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" 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
> >
>
