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From: "Dick" <w1ksz@...>
To: [email protected]
Sent: Monday, June 29, 2020 9:35:38 AM
Subject: Re: [TekScopes] What's the Tektronix part number for a dead spider

Where is it located ?

73, Dick, W1KSZ
________________________________
From: [email protected] <[email protected]> on behalf of snapdiode via
groups.io <snapdiode@...>
Sent: Sunday, June 28, 2020 10:41 PM
To: [email protected] <[email protected]>
Subject: [TekScopes] What's the Tektronix part number for a dead spider

Can you see it?



I thought it was funny.

Hello Saroj,

this is a good start! You confirmed your scope has the typical issue, it's
almost always the primary power supply with problems.

The Power Supply are basically TWO switching inverters after each other.
By means of bypassing the first - what you now did- you narrowed your
problem down to the first one.

First about the fan:
The fan is just a simple 60mm 12VDC fan, and usually draws about
150-160mA, and in the scope its running at a slightly lower voltage.
Did you use the proper polarity when you tested the fan? The board layout
and diodes in the scope create a negative voltage in respect to ground.
But, I assume you unplugged it to test, and if it does not turn and draws
500mA, I would say it is broken.

Smaller scopes in the 22xx range do not even have this fan, so again, for
now leave it disconnected until you got a proper replacement.

The wobbling of the screen, and lower DC voltages in the secondary PS are
probably due to the fact your temporary power supply is not regulated, a
bit low (38,7V) and therefor probably has a significant ripple, I would not
worry about these things right now.
The most important thing is: the second stage of the power supply works.
:-)

Now we concentrate on the first stage of the power supply:

I looked at all the different versions of the power supplies used in the
2213 2215 2215A 2230 etc scopes, and they are all similar, but not of great
design (Sorry for this remark, Tek!!)
I choose to use the following approach:

I changed R909 to 4,7 Ohm, instead of 39 Ohm.
This charges and discharges the input capacity of the FET Q9070 faster, so
it will switch ON and OF faster, therefor it will dissipate a bit less
power during switching.
You will find this lower value of R909 in some f the scopes I mentioned.

Furthermore: I replaced Q9070 by a FQPF4N90C.
This FET has a slightly lower ON-resistance (again, less dissipation while
ON) AND it has a full plastic housing.

Because of the plastic housing I put it directly on the metal mounting
plate while I added a TO-220 heatsink as well.
I even put a TO-220 heatsink at the other side of the metal plate, to
increase the cooling surface.

Recently I used the following components to repair this power supply:

CR907 MUR460 (a bit difficult, because of the thicker wires on this diode)
Q908 2N5401 (EBC) same pinout, so easy to replace
Q9070 FQPF4N90C Higher voltage, Lower ON resistance, plastic TO-220
housing, better mounting (IMHO)

But obviously, others will work too.

My first option would be:
Find suitable components, and leave the suspected fan disconnected for now.
See if it works, and while working on the repair, find another 60mm fan,
maybe from an old PC or other device.

God luck, you will get it up and running.

Leo

On 29 Jun 2020, at 15:41, snapdiode via groups.io <snapdiode@...> wrote:

Can you see it?



I thought it was funny.

29. jun. 2020 kl. 04:44 skrev Michael W. Lynch via groups.io <mlynch003@...>:

?On Sun, Jun 28, 2020 at 07:49 PM, momemeca wrote:

Along the same line of enquiry ... 120-0117-00?
I have one of those on my spares shelf but the assignment label on it fell off
and I no longer know what it belongs to :-(
Also ... What is the Tektronix RPR Catalog and can I access it On-Line?

Rick,

Here you go.

120-0117-00 is a Power Transformer for a 310A

The RPR catalogs are available at TEKWiki. Follow this link: then type "RPR" in the SEARCH box. This will take you to the repository for all the TEKTRONIX RPR catalogs. Super valuable resource. The RPR information is just a VERY small part of what is available at TEK-Wiki. I have downloaded a lot of this information to my hard drive for quick access.

Thanks

--
Michael Lynch
Dardanelle, Arkansas

Hello Variac, variac, and variable auto transformer users,

The first GR Variac I encountered was in about 1959. It was very old then. The brush is cylindrical, not rectangular like modern ones. I still have the thing, and though I have not used it for a few decades, it still works well.

I have written a “Diatribe” on variacs. It tells how you can by mistake apply ONE HUNDRED FIFTY TWO volts to your radio with a variac. It also tells how you can get the dial on your variac to indicate close to the actual output voltage with modern line voltage input.

I’m gad to send it to any one interested.

Another of my Diatribes tells how a fused line cord can make a widow of your wife.

Roy



Roy Morgan
K1LKY since 1958
k1lky68@...

Hey Tom,

Thanks for replying. I don't have any LED lights but I do have a florescence one (but that's spitting out crap at 50Hz so I assume it's fine). Either way, I took the scope to another room in the house and it's still the same. In fact, I'm facing a very similar problem to what's outlined here - /g/TekScopes/topic/7638108

I checked the grounding on the CRT tube, the resistance from the earth pin to the top of the tube, and it was in the order of ohms, so I cleaned up the ground clip contact, it reduced the resistance to sub-ohm, but this did not help.

So, I guess I had better start replacing some caps, the rifa ones looked cracked, so I'll start with these. The PSU filtering caps, are they all on A18?

Thanks again!

Max

Schematics for Tek part numbers 119-1303-00 and 119-1304-00 are now
archived on Tekwiki (Thank you Kurt).

These were purchased Power One supplies that are listed in Common
design Catalog 6 section 12-2.

Search Power One on Tekwiki.

I remember Power One being mentioned recently, maybe this will help
someone.

Best Regards to all,

Craig