Slightly OT: Differences between Tek TDS754A/C/D scopes
Joel Koltner
and TDS754D digital scopes? I finally found a Tek manual that had a table of
the specs for 744 vs. 754 vs. 784 vs. 794 and so on, but I've yet to find one
that spells out the salient A/C/D changes. (As far as I can tell, the 754 and
784 moved in lock-step between A, C, and D...)
I suspect one of the difference was the change from that funky monochrome CRT
+ R/G/B LCD shutter arrangement Tek had on some of the scopes to a regular
color CRT or LCD...
---Joel
JW
<zapwireD...@yahoo.com> wrote in Message id:
<DOAdp.3371$Lj7....@en-nntp-03.dc1.easynews.com>:
>Does anyone happen to know the differences between the Tek TDS754A, TDS754C,
>and TDS754D digital scopes? I finally found a Tek manual that had a table of
>the specs for 744 vs. 754 vs. 784 vs. 794 and so on,
I saw your post about that on Tekscopes, but the link you posted was
screwed up by Yahoogroups. I wish all the guys would move to Usenet, I
hate that crappy web interface. Could you re-post the link?
>but I've yet to find one
>that spells out the salient A/C/D changes. (As far as I can tell, the 754 and
>784 moved in lock-step between A, C, and D...)
Some of the things I can think of off the top of my head:
1. The D series would work with an external zip drive.
2. On the A series, option 1M gave a record length of 130,000 samples,
while on the C and D series option 1M was 500,000.
3. On the C and D series there was an option 2M which increased record
length to 8,000,000 samples.
4. The D series introduced DPO acquisition mode.
From the manual:
DPO acquisition mode reduces the dead time between waveform acquisitions
that normally occur when digitizing storage oscilloscopes (DSOs) acquire
waveforms. This dead-time reduction enables DPO mode to capture and
display transient deviations, such as glitches or runt pulses, often
missed during longer dead times that accompany normal DSO operation. DPO
mode can also display waveform phenomena at an intensity that reflects
their rate-of-occurrence. DPO XY and XYZ modes also provide intensity
information by accepting continuous, non-triggered data from the input
channels. This section describes how to use DPO mode and how it differs
from normal acquisition mode. DPO automatically selects record length and
sample rate to optimize the displayed image. DPO selects sample rates up
to 1 GS/s and record lengths up to 500 K and compresses them to 500 pixels
to produce the maximum display content.
>I suspect one of the difference was the change from that funky monochrome CRT
>+ R/G/B LCD shutter arrangement Tek had on some of the scopes to a regular
>color CRT or LCD...
I don't think that any of the TDS7XX scopes had a color CRT or a
non-aftermarket LCD. At least I've rooted around in many of them and never
seen one. I believe they used the shutter system to avoid problems with
RGB convergence that a color monitor would have.
Phil Hobbs
My TDS744 has a colour CRT.
Cheers
Phil HObbs
--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net
JW
<pcdhSpamM...@electrooptical.net> wrote in Message id:
<9_WdnVeSLMckF-rQ...@supernews.com>:
Nope. It has a monochrome CRT with an LCD shutter glommed onto the front
of the CRT tube. There is optical gel between the CRT face and the
shutter. When the CRT finally goes bad it's possible to replace it, but
you'll need to remove the shutter and put it on the new CRT. A very messy
job due to the gel.
Unless somebody has modified your particular scope...
Phil Hobbs
Sure looks like colour, but I'll take your word for it.
Cheers
Phil Hobbs
JW
Yes, it looks like color but it is the shutter that does the trick. More
detail can be found on page 6 of this document:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.14.2741&rep=rep1&type=pdf
and
http://www2.electronicproducts.com/Oscilloscope_makers_ride_the_color_bandwagon-article-OL3-apr1993-html.aspx
There used to be a document about it on the Tektronix website, but it
looks like it's no longer there.
The electronics to drive the shutter can be seen here:
http://www.qservice.tv/vpasp/shopexd.asp?id=8986
Joel Koltner
"JW" <no...@dev.null> wrote in message
news:velen65su1nh3neib...@4ax.com...
> I saw your post about that on Tekscopes, but the link you posted was
> screwed up by Yahoogroups. I wish all the guys would move to Usenet, I
> hate that crappy web interface. Could you re-post the link?
Try this:
http://www.em-tek.co.kr/download.asp?filename=TDS%20500D,600B,700D%20User%20Manual.pdf
It'll want to save a ~2.9MB file named "TDS". Let your browser do so, and
then rename the file so that it has a .PDF extension.
Page 1-3 there has a nice table ranging from the 520D up to the 794D.
> Some of the things I can think of off the top of my head:
> 1. The D series would work with an external zip drive.
> 2. On the A series, option 1M gave a record length of 130,000 samples,
> while on the C and D series option 1M was 500,000.
> 3. On the C and D series there was an option 2M which increased record
> length to 8,000,000 samples.
> 4. The D series introduced DPO acquisition mode.
Thanks!
This is what a helpful eBay seller told me as well:
---
The Tek TDS54X revision A did not have some options available. These are
communications trigger (2C), optical probe options (3C and 4C), hard drive
(HD), and expanded memory (2M)
Options available on 754A and 540A were 05 (video trigger), 13 (RS232 and
centronics Interface), 1F (floppy drive), 2f (FFT math option), and 1M
(expanded memory)
The InstaVu was renamed DPO in the D revisions of Tek scopes but InstaVu is
really the same thing as DPO mode. mostly a marketing and trendy renaming.
The scopes are basically all very similar except for options. The C and D
revisions are the last of the series and late 90's era vs early 90's era.
All are very reliable. I would recomend the C or D series over previous just
to have the newer internal boards.
Some of the early A series had electrolytic cap leakage issues and caused
board failures.
This issue was resolved in B-D series using tantalum caps.
---
> I don't think that any of the TDS7XX scopes had a color CRT or a
> non-aftermarket LCD. At least I've rooted around in many of them and never
> seen one. I believe they used the shutter system to avoid problems with
> RGB convergence that a color monitor would have.
Yes, I believe you're correct there -- it was just wishful thinking on my part
that the "D" revs switched to a color CRT or LCD.
---Joel
Joel Koltner
> The electronics to drive the shutter can be seen here:
> http://www.qservice.tv/vpasp/shopexd.asp?id=8986
I'm amazed how many parts that guy has! E.g., just for TDS500 series scopes
alone: http://www.qservice.tv/vpasp/shopcontent.asp?type=tds500