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Hello,

I am in the process of restoring a 577 Curve Tracer. Since there are a couple of previous, bodged repairs on the power supply, I decided to give it a good overhaul (replace caps, install repair eyelets in places where original pads were damaged, replace a non-fitting bridge rectifier that was "rigged in", etc.). Taking the power supply out of the frame is a major pain with the primary and secondary transformer leads directly soldered onto the PCB. I am considering putting Molex connectors (the ones that use 0.093" pins) in-between the PCBA and the transformer leads when I put it back together to make any repairs going forward a little easier. I would use a 15 circuit connector for the secondary and a 9 circuit one for the primary leads.
Has anyone done this before or see an issue with this?
Any reason you can think of why Tektronix chose to solder these to the PCB rather than using connectors like for all other connections to this board?

Thank you for any thoughts/insights,
wschraml, KI7PFX

Taking the power supply out of the frame is a major pain

Just be careful when you plug the regulated voltages back into unit. There are a bunch of them, and if
you make a mistake and plug one in one pin out it blows up the unit.

Done that, got the badge.

Craig

On Mon, Nov 12, 2018 at 03:29 PM, Craig Sawyers wrote:

Taking the power supply out of the frame is a major pain

Just be careful when you plug the regulated voltages back into unit. There are
a bunch of them, and if
you make a mistake and plug one in one pin out it blows up the unit.

Done that, got the badge.

Craig

I saw that post ... took a lot of pictures and plan to be extra careful when putting it back together. For now, waiting for the parts to show up.

Thank you,
wschraml, KI7PFX

In a general sense Wolfgang, as I am not a specialist with Tektronix...wiring p/s directly to the pcb may simply have been an assembly convenience.
Factory introducing of connectors along the way for other leads may be to increase technician convenience and reduce possible damage during board
service or replacement and to make easier the assembly-line wiring.

I can't see a technical reason against intervening in the power supply lead situation particularly if you do not have to unsolder from the board.

Although I have no experience with the connectors you mention I wonder whether power supply current could adversely heat them?; otherwise as there
here is no insertion loss or voltage drop enough to concern you...mains supply variations would provide a greater 'drop' than such intervention as you
are considering. Safety from transformer voltages during service might be reduced by any exposed connection 'along the way' to the pcb...again, I am
generalising.

My Regards

--
Jack

Hi Wolfgang,
I have to believe Tek soldered the leads in place because it is more reliable, faster, and less expensive. I guess the assumption was that the transformer wouldn't fail which is not unreasonable. Also, if the power supply failed the quickest way to repair it was to replace the entire unit and send the bad supply back to Beaverton to be refurbished.

I like the idea of the Molex connectors. I have used them on many things. I think it will be fine to do it that way. On the other hand if you do the job right and replace the caps, the power supply is likely to last many more years and not ever need to be opened again. So maybe the connectors are unnecessary.

Dennis Tillman W7PF

Hi Jack,
According to the specs the 0.093" Molex pins are rated for 17Amps so there is no problem with current or voltage drop.

Dennis Tillman W7PF

Ok thanks, Dennis, for that heads-up. I looked-up "Molex" instantly slightly embarrassed then as I do know them, but not
by that name

I've occasionally had problems with them, maybe half a dozen, when I had an automotive business. Only seemed to
be one pin each time and maybe once or twice on transceivers so they are pretty reliable. Yes, that rating sounds good
for Wolfgang's purposes, as you say.

I suppose Wolfgang's intervening with them now is as good a time as any, if going to be done. I suppose the other ones of
which he speaks are those small ones Tektronix uses to clip into my 425....+/- same as in computers...

The more I read on the site, irrespective of whether I ever use it...the more I learn and 'snap-out-of -it' I haven't had to think
about electronics much for several years, but now when completely rebuilding my test equipment, (5 units done in last fortnight)
and determined to get my 425 on the road, hopefully in a week or two and maybe the 564 Then with at least 7 WW11 Rx's, ART-13
and seven Rx's (Drake /Yaesu) a globe 303 and its VFO to rebuild ...I have to get back into that mind-space. I guess focussing on
Tektronix CRO's helps one into Tektronix' design mindset and that benefits to some degree, working on each of the various models.

On Wed, 14 Nov 2018 07:33:38 +1000, you wrote:

Ok thanks, Dennis, for that heads-up. I looked-up "Molex" instantly
slightly embarrassed then as I do know them, but not
by that name

I've occasionally had problems with them, maybe half a dozen, when I had an
automotive business. Only seemed to
be one pin each time and maybe once or twice on transceivers so they are
pretty reliable. Yes, that rating sounds good
for Wolfgang's purposes, as you say.

I've heard that they are not the most reliable. That will suggest
that at least for most purposes, don't connect and reconnect them a
lot.

On the current ratings, from what I understand, the current rating is
good, but goes down with the number of insertions.

I suppose Wolfgang's intervening with them now is as good a time as any, if
going to be done. I suppose the other ones of
which he speaks are those small ones Tektronix uses to clip into my
425....+/- same as in computers...

My feeling on the tektronix connectors is that they were never
designed for continuous (as in we're debugging this)
connects/disconnects. Look at the ratings on FPC connectors, which
are as little as about 20. These are not necessarily the same, but it
does suggest that tektronix was intending these connectors for board
replacement and disassembly, and not the same duty cycle as the
connectors for the 7000 series plugins were designed for.

The more I read on the site, irrespective of whether I ever use it...the
more I learn and 'snap-out-of -it' I haven't had to think
about electronics much for several years, but now when completely rebuilding
my test equipment, (5 units done in last fortnight)
and determined to get my 425 on the road, hopefully in a week or two and
maybe the 564 Then with at least 7 WW11 Rx's, ART-13
and seven Rx's (Drake /Yaesu) a globe 303 and its VFO to rebuild ...I have
to get back into that mind-space.

You've got a hobby. Welcome to the club.......

I guess focussing on
Tektronix CRO's helps one into Tektronix' design mindset and that benefits
to some degree, working on each of the various models.

True, and they designed and built lots of other stuff.

From what "we" are likely to find, oscilloscopes, then maybe
TM5000/TM500 stuff, then perhaps spectrum analyzers (7L series). You
could argue it from there.

Harvey

-----Original Message-----
From: Dennis Tillman W7PF
Sent: Wednesday, November 14, 2018 6:37 AM
To: [email protected]
Subject: Re: [TekScopes] Curve Tracer 577 - Power Supply Overhaul

Hi Jack,
According to the specs the 0.093" Molex pins are rated for 17Amps so there
is no problem with current or voltage drop.

Dennis Tillman W7PF

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Jack
Sent: Tuesday, November 13, 2018 11:00 AM
To: [email protected]
Subject: Re: [TekScopes] Curve Tracer 577 - Power Supply Overhaul

In a general sense Wolfgang, as I am not a specialist with
Tektronix...wiring p/s directly to the pcb may simply have been an
assembly
convenience.
Factory introducing of connectors along the way for other leads may be to
increase technician convenience and reduce possible damage during board
service or replacement and to make easier the assembly-line wiring.

I can't see a technical reason against intervening in the power supply
lead
situation particularly if you do not have to unsolder from the board.

Although I have no experience with the connectors you mention I wonder
whether power supply current could adversely heat them?; otherwise as
there
here is no insertion loss or voltage drop enough to concern you...mains
supply variations would provide a greater 'drop' than such intervention
as
you are considering. Safety from transformer voltages during service might
be reduced by any exposed connection 'along the way' to the pcb...again, I
am generalising.

My Regards

--
Jack

--
Dennis Tillman W7PF
TekScopes Moderator

Molex connectors are very inexpensive, quick to assemble, sold everywhere,
come in a very large variety of sizes and pin configurations, and keyed to
prevent insertion errors.

If their current rating degrades that would be with hundreds or thousands of
insertions, and that is not relevant in this case since Wolfgang will be
connecting and disconnecting them a few times at most. A 17Amp rating is so
much higher than any current inside a Tek Scope that even if they were to
degrade that won't affect their ability to work correctly in a scope or
curve tracer. The only exception might be with the 576 High Current Adapter
which uses Kelvin connectors to prevent a voltage drop from interfering with
accurate measurements.

If there is a more reliable connector that you have come across I could
always use them in my designs. So if you can point me to them please do.

Dennis Tillman W7PF

On Tue, Nov 13, 2018 at 06:19 PM, Dennis Tillman W7PF wrote:

Molex connectors are very inexpensive, quick to assemble, sold everywhere,
come in a very large variety of sizes and pin configurations, and keyed to
prevent insertion errors.

If their current rating degrades that would be with hundreds or thousands of
insertions, and that is not relevant in this case since Wolfgang will be
connecting and disconnecting them a few times at most. A 17Amp rating is so
much higher than any current inside a Tek Scope that even if they were to
degrade that won't affect their ability to work correctly in a scope or
curve tracer. The only exception might be with the 576 High Current Adapter
which uses Kelvin connectors to prevent a voltage drop from interfering with
accurate measurements.

If there is a more reliable connector that you have come across I could
always use them in my designs. So if you can point me to them please do.

Dennis Tillman W7PF

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Harvey
White
Sent: Tuesday, November 13, 2018 7:13 PM
Subject: Re: [TekScopes] Curve Tracer 577 - Power Supply Overhaul

On Wed, 14 Nov 2018 07:33:38 +1000, you wrote:

Ok thanks, Dennis, for that heads-up. I looked-up "Molex" instantly
slightly embarrassed then as I do know them, but not by that name

I've occasionally had problems with them, maybe half a dozen, when I
had an automotive business. Only seemed to be one pin each time and
maybe once or twice on transceivers so they are pretty reliable. Yes,
that rating sounds good for Wolfgang's purposes, as you say.

I've heard that they are not the most reliable. That will suggest that at
least for most purposes, don't connect and reconnect them a lot.

On the current ratings, from what I understand, the current rating is

good,

but goes down with the number of insertions.

I suppose Wolfgang's intervening with them now is as good a time as
any, if going to be done. I suppose the other ones of which he speaks
are those small ones Tektronix uses to clip into my
425....+/- same as in computers...

My feeling on the tektronix connectors is that they were never designed

for

continuous (as in we're debugging this) connects/disconnects. Look at the
ratings on FPC connectors, which are as little as about 20. These are not
necessarily the same, but it does suggest that tektronix was intending

these

connectors for board replacement and disassembly, and not the same duty
cycle as the connectors for the 7000 series plugins were designed for.

The more I read on the site, irrespective of whether I ever use
it...the more I learn and 'snap-out-of -it' I haven't had to think
about electronics much for several years, but now when completely
rebuilding my test equipment, (5 units done in last fortnight) and
determined to get my 425 on the road, hopefully in a week or two and
maybe the 564 Then with at least 7 WW11 Rx's, ART-13 and seven Rx's
(Drake /Yaesu) a globe 303 and its VFO to rebuild ...I have to get
back into that mind-space.

You've got a hobby. Welcome to the club.......

I guess focussing on
Tektronix CRO's helps one into Tektronix' design mindset and that
benefits to some degree, working on each of the various models.

True, and they designed and built lots of other stuff.

From what "we" are likely to find, oscilloscopes, then maybe
TM5000/TM500 stuff, then perhaps spectrum analyzers (7L series). You

could

argue it from there.

Harvey

-----Original Message-----
From: Dennis Tillman W7PF
Sent: Wednesday, November 14, 2018 6:37 AM
To: [email protected]
Subject: Re: [TekScopes] Curve Tracer 577 - Power Supply Overhaul

Hi Jack,
According to the specs the 0.093" Molex pins are rated for 17Amps so
there is no problem with current or voltage drop.

Dennis Tillman W7PF

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Jack
Sent: Tuesday, November 13, 2018 11:00 AM
To: [email protected]
Subject: Re: [TekScopes] Curve Tracer 577 - Power Supply Overhaul

In a general sense Wolfgang, as I am not a specialist with
Tektronix...wiring p/s directly to the pcb may simply have been an
assembly convenience.
Factory introducing of connectors along the way for other leads may
be to increase technician convenience and reduce possible damage
during board service or replacement and to make easier the

assembly-line

wiring.

I can't see a technical reason against intervening in the power
supply lead situation particularly if you do not have to unsolder
from the board.

Although I have no experience with the connectors you mention I
wonder whether power supply current could adversely heat them?;
otherwise as there here is no insertion loss or voltage drop enough
to concern you...mains supply variations would provide a greater
'drop' than such intervention as you are considering. Safety from
transformer voltages during service might be reduced by any exposed
connection 'along the way' to the pcb...again, I am generalising.

My Regards

--
Jack

--
Dennis Tillman W7PF
TekScopes Moderator

--
Dennis Tillman W7PF
TekScopes Moderator

Great feedback from everyone. Thank you.
I ordered the connectors and will give it a shot. Will post pictures when done - unless I mess up the whole job :)

Thanks again,
Wolfgang

I had a consulting contract years ago to help a
Swedish company with a problem they had in converting
from European 240V to the USA 120V. The engineer that
did the conversion didn't understand the ratings of the
molex connector.

He saw the 17A rating, and saw the 15A drawn by the heater,
and said, "Looks good, ship it!"

And, then the problems began. In the US, the connectors
burned up after the third or fourth cycle of the instrument.

The customers were not amused, and even less amused was
the guy that relocated his family to the US to become the
president of the USA division... My customer.

What happened?

Well, molex rates their connector at 17A with the following
stipulations:

1) 25C ambient temperature.
2) 12 inches of #14ga stranded wire on each side of the
connector with everything suspended in free air.
3) only one pin set per connector shell.

Does that sound like what you are doing? If so, you will
be fine.

It didn't sound like the Swedish company's 4 circuits in a
shell, with 3 inches of wire between connectors, and placed
next to a 700W heater... OOPS!

-Chuck Harris

Harvey White wrote:

On Wed, 14 Nov 2018 07:33:38 +1000, you wrote:

...

On the current ratings, from what I understand, the current rating is
good, but goes down with the number of insertions.

On Tue, Nov 13, 2018 at 07:31 PM, Chuck Harris wrote:

I had a consulting contract years ago to help a
Swedish company with a problem they had in converting
from European 240V to the USA 120V. The engineer that
did the conversion didn't understand the ratings of the
molex connector.

He saw the 17A rating, and saw the 15A drawn by the heater,
and said, "Looks good, ship it!"

And, then the problems began. In the US, the connectors
burned up after the third or fourth cycle of the instrument.

The customers were not amused, and even less amused was
the guy that relocated his family to the US to become the
president of the USA division... My customer.

What happened?

Well, molex rates their connector at 17A with the following
stipulations:

1) 25C ambient temperature.
2) 12 inches of #14ga stranded wire on each side of the
connector with everything suspended in free air.
3) only one pin set per connector shell.

Does that sound like what you are doing? If so, you will
be fine.

It didn't sound like the Swedish company's 4 circuits in a
shell, with 3 inches of wire between connectors, and placed
next to a 700W heater... OOPS!

-Chuck Harris

Harvey White wrote:

On Wed, 14 Nov 2018 07:33:38 +1000, you wrote:

...

On the current ratings, from what I understand, the current rating is
good, but goes down with the number of insertions.

I completed the overhaul including the installation of Molex connectors for the transformer leads. I posted before and after pictures here: /g/TekScopes/album?id=79113

Overall, it went well. A little crowded now inside with the addition of the Molex connectors.

I still have other issues with the 577 I need to track down - traces look OK for diodes but don't line up for transistors; as other have stated "the out and back I-V curves do not lie on top of each other". I saw other posts on that topic and will pursue this next. And the storage option doesn't work either (it's a D1).

Thank you,
Wolfgang

On Fri, Nov 23, 2018 at 09:35 AM, Wolfgang Schraml wrote:

On Tue, Nov 13, 2018 at 07:31 PM, Chuck Harris wrote:

I had a consulting contract years ago to help a
Swedish company with a problem they had in converting
from European 240V to the USA 120V. The engineer that
did the conversion didn't understand the ratings of the
molex connector.

He saw the 17A rating, and saw the 15A drawn by the heater,
and said, "Looks good, ship it!"

And, then the problems began. In the US, the connectors
burned up after the third or fourth cycle of the instrument.

The customers were not amused, and even less amused was
the guy that relocated his family to the US to become the
president of the USA division... My customer.

What happened?

Well, molex rates their connector at 17A with the following
stipulations:

1) 25C ambient temperature.
2) 12 inches of #14ga stranded wire on each side of the
connector with everything suspended in free air.
3) only one pin set per connector shell.

Does that sound like what you are doing? If so, you will
be fine.

It didn't sound like the Swedish company's 4 circuits in a
shell, with 3 inches of wire between connectors, and placed
next to a 700W heater... OOPS!

-Chuck Harris

Harvey White wrote:

On Wed, 14 Nov 2018 07:33:38 +1000, you wrote:

...

On the current ratings, from what I understand, the current rating is
good, but goes down with the number of insertions.

I completed the overhaul including the installation of Molex connectors for
the transformer leads. I posted before and after pictures here:
/g/TekScopes/album?id=79113

Overall, it went well. A little crowded now inside with the addition of the
Molex connectors.

I still have other issues with the 577 I need to track down - traces look OK
for diodes but don't line up for transistors; as other have stated "the out
and back I-V curves do not lie on top of each other". I saw other posts on
that topic and will pursue this next. And the storage option doesn't work
either (it's a D1).

Thank you,
Wolfgang

For reference, these are the parts and Mouser numbers I used in the restoration of the A3 Regulator Board:

Filter Capacitor replacements (Mouser numbers in parentheses); for the radial caps, I used Tektronix capacitor adapters from "voltair.us".
- C744 - 220uF/350V (647-UVZ2V221MRD)
- C751, C771 - 1500uF/63V (594-2222-021-18152)
- C711 - 330uF/63V (647-TVX1J331MCD)

Molex connectors and pins for the transformer leads:
- 15 pin housing, receptacle (538-03-09-1157)
- 15 pin plug (538-03-09-2159)
- 9 pin housing, receptacle (538-03-09-1094)
- 9 pin plug (538-03-09-2092)
- Crimp Socket (538-02-09-1104)
- Crimp pin (538-02-09-2103)

Since the transformer leads are solid wires and in some cases very thin, I secured them with a very small amount of solder after crimping.

Miscellaneous parts/components:
- Installed new PCB eyelets for CR711 and C744
- Replaced CR712 with 1N5404 (and soldered them into the through-holes rather than just onto the PCB traces as the previous repair did)
- Replaced CR711 with KBP202G (Mouser 621-KBP202G)
- Installed new fuses for F714 and F711 (Mouser 504-SS-5H-5A-AP)
- Tantalum caps C781, C767 - replaced with 47uF/50V electrolytic caps
- Tantalum cap C772 - replaced with 22uF/50V electrolytic caps


Wolfgang
.