I don't think B/W is the problem here, plenty enough signal amplitude.. looks more like a tired trigger circuit and I have no idea how to fix / diagnose that... no schematics around for the 544A, well unless it leaked since 5 years ago when I worked on it. Think I found schematics from a 520 or something, something like that... better than nothing... but still only partial schematic, so don't don't know it they show the trigger circuitry...
Anyway regardless, would be cool upping the B/W if it's just a cap to remove on the front end.. even if in practice it's not going to make much of a difference since the sampling rate and sweep sweep won't increase accordingly to make use of the extra B/W....
But for repetitive signals I guess it could still be somewhat useful.
Bring it on, give me instructions !
SPC ? No I didn't do that... I ran it 10 times in a row 5 years ago after fixing the scope, to make sure it was working fine... but have not run it ever since... OK will try that, though from memory it has nothing to do with triggering, SPC only compensates for small temperature induced DC offsets in the signal path ? Just from memory...
But it's free to try so will do !
FW versions ?
OK just powered them up to check... here goes :
TDS 544A: v3.8.3e with options 13 1F M
TDS 694C: v6.4e with options 13 1F 2F
Would be cool to extract the FW through GPIB, never done it ! Gimme the S/W and instructions even if you are not interested in my crusty old FW !
Here's a link to TDS554A schematics, in the sidebar on the right:
https://w140.com/tekwiki/wiki/TDS544A
Here's a link to some info on the TDS694C, it mentions a common issue with the triggering, maybe yours needs some love?
https://w140.com/tekwiki/wiki/TDS694
For the downloading of the firmware (and uploading of newer firmware), check this link:
https://www.eevblog.com/forum/repair/unified-tektool-released-!-(firmware-flash-tools-for-old-tds-series)/msg3758918/#msg3758918
I'll take both those firmwares if you can extract them.
The newest TDS6xx firmware I have is 4.2e, and I don't have TDS5xx 3.8.3e yet either. I've attached 3.8.4e firmware if you want to do a little upgrade too. It will take about 45 mins to upload, downloading is much faster (make sure to pull down the NVRAM as well as the firmware as in the instructions, that way it's basically impossible to brick your scope).
Also, follow this one to enable extra options:
Try the 2M option on the TDS694C, if it doesn't work, set it back to 0 and try 1M, and set 2F on the TDS544A.
Thanks a bunch for all that, you rock !
So the 544A schematics finally "leaked" then, that's fantastic ! Especially so since VintageTek museum said that despite them scanning their mega huge archive of Tek microfiches, they found no schematics for the 500/700 series, IIRC !
OK will play with FW and GPIB when I can... that is, not before some time... lab is no where near a state where I can clutter it with my old Pentium / GPIB PC....
When I get to that point, hopefully within 3 months, I will think of you ! If I don't... send me a PM !
OK running SPC was a good idea in fat, you were right...
Let the scope warm up for 20/25 minutes (they say 15 minutes minimum), ran SPC, got 3 errors. Let it warm up 20 more minutes, ran SPC again, got the exact same 3 errors, no more no less. The first two ones don't seem critical to me / relevant to my problem, but the last one looks like it is ! See screen capture below, it says that the trigger section failed to calibrate !!!
Without a PROPER service manual, to explain how the trigger circuit works and how to check for proper operation... no hope of fixing it.
My only hope of fixing it is that there is some corrosion that slowly progressed over the years.
Being a 5XX 'A', it is plagued with the dreaded myriad of leaky SMD electrolytic caps. ShakalNokturn who sold me the scope 5 year ago did a lot of work to bring it back from the dead.. replaced all caps, washed the boards several times in the dish washer, then fixed many broken traces in the analog part of the acquisition board, with a level of craftsmanship I envy. That got it working... but I still had weird errors, semi random, in the error log. So I looked at the corroded/reworked analog area that he fixed. I eventually found on the underside of the board, were these is nothing but a handful of discrete components IIRC... that a few SMD resistors had crappy looking/dull solder joints. Touched them up and that got rid of any and all error messages ! The dodgy joints were near a via. I suspect that the electrolyte managed to seep through these tiny open via and contaminated the bottom side of the board.
So.... since the trigger circuitry on these scopes IRC is all analog not digital, it's probably located in the same area that's been reworked / fixed. So all I can do is look at that area again and search for dodgy joints, rotten traces and what not. However since 99.9999% of hte work has already been done, it probably means that whatever problem remains, is bound to be NON obvious/blatant, so will need very careful inspection. Yes, this is a job for microscope. When I first fixed that board 5 years ago II suffered so much when going over that board, that I promised to myself I would NEVER do it again, to preserve my sanity (en eye balls).
So I will only look at this board... once I can afford to buy a microscope. No please people don't tell me about optivisor or what not. I have that... rubbish. I want/need to inspect this board in great detail, at length, in comfort. I am not looking at rushing this inspection, to the contrary I want to take my time and do properly when I am equipped to do so. Scope works fine below 400MHz so it's not like it was bricked... plus I rarely need it anyway. 99.99% of the time I just use my Combiscope...
@vince
i am a bit late, so catching up.. i am an owner 2be for an TDS744A, it seems easy to hack to TDS784A... (for yours is maybe the same) but.
if you need calibrating and want to use the original software, you need:
1. NI 8bit ISA or 7210 compatible ISA
-
https://www.ebay.nl/itm/283506706141 (i think)
2. bloody old pc p1 or p2 or below with ISA running DOS, 95 or 98 (the one you prob. trew away years ago, and its now called vintage gameing...so not cheap)
3. DC voltage calibrate will work with powersupply and a proper DMM
3. RF calibratiopn need 505 MHz and +17 dBm .. so you prob need a expensive generator or use an RF-amp behind an other generator (the marconi in my case)
So if you are not good with UNIX and or DOS emulators and tranlation-drivers-stuff to map adresses from PCI/USB to ISA vs-vs (like me),
you need a bunch of old stuff to get it working over GPIB with original Field Alignment Software from Tektronix (FAS)
then a USB-GPIB or PCI-GPIB won't work.
IF I UNDERSTAND CORRECT - from what i have read so-far.
just that you know before you start buying stuff and wast good money on GPIB stuff that then won't work.
cheers mate!
ps. there is an serial console kit for around 20 dollars from an Italian member from here, you find it on ebay.. if it is only for enabling the options.
- then you just hyperterminal yourself with this and no GPIB is needed. (when having this in place you need to have the PC switched on and connected, for the scope to boot, i have been told)
https://www.ebay.nl/itm/325015924779[edit1,2,3,4] bunch of typo's as usual