sci.electronics.repair@googlegroups.com

Today's topics:

* OT: Tek 465 - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/b9f473fde6856891?hl=en
* Motor start/stop switch with integrated mini contactor? - 2 messages, 2
authors
http://groups.google.com/group/sci.electronics.repair/t/13b233689d902984?hl=en
* Microwave oven diode bad? - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/68504020f6b6237b?hl=en
* How to resolder a cold solder connection? - 6 messages, 4 authors
http://groups.google.com/group/sci.electronics.repair/t/46868719284715b1?hl=en
* Tektronix 7603 - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/efb86f5dc14fc24b?hl=en
* t.v. volume remains static. - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/8fbadf0c35306061?hl=en
* Contactor coil: 50 Hz vs. 60 Hz - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/0d1a06068779ce43?hl=en

==============================================================================
TOPIC: OT: Tek 465
http://groups.google.com/group/sci.electronics.repair/t/b9f473fde6856891?hl=en
==============================================================================

== 1 of 3 ==
Date: Sun, Aug 28 2011 11:06 am
From: Jeff Liebermann

On Sun, 28 Aug 2011 07:15:36 -0500, "Mark Zacharias"
<mark_zacharias@labolgcbs.net> wrote:

>Never used a scope with cursor readout - I'm going to have a learning curve
>on this one.

It's easy, but I hardly ever use the cursor for repair work. If the
waveform looks "reasonable", that's usually good enough. If I were
back to doing design, I might find it useful. What I find handy on
the 2246A/2247A is the ability to store and recall setups. I have a
few stored for various things I tend to do repeatedly, which saves me
some knob twiddling.

Suggestion: Open the box and blow out the dust and crud. Test
equipment tends to live longer when the air path isn't clogged.

>I suspect it will mostly be used as a plain analog scope
>though, in 35 years mainly working audio I don't think I've ever "needed" a
>crt readout.

I suggest you look into a DSO (digital storage oscilloscope)
<http://www.rigolna.com/products/digital-oscilloscopes/>
or USB scopes. This is one that I borrowed, liked, but haven't
bought:
<http://www.syscompdesign.com/CGR101.html>
At 2Mhz max, it's good enough for audio except when you want to
measure near the noise floor. With only 10 bits, that's problematic.

>I did not have any illusions about being able to fix the 2246 when (not if)
>the time comes. I was probably lucky to get the 465 going.

Nothing wrong with believing in luck. Just don't try to rely on it.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 2 of 3 ==
Date: Sun, Aug 28 2011 4:34 pm
From: Jim Yanik

Jeff Liebermann <jeffl@cruzio.com> wrote in
news:18vk575npasgvjnhv61ab56hm4tgm8afr2@4ax.com:

> On Sun, 28 Aug 2011 09:50:24 -0500, Jim Yanik <jyanik@abuse.gov>
> wrote:
>
>>While at TEK,on 1720/1730 PS boards,I used to Dremel out the
>>carbonized area,fill in the hole with epoxy,and then lay new runs and
>>set eyelets. I used cellophane tape over the hole when putting in the
>>epoxy,less finish grinding to make it flat.
>
> I've done that a few times in the past with mixed results. I have a
> rather pricy power supply waiting for my attention, with a similar
> hole. Works ok for low impedance circuitry, but I wouldn't use it for
> hi-v or high impedance. I also use the Scotch tape trick, but also
> add some fiberglass matting. I've also found that Bondo works better
> than epoxy because it doesn't shrink when it hardens.

My carbonized hole was the HV osc xstr,a TIP31C.
I never had any problem with epoxy shrinkage. I used a clear epoxy from
Hysol.
Now I would use my RAKA boat-building epoxy with fumed silica filler.great
stuff.

>
>>yes,2245/6/7 scopes are a PITA to work on.
>
> The scopes that I and several friends have were purchased from a
> former large corporation, that cound them uneconomical to repair.
> There was a pile of them, which we purchased for peanuts. They were
> happy to see them go.
>
> Did you notice the TAS 465 scope in the pile to be fixed?
><http://802.11junk.com/jeffl/crud/scopes-to-be-fixed.jpg>

Missed that. Never worked on one.

> It lights up, runs, but the beam and alpha are stuck on the left side
> of the screen. Vertical seems to be working but it's difficult to
> tell with the beam off the screen. Obviously, a horizontal amp
> problem.

could also be a sweep problem;sweep triggered,but sweep gen not ramping.
might just be a CRT deflection pin lead fell off. I've seen them get
loose,and get shaken off in moving the scope.

> Yet, I've been inside 3 times and have not been able to find
> an obvious culprit. However, I just found a schematic and manual, so
> I'll probably try again. It has one big advantage... it's light
> weight.
>
> One of the T922 scopes on top of the pile works. Which one, I forgot.
> The other has a blown flyback xformer. I haven't found a substitute
> yet.

I always liked the T922/32/35/442. Not the T912.
>
> The two on the bottom of the pile are both HP 1740A 100MHz scopes.
> Both have power supply problems, which are probably bad electrolytics.
> I'm too lazy to fix them.
>
> There are also at least 4 more assorted scopes around the house, and 3
> more in the office, some of which work.
>
>

WOW,most people only have one or two scopes..... :-)

are you fixing them for friends,or the occasional sale?

--
Jim Yanik
jyanik
at
localnet
dot com

== 3 of 3 ==
Date: Sun, Aug 28 2011 6:13 pm
From: Jeff Liebermann

On Sun, 28 Aug 2011 18:34:22 -0500, Jim Yanik <jyanik@abuse.gov>
wrote:

>My carbonized hole was the HV osc xstr,a TIP31C.

The TIP31c is good for 100VDC. That's right on the border where I
would worry about any remaining carbonized epoxy causing a conduction
path. Good to know it worked.

>I never had any problem with epoxy shrinkage. I used a clear epoxy from
>Hysol.
>Now I would use my RAKA boat-building epoxy with fumed silica filler.great
>stuff.

Silica filler, as in sand? Well, that will give it considerable
hardness and strength. However, I don't think that will be necessary
to repair a PCB. I was dealing with a rather large hole, about 3/4"
in diameter. I wanted to make sure than any applied pressure would
not crack the epoxy. So, I added fiberglass matt reinforcing.

>> Did you notice the TAS 465 scope in the pile to be fixed?
>><http://802.11junk.com/jeffl/crud/scopes-to-be-fixed.jpg>
>
>Missed that. Never worked on one.

They look fairly nice inside and seem easy to work. Unfortunately,
there are plenty of proprietary parts.

>> It lights up, runs, but the beam and alpha are stuck on the left side
>> of the screen. Vertical seems to be working but it's difficult to
>> tell with the beam off the screen. Obviously, a horizontal amp
>> problem.
>
>could also be a sweep problem;sweep triggered,but sweep gen not ramping.
>might just be a CRT deflection pin lead fell off. I've seen them get
>loose,and get shaken off in moving the scope.

I checked all the loose connection possibilities. All the scope
deflections leads have voltage. I don't think it's a trigger problem
because the various text labels that should show up on the screen, are
also stuck on the left side. I can see them sorta move when I
randomly push buttons, so I know they're functional, just not
displaying. I'll figure it out eventually. Project for tonite is yet
another blown power supply in an IFR-1500 service monitor. Great
monitor, disgusting power supply design.

>> One of the T922 scopes on top of the pile works. Which one, I forgot.
>> The other has a blown flyback xformer. I haven't found a substitute
>> yet.
>
>I always liked the T922/32/35/442. Not the T912.

Yep. Not a bad scope, but the 922 is only good for 15Mhz. In these
daze of 100MHz scopes, it's kinda limiting.

>> The two on the bottom of the pile are both HP 1740A 100MHz scopes.
>> Both have power supply problems, which are probably bad electrolytics.
>> I'm too lazy to fix them.
>>
>> There are also at least 4 more assorted scopes around the house, and 3
>> more in the office, some of which work.

>WOW,most people only have one or two scopes..... :-)

I forgot to mention 6ea Tek 5110 scopes with 5A18 vertical plug-ins.
They're rack mounted into various ham radio repeaters, hi-fi racks,
and at radio sites. I got tired of dragging a scope with me every
time I needed to do some repairs. So, I just added one into every
rack where I thought it might be useful. Works great, except that all
the other techs steal my scope probes.

>are you fixing them for friends,or the occasional sale?

I have friends and I have customers. The difference is that the
customers pay me. Otherwise, they're the same.

Some of the better scopes were intended for me to use. Literally,
every scope required some form of repair or rework. I tend to buy
broken things, and fix them. (Don't ask me why I have 6 chain saws).
I plan to sell them eventually, but have not had the time or incentive
to fix any of them[1]. Diving into the shop, I see a Tek 2205, HP
182C, and Tek 213 scope/DVM, all of which are in need of something. I
didn't know I had that many scopes. Time to find some friends, err...
customers, and get rid of them. Otherwise, I'll just repupose my shop
as a museum.

[1] That may happen soon, as the computah repair biz is really slow.
What I usually do is take a few days off, and diagnose everything and
order parts. About 2 weeks later, when the parts arrive late, I do
assembly line repair on everything possible. I've done this several
times in the past and it works quite well for me. The problem is
finding the uninterrupted time.

Incidentally, I just found a box of Tek repair parts, dating back to
the 1970's era. Nuvistors, tubes, semiconductors, etc. There's an
inventory list, but the boxes have probably been pillaged. Any
interest?
<http://802.11junk.com/jeffl/crud/Tek-Parts.jpg>
There are 4 similar, but smaller plastic boxes stuffed with parts.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

==============================================================================
TOPIC: Motor start/stop switch with integrated mini contactor?
http://groups.google.com/group/sci.electronics.repair/t/13b233689d902984?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Aug 28 2011 12:03 pm
From: DaveC

Hi,
I just became aware of this item:

<http://img-europe.electrocomponents.com/images/R3985229-01.jpg>

Data sheet here:

<http://www.pdfdoc.ru/data/pdf42805>

It includes a 2-pole 16A contactor in that little size. Can also be ordered
with the option of external connection for safety stop push-button switch.

I can't find a USA distributor for these. Anybody know where to get these?

The company is in Germany:

<http://www.eichhoff.com/unternehmen_ueber-eichhoff_en.php>

Or is there a domestic (USA) product that is similar?

Thanks,
Dave

== 2 of 2 ==
Date: Sun, Aug 28 2011 7:12 pm
From: The Ghost In The Machine

On Aug 28, 3:03 pm, DaveC <inva...@invalid.net> wrote:
> Hi,
> I just became aware of this item:
>
> <http://img-europe.electrocomponents.com/images/R3985229-01.jpg>
>
> Data sheet here:
>
> <http://www.pdfdoc.ru/data/pdf42805>
>
> It includes a 2-pole 16A contactor in that little size. Can also be ordered
> with the option of external connection for safety stop push-button switch.
>
> I can't find a USA distributor for these. Anybody know where to get these?
>
> The company is in Germany:
>
> <http://www.eichhoff.com/unternehmen_ueber-eichhoff_en.php>
>
> Or is there a domestic (USA) product that is similar?
>
> Thanks,
> Dave

HAVE YOU ASKED "SWITCHES UNLIMITED" ONLINE...THEY ARE LOCATED IN THE
US.

TGITM

==============================================================================
TOPIC: Microwave oven diode bad?
http://groups.google.com/group/sci.electronics.repair/t/68504020f6b6237b?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Aug 28 2011 2:50 pm
From: "Michael A. Terrell"

Spamm Trappe wrote:
>
> On Sun, 28 Aug 2011 10:55:50 -0400, Michael A. Terrell wrote:
> ?
> ? There are not regular diodes. There are a stack of diodes, and have
> ? a higher forward voltage drop.
>
> Since there obviously lacking, their ought to be continuing education
> classes where illiterates can improve they're language skills.

Since you want to point out typos, it's 'their language skills',
jackass.

--
You can't have a sense of humor, if you have no sense.

==============================================================================
TOPIC: How to resolder a cold solder connection?
http://groups.google.com/group/sci.electronics.repair/t/46868719284715b1?hl=en
==============================================================================

== 1 of 6 ==
Date: Sun, Aug 28 2011 2:53 pm
From: "Michael A. Terrell"

Smitty Two wrote:
>
> In article ?eJidnYhXQd0W88TTnZ2dnUVZ_rCdnZ2d@earthlink.com?,
> "Michael A. Terrell" ?mike.terrell@earthlink.net? wrote:
>
> ? You want a good, mild RMA flux, not just liquid rosin. My favorite
> ? was Kester 1544, but I think they dropped that formula now that they
> ? concentrate on reflow solder products.
>
> 1544 is still around. A gallon is about $50 and would last your average
> DIY guy about 800 years, if it weren't for the fact that the volatiles
> seep through the plastic bottle.

My last bottle is about 25 years old. I bought four quart bottles of
it for $2.50 each from a surplus store in Dayton, Ohio. The others have
been used up.

--
You can't have a sense of humor, if you have no sense.

== 2 of 6 ==
Date: Sun, Aug 28 2011 7:39 pm
From: micky

On Sat, 27 Aug 2011 20:42:52 -0400, "Michael A. Terrell"
<mike.terrell@earthlink.net> wrote:

>
>> Nothing I read commented on the original solder job, IMO probably
>> because they can't tell and most of them own Hondas and don't want to
>> think it was made badly in the first place.
>
>
> Most of them aren't likely to know anything more than which end of
>the hot soldering iron to pick up, let alone the various failure modes
>of soldered connections.

Right. I'm happy they know which part is bad, roughly how to fix
it, and the write webpages for people like me.

== 3 of 6 ==
Date: Sun, Aug 28 2011 7:48 pm
From: micky

On Sat, 27 Aug 2011 12:23:28 -0700, Winston <Winston@BigBrother.net>
wrote:

>
>
>> BTW, I could find liquid flux nearby, in time for the repair tomorrow,
>> so I got flux paste. I thought I'd put a little on with a toothpick
>> or matchstick?? If the hurrican means I don't work on the car
>> tomorrow, should I go 10 miles farther to buy liquid flux?
>
>Flux paste will work fine as long as:
> 1) It matches the flux in your properly selected
> solder. (R, RMA or RA rosin in both cases).

I hate to say this but none of my solder is marked R, RMA, or RA. The
labels says nothing except that they have rosin.

Radio Shack solder mostly. I've used up other things I had.

Also the Radio Shack flux paste doesn't have an R-rating. It says
nothing about what kind of flux it is.

But the repair today was postponed, so I have time to go farther away
and buy liquid flus. I have another errand to do nearby.

> 2) You daub it on generously with an acid brush,
> covering the joint in question.

I can do that.

> 3) You clean the resulting joint carefully.

I can do that. It's still necessary with liquid, right?

>The beauty of the liquid rosin flux is that it's
>difficult to supply *too little* to the joint.

Does that also have to be R, RMA, or RA?

>--Winston

== 4 of 6 ==
Date: Sun, Aug 28 2011 9:50 pm
From: Smitty Two

In article <21vl571dj9f2tkcauunsns4vr2f0fqu2c2@4ax.com>,
micky <NONONOmisc07@bigfoot.com> wrote:

> Does that also have to be R, RMA, or RA?

Either Rosin Activated or Rosin Mildly Activated will be fine. Don't buy
any acid flux.

But the paste you already have should be fine. If you want it to be
liquid, just mix it with some alcohol. (IPA is fine, but get the pure
stuff if you can, not the 70% stuff.)

If you're soldering iron tip isn't shiny new, put a shiny new tip on it.
It will make a surprisingly large difference in the ease and quality of
your soldering.

== 5 of 6 ==
Date: Sun, Aug 28 2011 10:15 pm
From: Winston

micky wrote:
> On Sat, 27 Aug 2011 12:23:28 -0700, Winston<Winston@BigBrother.net>
> wrote:

(...)

> I hate to say this but none of my solder is marked R, RMA, or RA. The
> labels says nothing except that they have rosin.

Then it is very probably R (rosin only) RMA (rosin mildly activated)
or RA (rosin activated). No worries.

> Radio Shack solder mostly. I've used up other things I had.
>
> Also the Radio Shack flux paste doesn't have an R-rating. It says
> nothing about what kind of flux it is.

If it is the SP-44 stuff, you are in luck
because it is compatible:
http://support.radioshack.com/msds/msd91-484.pdf

> But the repair today was postponed, so I have time to go farther away
> and buy liquid flus. I have another errand to do nearby.

As Smitty Two says, you *can* thin your paste with
99% alcohol. I just find the Kester product to be
very convenient.
>
>> 2) You daub it on generously with an acid brush,
>> covering the joint in question.
>
> I can do that.
>
>> 3) You clean the resulting joint carefully.
>
> I can do that. It's still necessary with liquid, right?

Yes indeed. Extra points are rewarded for cleanliness.

>> The beauty of the liquid rosin flux is that it's
>> difficult to supply *too little* to the joint.
>
> Does that also have to be R, RMA, or RA?

Yup.
Most specifically NOT 'acid' or 'plumbing' flux.
Sorry for shouting but we don't want your relay
to turn green and fall apart.

--Winston

== 6 of 6 ==
Date: Sun, Aug 28 2011 10:20 pm
From: Winston

Smitty Two wrote:
> In article<21vl571dj9f2tkcauunsns4vr2f0fqu2c2@4ax.com>,
> micky<NONONOmisc07@bigfoot.com> wrote:
>
>> Does that also have to be R, RMA, or RA?
>
> Either Rosin Activated or Rosin Mildly Activated will be fine. Don't buy
> any acid flux.
>
> But the paste you already have should be fine. If you want it to be
> liquid, just mix it with some alcohol. (IPA is fine, but get the pure
> stuff if you can, not the 70% stuff.)
>
> If you're soldering iron tip isn't shiny new, put a shiny new tip on it.
> It will make a surprisingly large difference in the ease and quality of
> your soldering.

And to turn a dull, oxidized tip shiny new
with just a few stabs, I highly recommend
the Hakko tip cleaner:
http://www.all-spec.com/products/599B-02.html

It works a treat.

--Winston

==============================================================================
TOPIC: Tektronix 7603
http://groups.google.com/group/sci.electronics.repair/t/efb86f5dc14fc24b?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Aug 28 2011 3:43 pm
From: Jeff Urban

The old 7613 died. The power supply has a problem and I suspect
something is shorted somewhere. So I ran across a 7603 on craigslist
cheap, but with no plugins. So I figured there ya go, I don't have
much use for mesh type storage anyway, in fact I think it was pretty
much a waste of time, at least for my purposes.

So I figured there might be trouble when I got there, I expected to
see a spot in or near the center of the screen but it was not. There
was deflection without plugins, but at least it's not shorted out.

So I plug my plugins in ( care to rephrase that anyone ? ) and instead
of a flat trace in the absence of vertical input I have a sawtooth.
Changing the timebase only affects the trace slightly, through most
ranges it is showing one cycle, only the slope changes. It seems
obvious that the vertical deflection is polluted by the horizontal
deflection, and without the plugins it was deflected by power supply
ripple.

I downloaded the print from bama (the mirror site actually) and it is
a typical Tektronix manual. Like I really needed a refresher on how a
UJT works LOL. Of course it's useful in a sense but it doesn't really
point me in any meaningful direction. Soon I am going to have to go
hands on and just start taking the thing apart. Looking at the print I
have suspects but don't know where anything is.

The point is I'd like to get in and out of this thing. I want the
covers back on and it working without staying apart on the bench for a
week. I am fairly sure it's going to be a filter either in the power
supply or just after it somewhere. Could probably find it quick enough
with a scope..... should I break out the old B&K ?

Mainly I'm looking for some pointers to make this a bit more painless.
I wouldn't mind having the 7613 back up and running but this will do
just fine. In fact, once this is up and running I wonder if anyone
might be interested in the parts from the 7613. I don't even want to
speculate on the price of the CRT, which is strong and burn free BTW.
I'm thinking though for the furture alot of the 7613 parts should fit
the 7603, or am I wrong about that ?

Any help or advice will be highly appreciated.

J

==============================================================================
TOPIC: t.v. volume remains static.
http://groups.google.com/group/sci.electronics.repair/t/8fbadf0c35306061?hl=en
==============================================================================

== 1 of 2 ==
Date: Sun, Aug 28 2011 9:55 pm
From: delroy_dobbs1@yahoo.com

Panasonic t.v., TC 20RA10LP.I replaced the audio ic ,an7523n,and the
t.v
now has sound but the sound/volume remains at one pitch. whenever I
press
the volume button whether up/down the volume remains same but
whenever it
reaches 0 on the volume display on the screen you won't hear the
volume.
what is wrong here ?
N:B There is no bridges across the ic pins.

== 2 of 2 ==
Date: Mon, Aug 29 2011 1:18 am
From: "William Sommerwerck"

<delroy_dobbs1@yahoo.com> wrote in message
news:e5b4f6ac-86a4-47bc-9b31-6d7cadfa5568@a27g2000yqc.googlegroups.com...

> NB: There is no bridges across the IC pins.

1. The new chip is defective. --or--
2. This problem existed before you replaced the chip. --or--
3. You damaged something when you removed the old chip or soldered in the
new one. --or--
4. There really is a solder bridge across two of the IC pins (or elsewhere).

Always keep in mind what Sherlock Holmes said.

==============================================================================
TOPIC: Contactor coil: 50 Hz vs. 60 Hz
http://groups.google.com/group/sci.electronics.repair/t/0d1a06068779ce43?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Aug 28 2011 11:21 pm
From: DaveC

I may be able to obtain a very small 2-pole 240 vac contactor I need rated
for 50 Hz only.

If I install it in N. America, what's the implication? Is the hold-in
magnetism less than if it were 60 Hz? Just noisy?

Please don't ask or suggest other sources. This is a very specific device and
I've not been able to locate other than this.

Thanks,
Dave

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