted a 2465B/2467B to replace my 2247A.

I also picked up a HP 53310A modulation domain analyzer (with all options), it should be here tomorrow. I'll probably put my 5335A up for sale if it does everything I want.

Ran a dedicated 25 amp circuit for the 6813A last night, thing works perfectly! Looking forward to spending some more time with it..

 

[Nashou66]

@pac1085 I thought it might be you. Im keeping my 575 just cause they look so cool and have tubes !

I see those test fixtures with kelvin sensing all the time, what does that mean? Im not educated in these things so I like to learn as much as I can fro you fine folks here.

I have been reworking my shop so I can more easily use( well first learn to use) all the gear I have acquired. Running new sockets everywhere.

Now Im trying to figure out how to place the all on the shelving I made for ergonomics and what I use the most. Three levels all 9 inches tall and 58 inches wide with access to the back from another small storage space.

I just got another Nixie tube HP 3440A but this one has the resistance and current feature, I think its the 3441 module.


Here is a pic from a couple days ago.

Athanasios

 

[Cubdriver]

Resistance and current is probably the 3444A module.

Kelvin sensing is a four wire setup intended to eliminate losses in the wires driving the device under test from being a factor in the measurement. In, for instance, a handheld DMM, when taking a resistance measurement the meter applies a known current to the test leads and measures the resultant voltage developed by the leads + any contact resistance + the resistor being tested. The measurement displayed includes the lead resistance, because they’re in the entire circuit. With a Kelvin connection, there are separate drive and sense leads. The current from the source flows through the drive pair, and the voltage across the device under test is fed back through the sense pair. As the circuit within the meter that measures this voltage is a very high impedance, almost no current flows through the sense wires, so there is a negligible voltage drop across them, giving a more accurate reading of the actual resistance being measured as the lead resistance now isn’t a factor.

Circuit:


Kelvin clip:


Detail of wire to second contact:


The basic concept is to keep the potentially heavily loaded drive signal separate from the measurement as much as possible; this reduces the impact of supply lead resistance in the measurement. A similar concept is used with remote sensing for a power supply - rather than regulating the voltage at the output terminals (meaning that whatever you’re powering will get less voltage due to losses in the wires feeding it), you measure at the load, and the supply compensates for losses in the wiring and feeds the full required voltage at the load.

Hope this helps to explain it.

-Pat

<edit to clarify Kelvin explanation>

 

[pac1085]

Spent some time on the curve tracers tonight. The one on the left was sold to me as a parts unit. It actually works great. The previous owner thought the HV transformer was bad (it is one of the earlier brown ones) but I think the actual issue was with the relay on the step generator board. I found a guy selling drop in replacements on eBay and it solved that issue. I ended up using those new relays in both of the 576's as the originals both had issues. I probably didn't need to spend $180 on a replacement transformer, but it will be here in a few days anyways. I guess the brown ones all go bad eventually so it won't hurt. I don't need 3 curve tracers so I'll probably sell that extra 576 once it's fixed up. I have a bezel coming for it as well, as it was missing when I got it. Still gotta figure out that one knob. I have some of the parts for it, but not all.

I did have a weird issue with the one on the left. For some reason the test fixture didn't work correctly in that unit. If I took the test fixture out of the middle one and put it on the left one, it worked fine. And if I put the test fixture from the left one in the middle one, it worked fine. Anyways, after several hours of screwing around with it I found that Pin 1 on the test fixture wasn't making good connection with the chassis. I was able to pry it up a bit and now that test fixture works fine.


New relay on the right. It was actually listed as being for 7000 series scope plugins but I did a little research and risked it, turns out to work great. I bought 2 more from the guy once I made sure it worked.


The offending pin. There's no room to get in there and pry it up so I had to dig into the plastic a bit with a tiny flat screwndriver.


I've been wanting to build the Dennis Tillman vacuum tube curve tracer adapter, which you install in a tube tester like an Eico 667 and then connect it up to your curve tracer. I guess his health hasn't been too good and he isn't selling the board anymore. I posted a want ad on the telescopes group and someone sent me one for free. Very thankful for that. I assembled it but haven't tested it or installed it in my 667 yet. Here is a link to the PDF describing it if you're curious: http://www.ke5fx.com/A_VTCT_Adapter_for_All_Tektronix_SCTs_W7PF.pdf

 

[pac1085]

I made a replacement plastic piece for the Tektronix 576 curve tracer standard test fixture if anyone needs it. Does not have the provisions for the HV interlock cover, I don't have one so I didn't bother. The OpenSCAD file is in there though if you want to modify it for yourself.
Pretty sure I have it dialed in but the final copy is printing now. Will update it if I run into issues.

Tektronix 576/577 Standard Test Fixture Plate by pac1085 | Download free STL model | Printables.com

Replacement plate for Tektronix 576/577 Curve Tracer Standard Test Fixture Does not include HV interlock provisions | Download free 3D printable STL models

www.printables.com

 

[Nashou66]

I made a replacement plastic piece for the Tektronix 576 curve tracer standard test fixture if anyone needs it. Does not have the provisions for the HV interlock cover, I don't have one so I didn't bother. The OpenSCAD file is in there though if you want to modify it for yourself.
Pretty sure I have it dialed in but the final copy is printing now. Will update it if I run into issues.

Tektronix 576/577 Standard Test Fixture Plate by pac1085 | Download free STL model | Printables.com

Replacement plate for Tektronix 576/577 Curve Tracer Standard Test Fixture Does not include HV interlock provisions | Download free 3D printable STL models

www.printables.com

View attachment 3215957

Nice, Will it work for the 577? I think hey are the same , no?

Athanasios

 

[pac1085]

Nice, Will it work for the 577? I think hey are the same , no?

Athanasios

Good point didn’t think of that. It does look the same so unless it’s got different dimensions it looks like it would work

Printed one last night came out pretty good, but I do need to make a few minor tweaks. I didn’t test it with all 3 style test fixtures and have to change the spacing a bit.
edit: I updated the file on printables. Looks like I had to move the sense terminals up 1mm. printing another one now.. will have final confirmation in a few hours.
edit2: updated the file again. v3. 3rd time's a charm right? I'll know around 5 PM tonight

 

[pac1085]

Road trip tomorrow to pick up this bad boy

 

[Nashou66]

Road trip tomorrow to pick up this bad boy
View attachment 3260096

WTF!!! Where do you look for this stuff!!!

Love to add that to my collection!!!

In Canada again?

Nashou

 

[Cubdriver]

Goddamn!!! How'd you manage to score that?!? Color me extremely jealous!

-Pat

 

[pac1085]

Goddamn!!! How'd you manage to score that?!? Color me extremely jealous!

-Pat

Good question. I'll spill more details after I have the thing in my hands. $$ is part of it, lol. It's not cheap but honestly it seems like a decent deal compared to what I've seen other people say they are willing to pay for them.

This guy apparently has a few of them. Including the newer style one, with the sides that come off like the 575 (this one I'm buying, has a one piece case, early production, not fun to service). He doesn't seem too keen to sell them.

At first he was going to sell me that one and then changed his mind. I'm pretty sad, I really wanted that one. Since I plan to use this thing for the next 45 years or so (with any luck), the ease of serviceability would have been nice. I also try to get the best/latest of whatever piece I'm after.

He said he will have his wife call me and sell it to me after he dies. Lol.