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-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of Chris
Sent: Sunday, February 17, 2013 2:40 PM
To: TekScopes@...
Subject: [TekScopes] Re: Tektronix 2465 capacitors etc.

Thanks! I had actually decided to pull the board and give it a close
inspection and wrote down the values, then I had placed the order. Found
out when it showed up that I'd ordered the wrong frame size X2 and Y rated
capacitors, so I had to place another order of the correct size (had to
substitute different mfg's in as they didn't have the one the condor audio
pdf listed in stock) Good learning exercise if anything. The only
component I didn't replace was the CR1110, dual common-cathode Schottky
rectifier.

That said, I soldered everything in, re-assembled the boards and anxiously
turned it on, only to find the same problem. Doh. I tested the caps after
they were out with my ESR meter that I just built and they all looked
acceptable. At least I can say all the caps are new so I won't have to worry
about them in the future. I couldn't test the capacitance of a good handful
of them as my DMM only works up to 40 micro Farad. Time for a better tester
- anyone have a recommendation for a good capacitance meter? I looked at
the local radio shack (best electronics store we have around here - read
that as the ONLY one..) The Extech (I think it was a model 430) is listed
to only 100 micro Farad, so it would still fall short.

So to not get too drawn out, I printed off some sheets from the service
manual for the 2465B's: Checking the voltages (1st commandment, thou shalt
check voltages right?) I stand as follows:

+10.00v is adjusted to +10.00v
+87v line is giving me about 9.5 volts
+42.4v line is giving me about 7.4 volts
the +15 volt line is giving me 7.2 volts
Digital +5v supply is 4.98volts
Analog +5v supply is 4.58 volts (close, but a tad low and out of spec)
-5V is giving me -4.96v
-8v is -8.01v
-15v is -14.97

So there's a definite problem with the 87, 42.4 and 15 volt lines, and the
5v analog should be looked at. So I've got some more studying to do on the
schematics. It looks like for the most part there's an unregulated voltage,
and then the regulated voltage, so my plan of attack is to check the
unregulated supply voltages first as that can help narrow it down to a
supply vs regulator issue.

I got the scope hoping to get into some small circuit design and electronics
repair - didn't expect the scope to be the first project. Trial by fire!

So, any tips or pointers are welcome, as well as any recommendations for a
good capacitance meter. (I have the BlueESR meter, just assembled their kit
this last week - works like a charm)

Thanks!
Chris

--- In TekScopes@..., "random.path" <groups@...> wrote:

Chris -

I have a spreadsheet with parts for refreshing the 2465a LVPS along with

Mouser part numbers. This has worked well for my scope. After reading the
Condoraudio piece and looking at this list you can decide what you want to
do. You can grab the spreadsheet 2465LVPS_ReCap.xls from

or I can email it

directly to you if you can get your email address to me.

Chip


--- In TekScopes@..., "Chris" wrote:

Hello all,
I'll try and keep this short. When it comes to electronics I'm

somewhat a newb, but not entirely. I've always been interested in it, and
I've recently purchased a scope - the tek 2465 300Mhz unit. Spent some time
getting familiar with it, playing around in XY mode, and then used it for
some diagnostics with some inductive sensors I was having an issue with.
Just when I was getting ready to pack it up from verifying the sensors the
scope went a bit goofy. The display at the bottom appeared to be
"compressed" to a a central blur (I could change it's intensity with the
readout intensity) and my traces were a short line near the center of the
screen. I powered the scope off, waited a few seconds and then powered it
back on, and it now powers on, lights up all the LED's, and I get a super
bright --- display at the center of the screen (unaffected by intensity
adjustments etc).

So, as typical I pulled the cover and did an initial once-over. I found

that on the main power supply board by the mains that 2 of the capacitors
look rough (one with the outer shell opened up). If you reference this pdf
regarding a 2465B, the 2nd image of the A2 PCB has the very capacitors
circles in red. The lower most one in the image is the one that looks like
it may have blown. I haven't pulled the board out of the scope to get a
better view of it yet. The rest of the capacitors on the board are the
green and brown mix as the image in the PDF shows, which leads me to believe
they're still the original capacitors in the unit.

Now in researching and reading about these scopes before I purchased

one, I had read that the capacitors were a common issue in them. I have no
worries about un-soldering components and soldering new ones in as I've done
it numerous times to revive other old equipment. (And I've read about the
need to cool these scopes with a fan if you operate them with the cover off)

So sorry to drag this out, so I'll try to make this quick. For those in

the know about these scopes, is there a listing/BOM for what capacitors
should be purchased and replaced?

Does the 2465B use the same values/locations on their boards that I can

just follow the PDF I linked?

Does my issue sound like something that the capacitors could be causing?

Or is it likely more involved?

I'd be happy to provide images or video as requested if it will help.

A huge thank you for taking the time to read and/or respond!
Chris

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