Toshiba TV29C90 problem; Image fades to black...

[bz]

"Mark D. Zacharias" <mzacharias@nonsense.net> wrote in
news:xMDRj.860$To6.269@newssvr21.news.prodigy.net:

Gateway does not even support out-of warranty repair. No factory service
- nothing. If you call them they'll tell you to try to find some local
service. Of course they don't sell parts or service literature, so
"local service" is virtually impossible. These companies should be put
out of business for these practices.

We need for more states or the feds to pass laws such as
[quote from http://www.hdtvmagazine.com/forum/viewtopic.php?t=8655]

CALIFORNIA CODES
CIVIL CODE
SECTION 1792-1795.7
http://www.aroundthecapitol.com/code/getcode.html?file=./civ/01001-02000/17
92-1795.7

1792.1. Every sale of consumer goods that are sold at retail in this
state by a manufacturer who has reason to know at the time of the
retail sale that the goods are required for a particular purpose and
that the buyer is relying on the manufacturer's skill or judgment to
select or furnish suitable goods shall be accompanied by such
manufacturer's implied warranty of fitness.

Products less than $100

1793.03. (a) Every manufacturer making an express warranty with
respect to an electronic or appliance product described in subdivision
(h), (i), (j), or (k) of Section 9801 of the Business and Professions
Code, with a wholesale price to the retailer of not less than fifty
dollars ($50) and not more than ninety-nine dollars and ninety-nine
cents ($99.99), shall make available to service and repair facilities
sufficient service literature and functional parts to effect the
repair of a product for at least three years after the date a product
model or type was manufactured, regardless of whether the three-year
period exceeds the warranty period for the product.

Products over $100

(b) Every manufacturer making an express warranty with respect to an
electronic or appliance product described in subdivision (h), (i),
(j), or (k) of Section 9801 of the Business and Professions Code, with
a wholesale price to the retailer of one hundred dollars ($100) or
more, shall make available to service and repair facilities sufficient
service literature and functional parts to effect the repair of a
product for at least seven years after the date a product model or
type was manufactured, regardless of whether the seven-year period
exceeds the warranty period for the product
[end quote]

Talk to your legislators.





--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+spr@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[Bob F]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message news:TQARj.75480

If it's not a silly question, with the motor in question being offered "on the
web, really cheap", then if it's e-bay, why not use the 'ask the seller a
question' option, or if it's a reseller, use his on-site 'contact us' facility
? Then there would be no debate about typos and exotic voltage issues ...

Because it's long gone.

 

[Bob F]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message news:TQARj.75480

If it's not a silly question, with the motor in question being offered "on the
web, really cheap", then if it's e-bay, why not use the 'ask the seller a
question' option, or if it's a reseller, use his on-site 'contact us' facility
? Then there would be no debate about typos and exotic voltage issues ...

Because it's long gone.

 

[James Sweet]

"Wiebe Cazemier" <wiebe@halfgaar.net> wrote in message
news:ba068$481710b4$d4cc82be$30426@cache1.tilbu1.nb.home.nl...

I tried the tapping a bit more, and now the red gun also has this
problem... I
didn't tap that hard I think (from the description "not enough to break
it,
but close" I would think I need to tap a lot harder).

Now my question is: are those cathodes/filaments so fragile that I could
have
damaged them, or is it possible I dislodged dirt which now also affects
the
red gun?

The filaments were cold BTW, when I tried this. I suppose warm filaments
are
more easily damaged.

They could be that fragile, it depends, obviously one of them was fragile
enough to short in the first place. Now that you have two guns with issues,
there's no sense trying to isolate the heater because the guns would just
short to each other.

 

[James Sweet]

"Wiebe Cazemier" <wiebe@halfgaar.net> wrote in message
news:ba068$481710b4$d4cc82be$30426@cache1.tilbu1.nb.home.nl...

I tried the tapping a bit more, and now the red gun also has this
problem... I
didn't tap that hard I think (from the description "not enough to break
it,
but close" I would think I need to tap a lot harder).

Now my question is: are those cathodes/filaments so fragile that I could
have
damaged them, or is it possible I dislodged dirt which now also affects
the
red gun?

The filaments were cold BTW, when I tried this. I suppose warm filaments
are
more easily damaged.

They could be that fragile, it depends, obviously one of them was fragile
enough to short in the first place. Now that you have two guns with issues,
there's no sense trying to isolate the heater because the guns would just
short to each other.

 

[Dave Plowman (News)]

In article
<2480277e-daed-40ee-86bf-8b2757d1a2b1@l42g2000hsc.googlegroups.com>,
KC <kohemp@hotmail.com> wrote:

I began a dialog with the local NBC station engineer. Here's his
opinion of the problem:

"Part of the problem (foundational) is that SMPTE (creates standards
for television) chose not to include a method to synchronize video and
audio packets in the new digital standards in order to leave more
bandwidth available to improve quality.

I'm not in the US but I'll bet that's bollocks. Such constraints will be
to pack the maximum number of channels into a given bandwidth thinking the
punters won't notice or care.

--
*"I am " is reportedly the shortest sentence in the English language. *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Dave Plowman (News)]

In article
<2480277e-daed-40ee-86bf-8b2757d1a2b1@l42g2000hsc.googlegroups.com>,
KC <kohemp@hotmail.com> wrote:

I began a dialog with the local NBC station engineer. Here's his
opinion of the problem:

"Part of the problem (foundational) is that SMPTE (creates standards
for television) chose not to include a method to synchronize video and
audio packets in the new digital standards in order to leave more
bandwidth available to improve quality.

I'm not in the US but I'll bet that's bollocks. Such constraints will be
to pack the maximum number of channels into a given bandwidth thinking the
punters won't notice or care.

--
*"I am " is reportedly the shortest sentence in the English language. *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

In alt.engineering.electrical JANA <jana@nospamca.inter.net> wrote:

| If you are in North America, and have 120 VAC to the outlets, what you
| call 220 or 230 VAC in your home is actually 208 VAC, unless you
| installed some kind of transformer to compensate.

That's only true if the source transformer is a three phase WYE/star type.
If you have center tapped delta three phase, or single phase Edison split,
then you have genuine 240 volts (although with that delta you may also have
a third wire that is 208 volts relative to ground/neutral).


| I somehow think that the vendor of the motor made an error. Having 280
| VAC sounds to me very unconventional, unless this was some kind of
| special installation.

It may be a reference to working on 277 volts, which is an available voltage
in some large commercial/industrial locations.

--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

In alt.engineering.electrical JANA <jana@nospamca.inter.net> wrote:

| If you are in North America, and have 120 VAC to the outlets, what you
| call 220 or 230 VAC in your home is actually 208 VAC, unless you
| installed some kind of transformer to compensate.

That's only true if the source transformer is a three phase WYE/star type.
If you have center tapped delta three phase, or single phase Edison split,
then you have genuine 240 volts (although with that delta you may also have
a third wire that is 208 volts relative to ground/neutral).


| I somehow think that the vendor of the motor made an error. Having 280
| VAC sounds to me very unconventional, unless this was some kind of
| special installation.

It may be a reference to working on 277 volts, which is an available voltage
in some large commercial/industrial locations.

--
|WARNING: Due to extreme spam, I no longer see any articles originating from |
| Google Groups. If you want your postings to be seen by more readers |
| you will need to find a different place to post on Usenet. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |

 

[James Sweet]

"Wiebe Cazemier" <wiebe@halfgaar.net> wrote in message
news:5df16$481792d9$d4cc82be$14770@cache1.tilbu1.nb.home.nl...

On Tuesday 29 April 2008 22:57, Wiebe Cazemier wrote:

I can't be sure, but it seems the blue gun has become much less
sensitive,
and that the problem now is mainly is the red gun. Maybe it's wishful
thinking, because that would mean that it was some dislodged particle,
but
I'd rather not assume the worst yet, so...

Would anyone know if trinitron tubes have particularly fragile
heater/cathode
constructions?

The repair FAQ has a comment about having to tap the neck quite hard:
"not
enough to break it, but close". How fragile is the neck? It would be
difficult to describe how hard I could hit it without breaking it, but
any
advice is welcome.

I've got an additional question. When I put my continuity meter on the GND
and
R or B pin, I can't produce a short by any amount of tapping. A very brief
intermittant short should be very clear, because it has an audible beep.
Because I can only reproduce the fault when it's cold, having the heater
turned off would seem ideal.

What I want to do, is remove the neck board and do some more testing. Do I
need
to discharge the tube for this? I would guess not, but I thought I'd ask.

On Ground, or on one of the heater pins?

You might wanna just leave well enough alone and use the monitor the best
you can as it is.

 

[Martin Whybrow]

<Kotti75events@googlemail.com> wrote in message
news:097aae02-5230-459d-8a37-79da39984b01@m36g2000hse.googlegroups.com...

PS: it was the D1 diode that I replaced. It was broken (had burst) and
there's also a burn mark on the perf board. A near by wire was also
singed but I replaced that. I don't have many tools and am new at this
sort of thing, so any help is greatly welcomed!

On Apr 30, 12:41 am, Kotti75eve...@googlemail.com wrote:
I'm trying to repair this pedal for a friend. There appeared to be
only one burnt out component and I replaced it but it still doesn't
work. It did look like something was spilled inside the pedal and I've
cleaned that out. When in bypass, the signal passing through is
distorted and garbled, like hearing it on a faint radio station. But
when the pedal is engaged, it doesn't pass signal at all. I'm pretty
certain that this is a copy of the Boss TR-2 because the schematic
seems to fit with the exception of the IC
chips.http://www.schematicheaven.com/effects/boss_tr2_tremolo.pdf
Since the "bypass/engage mode" is triggered by a momentary switch, and
the dry signal goes down a very processed chain of components, I
haven't been able to figure it out. What typically goes bad when there
are spills? From looking at this schematic, how would I go about
figuring out where in the "dry signal" chain things are wrong?

Thank you very much!

Olivia

D1 is in the line for the external power supply, if it burned out then

there's a high probability that the wrong power supply was connected to it;
unless you really want the challenge of fixing it, I would recommend your
friend buy a new pedal as many components are liable to have been damaged.
Sorry to be so pessimistic!
Martin
--
martin<dot here>whybrow<at here>ntlworld<dot here>com

 

[DaveM]

stairs.
<Kotti75events@googlemail.com> wrote in message
news:2e4e0ced-4a24-453e-84d3-16e9e14b3142@d1g2000hsg.googlegroups.com...

I'm trying to repair this pedal for a friend. There appeared to be
only one burnt out component and I replaced it but it still doesn't
work. It did look like something was spilled inside the pedal and I've
cleaned that out. When in bypass, the signal passing through is
distorted and garbled, like hearing it on a faint radio station. But
when the pedal is engaged, it doesn't pass signal at all. I'm pretty
certain that this is a copy of the Boss TR-2 because the schematic
seems to fit with the exception of the IC chips.
http://www.schematicheaven.com/effects/boss_tr2_tremolo.pdf
Since the "bypass/engage mode" is triggered by a momentary switch, and
the dry signal goes down a very processed chain of components, I
haven't been able to figure it out. What typically goes bad when there
are spills? From looking at this schematic, how would I go about
figuring out where in the "dry signal" chain things are wrong?

Thank you very much!

Olivia

D1 is in the line from the external power adapter. It's only in the circuit if
the external adapter is in use. Since the 1N4004 has a PRV rating of 400V, it's
unlikely that its PRV was exceeded. More likely is that something downline from
D1 is shorted. Look at D4 and C9. If either of those are shorted, then the
external power adapter's output is shorted to ground, through D1, thereby
toasting its innards.
Since the +9V supply powers IC2, IC3 and IC4, it's possible that one or more of
those ICs might have failed, causing the short across the power supply.

Since you mentioned that something was spilled into the box, I'd look closely at
the switches and jacks. Even though you cleaned it out, you might not have
cleaned the gunk off the contacts of the switches and jacks. Go back to those
parts and really inspect the contacts carefully with a magnifier and make sure
they are operating room clean. Make sure that the contact leafs in the jack(s)
and switch(es) are moving freely and aren't sticking when a plug is inserted.

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

Some people are like Slinkies. Not really good for anything, but they bring a
smile to your face when pushed down the

 

[Arfa Daily]

"DaveM" <masondg4499@comcast99.net> wrote in message
news:1a6dnYDCq4K1WYrVnZ2dnUVZ_gadnZ2d@comcast.com...

stairs.
Kotti75events@googlemail.com> wrote in message
news:2e4e0ced-4a24-453e-84d3-16e9e14b3142@d1g2000hsg.googlegroups.com...
I'm trying to repair this pedal for a friend. There appeared to be
only one burnt out component and I replaced it but it still doesn't
work. It did look like something was spilled inside the pedal and I've
cleaned that out. When in bypass, the signal passing through is
distorted and garbled, like hearing it on a faint radio station. But
when the pedal is engaged, it doesn't pass signal at all. I'm pretty
certain that this is a copy of the Boss TR-2 because the schematic
seems to fit with the exception of the IC chips.
http://www.schematicheaven.com/effects/boss_tr2_tremolo.pdf
Since the "bypass/engage mode" is triggered by a momentary switch, and
the dry signal goes down a very processed chain of components, I
haven't been able to figure it out. What typically goes bad when there
are spills? From looking at this schematic, how would I go about
figuring out where in the "dry signal" chain things are wrong?

Thank you very much!

Olivia


D1 is in the line from the external power adapter. It's only in the
circuit if the external adapter is in use. Since the 1N4004 has a PRV
rating of 400V, it's unlikely that its PRV was exceeded. More likely is
that something downline from D1 is shorted. Look at D4 and C9. If either
of those are shorted, then the external power adapter's output is shorted
to ground, through D1, thereby toasting its innards.
Since the +9V supply powers IC2, IC3 and IC4, it's possible that one or
more of those ICs might have failed, causing the short across the power
supply.

Since you mentioned that something was spilled into the box, I'd look
closely at the switches and jacks. Even though you cleaned it out, you
might not have cleaned the gunk off the contacts of the switches and
jacks. Go back to those parts and really inspect the contacts carefully
with a magnifier and make sure they are operating room clean. Make sure
that the contact leafs in the jack(s) and switch(es) are moving freely and
aren't sticking when a plug is inserted.

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

Interestingly, Dave, it would appear to be a negative tip power supply that
it needs. Notice that the blown series protection diode, is bypassed when
the unit is on battery power only - presumably to avoid the forward drop of
that diode. So if anyone had tried to connect a power supply to the battery
connector instead - maybe one of those reversible universals with a PP3
connector on it, then protection would be via the shunt diode D4, which
would of course fail short circuit if enough current was available, and
which would then blow D1 next time power was applied correctly to the power
socket. (Reminds me a bit of that thread a few weeks ago about positive and
negative tips and shunt protection diodes ... ;-) )

I agree with you that the very first thing would be to check the contacts,
particularly the switch contacts on the input socket, as the 'ring' contact
is used to switch the battery / supply power, when a standard mono jack is
inserted into it. Beyond that, it might be getting a bit tough for a newbie,
depending on what experience level and test equipment is possessed. If this
landed on my bench, I would be immediately reaching for a current limited
power supply, my multimeter, a signal generator, and my 'scope probe ...

Arfa

 

[Gareth Magennis]

"DaveM" <masondg4499@comcast99.net> wrote in message
news:1a6dnYDCq4K1WYrVnZ2dnUVZ_gadnZ2d@comcast.com...

stairs.
Kotti75events@googlemail.com> wrote in message
news:2e4e0ced-4a24-453e-84d3-16e9e14b3142@d1g2000hsg.googlegroups.com...
I'm trying to repair this pedal for a friend. There appeared to be
only one burnt out component and I replaced it but it still doesn't
work. It did look like something was spilled inside the pedal and I've
cleaned that out. When in bypass, the signal passing through is
distorted and garbled, like hearing it on a faint radio station. But
when the pedal is engaged, it doesn't pass signal at all. I'm pretty
certain that this is a copy of the Boss TR-2 because the schematic
seems to fit with the exception of the IC chips.
http://www.schematicheaven.com/effects/boss_tr2_tremolo.pdf
Since the "bypass/engage mode" is triggered by a momentary switch, and
the dry signal goes down a very processed chain of components, I
haven't been able to figure it out. What typically goes bad when there
are spills? From looking at this schematic, how would I go about
figuring out where in the "dry signal" chain things are wrong?

Thank you very much!

Olivia


D1 is in the line from the external power adapter. It's only in the
circuit if the external adapter is in use. Since the 1N4004 has a PRV
rating of 400V, it's unlikely that its PRV was exceeded. More likely is
that something downline from D1 is shorted. Look at D4 and C9. If either
of those are shorted, then the external power adapter's output is shorted
to ground, through D1, thereby toasting its innards.
Since the +9V supply powers IC2, IC3 and IC4, it's possible that one or
more of those ICs might have failed, causing the short across the power
supply.

My diagnosis too. Its also possible that one of the IC's shorted out the
supply for a while before burning itself into an open circuit, so the power
supply may no longer be shorted, and replacing the diode has fixed it. The
only solution then is systematic replacement of the IC's. (Note that a
distorted signal is passed, probably wouldn't get this with no power supply
at all)

Use IC sockets when changing IC's, a good desoldered IC can be re-used
easily or moved around, and there is less overall heat damage risk to PCB
and IC's.

Its also possible that a shorted IC has burnt the power supply trace to it
into an open circuit instead - you often are able to see some discolouration
of the track concerned.

Since you mentioned that something was spilled into the box, I'd look
closely at the switches and jacks. Even though you cleaned it out, you
might not have cleaned the gunk off the contacts of the switches and
jacks. Go back to those parts and really inspect the contacts carefully
with a magnifier and make sure they are operating room clean. Make sure
that the contact leafs in the jack(s) and switch(es) are moving freely and
aren't sticking when a plug is inserted.

God advice, but it is also possible that this spillage happened a while ago
and has nothing to do with the current fault. It's easy to be misled by
things like this.



Gareth.

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

Some people are like Slinkies. Not really good for anything, but they
bring a smile to your face when pushed down the

 

[bz]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in news:qdWRj.17931$244.4187
@newsfe1-win.ntli.net:

I would be immediately reaching for a current limited
power supply, my multimeter, a signal generator, and my 'scope probe .

I have heard about being 'four armed' but it must be hard to find shirts!




--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[bz]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in news:qdWRj.17931$244.4187
@newsfe1-win.ntli.net:

I would be immediately reaching for a current limited
power supply, my multimeter, a signal generator, and my 'scope probe .

I have heard about being 'four armed' but it must be hard to find shirts!




--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[GregS]

In article <efbd930d-2a48-42f0-95a1-4e12bdea720c@k13g2000hse.googlegroups.com>, bud.iaauction@gmail.com wrote:

We have been operating in Michigan for about 30 years and have decided
to throw in the towel. Selling our entire inventory of Video, Pinball,
Jukebox; Coin sorting, vending, counting equipment. Many complete
cabinets and lots of parts, manuals, and test equipment. Some working
and in great condition, some non-working or need various repairs or
reconditioning. We also have many items related to Audio/Video, Tel-
Com, & Surveillance, up for bid.
Located in Central Lower Michigan, one day auction internet bidding
only. All items will be on display for personal & physical inspection
the day before and day of the auction. All items can be picked up the
day after and within 3 days following auction end.
All auction lots will be starting between $5 & $50 with no reserve.
The auction catalog is in process of being posted at this time and
should be completed by Friday or Monday at the latest. Here's a link
to the auction: http://www.1800lastbid.com/Redirect/Terms.cfm?ID=1001
, and you can also preview a few of the item photos by clicking on the
"more Info" link posted on the auction calendar.
Before asking, "NO", I will not sell any item outright, "all items
are up for auction ONLY" and I will not ship, all items must be picked
up by buyer or buyer's representative. Please feel free to contact me
directly at any time, for any other questions or concerns before the
auction or bidding. bud.iaauction@gmail.com or 989-239-4569.

Many have Google blocked.

greg

 

[Arfa Daily]

"bz" <bz+ser@ch100-5.chem.lsu.edu> wrote in message
news:Xns9A90518D623A8WQAHBGMXSZHVspammote@130.39.198.139...

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in news:qdWRj.17931$244.4187
@newsfe1-win.ntli.net:

I would be immediately reaching for a current limited
power supply, my multimeter, a signal generator, and my 'scope probe .

I have heard about being 'four armed' but it must be hard to find shirts!





--
bz 73 de N5BZ k

Then you sir, must not be self-employed !! It is completely necessary for
any self-employed person to have at least four arms, and an iron
constitution so as to never get ill. You must also have perfect eyesight for
looking at manufacturer's poor schematic prints and pdf's, and a degree in
accountancy and book-keeping. A degree in sociology is also helpful for
dealing with customers, and a modicum of deafness is desirable so that
endless manufacturer's phone-hold music, does not wear you down too much ...
d;~}

Arfa

 

[bz]

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in
news:jR7Sj.61$EH2.7@newsfe1-win.ntli.net:

"bz" <bz+ser@ch100-5.chem.lsu.edu> wrote in message
news:Xns9A90518D623A8WQAHBGMXSZHVspammote@130.39.198.139...
"Arfa Daily" <arfa.daily@ntlworld.com> wrote in
news:qdWRj.17931$244.4187 @newsfe1-win.ntli.net:

I would be immediately reaching for a current limited
power supply, my multimeter, a signal generator, and my 'scope probe .

I have heard about being 'four armed' but it must be hard to find
shirts!



Then you sir, must not be self-employed !!

Been there. Done that. Couldn't afford it as my soul[sic] means of support.

Now, I have a full time 'job', work part time in another industry, help my
wife do the same, help her with an on line store AND co-author books with
her in yet another field.

It is completely necessary
for any self-employed person to have at least four arms, and an iron
constitution so as to never get ill.

four-ti-tude!, and temper-ance

You must also have perfect eyesight
for looking at manufacturer's poor schematic prints and pdf's

Used to have fun fixing shipboard radio/radar equipment. Manual in
Japanese, crew from Norway.
Then there were the Greek ships with the boxes of 'used spare' tubes marked
65%, 75% .... etc.

, and a
degree in accountancy and book-keeping. A degree in sociology is also
helpful for dealing with customers, and a modicum of deafness is
desirable so that endless manufacturer's phone-hold music, does not wear
you down too much ... d;~}

And then there are the warranty claims.... getting billed for the parts by
the company and then getting the claim denied.

Oh, and don't forget the degree in law. You need it for small claims court
on the 'stop payment' checks.

Then there is licensing.




--
bz 73 de N5BZ k

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap

 

[Gareth Magennis]

<Kotti75events@googlemail.com> wrote in message
news:66ca1bd9-7b59-4db3-98a5-652fe475060d@k13g2000hse.googlegroups.com...

So, I was wrong when I said that D1 burnt out. This pedal compared to
the schematic, D1 doesn't exist and it was D4 that burned out. And D4
appeared to be a 1N4007 diode. I'm not sure how big if a difference
that makes for what was said. I did clean the contacts and nothing
changed. And here's where my ignorance will really start to show. My
VOM meter is as cheap as can be (Voltcraft VC-120,
http://www.ciao.de/Voltcraft_Digital_Multimeter_VC_120__2253015 Sorry
I can't find an english page on it). And I know you probably aren't
supposed to do this but I've been using the "diode" mode on it to
check for continuity within a circuit. It reads "1" if there's none
and some other random numbers when it appears there is continuity. So
to take this a step further, (and I'm guessing I could probably ruin
my VOM meter this way?) I check for continuity in this way by touching
the leads on C9 and yes there's continuity. I'm guessing that that
means it's bad?

That meter should be perfectly adequate for this application. Does it not
have a continuity check that buzzes or beeps? If not, use the Ohms range to
determine a short or near short circuit.

No it doesn't necessarily mean that C9 is bad, because there are many things
connected in parallel with C9, any one of which could be bad. Well actually
there is only D4 and the three IC's that are directly connected across C9,
so if you are reading a short or near short circuit, it should be easy to
establish which of these 5 components is the culprit.

Another thing is that I don't have a working 9v adapter so I've been
using a new 9v battery to test this. So if that portion of the circuit
with D4 and C9 is only engaged when the power supply is connected,
then C9 shouldn't be the problem if I'm using a battery. Is that
correct?

No, only D1 is not in circuit with the battery, everything else is.



Note that for it to work with the battery, you must insert a mono jack plug
into the input jack - this switches the battery in circuit so it doesn't run
down when the pedal is not in use. (like an automatic on/off switch) Do
not connect the battery until you are sure you have removed the short
circuit or you will drain the battery very quickly.

In fact, you had better measure the battery voltage with your meter, in case
your only problem is a flat battery.

So that brings me to the next possibly problem, the IC chips.
Is there a way to test IC chips to see if they're broken or not, or do
they just have to be replaced? If I remove one, using the info on the
data sheet:
http://zeta.octopart.com/Mitsubishi__M5218AL__0.pdf
is it possible to test whether it works or not?

No. These are standard Op-amp chips - the datasheet says 4558 is identical,
and these types are very cheap and very available.

There's also a second # on the IC chips under "M5218AL" which on IC2
and 3 is "747007" and on IC4 "750005". Are these #'s significant when
replacing the chips? I also noticed other manufactures make this chip
as well, or at least chips with the same name. Does it matter which
manufacturer I should get them from (are they that different)? I would
be nice to know how many I have to replace and buy them (order them)
all at once.

Just replace them with 4558 chips.

I really appreciate everyone's help and patience to help me since I'm
so new at this. I'm interested in learning electronics more and this
place seems really helpful.

One more question though, regarding my non working 9v AC power
adapters. They do "work" except that the output voltage is between
12-15V on each, not 9v. And I realize that this should drop when a
load is "attached" but when plugging it in to my guitar pedals, none
of the AC power adapters work with any of my guitar pedals. It is
possibly that all of them never worked (the wallwarts that is, I
bought them all at flea markets. Do they not work because the amps
that the pedals draws is low, forcing the voltage to be too high (the
wall warts support up to 500-600mA each)? It seems fishy that all of
them don't work. I've tried other circuits in my house too, no change.
And here's maybe a bad idea but can you put a secondary "load" on the
PSU to get the voltage to drop to 9V?

AC power adaptors are misnamed because they are mostly DC power adaptors,
i.e. they output DC. This means that the centre pin can be either negative
or positive, there is no fixed convention. Which means that if you plug a
positive pin power supply into a pedal which is meant to have a negative pin
power supply, you run the risk of burning out a diode and possibly one of
the 3 IC's and having to post on usenet for help in trying to fix it.
Do not just go around plugging every wall wart you have into every piece of
equipment you have as you will very soon have several dead pieces of
equipment, dead wall warts, or both. Which is quite possibly what you have
right now. Especially if the wall wart output is a higher voltage than the
equipment requires.

Some wall warts really are AC adaptors in that they output AC. Plug this
into all of your pieces of equipment you have lying around and you have
double the chance of burning out your equipment or wall wart, as they output
both positive and negative voltages at the same time.



Blimey.