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B&K E-200D signal generator - no signal
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Asimov
electronics forum Guru


Joined: 24 Mar 2005
Posts: 322

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: B&K E-200D signal generator - no signal Reply with quote

"Mike" bravely wrote to "All" (23 Mar 05 21:48:49)
--- on the heady topic of "Re: B&K E-200D signal generator - no signal"

Mi> From: Mike <blahblahblah@blahblahblah.com>
Mi> Xref: aeinews sci.electronics.repair:43944

Mi> I have checked the power supply and the voltage levels (10v, 9v) are
Mi> okay - a scope on the 10v line looks clean to me, the 9v line seems to
Mi> have a little ripple. Could that cause the freq drift in adjusting the
Mi> Fine Attenuator knob? I checked the rf level and the attenuator is
Mi> doing its job of adding attenuation, it just that it also moves the
Mi> signal around a little as you change it. The only other thing that
Mi> looks fishy to me are some of the voltages associated with the Q3
Mi> modulator (which I replaced). The base according to the schematic
Mi> should be 2V, I am getting 3.6v. The emitter should be 1.3, I am
Mi> getting 2.86. The collector looks okay at 8.6v (schem shows 8.Cool.

Clearly too much input biasing voltage so something must overdriving
the transistor. Keep looking upstream of the base for a leaky coupling
electro or something else such as a resistor gone off-value high.

A*s*i*m*o*v

.... I worked hard to attach the electrodes to it.
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Mark D. Zacharias
electronics forum Guru


Joined: 23 Apr 2005
Posts: 423

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Pioneer VSX-D503S repaired Reply with quote

The first thing I would look for in this situation is bad solder
connections, at the speaker terminals, and maybe at the output IC and
protection relay. Also the relay could be cutting out, though this is less
common on receivers of this type.
Most Pioneer models of recent (the last 15 years or so) have little to no
direct access to the main board - even just to look at it will require a
major disassembly.


Mark Z.


"iamnathanhudson" <iamnathanhudson@protected> wrote in message
news:452491def371e3fb985da993868bd46c@localhost.talkaboutelectronicequipment.com...
Quote:
i have my front right channel going bad.....it distorts and barely gets any
signal.....but then last night it worked fine........now today it won't
work......i know it is the front right because i hooked my left speaker to
it and it isn't the speaker it is the output........is there anyway you
could take a picture or something to show me some of the things to look
out....i have it here sitting open so knowing the more important things to
look at and kind of where they are would help greatly. thanks
-Nate
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JW
electronics forum Guru Wannabe


Joined: 05 May 2005
Posts: 119

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Need help with possibly defective Fluke 9010a, or pod. Anyone help/repair? Reply with quote

On Wed, 02 Feb 2005 04:48:01 GMT "James Sweet" <jamessweet@hotmail.com>
wrote in Message id: <5YYLd.2200$uc.1120@trnddc09>:

Quote:


At 4.8 volts you may want to see what's going on there with the power
supply, have you looked at the +5 with a scope?



Pac boards use an onboard linear regulator, it's a fairly common trouble
spot, first thing to do is resolder everything suspect in that area, get
very close to 5v and go from there. It's surprising how intolerant some TTL
chips are to low or high supply voltage.

I hadn't realized that with regards to the linear regulator. Could very
well be some failing electrolytic caps, causing a lot of ripple in the +5
rail. That would certainly explain a low reading if he were using a DMM
instead of a scope.
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Art
electronics forum Guru


Joined: 03 May 2005
Posts: 331

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Sony KV-25XBR no picture Reply with quote

May we therefore presume that you have checked all the operational voltages
at the tuner and confirmed that they are all there?? If so then the
recommendations of resoldering the probable cracked connections is a viable
suggestion.
"JURB6006" <jurb6006@aol.com> wrote in message
news:20050202012821.13716.00000243@mb-m23.aol.com...
Quote:
Excuse me? I'm a senior tech

Sorry about that, but I couldn't assume anything due to the general nature
of
your question.

Actually now that I think about it, the KV-25XBR only has the tuner box.
Later
Sonys had an IF box too, and it was a source of considerable trouble.
Always
had to solder the pins of the coils. When it gets really bad you might
even
have normal snow off channel, but completely black, or white video when a
signal is present. (beat frequency of VCO and carrier swamps composite
video
buffers)

The KV-25XBR had the IFs on the one main board. (left side from the back I
think). It is under a shield, but you only need to resolder (maybe), and
the
foil side of the board is right there. It is the same thing, resolder the
coils
that tune the AFT and VCO, and hit the audio one while you're in there.

You might have a different problem if you don't have normal snow when off
channel or no input. Also I do know where to get parts for those things. I
actually have a signal board complete, but the donor has no picture so I
don't
know it's good.

I also have the print for a KPR-4110 which shares the same chipset, and
damnear
the layout too, if I can find it I can scan the IF and video switching
sections
and email them.

All I can say about that set is before taking drastic measures, like
getting a
print etc., is to solder, solder and then solder somemore. Component
failures
have been really rare in my realm on these sets.

Dave, you could be a better tech. than me, sans experience on that family
of
Sonys. I meant no disrespect, but I can't assume anything. These are
excellent
sets and well worth saving. I think soldering has a 90% chance of working.

If not post back here.

JURB
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John Bachman
electronics forum beginner


Joined: 01 May 2005
Posts: 31

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: What is your favorite small tester? Reply with quote

On Wed, 2 Feb 2005 07:40:01 GMT, ato_zee@hotmail.com wrote:

Quote:

On 2-Feb-2005, et472@FreeNet.Carleton.CA (Michael Black) wrote:

For what I do (mostly reverse enginneering), I have one of those
continuity testers that are a couple AA batterie, a light bulb
(changed to LED), a probeand a wire with an alligator clip.

On the subject of reverse engineering. I can photocopy the copper
side of a board and photograph the component side. What I wan't is
a program that lets me superimpose, suitably scaled, one on top
of the other. So the plated through holes are roughly superimposed.
This might facilitate producing a wiring list/table. Being able to
vary the percent show through would be needed. Any known s/w
for this.

You can do that with any graphics program that has "layers" capability
such as Paint Shop Pro. They tend to be a bit pricey though.

John
AnaTek Corporation
The Electronic Repair Center at www.anatekcorp.com
Professional electronic service discussions at
www.anatekcorp.com/elrepair/elrepair.htm
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Guest






PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Anyone got Schematic for JVC AV 27 820 color tv? Reply with quote

I resoldered all the solder joints by the vertical output and it fixed
it. I was asking for the cap values from the schematic to buy them
before I opened the tv. I have run 2 tv repair shops so I had no prob
fixing it.

Thanks
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kip
electronics forum addict


Joined: 24 Mar 2005
Posts: 81

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Anyone got Schematic for JVC AV 27 820 color tv? Reply with quote

Yea Right
<topdogqqq@rock.com> wrote in message
news:1107346790.437950.32940@c13g2000cwb.googlegroups.com...
Quote:
I resoldered all the solder joints by the vertical output and it fixed
it. I was asking for the cap values from the schematic to buy them
before I opened the tv.
I have run 2 tv repair shops so I had no prob fixing it.

Thanks
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Gerard Bok
electronics forum addict


Joined: 04 May 2005
Posts: 88

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Best Data 56SX modem power supply voltage? Reply with quote

On Tue, 01 Feb 2005 16:32:52 -0600, James Jones
<junebug@yahoo.com> wrote:

Quote:
I have a Best Data "Smart One" 56SX V.90 external modem that I want to
give to a friend. However, I seem to have misplaced the "wall wart" and
there is no indication on the unit as to the voltage requirements. I
don't even know if it's AC or DC. Does anyone know what voltage this
thing needs?

Not for sure, but many modems require 12 volts AC.
So if you have such a wall wart lying around it is likely to
match the modem :-)

--
Kind regards,
Gerard Bok
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Bob Parker
electronics forum Guru Wannabe


Joined: 03 May 2005
Posts: 120

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: What is your favorite small tester? Reply with quote

electricitym@yahoo.com wrote:

Quote:
You do NOT NEED to accurately read an analog meter to perform basic
troubleshooting. When checking diodes, transistors and general
voltages all you are looking for is approximate meter swing. No need
to actually read a digitally presented number and figure out if it is
in an acceptable range. Of course the digital is best for accurate
settings and voltage measurements but for most troubleshooting an old
analog is quick and fast.
electricitym


I entirely agree. I still go for my Jemco 20K ohm/volt analog meter
I bought in 1973, over my Fluke DMM unless I'm doing some critical
adjusting. :)

Bob
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worldcitizen
electronics forum beginner


Joined: 22 Feb 2005
Posts: 25

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Panasonic Home Theater System sound keeps shutting off Reply with quote

CharlesWGreenJr@NetScape.Net wrote:
Quote:
I have a Panasonic SA-HT790V combination DVD/VCR/tuner/surround sound
with SB-WA312 "active subwoofer" unit. Recently the sound has begun
to
shut off during relatively louder passages. It is necessary to
either
plug in and remove headphones, or power-cycle the subwoofer unit, to
bring it back.

I suspect that the 5 channel amps are actually a part of this
"subwoofer" unit, as well. At first I wondered if overheating could
be
the culprit, but now I suspect the low-frequency vibration from the
subwoofer is tripping something in the unit.

Is anyone aware of an issue such as this with Panasonic gear? Any
suggestions on where to poke and prod?

Thanks!

-Charles Green
If I were you I'd check to see that the load on the output of your unit

is what it should be. It sounds like you may have put some speakers in
parallel or in some other way put too much load on your amp. Try
running your amp with just one left and one right speaker and see if
you still have the same problem. If the problem goes away then you
have a speaker load problem. It could be that your unit is doing
exactly what it should be doing in order to protect itself from too
much load. Good luck.
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lavinci
electronics forum beginner


Joined: 24 Mar 2005
Posts: 10

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Where can I buy a single Fairchild KA5S Power Switch? Reply with quote

we've in stock, contact me
low quantity if you need.
bye luca info@lavinci.it
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lavinci
electronics forum beginner


Joined: 24 Mar 2005
Posts: 10

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Where can I buy a single Fairchild KA5S Power Switch? Reply with quote

we've in stock. contact me for few pieces.
bye Luca info@lavinci.it
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Warren Post
electronics forum beginner


Joined: 24 Mar 2005
Posts: 1

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Determining TX frequency of cordless telephone - SOLVED Reply with quote

Thank you, Fred. The base unit now works fine with a simple TX whip
antenna made for 49.74 MHz. I´m not getting the 1 km range I need, but
externally mounting the base´s antennas up high ought to fix that.

--
Warren Post
Santa Rosa de Copán, Honduras
http://srcopan.vze.com/
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Fred McKenzie
electronics forum addict


Joined: 12 May 2005
Posts: 80

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Why do Fluke multimeter LCD displays fade? Any Fluke model immune? Reply with quote

tunesandballoons@yahoo.com (fancy nospam tunes) wrote:

Quote:
There are third-party Display Fade Kits for Fluke multimeters. Gives
me an impression, from used/for sale Flukes, that fading is an
inevitable outcome. Any opinion of the the fading/durability of the
Fluke 87, 111, 110, 112, or 81438 models? Are any Fluke multimeters
immune (or less-apt) from display fade?

I'm asking this because Fluke multimeters cost $300-$400 for the new
models replacing the 80 series.

Tunes-

My old Fluke 8020A display turned black within a couple of years. When I
obtained a replacement, I found that Fluke had changed to a newer display. The
replacement display has stayed clear for over 25 years now, and I haven't seen
the problem with other Flukes.

Fluke apparently solved their problem. However there is always the rare case
where the display loses its seal, possibly due to damage, and moisture from
atmospheric humidity causes it to blacken. If any brand is more immune to this
it would be Fluke.

Fred
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Fred Bloggs
electronics forum Guru


Joined: 25 Mar 2005
Posts: 2468

PostPosted: Thu Mar 24, 2005 3:15 pm    Post subject: Re: Sony CCD-FX620 microphone too sensitive. Reply with quote

"Mike" <mjb@posie.local.dom> wrote in message
news:cr8v0b$r4h$1@posie.local.dom...
Quote:
In article <20041227002021.21518.00002289@mb-m11.aol.com>,
David Farber <farberbear@aol.com> wrote:
a sensitive stethoscope. Each left and right mic contains two small mics
that
face each other.

The shield stuff is probably just foam to keep wind and dust out of the
mics. This won't make the mics more sensitive in the way you describe --
it's absence will make wind noise more objectionable. Try and find a
suitable foam replacement. Codge something together from a standard foam
mic-protector if necessary.

If your mics really are *each* made of 2 small mics facing each other,
that
is, 4 mics total ... it sounds like they are being used to do noise
cancellation or directional control of the sound (like a wide-tele zoom
setting). The original positioning and wiring of the mics would be
important. It is possible to create cardiod/hyper cardiod patterns by
sticking 2 capsules back to back and then "mixing" the resultant signal.

[If you've ever seen studio mics with the omni/fig 8/cardiod switches,
that's
one way they achieve it]

Did you wire the new capsules in *exactly* the same, and are you sure? The
wiring of the old ones may have been counter-intuitive, and you've
accidentally wired the new ones "intuitively", if you get me.

Did you get them in the right physical locations?

There are two ways to install the mic pairs. That would be either facing
toward each other or facing away from each other. I installed them facing
away from each other because it made more sense to have them facing the wind
screen where the sound would presumably be entering.

Quote:

Have you mixed and matched old capsules and new, or replaced wholesale?

Have you still got the old capsules?

The picture at the link below shows the new capsules and they are identical
to the old capsules.
Quote:

Any details on how the mics are wired (series, parallel, their own
separate


Each pair has its own four pin plug. The pc board wiring connects the two
mics in parallel. The net result is that you have two left mic's, two right
mic's, and each left/right pair in parallel.

Quote:
inputs etc.) ?

Mike.
--
--------------------------------------+-----------------------------------
-
Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/

The new mic's come prewired with connectors that match the PC board
connectors. Each microphone pair is in a metal casing which itself is
encased in a rubber fitting. Here is a link to the picture.
http://www.pbase.com/image/39324113/original

Thanks for your reply.
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Google

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