Date
1 - 7 of 7
067-0912-00 needed
|
Eric
I am thinking about trying to tackle a calibration on my 7854. I have confirmed that the digital and analog sections are out of adjustment. The digital section is about .8 division left of center. In looking through the calibration document It seems I have everything I need to do the calibration except the 067-0912-00 the analog test board. How likely is this something that I am going to be able to acquire it does not look too complex from the schematic just a few IC’s and a data bus.
|
|
|
|
Hi Eric,
toggle quoted messageShow quoted text
I can't help with a schematic, but there is some information on this card on TekWiki at http://w140.com/tekwiki/wiki/067-0912-00 Dennis Tillman W7pF
-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Eric Sent: Wednesday, October 21, 2020 8:55 AM To: TekScopes@groups.io Subject: [TekScopes] 067-0912-00 needed I am thinking about trying to tackle a calibration on my 7854. I have confirmed that the digital and analog sections are out of adjustment. The digital section is about .8 division left of center. In looking through the calibration document It seems I have everything I need to do the calibration except the 067-0912-00 the analog test board. How likely is this something that I am going to be able to acquire it does not look too complex from the schematic just a few IC’s and a data bus. -- Dennis Tillman W7pF TekScopes Moderator
|
|
|
|
Dave Daniel
A schematic for the -00 version of the board is in the datasheet link on the TekWiki page to which Dennis pointed.
toggle quoted messageShow quoted text
DaveD
On Oct 21, 2020, at 13:45, Dennis Tillman W7pF <dennis@ridesoft.com> wrote:
|
|
|
|
Clark Foley
Dennis,
Did you ever make duplicates of that early 7804N conversion board (K7-1286-XA)? Clark
|
|
|
|
Dave Casey
That schematic has some curious idiosyncrasies. The logic is powered by
toggle quoted messageShow quoted text
+5VD, but all the pull ups being used are to +5V. (The ones that are shown, anyway; there are unused inputs on U420 and U520 that must also be pulled high for the board to work, but these aren't indicated in the schematic.) Also, the inputs from the mode switches on A2 are referenced to +5V (not +5VD). +5V and +5VD are basically two copies of the same supply, powered from the same output of the switcher, and their domains cross in a few places within the scope without any real decoupling. That spirit continues in the 067-0912-00 board. The parts list and schematic do not appear to line up 1:1 (C621 on the schematic is very probably C620 on the parts list, but R520 is in the parts list and so far escapes detection on the schematic. Another interesting observation is that the _FPR ("Front Panel Read", active low) signal is left floating when using the 067-0912-00, meaning that A2U61 and A2U62 are not guaranteed to be tri-stated and could be fighting U430 and U530 of the 067-0912-00 for D0:D8. I'm sort of surprised there's no pull-up on the A2 board, but the schematic shows that signal being driven directly by the MPU board (which would be absent when using the 067-0912-00). Enough mysteries for tonight... Dave Casey
On Wed, Oct 21, 2020 at 1:12 PM Dave Daniel <kc0wjn@gmail.com> wrote:
A schematic for the -00 version of the board is in the datasheet link on
|
|
|
|
Eric
Dave,
toggle quoted messageShow quoted text
The board is weird. My understanding of this is all this board does is allow you to check the lights “I know mine are ok” and it passes analog signals to the tube amplifiers so you can calibrate the analog portions of the scope with out any of the digital circuits being installed. Eric
-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Dave Casey Sent: Thursday, October 22, 2020 4:48 AM To: TekScopes@groups.io Subject: Re: [TekScopes] 067-0912-00 needed That schematic has some curious idiosyncrasies. The logic is powered by +5VD, but all the pull ups being used are to +5V. (The ones that are +shown, anyway; there are unused inputs on U420 and U520 that must also be pulled high for the board to work, but these aren't indicated in the schematic.) Also, the inputs from the mode switches on A2 are referenced to +5V (not +5VD). +5V and +5VD are basically two copies of the same supply, powered from the same output of the switcher, and their domains cross in a few places within the scope without any real decoupling. That spirit continues in the 067-0912-00 board. The parts list and schematic do not appear to line up 1:1 (C621 on the schematic is very probably C620 on the parts list, but R520 is in the parts list and so far escapes detection on the schematic. Another interesting observation is that the _FPR ("Front Panel Read", active low) signal is left floating when using the 067-0912-00, meaning that A2U61 and A2U62 are not guaranteed to be tri-stated and could be fighting U430 and U530 of the 067-0912-00 for D0:D8. I'm sort of surprised there's no pull-up on the A2 board, but the schematic shows that signal being driven directly by the MPU board (which would be absent when using the 067-0912-00). Enough mysteries for tonight... Dave Casey On Wed, Oct 21, 2020 at 1:12 PM Dave Daniel <kc0wjn@gmail.com> wrote: A schematic for the -00 version of the board is in the datasheet link
|
|
|
|
Dave Casey
For sure it's a weird board, but there's one more thing it does besides
toggle quoted messageShow quoted text
letting you test the lamps and control the analog portion of the scope without the processor. Item 4 in the list of "other analog test functions" indicates it can be used in calibrating the vertical channel switch in conjunction with a 067-0587 mainframe calibrator. For that, it just provides a simple buffer amplifier for the pretrigger signal from the 067-0587 to convert it to TTL. It also has a few terminations for analog signals that normally connect to the digital section so they don't negatively impact the calibration process. It looks like it will be a pretty simple board to build; my planned approach is to build the functional parts of the board in two small pieces which will then mount in a larger FR-4 or plastic frame for installation into the scope. This will keep the board fab cost down. The +5V vs +5VD discrepancy is probably moot. The engineer in me wants to use the same rail for everything, but there's probably no real harm in splitting them the way Tek seems to have. The missing pull up on _FPR is the only hanging chad I find truly irksome. Only the MPU and RAM boards even have a chance to touch that signal, and only the MPU board actually does. For whatever reason, it wasn't important enough to include on the A2J9 test connector. Perhaps there's a tendency of the PNP inputs of the 81LS series to float high? I couldn't find a circuit diagram for a device in the series to investigate further. Dave Casey
On Thu, Oct 22, 2020 at 9:09 AM Eric <ericsp@gmail.com> wrote:
Dave,
|
|
|