Date   

Re: Any advice on 547 power supply repair?

hpxref
 

"That raises a question. Is there anything we can do to *accelerate* the degradation of the epoxy, for the purpose of removing it more easily with less damage to the parts we wish to save? Would boiling the transformer in water, for example, help in softening up the epoxy?"

A few years ago a local tech magazine (Silicon Chip) ran a pane which stated that soaking ferrite cored transformers in
paint thinner melted the epoxy so the cores easily separated:
This did not work for me either on old TV EHT transformers when they were of "open" construction or on
more modern , but smaller cores, such as ex switch mode PSU's.
But it may be worth a try as it seemed to have worked for them.
Maybe my epoxy was a bit different in its make up
I tried expensive thinners used by Auto professionals (at 10 times the cost) but with no luck either.
It may be that the thinners need to be near boiling point but as this stuffs so easily flammable when it condensates
you would have to be very careful.
I thought of heating it with the sealed can type electric heaters from old plan printers (remember them?) which were quite small in size, but never had the courage to do so
The thinners did remove the enamel from the wire, though.

Just a thought
John


Re: 453A intensity fluctuates

Bob Albert
 

I love when that happens!  I have repaired things more than once that way.  A good zap sometimes is just what it needs.

Bob


--- On Mon, 4/15/13, doug1052365 wrote:

From: doug1052365
Subject: [TekScopes] Re: 453A intensity fluctuates
To: TekScopes@...
Date: Monday, April 15, 2013, 2:17 PM

 

I tried a different capacitor for C945 - all I had handy was
a .01/4KV. No change. Spayed a little silicone into the
grid bias pot. No change. I the took apart the H.V. box,
temporarily extending the Anode Lead so I could probe the back
of the grid bias pot with the P6013A. As I was probing there
was a large spark. Maybe I pushed something too close to the
chassis, whatever happened it fixed it. Intensity is stable now.
I'm not expecting it to stay that way. I'm sure after I re-assemble
everything it will act up again. Or if I'm lucky the spark welded
a bad connection or vaporized a conductive path. I can't do anything more now that it's working. Thanks for all suggestions.

Doug

ps I found the little spool of silver solder inside.

--- In TekScopes@..., David wrote:
>
> On Mon, 15 Apr 2013 17:44:29 -0000, "doug1052365"
> wrote:
>
> >I'm trying to track down the cause of a fairly rapid intensity fluctuation in my 453A. All power supplies including -1960 and
> >12KV are stable. I see it on the CRT grid, but not on the anode
> >of CR940 and not on the Z axis amplifier output. Turning the
> >grid bias pot a little changes the overall intensity, but the fluctuation is always there.
> >
> >I conclude the pot is OK, the problem must be C945, R944-948,
> >the neon lamps or , the CRT. I've looked inside the
> >H.V. box, all connections look good, neons are not lit and
> >don't see any arcing.
> >
> >Anyone have any ideas? I'm at the point of replacing parts
> >in trial and error fashion.
> >
> >Doug
>
> And C946. Since you eliminated the z-axis amplifier output and both
> high voltage supplies, C945, C946, and R944 to R948 are all about all
> that is left.
>
> If the problem was the 12KV, then I would expect the display
> horizontal and vertical scale to change with the brightness.
>
> Maybe there is breakdown across the printed circuit board itself that
> you will be able to see in the dark. After checking for that, I would
> change the 2 capacitors and 5 resistors.
>


Re: 453A intensity fluctuates

Doug
 

I tried a different capacitor for C945 - all I had handy was
a .01/4KV. No change. Spayed a little silicone into the
grid bias pot. No change. I the took apart the H.V. box,
temporarily extending the Anode Lead so I could probe the back
of the grid bias pot with the P6013A. As I was probing there
was a large spark. Maybe I pushed something too close to the
chassis, whatever happened it fixed it. Intensity is stable now.
I'm not expecting it to stay that way. I'm sure after I re-assemble
everything it will act up again. Or if I'm lucky the spark welded
a bad connection or vaporized a conductive path. I can't do anything more now that it's working. Thanks for all suggestions.

Doug

ps I found the little spool of silver solder inside.

--- In TekScopes@..., David <davidwhess@...> wrote:

On Mon, 15 Apr 2013 17:44:29 -0000, "doug1052365" <dmeek@...>
wrote:

I'm trying to track down the cause of a fairly rapid intensity fluctuation in my 453A. All power supplies including -1960 and
12KV are stable. I see it on the CRT grid, but not on the anode
of CR940 and not on the Z axis amplifier output. Turning the
grid bias pot a little changes the overall intensity, but the fluctuation is always there.

I conclude the pot is OK, the problem must be C945, R944-948,
the neon lamps or <gulp>, the CRT. I've looked inside the
H.V. box, all connections look good, neons are not lit and
don't see any arcing.

Anyone have any ideas? I'm at the point of replacing parts
in trial and error fashion.

Doug
And C946. Since you eliminated the z-axis amplifier output and both
high voltage supplies, C945, C946, and R944 to R948 are all about all
that is left.

If the problem was the 12KV, then I would expect the display
horizontal and vertical scale to change with the brightness.

Maybe there is breakdown across the printed circuit board itself that
you will be able to see in the dark. After checking for that, I would
change the 2 capacitors and 5 resistors.


Re: OT: the capacitor curse

magnustoelle
 

Hi Dave,

Yes, sorry if that was not clear. ChipQuick for removal only.

I use regular solder wick and IPA to thoroughly clean the pads after the removal of the device. Then regular solder (Sn60Pb39Cu1 or lead-free, the latter only if required) to populate new parts...

Cheers,

Magnus

--- In TekScopes@..., DaveC <davec2468@...> wrote:

Magnus
I presume you mean that you use CQ to remove SMDs and you use solder when placing new components?

Dave

Sent from my iPhone


Re: OT: the capacitor curse

 

Bismuth is often used for specialty solders. From Wikipedia:

"Bismuth significantly lowers the melting point and improves
wettability. In presence of sufficient lead and tin, bismuth forms
crystals of Sn16Pb32Bi52 with melting point of only 95 °C, which
diffuses along the grain boundaries and may cause a joint failure at
relatively low temperatures. A high-power part pre-tinned with an
alloy of lead can therefore desolder under load when soldered with a
bismuth-containing solder. Such joints are also prone to cracking.
Alloys with more than 47% Bi expand upon cooling, which may be used to
offset thermal expansion mismatch stresses. Retards growth of tin
whiskers. Relatively expensive, limited availability."

I just add tin-lead solder to dilute the higher temperature alloy.

On Mon, 15 Apr 2013 20:54:51 +0200, Stefan Trethan
<stefan_trethan@...> wrote:

OK, and why is Bismuth bad?

I'm not just asking to waste your time, a colleague recently proposed using
it as permanent solder.
Intuitively I felt it wasn't a good idea, but don't really know why.

This isn't totally off topic by the way - low melting point solder was used
in a Tek product - the P6401 has a thermal fuse held down by some low melt
alloy.


Re: 180-S1 Time Mark Gen on ebay

teamlarryohio
 

bonddaleena@... wrote:
If you check out the 'other items'....you will see a great deal on a
pair of 12AU7 tubes.
...pulled out of something Tek. 157-XXXX labels.
-ls-


Re: 180-S1 Time Mark Gen on ebay

Craig Sawyers <c.sawyers@...>
 

This is a Tektronix 180-S1 Time Mark Generator. It looks to be mostly
complete from the pictures. I am not affiliated to the seller.
========================

The S1 is the version with temperature stabilised crystal, good to 2ppm in
25 hours. Whopping $625 in 1955 - the 570 tube curve tracer was $925 in the
same catalogue to compare.

Clearly needs a good clean up, inside and out - but it probably hasn't seen
massive use. Just looks like storage dirt. And that selenium rectifier
needs to be powered up with caution.

And if anyone buys it, make sure the seller packs it well - it is a pretty
chunky 35lbs.

Craig


Re: 180-S1 Time Mark Gen on ebay

Artekmedia <manuals@...>
 

Tektronix museum piece to be sure. No particularly rare tubes in the line-up which is also  makes it a little less attractive to the tube mongers..... if nothing else with the fan and all it could be used as a space heater in the winter time to heat the lab.

Dave
ArtekManuals.com

On 4/15/2013 2:18 PM, d.seiter@... wrote:
 

Hopefully at that price, the tube harvesters will be kept at bay. 

 

-Dave


From: "Cliff White"
To: "TekScopes"
Sent: Monday, April 15, 2013 10:27:47 AM
Subject: [TekScopes] 180-S1 Time Mark Gen on ebay

 

This is a Tektronix 180-S1 Time Mark Generator. It looks to be mostly complete from the pictures. I am not affiliated to the seller.


 http://www.ebay.com/itm/Tektronix-180-S1-Time-Mark-Generator-52-Tubes-12AU7-6AL5-12AT7-6AH6-more-/140940116625?pt=LH_DefaultDomain_0&hash=item20d0af8291


--
Respectfully,
Cliff White, W5CNW
w5cnw@...



-- 
Dave Henderson
Manuals@...
www.Artekmanuals.com
PO Box 175
Welch,MN 55089
651-269-4265


Re: 180-S1 Time Mark Gen on ebay

bonddaleena@...
 

If you check out the 'other items'....you will see a great deal on a pair of 12AU7 tubes.

ONLY $425. Got to be a typo.... ha ha  Better hurry!!!!!

At that rate, I must have a couple of million $ worth of tubes here.....

ron
N4UE



-----Original Message-----
From: d.seiter
To: TekScopes
Sent: Mon, Apr 15, 2013 3:19 pm
Subject: Re: [TekScopes] 180-S1 Time Mark Gen on ebay

 
Hopefully at that price, the tube harvesters will be kept at bay. 
 
-Dave


From: "Cliff White" <w5cnw@...>
To: "TekScopes" <TekScopes@...>
Sent: Monday, April 15, 2013 10:27:47 AM
Subject: [TekScopes] 180-S1 Time Mark Gen on ebay

 
This is a Tektronix 180-S1 Time Mark Generator. It looks to be mostly complete from the pictures. I am not affiliated to the seller.


 http://www.ebay.com/itm/Tektronix-180-S1-Time-Mark-Generator-52-Tubes-12AU7-6AL5-12AT7-6AH6-more-/140940116625?pt=LH_DefaultDomain_0&hash=item20d0af8291


--
Respectfully,
Cliff White, W5CNW
w5cnw@...



Re: 180-S1 Time Mark Gen on ebay

J. D. Leach
 

From: "Cliff White" <w5cnw@...>
To: "TekScopes" <TekScopes@...>
Sent: Monday, April 15, 2013 10:27:47 AM
Subject: [TekScopes] 180-S1 Time Mark Gen on ebay
This is a Tektronix 180-S1 Time Mark Generator. It looks to be mostly
complete from the pictures. I am not affiliated to the seller.
This thing has been up for auction for months now. If I recall correctly, the
price was originally around $150.

I figure it will finally sell when it drops to $75. At that point, the
audiophools will be able to realize a good profit on the tubes.

--
J. D. Leach


Re: 475A and de-solder station

jonathanrwbrooks <jonathan@...>
 

I am very impressed with the Duratool for under a £100. I have practiced with a PCI card removing small components and the RF RX metal can, no problem. I have also de-soldered rectifier diodes on solder tags and some of the wires to the solder tags also came away unintentionally. So I have now bought some spare tips as they do 0.8, 1.0 and 1.3 mm as options. Back to the 475A when I get some quotes in for pcb equipment.

Kind regards Jonathan.

--- In TekScopes@..., Stefan Trethan <stefan_trethan@...> wrote:

First, open it up and see if you got the transformer or switchmode version.
If you got the transformer version add a switchmode supply of 15 to 24V for
the motor cirucit (a laptop supply should work).
The transformer version will have a slowly starting tired sound when you
pull the trigger, with the SMPS the motor should immediately get up to
speed and make a much more business-like noise. Don't worry about
overvoltage on the motor, it's only on for seconds.

Take out the filter tube and have a look how far the metal tube protudes
into the filter. This should at most be flush with the black cap, there is
no sense of it sticking into the tube. It will only make it hard to pull
the filter out so curt the tube with a dremel or similar grinder.

While the filter tube is out add a small wad of wire or metal wool inside
the spring. This will catch the solder and make emptying it much easier.

Make some small kinks in the spring with pliers, some are so tightly wound
they are actually airtight and restrict flow. Don't worry the solder will
fly straight towards the end from inertia and not come out the sides.

The little black silicone washer sealing the filter tube to the metal tube
will eventually wear out (the hole gets larger) and not form a proper seal.
A short section (2mm) of silicone tubing slipped on the metal tube fixes
this.

Ideally you'd get a drill to drill out the metal tube, it eventually
accumulates burnt flux residue and solder oxide. You'll need an extra long
drill to reach through. Since extra long drills cost about as much as a new
handpiece this is optional but it's really worth it if you use the unit
much. The cleaning rods are really insufficient.

Don't wait till the tube is blocked, clean it often.

A small vacuum gauge (0 to -1 atmosphere) is really useful in diagnosing
any problem with insufficient suction.

ST

On Sat, Apr 6, 2013 at 10:24 PM, jonathanrwbrooks <
jonathan@...> wrote:

Hi Stephan,

I have bought one and would apprecaite any tips. It does seem to come with
a good few spares.

Kind regards Jonathan.


Re: 180-S1 Time Mark Gen on ebay

d.seiter@...
 

Hopefully at that price, the tube harvesters will be kept at bay. 

 

-Dave


From: "Cliff White"
To: "TekScopes"
Sent: Monday, April 15, 2013 10:27:47 AM
Subject: [TekScopes] 180-S1 Time Mark Gen on ebay

 

This is a Tektronix 180-S1 Time Mark Generator. It looks to be mostly complete from the pictures. I am not affiliated to the seller.


 http://www.ebay.com/itm/Tektronix-180-S1-Time-Mark-Generator-52-Tubes-12AU7-6AL5-12AT7-6AH6-more-/140940116625?pt=LH_DefaultDomain_0&hash=item20d0af8291


--
Respectfully,
Cliff White, W5CNW
w5cnw@...



Re: OT: the capacitor curse

vdonisa
 

From what I understood it will help develop micro cracks and filament growth. There are many conflicting articles on the net, I suggest to try a google search for "hp agilent bismuth solder" you'll get links to a couple of PDFs written from the perspective of a quality electronics manufacturer.

--- In TekScopes@..., Stefan Trethan <stefan_trethan@...> wrote:

OK, and why is Bismuth bad?

I'm not just asking to waste your time, a colleague recently proposed using
it as permanent solder.
Intuitively I felt it wasn't a good idea, but don't really know why.

This isn't totally off topic by the way - low melting point solder was used
in a Tek product - the P6401 has a thermal fuse held down by some low melt
alloy.

ST


On Mon, Apr 15, 2013 at 8:17 PM, vdonisa <vdonisa@...> wrote:

Bismuth if it contains any. If so I personally would use it just to help
remove the ROHS solder then clean out the resulting concoction and do the
final soldering with standard 63/37.

--- In TekScopes@..., Stefan Trethan <stefan_trethan@>
wrote:

Do you have any more information on this?
What are the potential problems of leaving CQ in place as a solder?

ST

On Mon, Apr 15, 2013 at 5:30 PM, Dave C <davec2468@> wrote:

As Carlos said, Field's Metal is the prefered one: it has no lead.

Don't confuse ChipQuik (don't know QuickChip) with real solder. CQ is
not
a substitute for solder, it's a desoldering aid. Solder paste is
usually
used for reflow soldering of SMDs.

Dave



------------------------------------

Yahoo! Groups Links




Re: 453A intensity fluctuates

 

On Mon, 15 Apr 2013 17:44:29 -0000, "doug1052365" <dmeek@...>
wrote:

I'm trying to track down the cause of a fairly rapid intensity fluctuation in my 453A. All power supplies including -1960 and
12KV are stable. I see it on the CRT grid, but not on the anode
of CR940 and not on the Z axis amplifier output. Turning the
grid bias pot a little changes the overall intensity, but the fluctuation is always there.

I conclude the pot is OK, the problem must be C945, R944-948,
the neon lamps or <gulp>, the CRT. I've looked inside the
H.V. box, all connections look good, neons are not lit and
don't see any arcing.

Anyone have any ideas? I'm at the point of replacing parts
in trial and error fashion.

Doug
And C946. Since you eliminated the z-axis amplifier output and both
high voltage supplies, C945, C946, and R944 to R948 are all about all
that is left.

If the problem was the 12KV, then I would expect the display
horizontal and vertical scale to change with the brightness.

Maybe there is breakdown across the printed circuit board itself that
you will be able to see in the dark. After checking for that, I would
change the 2 capacitors and 5 resistors.


Re: OT: the capacitor curse

stefan_trethan
 

OK, and why is Bismuth bad?

I'm not just asking to waste your time, a colleague recently proposed using it as permanent solder.
Intuitively I felt it wasn't a good idea, but don't really know why.

This isn't totally off topic by the way - low melting point solder was used in a Tek product - the P6401 has a thermal fuse held down by some low melt alloy.

ST


On Mon, Apr 15, 2013 at 8:17 PM, vdonisa <vdonisa@...> wrote:
Bismuth if it contains any. If so I personally would use it just to help remove the ROHS solder then clean out the resulting concoction and do the final soldering with standard 63/37.

--- In TekScopes@..., Stefan Trethan wrote:
>
> Do you have any more information on this?
> What are the potential problems of leaving CQ in place as a solder?
>
> ST
>
> On Mon, Apr 15, 2013 at 5:30 PM, Dave C wrote:
>
> > As Carlos said, Field's Metal is the prefered one: it has no lead.
> >
> > Don't confuse ChipQuik (don't know QuickChip) with real solder. CQ is not
> > a substitute for solder, it's a desoldering aid. Solder paste is usually
> > used for reflow soldering of SMDs.
> >
> > Dave
> >
>




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Re: 453A intensity fluctuates

Bob Albert
 

How about the intensity pot itself?

Bob


--- On Mon, 4/15/13, doug1052365 wrote:

From: doug1052365
Subject: [TekScopes] 453A intensity fluctuates
To: TekScopes@...
Date: Monday, April 15, 2013, 10:44 AM

 

I'm trying to track down the cause of a fairly rapid intensity fluctuation in my 453A. All power supplies including -1960 and
12KV are stable. I see it on the CRT grid, but not on the anode
of CR940 and not on the Z axis amplifier output. Turning the
grid bias pot a little changes the overall intensity, but the fluctuation is always there.

I conclude the pot is OK, the problem must be C945, R944-948,
the neon lamps or , the CRT. I've looked inside the
H.V. box, all connections look good, neons are not lit and
don't see any arcing.

Anyone have any ideas? I'm at the point of replacing parts
in trial and error fashion.

Doug


Re: 7904A and X-Y Display -- Help !

Albert <aodiversen@...>
 

Hi Jerry and Dennis,

I now verified this with a 7B53A in the A horizontal slot and in Ampl position of the Time/div knob. The switch S4488 should be slided inwards for normal XY-operation. In the slided outwards position the Z-axis is controlled by the time base amplifier in the B slot (Meaning that the trace is visible while the B sweep is running and blanked during retrace.) The B Intensity bulb gets lit then.
Like in the 7104, the switch is located at the right side of the 'scope, at the upper corner of the A13 board. Best viewed from rear side of the 'scope and switchable with your finger.

Albert

---
FINALLY, I did check the A and the B lights and in every combination of
switch settings I could think of the A light never went out or switched to
the B light. This is why I think you should try what Albert suggested. It
sounds like he has a 7904A in which case he would know what this switch
does.

Dennis

Try with S4488 (corner logic board A13) in the other position?
Albert


Re: OT: the capacitor curse

vdonisa
 

BTW I guess this would be the ultimate way to get rid of that pesky ROHS stuff, at room temperature - no iron needed:

http://www.youtube.com/watch?v=FaMWxLCGY0U

Of course you also wouldn't have much pads left to solder the new component to :-) :-) :-)


--- In TekScopes@..., "vdonisa" wrote:
>
> Bismuth if it contains any. If so I personally would use it just to help remove the ROHS solder then clean out the resulting concoction and do the final soldering with standard 63/37.
>
> --- In TekScopes@..., Stefan Trethan stefan_trethan@ wrote:
> >
> > Do you have any more information on this?
> > What are the potential problems of leaving CQ in place as a solder?
> >
> > ST
> >
> > On Mon, Apr 15, 2013 at 5:30 PM, Dave C davec2468@ wrote:
> >
> > > As Carlos said, Field's Metal is the prefered one: it has no lead.
> > >
> > > Don't confuse ChipQuik (don't know QuickChip) with real solder. CQ is not
> > > a substitute for solder, it's a desoldering aid. Solder paste is usually
> > > used for reflow soldering of SMDs.
> > >
> > > Dave
> > >
> >
>


Re: OT: the capacitor curse

DaveC <davec2468@...>
 

Magnus
I presume you mean that you use CQ to remove SMDs and you use solder when placing new components?

Dave

Sent from my iPhone

On Apr 15, 2013, at 9:57 AM, "magnustoelle" <magnustoelle@...> wrote:

I can confirm that ChipQuick works nicely for SMD components. We are using it to rework 10-pin to 28-pin-SMD-components on multilayer PCBs, and it is a great aid for manual, easy repair work. Their flux is also good, as it is very sticky.


Re: OT: the capacitor curse

vdonisa
 

Bismuth if it contains any. If so I personally would use it just to help remove the ROHS solder then clean out the resulting concoction and do the final soldering with standard 63/37.

--- In TekScopes@..., Stefan Trethan <stefan_trethan@...> wrote:

Do you have any more information on this?
What are the potential problems of leaving CQ in place as a solder?

ST

On Mon, Apr 15, 2013 at 5:30 PM, Dave C <davec2468@...> wrote:

As Carlos said, Field's Metal is the prefered one: it has no lead.

Don't confuse ChipQuik (don't know QuickChip) with real solder. CQ is not
a substitute for solder, it's a desoldering aid. Solder paste is usually
used for reflow soldering of SMDs.

Dave

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