7704 issues


regman10
 

I have a 7704A that the small black in line connectors on J20 (?) the link between the display unit and the mainframe. They're all unplugged and I have no ides where they go. If anyone has a drawing or photo I'd really appreciate it. send to ga4blues@gmail.com Thanks in advance!


 

Go to the this TekWiki URL and download a service manual for the 7704A:
http://w140.com/tek-7704a.pdf

For future reference make a note of the TekWiki site since it is a goldmine
of Tek manuals.
http://w140.com

Now there are several straightforward clues that will guide you to hooking
them up properly:
1) the connector number markings on the PC Boards
2) the different number of pins on each of these Harmonica Connectors
(that's what they are called)
3) the way the ribbon cables have a natural bend or twist in them from the
way they were placed
4) Pin 1 of each harmonica connector has a tiny arrow point on it. This is
pin 1. There is always a corresponding arrow head on the PC board to
indicate which end of the row of pins is pin 1.
5) the schematics in the manual are a little less obvious (or a bit harder
to follow) but they are you last resort, and the official standard, if you
find two connectors that appear to be easy to mix up.
6) Many of the Tek service manuals (but not all) have cross reference charts
and photos of the PC Boards and schematics which show where everything is.
If you have a connector you are looking for the charts and photos can help
you locate where it belongs.

Dennis Tillman W7PF

-----Original Message-----
Sent: Monday, August 28, 2017 9:41 PM
Subject: [TekScopes] 7704 issues

I have a 7704A that the small black in line connectors on J20 (?) the link
between the display unit and the mainframe. They're all unplugged and I have
no ides where they go. If anyone has a drawing or photo I'd really
appreciate it. send to ga4blues@gmail.com Thanks in advance!
------------------------------------
Posted by: regman10@comcast.net
------------------------------------


regman10
 

I have the manual. I've spent an hour trying to find that connector on the schematics. Maybe I'm just blind in one eye cant see out of the other one! There is no nomenclature on the plug and not a whole lot on the PCB that the connector mates with...


regman10
 

These harmonica connectors plug into a dual in-line connector which is numbered 1-60. They were all unplugged and in disarray when I opened the scope up. None of the lights light up on the vertical and horizontal mode selector switches or the left right switches.


Albert Otten
 

Have a look at diagram <11> Main Interconnect, and Fig. 3-7.
In <11> the "empty" space between D unit and A unit (at the left of the diagram) and A unit and D unit (at the right) is actually the vertical 2-sided PCB. At the bottom this PCB plugs into a connector at the main interface board. At the Display side the big U-shaped interconnect plug assembly fits on the edge of the PCB and also connects to the Peltona cable feed-thru blocks at its left and right side. The Peltona wiring is shown at the bottom of the diagram.. The harmonica connectors you mentioned are shown in the diagram as thin rectangular dashed strips, 5 of them in the manual version I have. They seem to have no individual part number.
Hope this helps.
Albert


---In TekScopes@yahoogroups.com, <regman10@...> wrote :

These harmonica connectors plug into a dual in-line connector which is numbered 1-60. They were all unplugged and in disarray when I opened the scope up. None of the lights light up on the vertical and horizontal mode selector switches or the left right switches.


Harvey White
 

On 29 Aug 2017 05:45:21 +0000, you wrote:

These harmonica connectors plug into a dual in-line connector which is numbered 1-60. They were all unplugged and in disarray when I opened the scope up. None of the lights light up on the vertical and horizontal mode selector switches or the left right switches.
It's possible that someone tried to diagnose a short in the frame by
removing all the connectors. I'd check the supply voltages before I
close it up.

Harvey




regman10
 

Thanks I will!


regman10
 

Thanks Dennis! That little bugger hides pretty good in all of those schematics. They marked all off the other connectors and jacks pretty well - no so much on this one.


regman10
 

I've been pondering the schematic for 2 days now and its really poorly documented and kind of surprising compared to the rest of the scope. None of the schematics match up with the what I've got, maybe theres an older (or newer service manual). I pulled together a manual from 2 different sources for the 7704A as the schematics were fragmented over several pages on the link provided and added to the manual, schematics that either fit the pager, or are simply taped together to create the foldout.

My supply voltages are fine and I'm not seeing any shorts. My theory is that for one reason to another those harmonica connectors were unplugged from the green connector and since there are no clear indications of where they go. The pin outs alone are enough to drive you crazy. Every connector has a different number of pins so that part of it is pretty easy, determining where exactly they plug into the host connector that plugs into A20. So the Navy tech working on it gave up.


The scope is fully functional, readouts work fine, analog, no issues, was last calibrated on 2009.


Once again, if someone could snap a photo like the one in fig 6-30 but with a close up of the harmonica connectors, I would be eternally grateful. email to ga4blues@gmail.com


Dave / NR1DX
 

OK

For starters what is the serial number of your unit? Bxxxxxx ?
What manual are you using 070-xxxx-yy? and what release date is on the
bottom of the title page

What board are you struggling with in particular A?? there are some
18-20 different ckt boards in the 7704A, some of them were released with
4 different versions of the board over the years, some never changed?

If you can tell what is the part number of the board in particular you
are struggling with? This may or may not be printed on the board itself,
some are some are not. For the 7704A most likely the part number is
something like 070-18xx-yy

Figure 6-30 in my manual is a photo of the HV test point and doesn't
show any board?

Dave
manuals@artekmanuals.com

On 8/30/2017 1:57 PM, regman10@comcast.net [TekScopes] wrote:

I've been pondering the schematic for 2 days now and its really poorly
documented and kind of surprising compared to the rest of the scope.
None of the schematics match up with the what I've got, maybe theres
an older (or newer service manual). I pulled together a manual from 2
different sources for the 7704A as the schematics were fragmented over
several pages on the link provided and added to the manual, schematics
that either fit the pager, or are simply taped together to create the
foldout.

My supply voltages are fine and I'm not seeing any shorts. My theory
is that for one reason to another those harmonica connectors were
unplugged from the green connector and since there are no clear
indications of where they go. The pin outs alone are enough to drive
you crazy. Every connector has a different number of pins so that part
of it is pretty easy, determining where exactly they plug into the
host connector that plugs into A20. So the Navy tech working on it
gave up.


The scope is fully functional, readouts work fine, analog, no issues,
was last calibrated on 2009.


Once again, if someone could snap a photo like the one in fig 6-30 but
with a close up of the harmonica connectors, I would be eternally
grateful. email to ga4blues@gmail.com

[Non-text portions of this message have been removed]

--
Dave
Manuals@ArtekManuals.com
www.ArtekManuals.com


Albert Otten
 

I feel unsure now about whether or not you have saved the problem. You say the scope is fully functional? But you still want a photograph?
I probably have the same schematics you have, 1973 but containing pages up to at least Rev H 1978. One of my 7704As dates from 1979. The connectors are as in diagram <11>, except for one. At <11> P20F is Front and P20R is Rear, while pins 1 are at the right side (outer side) of the scope. All connector are oriented with their open sides away from the PCB, so you see immediately that many positions in a connector are not used at all.
My connector over pins 13-19 of P20F is longer, 10 pins in stead of 7, it covers pins 10-19 of P20F. But only 2 wires go to the connector, exactly is in the diagram, so effectively to pin 13 and to pin 19.
It's not so easy to make a clear photograph since there is little space between the big connector assembly and the HV box.


Albert


---In TekScopes@yahoogroups.com, <regman10@...> wrote :

I've been pondering the schematic for 2 days now and its really poorly documented and kind of surprising compared to the rest of the scope. None of the schematics match up with the what I've got, maybe theres an older (or newer service manual). I pulled together a manual from 2 different sources for the 7704A as the schematics were fragmented over several pages on the link provided and added to the manual, schematics that either fit the pager, or are simply taped together to create the foldout.

My supply voltages are fine and I'm not seeing any shorts. My theory is that for one reason to another those harmonica connectors were unplugged from the green connector and since there are no clear indications of where they go. The pin outs alone are enough to drive you crazy. Every connector has a different number of pins so that part of it is pretty easy, determining where exactly they plug into the host connector that plugs into A20. So the Navy tech working on it gave up.


The scope is fully functional, readouts work fine, analog, no issues, was last calibrated on 2009.


Once again, if someone could snap a photo like the one in fig 6-30 but with a close up of the harmonica connectors, I would be eternally grateful. email to ga4blues@... mailto:ga4blues@...


Albert Otten
 

I posted 2 close-up pictures of the 7704A interconnect plug in the 7704A section of Tekwiki.
Albert


---In TekScopes@yahoogroups.com mailto:TekScopes@yahoogroups.com, <regman10@...> wrote :

Once again, if someone could snap a photo like the one in fig 6-30 but with a close up of the harmonica connectors, I would be eternally grateful.


Albert Otten
 

Here I made a confusing mistake, probably because I was thinking of the APD interface board in the P7001.
In the normal 7704A the big interconnect plug is simply an egde connector at the Main Interface board, diagram <3>, with adjacent feed-thru for the coax cables.

Albert


---In TekScopes@yahoogroups.com, <aodiversen@...> wrote :

Have a look at diagram <11> Main Interconnect, and Fig. 3-7.
In <11> the "empty" space between D unit and A unit (at the left of the diagram) and A unit and D unit (at the right) is actually the vertical 2-sided PCB. At the bottom this PCB plugs into a connector at the main interface board.