开云体育

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

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

On August 3, 2018 at 11:10 AM zenith5106 <hahi@...> wrote:


On Fri, Aug 3, 2018 at 04:26 PM, Fabio Trevisan wrote:

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.

The IC controlled Trigger board as well as other improvements was introduced at SN B200000. The Service manuals 464 / 070-4795-00 and 466 / 070-4796-00 are for B020000 and up.
Before that SN the Trigger board could be 670-3324-00 through -03. If I interprete the RPR (Replaceable Parts Record) correctly, and it could be wrong, only -02 or -03 would work
with DM44. Although no SN limits are given in the RPR there are in DM44 instruction sheet so it is probably right.
/H?kan

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

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

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

On August 6, 2018 at 11:58 AM Fabio Trevisan <fabio.tr3visan@...> wrote:


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=65983

As 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 thanks for some reason I did not receive the PM responce but oh well I
have it now. The only problem with your idea on this board is that none of the
through hole vias is they were never soldered at all absolutely no trace of
solder anywhere around all the holes. I have not investigated the A6 inter
board to see if something has been done there and also with any extra wiring
from somewhere else.

Jim

On August 6, 2018 at 11:58 AM Fabio Trevisan <fabio.tr3visan@...>

wrote:

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=65983

As 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

On August 7, 2018 at 3:39 PM Fabio Trevisan <fabio.tr3visan@...> wrote:


Hi Jim,
If you look at the picture of this same board on the TekWiki website (here: ) , you will see that those vias are also not filled with solder...
I don't know exactly why Tek did it like that back then, but apparently they either covered those vias / pads during wave soldering, or - maybe - the solder mask is covering those vias and therefore, preventing them to be filled with solder.

Apologies for the following outrageous question but... Do you know what I mean when I say PLATED through holes? That those holes, regardless not having any component lead traversing them, are copper plated and therefore, connects the traces on both sides of the board?
Did you really check that the traces are not connected, or you're just assuming they aren't because you didn't see any sign of solder there?
Please don't feel insulted, but it just crossed my mind that depending on one's line of business, one may have never seen a plated through hole (or plated "via"), as we call it, and may just think that the component leads MUST be soldered at both sides to establish that connection.

If, however, you DO know what the plated holes are, and if - still - your board is really missing the plating and both sides of those traces are indeed disconnected, I can't explain how in this world it could have happened, but it doesn't change the fact that the cure for this problem is to just solder tiny pieces of wire to both sides.
Sure enough, if the failed plating is present anywhere else on the board, you will need to look for missing connections under components that may hide the traces, like the ICs, and the connectors J5 & J6

Rgrds,

Fabio


On Mon, Aug 6, 2018 at 07:22 PM, Jim Olson wrote:

Fabio thanks for some reason I did not receive the PM responce but oh well I
have it now. The only problem with your idea on this board is that none of the
through hole vias is they were never soldered at all absolutely no trace of
solder anywhere around all the holes. I have not investigated the A6 inter
board to see if something has been done there and also with any extra wiring
from somewhere else.

Jim

On August 6, 2018 at 11:58 AM Fabio Trevisan <fabio.tr3visan@...>

wrote:

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=65983

As 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 no apologies necessary my friend, no worries. My back ground is radio,
electronics, in high school back in the tube, super het days, scratch crystal
tuning, morse code (10 words min), and a Bell & Howell correspondence course
digital solid state, 60"s GI bill. 17yrs Navy as a aircraft electrician Ret.
2003. Pulled a stint in the AMID instrument shop for P3's and sat in on a
micro soldering session so I'm fairly familiar with how boards are made.
Looking at all the pads with my head band magnifier it looks like all the
through hole plating is in tact.
Picked up a new battery for my meter and even though the holes are not
soldered closed like the later boards checking continuity it is there through
the traces top and bottom all their different sections and lengths.
I suspect Tek found leaving to much to chance with not soldering them closed
for continuity faults?

Jim

On August 7, 2018 at 3:39 PM Fabio Trevisan <fabio.tr3visan@...>

wrote:

Hi Jim,
If you look at the picture of this same board on the TekWiki website (here:

) , you will see
that those vias are also not filled with solder...

I don't know exactly why Tek did it like that back then, but apparently they

either covered those vias / pads during wave soldering, or - maybe - the
solder mask is covering those vias and therefore, preventing them to be filled
with solder.

Apologies for the following outrageous question but... Do you know what I

mean when I say PLATED through holes? That those holes, regardless not having
any component lead traversing them, are copper plated and therefore, connects
the traces on both sides of the board?

Did you really check that the traces are not connected, or you're just

assuming they aren't because you didn't see any sign of solder there?

Please don't feel insulted, but it just crossed my mind that depending on

one's line of business, one may have never seen a plated through hole (or
plated "via"), as we call it, and may just think that the component leads MUST
be soldered at both sides to establish that connection.

If, however, you DO know what the plated holes are, and if - still - your

board is really missing the plating and both sides of those traces are indeed
disconnected, I can't explain how in this world it could have happened, but it
doesn't change the fact that the cure for this problem is to just solder tiny
pieces of wire to both sides.

Sure enough, if the failed plating is present anywhere else on the board,

you will need to look for missing connections under components that may hide
the traces, like the ICs, and the connectors J5 & J6

Rgrds,

Fabio


On Mon, Aug 6, 2018 at 07:22 PM, Jim Olson wrote:

Fabio thanks for some reason I did not receive the PM responce but oh well

I

have it now. The only problem with your idea on this board is that none of

the

through hole vias is they were never soldered at all absolutely no trace

of

solder anywhere around all the holes. I have not investigated the A6 inter
board to see if something has been done there and also with any extra

wiring

from somewhere else.

Jim

On August 6, 2018 at 11:58 AM Fabio Trevisan <fabio.tr3visan@...>

wrote:

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=65983

As 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

From: Fabio Trevisan <fabio.tr3visan@...>

Wow Jim,
Scratch crystal tuning is awesome! Never thought this was something doable.
10 words per minute morse code seems quite impressive (to me at least, but I've never been much into Ham and less yet CW).
I`m from a newer generation where crystals were already ubiquitous and taken for granted as spot on 100%, and not something that one would tweak...

So... did I understand correctly that, after all, there's no problem with those vias (apart from the oddity of them being hollow) and they are all conducting well?

Regarding why Tek wasn't solder filling those vias, in retrospect, I recall of the first computer boards I've worked at, they would also have all the vias unfilled (covered by the solder mask). Back then this was new to me and I loved to look at how the hole walls were shiny.
I`m not sure if the solder improves the conductivity by much, and arguably there's an advantage to not doing it... It's easier to spot a board with a missing hole (due to a broken drill bit).
I`m not sure if boards were visually inspected (for missing vias) before going into assembly and, If a board would have a missing hole in a component pad, it would be easily detected at the assembly line, but a via would go unnoticed and after they're all filled with solder... would be hard to spot.

I'm only sad that few people showed up on this thread... It would be nice to hear more from other fellows who have more experience with the 464 / 466.

Rgrds,

Fabio

On August 8, 2018 at 12:39 PM "Michael A. Terrell" <mike.terrell@...> wrote:


I would think that Tektronix would have used 'bed of nails' test fixtures to test blank circuit boards before stuffing them. That would cull open or high resistance vias. As far as using the silicone to cover unused holes, that requires extra steps in manufacturing that would outweigh the cost of the solder. Most of the time this is still done, is when a connector or other item can't go through wave or reflow soldering and has to be added at the next stage.

Crystals are rarely exactly on the marked frequency, and only over a very narrow temperature range. That is why you see so many ovenized crystals.


Michael A. Terrell


-----Original Message-----

From: Fabio Trevisan <fabio.tr3visan@...>

Wow Jim,
Scratch crystal tuning is awesome! Never thought this was something doable.
10 words per minute morse code seems quite impressive (to me at least, but I've never been much into Ham and less yet CW).
I`m from a newer generation where crystals were already ubiquitous and taken for granted as spot on 100%, and not something that one would tweak...

So... did I understand correctly that, after all, there's no problem with those vias (apart from the oddity of them being hollow) and they are all conducting well?

Regarding why Tek wasn't solder filling those vias, in retrospect, I recall of the first computer boards I've worked at, they would also have all the vias unfilled (covered by the solder mask). Back then this was new to me and I loved to look at how the hole walls were shiny.
I`m not sure if the solder improves the conductivity by much, and arguably there's an advantage to not doing it... It's easier to spot a board with a missing hole (due to a broken drill bit).
I`m not sure if boards were visually inspected (for missing vias) before going into assembly and, If a board would have a missing hole in a component pad, it would be easily detected at the assembly line, but a via would go unnoticed and after they're all filled with solder... would be hard to spot.

I'm only sad that few people showed up on this thread... It would be nice to hear more from other fellows who have more experience with the 464 / 466.

Rgrds,

Fabio