MessageView 421F schematic

[DaveM]

"CLFE" <Junkmail@CLFURENT.COM> wrote in message
news:4425b136$0$3689$ecde5a14@news.coretel.net...

"CLFE" <Junkmail@CLFURENT.COM> wrote in message news:...
I am wondering about the design of a particular power supply. I started trying
to skip around the issue at hand, but got busy with other things - thus the PS
project got shoved to the back burner.

CONAR 324 Power Supply - offered as a part of some Electronics Courses via
National Radio Institute.

It used an UA78HG Voltage Regulator - capable of allowing


Sorry, a glitch sent the post before I finished........

The regulator allowed for 5-15 VDC - sometimes a tad over - closer to 17 or
so - controlled vai a Pot. The current was a constant 6-7 Amps - I believe it
was listed as 6 but some may have went to 7. Anyway, the regulator to my
knowledge is no longer available and I was wondering if anyone else has
attempted to try to work around that problem - using the rest of the
components which came in the Power Supply?

IF so, I'd be glad to hear your input. I have like 5 of these supplies - all
but one works. IF nothing else - I can use the non-working for parts - ie
cabinet, hardware, meter movement, pot, bridge rectifier, etc. But, if I can
get it working to some degree - I'd prefer that. As I alluded to - before I
was rudely interrupted with the glitch, I "started" working around the part
via some sort of design - but got pulled away from it. Time for designing is
in short supply these days.

Thanks in advance for any input/ideas.

clf

The uA78HG is obsolete, as you said. I don't know that there is a direct
replacement, but there are alternatives, such as the LM338. It's a 5A
regulator, same as the uA78HG, but its reference voltage is 1.2 volts instead of
5 volts on the uA78HG. The LM338 is available from a number of sources online,
such as www.mouser.com.
I suggest that you download the datasheet for the LM338 from National
Semiconductor at http://www.national.com/ds.cgi/LM/LM138.pdf and look at the
suggested circuits. You will have to change out one or two resistors, but it
will work just as well as the old regulator. In fact, the LM338 regulator will
allow your power supply to go down to 1.2 volts instead of stopping at 5 volts.
If you have the schematic for your supply, we can make recommendations on
exactly what needs to be changed to get it up and running. The formulae for
component values are in the LM338 datasheet, so with a little bit of ciphering,
you can make the necessary changes yourself.

Cheers!!!!
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Never take a laxative and a sleeping pill at the same time!!

 

[Boris Mohar]

On Thu, 23 Mar 2006 23:20:46 -0600, "Tim Williams" <tmoranwms@charter.net>
wrote:

I should build an induction heated soldering iron. I've heard of Weller
irons that work like that. Mmmm, isolated tip. Tack on a thermocouple and
I've got it made.

Tim

There is one. It is called Metcal now owned by OKI. The Curie point of the
slug regulates the temperature. It comes up to temperature in seconds.
I had one for number of years.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place

 

[Sam Goldwasser]

David Peters <no-email@mail.com> writes:

On 27 Mar 2006, Sammy<no-one@no-where.com> wrote:

My PC monitor (17 inch glass tube) is about 4 years old and has
been used heavily. I took the cover off to fix a loose
connection because the picture was sometimes jumping.

Inside the circuit board was quite dusty and rather sooty. The
CRT tube and anything neary was very sooty.

Is there any merit in cleaning (hoovering or gently
wiping) this dirt?


Thank you all for your advice.

All this now makes me think that my TV (which uses a 19 inch glass
tube) would also show an improved oicture if it too had the dust
cleaned out of it.

Is this correct? Or does a TV differ in some way from a PC monitor
when it comes to getting visible improvements from dusting?

Let's take a survey.... How many of the professional techs, engineers,
and scientists who read this group actually do periodic cleaning of inside
of their monitors and TVs?

If you're obsessive-compulsive and have nothing better to do, by all
means clean the insides of your CRT equipment. But it's probably more
likely that something will get messed accidentally, than any significant
improvement in either performance or life span.

The high voltage area of modern CRT equipment is generally enclosed and
or sealed with HV grease or adhesive. It's not like old all-tube-type
TVs where everything collected an inch of dust if you turned your back.

Yes, dust does collect. And yes in principle that may affect something
eventually. But if there are no symptoms, leave it alone. It's not
likely that a gradually degradation in performance is dust related.
My approach about these things is that "if it ain't broke, don't
fix it". Seriously, if you're in a dusty dirty shop floor, then
there may be some benefit. But if it's a home or office environment,
don't you have better things to worry about than to clean the insides
of your 34,153 electronic gadgets????

For the record, I do not clean inside electronic equipment unless there is
a reason to go inside. My TV is 26 years old and I've repaired it twice
over that span due to defective chokes (probably a parts problem from the
supplier at the time of manufacture). Other TVs in the house are all more
than 15 years old and except one set of cracked solder joints, havne't
needed repair since I acquired them. I generally keep computer monitors
for 8 or 10 years without problems.

Let the flame wars begin... NOW! ;-)

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

 

[Benjamin Gawert]

KC schrieb:

The PM3320A is not a Philips I think. Its Philips out-side and Hameg
in-side

Nope, Hameg never made anything which even comes close to a PM3320A. The
PM3320A is made by Philips.

Benjamin

 

[carneyke]

Hook up some AC from a function generator across the coil and rattle
the contacts. That may help if the coil isn't open. Take Care, Kevin
David C. Partridge wrote:

My Racal 1992 is bringing up error 52 on the Channel A relay test (Relay C,
50 Ohm/1Meg switching), and error 56 on the Channel B relay test (Relay G,
x1, x10 switching).

Racal part numbers 23-7529 and 23-7528.

Can anyone help (if you have a dead 1991/1992 perhaps)?

Based in UK.
--
Dave Partridge (remove xwy from replyto email address)

 

[Achim Metzen]

David C. Partridge schrieb:

My Racal 1992 is bringing up error 52 on the Channel A relay test (Relay C,
50 Ohm/1Meg switching), and error 56 on the Channel B relay test (Relay G,
x1, x10 switching).

Racal part numbers 23-7529 and 23-7528.

Can anyone help (if you have a dead 1991/1992 perhaps)?

Based in UK.

David, please allow one question: Did You connect the SDT OUTPUT to the
right inputs for the test (to A for SF 77, to B for SF 78)?

Achim

 

[David C. Partridge]

I understand why you ask, and yes, I did connect the reference out to input
A for test 77 and input B for test 78. I used a piece of coax 90cm in
length.

Dave
"Achim Metzen" <Achim.Metzen@nospam.de> wrote in message
news:e11cag$mni$1@newsreader3.netcologne.de...

David C. Partridge schrieb:

David, please allow one question: Did You connect the SDT OUTPUT to the
right inputs for the test (to A for SF 77, to B for SF 78)?

Achim

 

[Achim Metzen]

Did You try helpdesk@racalinstruments.com? I found them very helpfull
some years ago. But I'm not sure, if they are still alive...
I ordered some parts from racalinst Germany, which took a lot of time.
The parts itself were not very expensive, but they had a minimum order
of 25 or 50¤. UK was a lot easier, but I was foced to order in Germany...

Achim

 

[David C. Partridge]

It's not the Channel A 50 Ohm/1M relay whatever SF77 tells me. All the
channel A relays are switching and doing what they should when driven with
the front panel controls.

Unfortunately, the manual doesn't say exactly what SF77 actually does -
clearly it is more than just exercise the relays. What is notable is that
the only relays that appear to be switching are the 50Ohm and x10 relays,
but the other relays that are supposed to be switching in this test mode
(DC, FILTER and COM A) do not appear to be being driven.

The STD out is 3.5Vpp with the baseline sat at 0V (i.e. varying DC, not
strictly AC). Will count with 1M input / AC coupling

Switching in 50 Ohm termination drops this to about 1.3V pp and will still
count.

Switching to DC coupling - stops counting.

Switching back to 1M termination - will count again but somewhat
erratically.

SF78 for channel B doesn't seem to be doing much in terms of driving relays,
though the front panel controls DO seem to work to actuate the channel B
relays???

Dave

"Achim Metzen" <Achim.Metzen@nospam.de> wrote in message
news:e12kst$cin$1@newsreader3.netcologne.de...

Did You try helpdesk@racalinstruments.com? I found them very helpfull some
years ago. But I'm not sure, if they are still alive...
I ordered some parts from racalinst Germany, which took a lot of time. The
parts itself were not very expensive, but they had a minimum order of 25
or 50¤. UK was a lot easier, but I was foced to order in Germany...

Achim

 

[David C. Partridge]

I've been doing some further checking - definitely something is sick around
the A/B amp or the DAC (TEC) on the H2 hybrid.

Here's what I see:

SF76 (trigger DAC exerciser) gives sawtooth between 0 and -10V on channel A
trigger level output, and pretty close to 0V on channel B trigger level
output. It should be a sawtooth between +5.1 and -5.1V on both.

DC trigger levels:

For channel A using TRIG Level control for +5 seems to be at -9.3V, and
for -5V drifting between -8.8V and -9.3V (where it eventually settles).

For channel B voltage does change but not very far from 0V (small number of
mV).

D.

 

DaveC wrote:

Not that there's anything wrong with Flukes, inherently, but I like having
choices.

Are there other brands that are considered as good quality as Fluke?

Thanks,
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

a used Fluke might be as good qaulity as a Fluke!

just kidding. I don't know the answer.

I bought a cheapy ($30) Right Tech 2323552 or something like that from
Marvac.com cause it had min max and i wanted to test auto sensors. Then
i found out that it didn't have min max AND average the way fluke had
it setup. Even worse min max was manual and limited to voltage!!!
Absuloute junk!. Well, a fluke is about 300 dollars or so. Now i have a
junk fluke wannabe so my inevitable Fluke is now gonna cost 30 dollars
more (to include my cheap shortcut).
Paying for more is worth it only when you pay for the best. The best is
always priceless.
The only problem is that all of us have paid for the best and have only
gotten the bwerst.

Please tell us what your research finds! Although i have given up and
am saving money for that fluke 80 series already. Still doesn't hurt to
imagine that someone out there would be willing to give more than they
take like is prevalent with all these freeware software folks on the
net.

 

[jclause]

In article <0001HW.C05AB65500439BB9F04075B0@news.readfreenews.net>,
me@privacy.net says...

Are there other brands that are considered as good quality as Fluke?

Thanks,
--
DaveC

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


We use a lot of meters here. The following might be of interest,
where we checked them out a few months back on low AC voltage..

meter reading

Fluke 8600A 1.500 volts bench type maybe 10 years old
Fluke 189 1.4975 about 1 year old
Fluke 83 III 1.497 new
" 1.497 new
" 1.497 new
HP 8060A 1.497 about 5 years old
HP 8060A 1.499 "
HP 3465A 1.497 bench type about 10 years old
Simpson 360A 1.499 bench type about 25 years old
Triplett 9015A 1.498 2 years old
Triplett 9015A 1.501 "
Valhalla 2101 1.500 6 months old. This measures power,
current, and voltage.

Of the above, only the Simpson 360A and the Fluke 8600A have been
recalibrated since leaving the factory.

jc the elder

 

[Achim Metzen]

David C. Partridge schrieb:

I've been doing some further checking - definitely something is sick around
the A/B amp or the DAC (TEC) on the H2 hybrid.

Here's what I see:

SF76 (trigger DAC exerciser) gives sawtooth between 0 and -10V on channel A
trigger level output, and pretty close to 0V on channel B trigger level
output. It should be a sawtooth between +5.1 and -5.1V on both.

Checked: both are here at +5 and -5 sawtooth.

DC trigger levels:

For channel A using TRIG Level control for +5 seems to be at -9.3V, and
for -5V drifting between -8.8V and -9.3V (where it eventually settles).

For channel B voltage does change but not very far from 0V (small number of
mV).

D.

Strange...

some ideas:
check D.A.C +-11.2V (7,8 against 3,11)
Check Powerless Resistance of D.A.C. 1,2 against ground... Check
C84,C14,C108 (short?)
What about IC25?

Achim

 

[David C. Partridge]

+/-11.2V rails are good.
DAC pins 1 and 2 are 1.55M to ground.
Caps are good.
IC25 seems alive at least as far as putting a logic clip on it is concerned.

I think that I've got a sick H2 hybrid here. I'd like to think it was
something else of course, as no doubt this is either unobtainable or very
expensive.

D.

"Achim Metzen" <Achim.Metzen@nospam.de> wrote in message
news:e1532o$kqe$1@newsreader3.netcologne.de...

Strange...

some ideas:
check D.A.C +-11.2V (7,8 against 3,11)
Check Powerless Resistance of D.A.C. 1,2 against ground... Check
C84,C14,C108 (short?)
What about IC25?

Achim

 

[Rich Grise]

On Wed, 05 Apr 2006 12:59:59 +0000, TJS wrote:

I'm a little skeptical that this is the problem, but it is true that 2
months ago we pulled floor tiles to look for fiber conduits and that about
the time the problems began

Well, skeptical is good, but usually when troubleshooting, the first
question is, "What changed?"

This is a no-brainer. Start looking through your contract with the floor
installer, to see if you can have him eat the cost of replacing the killer
tile.

Good Luck!
Rich

 

[Rich Grise]

On Thu, 06 Apr 2006 08:05:33 +1000, Franc Zabkar wrote:

On Wed, 05 Apr 2006 12:59:59 GMT, "TJS" <anon@anon.net> put finger to
keyboard and composed:

An update; We are investigating "zinc whiskers" phenomina as a possible
cause. The zinc filaments are produced from the plywood core floor panels
supported by the zinc electrocoted support structure. When floor panels are
lifted or disturbed the conductive dust can get into the power supply and
lead to shorts between the modern closely spaced SMT devices.
See here for a white paper http://www.dataclean.com/pdf/zincwhiskers3.pdf

The failures/arcs in our supplies have all arced from the 120vac chopper
regulator collector to the PS case. If the zinc whisker problem is our case
then the blue flash is just a 120/170p-p vac arc to ground, and not a static
discharge.

We are looking at replacing our floor tiles with the modern ultra low static
floor tiles.

I'm a little skeptical that this is the problem, but it is true that 2
months ago we pulled floor tiles to look for fiber conduits and that about
the time the problems began

TJS

What are the chances of zinc whiskers causing *exactly* the same fault
in *8* PSUs?

Pretty good, considering that the tiles are the only thing that changed.

I probably wouldn't say, "zinc whiskers", but I'm pretty sure that, except
for galvanizing garbage cans, zinc is AWFUL! It gets all over everything.
I once worked at a place where they had to scrap a $100,000.00 (or so)
Ultra-High-Vacuum bell jar because someone had installed brass connectors -
the zinc outgassed, and contaminated the whole thing.

Maybe you could leach the zinc out of your tile by washing it down with
muriatic acid. ;-) [1]

I've also seen an installation where a bunch of boxes running off 277V
lighting power started arcing, and the only conductive thing in the room
was the dust from the desert setting, which could very well have been
conductive - it was only about 100 miles from Great Salt Lake. We fixed
it by putting furnace filters on top of all of the boxes, which the idiot
designer had put all of the intake air vents on the top of. =:-O

It was a pretty sweet TDY[2], though - $1000.00/week plus per diem plus
expenses plus airplane ticket plus car rental. ;-)

Good Luck!
Rich
[1] That's a joke, by the way. If you do use muriatic acid on zinc, be
sure that you're in a very very well-ventilated place, because it makes
hydrogen gas. But then, you could use the zinc chloride for sunscreen;
just mix it with yogurt. ;-)
[2] Temporary DutY

 

[Rich Grise, but drunk]

On Thu, 06 Apr 2006 16:42:35 +1000, Franc Zabkar wrote:

On Wed, 5 Apr 2006 22:05:11 -0400, "T" <anon@anon.org> put finger to
keyboard and composed:

I'm skeptical about zinc whiskers and the white paper does come from a
cleaning service company, enough said. But still it is a consideration

I wonder why the arc jumps a 1" gap between the chopper and the
chassis. Why not the much smaller (?) gap on the underside of the PCB?

- Franc Zabkar

Poltergeists.

Cheers!
Rich
--
-----BEGIN GEEK CODE BLOCK-----
Version: 3.1
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PE Y+ PGP- t 5+++)-; X- R- tv+ b+ DI++++>+ D-? G e+$ h+ r-- z+
------END GEEK CODE BLOCK------

 

[Robert Baer]

DAMN!
I was really hoping that you had springs on sale.

 

[Alan Holmes]

"Denise" <kdsprod@comcast.net> wrote in message
news:1145047042_8719@sp6iad.superfeed.net...

Get up to 50% Off our Ultimate Protein Plus Weight Loss Program now
through the end of April.

And what price are the springs?

Alan

 

[Michael A. Terrell]

Robert Baer wrote:

DAMN!
I was really hoping that you had springs on sale.

I can give you a great deal on trampoline springs, I've got hundreds
of the things hiding in my garage and shop. I already took several sets
of legs to the recycling center, but more springs just keep showing up,
week after week.

Anyone want to make it REALLY hard to push their gas pedal to the
floor? ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida