Re: Help with a Tek 575 Curve tracer - New to group

Bob Koller <testtech@...>

No, I have never seen any docs, and speaking with knowledgeable ex-Tek guys, as I recall, they thought it was a factory mod, but didn't have any documentation. I have only worked on one or two that had it.

From: Tom Miller
To: TekScopes@...
Sent: Tuesday, October 2, 2012 1:27 PM
Subject: Re: [TekScopes] Help with a Tek 575 Curve tracer - New to group


Interesting. Is there any documentation on a fet conversion for the 575?
I fully agree that the tube matching makes a difference. You might try swapping a few around looking for an improvement. If you pulled all the tubes to clean the scope, that will mess things up for sure. Please don't ask me how I know this fact :(.
Thanks Bob.
----- Original Message -----
From: Bob Koller
Sent: Tuesday, October 02, 2012 4:03 PM
Subject: Re: [TekScopes] Help with a Tek 575 Curve tracer - New to group

A picture of the CRT trace would be very helpful. As the other post indicated, check the power supplies first for both regulation and ripple. Also, it is quite common to have poor and unmatched tubes in these. I have repaired several, and often found weak tubes. Does this one have tubes or the FET retrofit in the front ends? A pass through the cal procedure will often lead to the problem area. One other thing, be suspicious of resistors that have gone out of tolerance, often by a lot, as well as leaky caps.

From: bldrbldr5
To: TekScopes@...
Sent: Tuesday, October 2, 2012 9:36 AM
Subject: [TekScopes] Help with a Tek 575 Curve tracer - New to group

Hi, I just got a Tek 575 and it seems to generally work. E.g. I can get a I-V trace for a diode and neon bulb that makes sense. When I trace a 2N2222 transistor plotting collector I-V and stepping base current, I get the general shape that I expect. However, the horizontal traces going out and back on collector voltage sweep are not on top of each other; they are displaced vertically, and one of the traces has a odd hitch in it.

Brief troubleshooting (I've only had the unit since Sunday):

1. I can not get the AB phase plots to look like those in the manual. The vertical traces that should be lines look like very narrow, tall triangles.

2. If I short C to E and with a load resistor of 1K, sweep collector voltage and plot collector current vs base voltage with the step generator turned off, I don't get a vertical line as expected. I get a tall, skinny oval.

Any ideas about where to start would be very helpful.

I'm also hoping to find somebody in the Denver/Boulder area with a tube tester so I can test all the tubes.

I can post pictures of the traces if that will help.

Thanks for any suggestions.

-Scott, N8YY

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