Re: Again a 7854 power supply beast to be repaired...
On Sun, May 5, 2019 at 6:18 PM Raymond Domp Frank <hewpatek@...> wrote: On Sun, May 5, 2019 at 11:28 PM, Raymond Domp Frank wrote:
I think most or all portables are of the "out through the back" type.
Oops! the other way around: *In* through the back...
The 485 as well as the 2400 series are all out through the back.
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Re: Again a 7854 power supply beast to be repaired...
On Sun, May 5, 2019 at 11:28 PM, Raymond Domp Frank wrote:
I think most or all portables are of the "out through the back" type.
Oops! the other way around: *In* through the back... Raymond
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Re: Again a 7854 power supply beast to be repaired...
On Sun, May 5, 2019 at 11:13 PM, unclebanjoman wrote:
I asked that because on my 465 the fan blows air into the case instead...
That's why you can see the filter "in front of" the fan in the 465 or at least the rattling grate where the filter once was - and nothing in the 7854... The question makes complete sense since the direction was different for different instruments. I think most or all portables are of the "out through the back" type. Raymond
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Re: Again a 7854 power supply beast to be repaired...
Thanks Raimond,
I asked that because on my 465 the fan blows air into the case instead...
Max
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Re: Again a 7854 power supply beast to be repaired...
On Sun, May 5, 2019 at 09:52 PM, unclebanjoman wrote:
Since there's not a polarization sign on the fan connector, question arise:
the fan must blow air INTO the case or SUCK air OUT of the case?
That's the newer PC-style fan with series resistor, as opposed to the older tubular style (Siemens) motor. The air must be sucked out of the case by the fan. The fan contains an arrow on the housing, indicating the flow direction. Another key is that the air must be sucked towards the (more) concave side of the rotor blades. Sometimes a bit difficult to see. Raymond
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Re: Again a 7854 power supply beast to be repaired...
No socketed semiconductor at all on this board. Tapping has no effects (for now...) :-P
Just another stupid question:
the fan in my 7854 is just... a fan with one resitor in series. No fan board and circuitry.
Since there's not a polarization sign on the fan connector, question arise:
the fan must blow air INTO the case or SUCK air OUT of the case?
Max
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Re: [OT] Best glue to repair lifted trace?
A good structural epoxy, designed to join the materials in use, can be very
strong. PWBs are made of fiberglass and epoxy resin. I've held down heavy
parts to PWBs in extreme vibration. Unfortunately, I can't suggest a
specific epoxy as what I used to use was proprietary to the company and I
do not know the manufacturer anyway.
You can get data sheets from the manufacturers that will tell you what
materials it can join and how long the opened package will last. Look for
the TDS and SDS from the manufacturer. They will also have selector guides.
I wish I could be of more help and have a specific epoxy to suggest.
Regards,
Mark
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Show quoted text
On Sun, May 5, 2019 at 8:34 AM cheater cheater <cheater00@...> wrote: Ouch, I'll steer clear then! Thanks!
On Sun, May 5, 2019 at 2:52 AM Daveolla <grobbins@...> wrote:
Greetings, I dunno how much I would trust a glue to hold down the
connector . From looking at the picture I would be inclined to drill
a fine hole on either side of the pin or pins and tie it down with a
copper wire and then solder it to the pin to remove any slack in the
tiedown. Or a single hole for each pin and push a sewing pin thru
the hole with the head of the pin on the other side of the board (pin
head bigger than the hole) and curl the other end over the connector
pin , nip it off and solder out any slack
If there is something on the other side of the board that would be
shorted to the pin, a few wraps of thread could also hold things down
and give the thread a drip of CA glue to harden up
thread. Presumably the connector pins are supposed to hold the
connector down but perhaps the plastic connector body could be
tacked down with variations of the above techniques and relieve the
pins from that duty.
And like other have said, getting CA glue fumes from soldering in
yours eyes is a real eye sore! Your eye muscles will shut your eyes
so tight the sun won't make it thru!!!
Dave
Here you go!
On Sat, 4 May 2019, 14:02 Adrian <Adrian@... wrote:
okay, help me out here because I'm confused/bemused by 25+ posts
about
high temp glue needed to hold down a connector on a PCB so I've
obviously missed something!
First off, am I right in that:
a) A (thru-hole?) internal connector has come off a PCB and busted a
ground pin in the process.
b) It left (one?) other pin still electrically connected to its pad
and
trace but those have peeled of the surface of the board.
c) You think can reposition the connector to the board and sort the
ground pin by somehow re-soldering it
d) You believe you can add glue (epoxy) around the connector to
secure
it to the PCB.
If the above is correct why do you need glue for a trace that can
withstand soldering temperatures - the trace/PCB bond cannot be
adding
to the retention of the connector against connection/disconnection
forces - so why not re-position/solder everything then add the epoxy
when you're done and brush on a bit of conformal coat or wire-tak or
something to protect/secure the 'loose' trace?
BTW you know that saying " A picture is worth a thousand words"?
That is
very true in cases like this!
Adrian
On 5/4/2019 9:20 AM, cheater cheater wrote:
Thanks. This is an internal plug which is not accessible from the outside.
On Sat, May 4, 2019 at 3:06 AM John Kolb <jlkolb@...>
wrote:
After repair, I would suggest a short extension cable left
attached to
the equipment, so all plugging/inplugging stresses are moved to
the end
of the extender.
Jophn
On 5/3/2019 6:28 AM, cheater cheater wrote:
I have a piece of equipment where a trace was lifted. The part
is still
attached and I would like to glue it down. The part is a socket
for a
cable, and the plug is difficult to insert and remove. I will
have to
solder the other pin which is the ground plane, and broke off,
so the
glue
has to survive that. I'll also need to add some structural
solder on
the
sides. Is cyanoacrylate a good idea here? Anything better than
that?
Thanks.
|
Re: 577 caused 754D go malfunction
Marginal power supply in 754D?
Earthing is easiest to check and fix.
Raymond
|
Re: 577 caused 754D go malfunction
On Sun, May 5, 2019 at 07:02 PM, DW wrote:
Perhaps the 577 curve tracer was emitting strong EMP's causing the the 754D to
go haywire.
Also, *very* unlikely. "EMP" is generally associated with atomic explosions and the like, though not strictly true. As I mentioned before, (lack of or wrong) earthing seems much more likely. Raymond
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Re: 577 caused 754D go malfunction
On Sun, May 5, 2019 at 08:59 PM, Dave Voorhis wrote:
anyone experience emitted interference from a 577 of nearby electronics?
From a mostly DC and strictly LF (except HV) device like the 577? *Very* unlikely. Raymond
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Re: 577 caused 754D go malfunction
On 5 May 2019, at 18:02, DW <wilson2115@...> wrote: ¡ Perhaps the 577 curve tracer was emitting strong EMP's causing the the 754D to go haywire. The right cover was removed on the 577 and the 754D was sitting just a few inches from it, anyone experience emitted interference from a 577 of nearby electronics? No, not at all.
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Re: Again a 7854 power supply beast to be repaired...
On Sun, May 5, 2019 at 07:57 PM, unclebanjoman wrote:
And so?
I can assume two possibilities:
1) A cold/poor welding on Q142 or,
2) A peltola connector oxidized.
Any socketed semiconductors on that Z-axis board? I guess not. Try tapping the PCB while 'scope is on and see. Components themselves sometimes develop intermittent contacts. Raymond
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Re: [OT] Best glue to repair lifted trace?
Cheeter asked: "Does anyone see a reason not to use UHU Endfest?"Yes, I do.? It has a very low temperature range (80 Deg C max).? They also make no mention of electrical conductivity.? While most epoxies are insulators and it is simple to test a sample, the lack of this information implies they have no expectation of this kind of use.? That is another red flag to me.
BTW, my favorite, CW2500, boasts short term service temperature to 600 Deg F.? And, its made for this purpose.? My experience has been all epoxies begin to fail around 80 deg C (Water boils at 100 Deg C).? But they each fail in different ways.? CW2500 begins to soften, then turns to sticky goo which hardens once cooled.? If the overheating period is short, the final result is still sound.
Cheeter asked: "What is the shelf life of these products?"CW2500 is 12 months according to the manufacturers data sheet.
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Show quoted text
On Sunday, May 5, 2019, 11:43:30 AM CDT, cheater cheater <cheater00@...> wrote: Does anyone see a reason not to use UHU Endfest? Here's a datasheet in English: It looks like a good contender for an OK glue for this purpose. But I wouldn't know what might be wrong with a glue used for glueing down traces. Thanks. On Sun, May 5, 2019 at 5:46 PM cheater00 cheater00 <cheater00@...> wrote:
How long do the Loctite, MG Chemicals, Hardman, and Circuit Works
epoxy glues hold after opened? Days, months, or years? Thanks
On Sun, May 5, 2019 at 5:34 PM cheater00 cheater00 <cheater00@...> wrote:
Ouch, I'll steer clear then! Thanks!
On Sun, May 5, 2019 at 2:52 AM Daveolla <grobbins@...> wrote:
Greetings, I dunno how much I would trust a glue to hold down the
connector . From looking at the picture I would be inclined to? drill
a fine hole on either side of the pin or pins and tie it down with a
copper wire and then solder it to the pin to remove any slack in the
tiedown.? Or a single hole for each pin and push a sewing pin thru
the hole with the head of the pin on the other side of the board (pin
head bigger than the hole) and curl the other end over the connector
pin , nip it off and solder out any slack
If? there is something? on the other side of the board that would be
shorted to the pin, a few wraps of thread could also hold things down
and give the thread a? drip of CA glue to? harden? up
thread.? Presumably the connector pins are supposed to hold the
connector? down but perhaps? the plastic connector body could be
tacked down with variations of the above techniques? and? relieve the
pins from that duty.
And like other have said, getting CA glue fumes from soldering? in
yours? eyes is a real eye sore! Your eye muscles will shut your eyes
so tight the sun won't make it thru!!!
Dave
Here you go!
On Sat, 4 May 2019, 14:02 Adrian <Adrian@... wrote:
okay, help me out here because I'm confused/bemused by 25+ posts about
high temp glue needed to hold down a connector on a PCB so I've
obviously missed something!
First off, am I right in that:
a) A (thru-hole?) internal connector has come off a PCB and busted a
ground pin in the process.
b) It left (one?) other pin still electrically connected to its pad and
trace but those have peeled of the surface of the board.
c) You think can reposition the connector to the board and sort the
ground pin by somehow re-soldering it
d) You believe you can add glue (epoxy) around the connector to secure
it to the PCB.
If the above is correct why do you need glue for a trace that can
withstand soldering temperatures - the trace/PCB bond cannot be adding
to the retention of the connector against connection/disconnection
forces - so why not re-position/solder everything then add the epoxy
when you're done and brush on a bit of conformal coat or wire-tak or
something to protect/secure the 'loose' trace?
BTW you know that saying " A picture is worth a thousand words"? That is
very true in cases like this!
Adrian
On 5/4/2019 9:20 AM, cheater cheater wrote:
Thanks. This is an internal plug which is not accessible from the outside.
On Sat, May 4, 2019 at 3:06 AM John Kolb <jlkolb@...> wrote:
After repair, I would suggest a short extension cable left attached to
the equipment, so all plugging/inplugging stresses are moved to the end
of the extender.
Jophn
On 5/3/2019 6:28 AM, cheater cheater wrote:
I have a piece of equipment where a trace was lifted. The part is still
attached and I would like to glue it down. The part is a socket for a
cable, and the plug is difficult to insert and remove. I will have to
solder the other pin which is the ground plane, and broke off, so the
glue
has to survive that. I'll also need to add some structural solder? on
the
sides. Is cyanoacrylate a good idea here? Anything better than that?
Thanks.
|
Anybody need some 2-01C tubes Or Admiralty Pattern Tubes?
I found five new boxed tubes in perfect condition during the after-stuff-day clean up
effort. I believe this is used in the hp 410A probe, if you need some.
Also found a box of old (but new in the box) Admiralty Pattern tubes,
with numbers like NR 87, NR16A, UV199 and others. some CV types too.
these have odd bases, and seem to be from WW2 era british radio gear.
no use to me, happy to move them on to somebody that can use them.
Tubes look perfect, but I can't test them on my gear. Some very interesting
looking tubes in this pile.
I also found some new in the box 154-xxxx Tek vacuum tubes if anybody is looking for some,
some matched pairs too. They don't fit anything I have left, so happy to
send them on. I have some of the plug in vacuum-tube-style thermal delay relays too, same story.
I am still looking for a span knob set for my hp 8558B SA too...
Off list is the best way to contact me about these, please see below.
all the best,
walter (walter2 -at- sphere.bc.ca)
sphere research corp.
54-xxxx Tek vacuum tubes
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Re: Again a 7854 power supply beast to be repaired...
Good news! The 7854 works perfectly now!
But I don't know how I did it!
Here's the story.
After some (long!) mumbling I tried to disconnect peltola connectors J91 and J78 to exclude some bad effects from these signals. No change.
So I tried to disconnect J110, the main Z-axis signal from board A14 (mainframe logic). No changes. The trace was still here, somewhat bright and poor intensity control.
Then I disconnected all the peltola connector (last chance, just for curiosity) : no changes.
I detach the z-axis board (A21) to re-check all the bjts, especially Q173 and all around. Everything looks o.k..
Just for curiosity, I connect (solderi) a short wire between E and C of Q142. According to the manual this should completely shut-off all the display.
I reconnect the Z board. Power on. Well, no trace and no readout are visible, not even acting on intensity controls.
This is almost good, means my brain still works :-D
In the meantime I continue to think about what the defect may be. Mumble....
To perform other checks, I keep the z board in place and to do a more quickly job, I cut the little wire jumper that I had previously soldered using a nipper.
Power on and... SURPRISE! The trace is perfect and both the intensity and focus controls works!
I perform a fast check of both analog and digital functions of the 7854. Everything seems to work.
I dismount again the z-axis board, removing the little wires placed as jumper. Remount the board in place.
Remount all the connectors.
Power on. All look good and O.K.
I leave the oscilloscope turned on for 15-20 minutes and in the meantime I do some measurements using the analog and digital sections. Everything works perfectly.
And so?
I can assume two possibilities:
1) A cold/poor welding on Q142 or,
2) A peltola connector oxidized.
What do you think?
In the meantime I will use the oscilloscope for a few hours before remounting it all again.
Thanks to you all for your efforts!
Max
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Re: 577 caused 754D go malfunction
Could well be a grounding problem. Are both instruments grounded?
Raymond
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577 caused 754D go malfunction
With a differential probe P5205 connected to the 754D with the negative on the chasis ground and positive measuring the base of the 177 test fixture some strange results occured.
I found if I changed the collector supply polarity the 754D would react with a brief waveform. When probing the base the trigger level was moving all around on the 754D, even when the probe was removed. Power cycling the 754D fixed the problem and the probe and input appears fine. Perhaps the 577 curve tracer was emitting strong EMP's causing the the 754D to go haywire. The right cover was removed on the 577 and the 754D was sitting just a few inches from it, anyone experience emitted interference from a 577 of nearby electronics?
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Re: [OT] Best glue to repair lifted trace?
Sorry, that was the wrong link. The right product is UHU Endfest 300.
Datasheet here:
toggle quoted message
Show quoted text
On Sun, May 5, 2019 at 6:43 PM cheater00 cheater00 <cheater00@...> wrote:
Does anyone see a reason not to use UHU Endfest? Here's a datasheet in
English:
It looks like a good contender for an OK glue for this purpose. But I
wouldn't know what might be wrong with a glue used for glueing down
traces. Thanks.
On Sun, May 5, 2019 at 5:46 PM cheater00 cheater00 <cheater00@...> wrote:
How long do the Loctite, MG Chemicals, Hardman, and Circuit Works
epoxy glues hold after opened? Days, months, or years? Thanks
On Sun, May 5, 2019 at 5:34 PM cheater00 cheater00 <cheater00@...> wrote:
Ouch, I'll steer clear then! Thanks!
On Sun, May 5, 2019 at 2:52 AM Daveolla <grobbins@...> wrote:
Greetings, I dunno how much I would trust a glue to hold down the
connector . From looking at the picture I would be inclined to drill
a fine hole on either side of the pin or pins and tie it down with a
copper wire and then solder it to the pin to remove any slack in the
tiedown. Or a single hole for each pin and push a sewing pin thru
the hole with the head of the pin on the other side of the board (pin
head bigger than the hole) and curl the other end over the connector
pin , nip it off and solder out any slack
If there is something on the other side of the board that would be
shorted to the pin, a few wraps of thread could also hold things down
and give the thread a drip of CA glue to harden up
thread. Presumably the connector pins are supposed to hold the
connector down but perhaps the plastic connector body could be
tacked down with variations of the above techniques and relieve the
pins from that duty.
And like other have said, getting CA glue fumes from soldering in
yours eyes is a real eye sore! Your eye muscles will shut your eyes
so tight the sun won't make it thru!!!
Dave
Here you go!
On Sat, 4 May 2019, 14:02 Adrian <Adrian@... wrote:
okay, help me out here because I'm confused/bemused by 25+ posts about
high temp glue needed to hold down a connector on a PCB so I've
obviously missed something!
First off, am I right in that:
a) A (thru-hole?) internal connector has come off a PCB and busted a
ground pin in the process.
b) It left (one?) other pin still electrically connected to its pad and
trace but those have peeled of the surface of the board.
c) You think can reposition the connector to the board and sort the
ground pin by somehow re-soldering it
d) You believe you can add glue (epoxy) around the connector to secure
it to the PCB.
If the above is correct why do you need glue for a trace that can
withstand soldering temperatures - the trace/PCB bond cannot be adding
to the retention of the connector against connection/disconnection
forces - so why not re-position/solder everything then add the epoxy
when you're done and brush on a bit of conformal coat or wire-tak or
something to protect/secure the 'loose' trace?
BTW you know that saying " A picture is worth a thousand words"? That is
very true in cases like this!
Adrian
On 5/4/2019 9:20 AM, cheater cheater wrote:
Thanks. This is an internal plug which is not accessible from the outside.
On Sat, May 4, 2019 at 3:06 AM John Kolb <jlkolb@...> wrote:
After repair, I would suggest a short extension cable left attached to
the equipment, so all plugging/inplugging stresses are moved to the end
of the extender.
Jophn
On 5/3/2019 6:28 AM, cheater cheater wrote:
I have a piece of equipment where a trace was lifted. The part is still
attached and I would like to glue it down. The part is a socket for a
cable, and the plug is difficult to insert and remove. I will have to
solder the other pin which is the ground plane, and broke off, so the
glue
has to survive that. I'll also need to add some structural solder on
the
sides. Is cyanoacrylate a good idea here? Anything better than that?
Thanks.
|
Re: [OT] Best glue to repair lifted trace?
Does anyone see a reason not to use UHU Endfest? Here's a datasheet in
English:
It looks like a good contender for an OK glue for this purpose. But I
wouldn't know what might be wrong with a glue used for glueing down
traces. Thanks.
toggle quoted message
Show quoted text
On Sun, May 5, 2019 at 5:46 PM cheater00 cheater00 <cheater00@...> wrote:
How long do the Loctite, MG Chemicals, Hardman, and Circuit Works
epoxy glues hold after opened? Days, months, or years? Thanks
On Sun, May 5, 2019 at 5:34 PM cheater00 cheater00 <cheater00@...> wrote:
Ouch, I'll steer clear then! Thanks!
On Sun, May 5, 2019 at 2:52 AM Daveolla <grobbins@...> wrote:
Greetings, I dunno how much I would trust a glue to hold down the
connector . From looking at the picture I would be inclined to drill
a fine hole on either side of the pin or pins and tie it down with a
copper wire and then solder it to the pin to remove any slack in the
tiedown. Or a single hole for each pin and push a sewing pin thru
the hole with the head of the pin on the other side of the board (pin
head bigger than the hole) and curl the other end over the connector
pin , nip it off and solder out any slack
If there is something on the other side of the board that would be
shorted to the pin, a few wraps of thread could also hold things down
and give the thread a drip of CA glue to harden up
thread. Presumably the connector pins are supposed to hold the
connector down but perhaps the plastic connector body could be
tacked down with variations of the above techniques and relieve the
pins from that duty.
And like other have said, getting CA glue fumes from soldering in
yours eyes is a real eye sore! Your eye muscles will shut your eyes
so tight the sun won't make it thru!!!
Dave
Here you go!
On Sat, 4 May 2019, 14:02 Adrian <Adrian@... wrote:
okay, help me out here because I'm confused/bemused by 25+ posts about
high temp glue needed to hold down a connector on a PCB so I've
obviously missed something!
First off, am I right in that:
a) A (thru-hole?) internal connector has come off a PCB and busted a
ground pin in the process.
b) It left (one?) other pin still electrically connected to its pad and
trace but those have peeled of the surface of the board.
c) You think can reposition the connector to the board and sort the
ground pin by somehow re-soldering it
d) You believe you can add glue (epoxy) around the connector to secure
it to the PCB.
If the above is correct why do you need glue for a trace that can
withstand soldering temperatures - the trace/PCB bond cannot be adding
to the retention of the connector against connection/disconnection
forces - so why not re-position/solder everything then add the epoxy
when you're done and brush on a bit of conformal coat or wire-tak or
something to protect/secure the 'loose' trace?
BTW you know that saying " A picture is worth a thousand words"? That is
very true in cases like this!
Adrian
On 5/4/2019 9:20 AM, cheater cheater wrote:
Thanks. This is an internal plug which is not accessible from the outside.
On Sat, May 4, 2019 at 3:06 AM John Kolb <jlkolb@...> wrote:
After repair, I would suggest a short extension cable left attached to
the equipment, so all plugging/inplugging stresses are moved to the end
of the extender.
Jophn
On 5/3/2019 6:28 AM, cheater cheater wrote:
I have a piece of equipment where a trace was lifted. The part is still
attached and I would like to glue it down. The part is a socket for a
cable, and the plug is difficult to insert and remove. I will have to
solder the other pin which is the ground plane, and broke off, so the
glue
has to survive that. I'll also need to add some structural solder on
the
sides. Is cyanoacrylate a good idea here? Anything better than that?
Thanks.
|
2246 no display/odd behavior
Ok - some progress.
I replaced the battery. No change in startup (front panel controls still hang until I fiddle with the buttons for about 45 seconds). It's now returning to the previous state after a reboot though. No codes displayed in the trigger section.
I adjusted R2719 and we have a dot! Here's a shot:
If I deviate from the procedure and turn the Readout knob up I can also see the standard display and even a waveform I fed in.
Now I'm confused because the manual procedure concludes with "adjust R2719 so dot is no longer visible" which then kills the whole display. Turning the readout knob back up after adjusting R2719 'correctly' results in no display or trace.
Still some lingering questions in my head too like how J2208 got installed backwards and how the trace between C2244 and R2231 'disappeared' but this is definitely progress.
Suggestions on how to proceed welcome.
|
Raymond Domp Frank