Oh good grief. No good deed goes unpunished. I was going to
backup the firmware on the A5 board, but apparently
it's a bad thing to use the "identify chip" function
of my PROM burner, as it seems to have broken one of
the EPROM chips.
Does anyone have images for the following?
160-1625-06
160-1626-06
160-1627-06
160-1628-06
I've already checked the bluefeather and a couple other sites.
I thought I could just take it from my other 2465, but that
has a slightly different A5 board, with only 2 EPROM chips
on it instead of 4, and the part numbers are different.
I'm guessing they are higher density, and in a pinch I could
try to read those and split the image into 4 chips for this scope,
but I have no idea what might have changed in the firmware
releases.
Scott
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--- In TekScopes@..., "Ed Breya" wrote:
Since you have two identical scopes, you can try swapping A5 or other modules, if it's not too complicated or risky - that would narrow down the problem areas. Just keep track of which goes with which to keep the calibrations right.
Your cursor problem may be DAC-related. Since the count is working, it seems like the incrementing signal is being processed OK by the brain, but the DAC which places the cursor location in the display isn't getting the message, presuming it's an analog or time positioning type scheme. Maybe one or more fairly significant DAC bits are stuck or missing.
Ed
Also, Happy New Year all, we're only a few hours away here, although it's already 2013 for some.
--- In TekScopes@..., Scott Burris wrote:
This is a plain vanilla 2465, no A or B. The A5 display board (and the
entire scope) is all
through hole construction. So it doesn't have those leaky SMD
tantalums. Not saying
there aren't bad caps somewhere, but at least they shouldn't spew out
corrosive electrolyte
all over the board.
Also, this has an EAROM chip instead of the Dallas NVRAM. Sure would
like to know why
they switched to the Dallas part in later scopes, was the EAROM unreliable?
I purchased this essentially as a parts scope for my *other* 2465, which
works wonderfully.
Unfortunately, this scope works well enough that I'm feeling motivated
to repair it
instead of using it for parts :-)
Scott
On 12/31/2012 9:06 AM, Ed Breya wrote:
If the scope is a 2465B, this may be a symptom of a well-known problem with leaky SMT electrolytic caps on the display board, as I recall. This issue comes up quite often - in fact, when I first joined the group, I noticed such a discussion and got concerned about my 2465B, so I started asking about it. Thanks to the group, I found that mine did indeed have the problem, and I managed to fix it before any serious damage was done. If not for that, it would have been damaged eventually, since this is my "best scope" that sits on the shelf - reserved for when all the others have crapped out. I would have never known until the time came to use it.
The other long-term deterioration issue is the battery-backed RAM for the calibration constants - mine is OK for now, but I still haven't resolved a "permanent" solution. This issue also comes up regularly.
Ed
--- In TekScopes@..., "Scott Burris" wrote:
Hi,
I'm hoping for a hint in the right direction on two problems
I'm trying to solve on a Tek 2465 scope. I've already done the
power supply tests in Table 5-1 of the service manual and
all voltages seem to be in tolerance, including ripple.
Problem #1: One of the cursors can only be adjusted over the left
1/3rd of the screen. It can go all the way to the left, but when
adjusting it to the right, it gets "stuck" about part way over.
However, the on screen readout, measuring frequency, continues
to change as the knob is turned. If you turn the knob in the
opposite direction, eventually the cursor become "unstuck" and
can be returned to the left side of the screen.
Problem #2: The on-screen readouts can't be brought into focus
at the same time. Turning the focus control, I can bring either
the upper readout or the lower readout into focus, but then the
other is slightly fuzzy. I tried tweaking the astigmatism control,
but no luck in getting this to improve.
Do these problems ring a bell with anyone? Otherwise the scope
seems to be working fine.
Although the power supplies seem to be OK, should I recap them
as a proactive measure? Presumably this won't help my two
problems. I'm aware of the condoraudio.com document for a
2465B. Is there a list of caps to order and replace for a 2465?
If not, I guess I could make one up and publish it.
I'm tempted to thermal epoxy a small heatsink on U800 for good
measure. Any downsides to doing that? Mine seems to be a Tek
made part, not a Maxim, does that improve heat reliability?
Thanks!
Scott
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