Hello Jim,
The pictures did arrive correctly to me and I just posted the pictures to the Tekscopes photo section:
link is here:
/g/TekScopes/album?id=65983As I already replied in PM to you, I'll repeat it here... This rather odd missing of the through hole plating of **ONLY** the power supply rails, to me, seems like an effort of a previous owner to isolate a short-circuit in the power rails.
Given the age of those scopes, it can very well have happened before this group even existed, and before it became common knowledge that this kind of problem is often caused by a shorted tantalum capacitor, and then the scope was tossed away for - say - 20 years.
I would suggest you take advantage that the through holes are stripped out, and try to measure ohms from each of those traces to ground, everywhere that you can follow them and, if you happen to find some spot that is showing low impedance to ground... you'd have probably found the culprit.
If you can't find any of those traces shorted to ground, I would just rebuild the through-hole vias and try to apply power to the thing.
As I mentioned earlier, I don't think the presence or absence of the DM44 is too involving, in regards to the A5 trigger board and, sure enough, it has nothing to do with this mystery of the missing vias.
The only there is between the DM44 & the A5 trigger board, is the pick-off signal from the ALT TRACE SYNC PULSE, from the emitter of Q916, shown on diagram <8> of the 464 and connected through a 20K resistor, from this transistor, to a wire and then to the DM44 through pin 2 of P3201, as shown on the DM44's service manual, diagram <3> "TIME & 1/TIME <3>" and diagram <9> "464,465 & 466 INTERFACE".
The latter is the signal that tells the DM44 the end of a sweep, to allow the DM44 to switch the delay time control voltage at the end of every sweep, between the scope's own Delay time multiplier pot, and the DM44's Delta time pot (and v-v) which, ultimately is what allows the measurement of TIME and 1/TIME.
Please let us know what else did you find on this board power rails.
KRgrds,
Fabio
On Sat, Aug 4, 2018 at 09:23 PM, Jim Olson wrote:
Hi Fabio I sent the picts in an email to you PM but comcast has changed there
email to a new system so I'm not sure if you got it or not.
Jim
On August 3, 2018 at 12:23 PM Fabio Trevisan <fabio.tr3visan@...>
wrote:
Hi Jim,
Feel free to send me the pictures (PM to fabio.tr3visan@...).
I will be glad to post it to the photos area of Tekscopes.io, and reply to
you with a link to the folder.
Rgrds,
Fabio
On Fri, Aug 3, 2018 at 03:07 PM, Jim Olson wrote:
Fabio I have the pictures but I'm not using any kind of photo posting
service
it's gotten to complicated and I don't post much to forums anyway so can I
send them to you and you can post them up?
Jim
On August 3, 2018 at 7:26 AM Fabio Trevisan <fabio.tr3visan@...>
wrote:
Hello Jim,
I owed and restored a 464 with DM44 (now given to a friend) and I don't
think there are any other "optional" boards linked to the presence (or
absence) of the DM44.
The only optional boards that apply to the 464 / 466 are:
A. The optional DC inverter board (option 7)... That one can't co-exist
with
the DM44 (the inverter uses the same windings on the main transformer that
are
used to power the DM44).
B. The composite video Sync Separator (Option 5), which bears some
relation
to the A5 sync board and could explain some changes.
I did hear once, from someone of this group, there was two versions of
the
A5 Sync board... one that used the Tunnel Diodes, and another one which
used a
Custom Tek IC to discriminate the trigger edge.
I`m not sure, but maybe this is what the -01 means...
I've never landed my eyes, however, on a schematic of the latter, or a
later
manual that included both.
But regardless of this board versioning, It seems rather odd to me that
the
connections to the J6 are disconnected, and more so, that there is no
connection between the top and bottom side THROGUHOUT the board...
Moreover, there's nothing about the DM44 vs power to the A5 Trigger
board...
The DM44 takes its power from its own power supply and it's neither fed by
the
A5 board, nor the A5 board feeds it.
Yet, the only reason I can think of for the through hole plating is
missing
throughout the board is, either a mass murderer technician stripped them
off
by careless unsoldering, or yet, that it's a prototype board...
If it's the latter case, it could explain many things...
Maybe you can take a picture, post somewhere and link it here.
KRgrds,
Fabio
On Thu, Aug 2, 2018 at 11:40 PM, Jim Olson wrote:
I have a question about the A5 trigger generator sweep logic board
differences. I have two 466's with out the DM44 with the same trigger
board
670-3324-00 boards. I have a 464 with a DM44 with the 670-3324-01
board
and it
is vastly different from the 466 boards. All the DC voltage traces
from
J-6
are disconnected all the through holes are unsoldered so there is no
interconnection from top to bottom through out the board. There
appears to
be
no cable connection to the board from the DM44 to supply these?
The DM44 manual parts list's don't show that part number used for the
464/466
with the DM44 it shows the later 466 board and I can not find the
optional
boards listed in the service manuals listed in the DM44 one.
The installation sheets for installing the DM44's don't list different
or
optional boards used like the service manuals do?
So whats up with this bunch of missing info here!
Jim O
Fabio Trevisan