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 Post subject: Tektronix 130 components, calibration
PostPosted: Jan Sun 08, 2017 10:04 pm 
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Location: Rockville, MD
I've recently acquired a Tektronix 130 LC meter. The unit smelled and was dirty throughout from decades of grime and cigarette smoke. I cleaned it thoroughly inside and out; cleaned the switch contacts with isopropyl alcohol; repaired the fuse assembly; and tested and replaced several tubes before bringing it up slowly on a variac and current limiter. Low and behold, no smoke.

Moreover, it works, though it performs better on some scales of L and C than others, which doesn't seem surprising given that I haven't checked resistor and capacitor values or made any attempt to calibrate the instrument. I did check the 150 volt and 270 volt levels, and found them to be near the desired values, and also the 140 KHz fixed oscillator frequency and found that to be accurate as well.

That it functions so well after only cleaning and replacing the needed tubes astonishes me. I have to work through the manual and verify operations plus trouble shoot as needed, but I wonder what the forum's wisdom is on two issues: (1) Presumably Tektronix used first rate components, and of course there's no substitute for testing (which I will do), but I'm curious about what others have found in terms of leaky capacitors and drifted resistors in Tek instruments of this era (late 1950s/early 1960s). (2) Before snagging a delta standard calibration unit, does anyone know of an alternate calibration procedure that does not use that unit? Searching thus far has not turned up anything.

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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Mon 09, 2017 12:33 am 
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I have owned two of those 130s and neither one of them needed calibration or repair.


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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Mon 09, 2017 1:56 am 
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I have an early (square corners, brown case) purchased off this forum. Before I got it a couple of caps had been replaced. Think I ended up replacing the power supply caps. Just depends on it's prior life.

I did eventually find and buy the Tek standard also; but paid too much. And they go for way too much. Can't help myself sometimes. Some known caps would be fine.

Does yours still have some of the repair silver solder Tek put inside?

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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Mon 09, 2017 12:29 pm 
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I had one several years ago, and liked it. Easy to use, accurate, dependable, what more could you ask of it. But, as happens all too often I sold it at a profit so I could buy something bigger and better(?). ...And no its not broken, if you look carefully you'll see a small ceramic disc across the SO-239 input connector. :wink:

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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Mon 09, 2017 2:58 pm 
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Thanks for the responses.

Johnnysan, good to know that these are hardy and reliable.

W0MPM, I'll look for leakage and ripple on the filter caps and act accordingly. The upper ranges on both L and C are off by ~25% or more, while the lower L and C ranges are much more accurate, so I'll look for failed or drifted components specific to those circuits. Hopefully when found and replaced the accuracy will be better and I can look into calibrating if needed. As for the silver solder, there were maybe 6-8 straight wires rolling around loose in the bottom of the chassis (!), each ~2 inches long. I haven't tried to see if they melt on a soldering iron, but perhaps they are the repair solder? They're a mess with dirt etc like the rest of the unit was, and would have to be cleaned up to be used at this point; I did, however, purchase new silver solder for potential repairs.

Mikeinkcmo, yes, that looks like mine :D

One additional interesting thing: Tek must have changed tube V76 at some point in the production run. The manuals I've found online list V76 as a 6DJ8, but the chassis in mine labels V76 as a 6BQ7A.

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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Fri 13, 2017 12:44 am 
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Location: Leesburg, Virginia
Nice YouTube.

Presumably as shipped: little spool of solder at the bottom.


Attachments:
Tek130repairsolder.JPG
Tek130repairsolder.JPG [ 232.93 KiB | Viewed 982 times ]

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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Fri 13, 2017 12:49 am 
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Location: Maryland 20709, USA
W0MPM wrote:
Presumably as shipped: little spool of solder at the bottom.
That solder is important. It contains 3% silver.

It needs to be used whenever you solder any of those ceramic terminal strips.

Using regular solder for those connections can cause the metalization to separate from the ceramic.

Don't use it for other connections, like tube sockets or switch contacts.
It will work for those, but you only have a small amount of it, and modern silver-content solder is expensive.

- Leigh

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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Fri 13, 2017 2:43 am 
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W0MPM -- I'm pleased you liked the videos. Working my way through the unit, I'm finding that while the capacitors generally test within the tolerances listed in the manual, they leak terribly. The four tested thus far (C91-94, the four yellow caps in the center of your picture) leak at 25 volts even though they are rated for 400 volts or greater. I fear many resistors will be drifted, too; they will be tested shortly.

My unit (s/n 5700) has no silver solder in the bottom, nor any spools affixed to the case or chassis. The short, straight wires that were loose in the bottom of the unit are definitely not solder. They remain a mystery.

Leigh -- Thanks for the warning and pointers. I've procured some modern silver solder for the ceramic strips.

Onward! Best regards,

David

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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Fri 13, 2017 2:56 am 
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Joined: Aug Wed 04, 2010 5:40 pm
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Location: Tyngsborough, Massachusetts
Regarding your comment on V76, in my 130 the V76 socket is marked "6DJ8/6922/6BQ7A". My unit came with a 6DJ8 in that spot.

Unfortunately, mine didn't have the piece of solder, or the spools for it, either.

Jeff


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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Fri 13, 2017 3:39 am 
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jeffs01879 wrote:
Unfortunately, mine didn't have the piece of solder, or the spools for it, either.
In the 5xx-series scopes of the same era, the silver solder was wound on a small white plastic spool.
The spool had a square teat sticking out one side that went into a square hole on the chassis wall.

Image

If your 130 has such a square hole, that's why it's there.

- Leigh

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 Post subject: Re: Tektronix 130 components, calibration
PostPosted: Jan Fri 13, 2017 4:14 am 
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Joined: Aug Wed 04, 2010 5:40 pm
Posts: 275
Location: Tyngsborough, Massachusetts
I'll have to look for the hole in my 130. I have a Tek 531 that still has at least a portion of the piece of solder. It's wound around two spools like those shown in W0MPM's post.

I picked up a roll of silver bearing solder for working on the Tek ceramic strips.

Jeff


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