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Sci.Electronics.Basics -> troubleshooting method for micro-controller board ?
There are 103 messages in this thread.
You are currently looking at messages 40 to 60.
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Author: EeyoreDate: 19:28 07-11-07
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Jamie wrote:
> I have an idea for you.
> get your self a low voltage auto tail light lamp.
> use it in place of the fuse that blows. start disconnecting
> things until the lamp glows dim or not at all.
> this will allow you to keep the circuit on, you can then
> track down some heat traces which won't be much..
> actually, you'll be able to do a volt tracking using that
> method..
> You might have some logic issues that is causing current
> to exist only when the circuit is fired up.
Good Lord. You made a suggestion that's slightly sensible !
Lightbulbs do make practical current limiters when selected appropriately.
In this case an auto 12V lightbulb will be no good however, the volts involved
won't even barely make it warm. I'd initially suggest a 1.5V or 3V type. Then it
may serve some purpose.
Graham
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Author: JamieDate: 20:54 07-11-07
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Eeyore wrote:
>
> Jamie wrote:
>
>
>>I have an idea for you.
>> get your self a low voltage auto tail light lamp.
>>use it in place of the fuse that blows. start disconnecting
>>things until the lamp glows dim or not at all.
>> this will allow you to keep the circuit on, you can then
>>track down some heat traces which won't be much..
>>actually, you'll be able to do a volt tracking using that
>>method..
>> You might have some logic issues that is causing current
>>to exist only when the circuit is fired up.
>
>
> Good Lord. You made a suggestion that's slightly sensible !
>
> Lightbulbs do make practical current limiters when selected appropriately.
>
> In this case an auto 12V lightbulb will be no good however, the volts involved
> won't even barely make it warm. I'd initially suggest a 1.5V or 3V type. Then it
> may serve some purpose.
>
> Graham
>
Jesus..
If only I could really direct that in proper context to you with out
offending some one else here.
If you really knew how to debug things (something I learned from
those that really knew what they were doing at age 13), the incandescent
lamp has always been the choice of current regulators in debugging and
in practical use of circuits.
And in his case, 3 volt lamp is to low of voltage. come on , you can
do better than that!..
You must have one that is at least rated to the voltage set you are
connecting it into.. In this case, 5 VOLTS.. and that means a common
12 is fine for current testing. 6 volt at the smallest.
Please come back later when you have something that is worth
absorbing. I may even thank you, although I doubt it.
As you pointed out indirectly or directly before, I can be just as
rood an obnoxious as you can!
--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
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Author: EeyoreDate: 21:15 07-11-07
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Jamie wrote:
> Eeyore wrote:
> > Jamie wrote
> >
> >>I have an idea for you.
> >> get your self a low voltage auto tail light lamp.
> >>use it in place of the fuse that blows. start disconnecting
> >>things until the lamp glows dim or not at all.
> >> this will allow you to keep the circuit on, you can then
> >>track down some heat traces which won't be much..
> >>actually, you'll be able to do a volt tracking using that
> >>method..
> >> You might have some logic issues that is causing current
> >>to exist only when the circuit is fired up.
> >
> >
> > Good Lord. You made a suggestion that's slightly sensible !
> >
> > Lightbulbs do make practical current limiters when selected appropriately.
> >
> > In this case an auto 12V lightbulb will be no good however, the volts involved
> > won't even barely make it warm. I'd initially suggest a 1.5V or 3V type. Then
it
> > may serve some purpose.
> >
> > Graham
> >
> Jesus..
> If only I could really direct that in proper context to you with out
> offending some one else here.
>
> If you really knew how to debug things (something I learned from
> those that really knew what they were doing at age 13), the incandescent
> lamp has always been the choice of current regulators in debugging and
> in practical use of circuits.
> And in his case, 3 volt lamp is to low of voltage. come on , you can
> do better than that!..
> You must have one that is at least rated to the voltage set you are
> connecting it into.. In this case, 5 VOLTS.. and that means a common
> 12 is fine for current testing. 6 volt at the smallest.
>
> Please come back later when you have something that is worth
> absorbing. I may even thank you, although I doubt it.
>
> As you pointed out indirectly or directly before, I can be just as
> rood an obnoxious as you can!
YOU'RE A FUCKING IDIOT.
DON'T UPSET THE OP'S ATTEMPS TO FIX HIS PROBLEM WITH YOUR USELESS SHIITY IDEAS.
Graham
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Author: James SweetDate: 21:58 07-11-07
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"robb" <some@where.on.net> wrote in message
news:13j4jd6l49bht92@corp.supernews.com...
>
> "Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
> message news:473243FC.6DF1C352@hotmail.com...
>> tonym924@gmail.com wrote:
>>
>> > "robb" <s...@where.on.net> wrote:
>> > >
>> > > no shorts on any of the power regulator chips 5v L387 or
> the L298s
>> > >
>> > > and still get 76 ohm continuity between 5v an 0v ref.
>> >
>> > Ummm, what's wrong with that? I = E/R: 66mA. This
>> > (static) current isn't blowing the fuse.
>>
>> Yes.
>>
>> I thought it was a SHORT ! Not 76 ohms ! Looks like there may
> be hope yet.
>>
>> Graham
>>
>
> apologies graham and anyone else who thpught i knew what i was
> saying :{
>
> well i did say i was an amateur, i guess everyone forgot to ask
> me if i plugged it in :}
>
> ok, well i thought any thing less than couple of 100K Ohms was
> bad news ( rather a short )
>
> i said short because my meter (fluke 177) has continuity setting
> that measures anything less than 250 Ohms as having continuity
> (beep) and i thought this was a bad thing between high/low that
> is 5v and 0v rails
>
> so does this new light change my tactics any ?
>
> maybe all are to upset with my mis-use of "short" ?
>
>
> still in need of help,
> robb
>
>
It depends on the type of IC's, but a couple hundred ohms is not uncommon
for a fully functional circuit. "Shorted" implies near zero ohms, maybe 1 or
2 ohms of resistance in the traces and connectors leading into the thing.
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Author: JamieDate: 23:01 07-11-07
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Eeyore wrote:
>
> Jamie wrote:
>
>
>>Eeyore wrote:
>>
>>>Jamie wrote
>>>
>>>
>>>>I have an idea for you.
>>>> get your self a low voltage auto tail light lamp.
>>>>use it in place of the fuse that blows. start disconnecting
>>>>things until the lamp glows dim or not at all.
>>>> this will allow you to keep the circuit on, you can then
>>>>track down some heat traces which won't be much..
>>>>actually, you'll be able to do a volt tracking using that
>>>>method..
>>>> You might have some logic issues that is causing current
>>>>to exist only when the circuit is fired up.
>>>
>>>
>>>Good Lord. You made a suggestion that's slightly sensible !
>>>
>>>Lightbulbs do make practical current limiters when selected appropriately.
>>>
>>>In this case an auto 12V lightbulb will be no good however, the volts
involved
>>>won't even barely make it warm. I'd initially suggest a 1.5V or 3V type.
Then it
>>>may serve some purpose.
>>>
>>>Graham
>>>
>>
>>Jesus..
>> If only I could really direct that in proper context to you with out
>>offending some one else here.
>>
>> If you really knew how to debug things (something I learned from
>>those that really knew what they were doing at age 13), the incandescent
>>lamp has always been the choice of current regulators in debugging and
>>in practical use of circuits.
>> And in his case, 3 volt lamp is to low of voltage. come on , you can
>>do better than that!..
>> You must have one that is at least rated to the voltage set you are
>>connecting it into.. In this case, 5 VOLTS.. and that means a common
>>12 is fine for current testing. 6 volt at the smallest.
>>
>> Please come back later when you have something that is worth
>>absorbing. I may even thank you, although I doubt it.
>>
>> As you pointed out indirectly or directly before, I can be just as
>>rood an obnoxious as you can!
>
>
> YOU'RE A FUCKING IDIOT.
>
> DON'T UPSET THE OP'S ATTEMPS TO FIX HIS PROBLEM WITH YOUR USELESS SHIITY IDEAS.
>
> Graham
>
Useless? I bet it's adding to your education,
arm chair bull shit artist.
It's you that seems to have problems.
As you once posted and I replied.
Eeyore = "Think"
Jamie = "Practice what you post"
If you don't live by your own rules, then what gives you
the right to push such rules onto others?
You must be a real party animal. I bet you sit back
there by your self and do nothing but find fault in every
one and everything. And i'm sure you let any one that will
listen to you know about it.
Does that sound about right?
--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
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On Nov 7, 3:47 pm, "robb" <s...@where.on.net> wrote:
> <francesco.messi...@gmail.com> wrote in message
>
> news:1194465281.003352.4480@d55g2000hsg.googlegroups.com...
>
> > On 7 Nov, 20:40, "robb" <s...@where.on.net> wrote:
> > ...
>
> > As someone else pointed out, 73 ohms at 5V means a static draw
> of 5/73
> > = (about) 68 mA, which for a digital circuit sounds reasonable
> imho.
> > It is definitely not a short. What's the fuse rating on the 5V
> rail?
>
> the fuse was a "T 630 mA 250v" so slow blow bussman type fuse
>
> originally the 5v fuse blew i checked transformer out put then
> replaced and powered and then all three fuses blew the 5v 12v 30v
>
> maybe i need to take a closer look at the power regulators again
Yeah - I was thinking that the fuses were on the DC rails, but reading
your original post again you state that they are between the
transformer and rectifiers. But you also said that there were two
rectifiers (on 8 [or 12]V, and on 32 [or 30]V). What about the 5V
rectifier? And did you check those
bridges for shorted diodes? That continuity wouldn't necessarily show
up downstream (especially with the fuses blown).
TM
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Author: robbDate: 01:04 08-11-07
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"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote
in message news:KqsYi.131$5R7.3@newsfe02.lga...
> robb wrote:
>
> I have an idea for you.
> get your self a low voltage auto tail light lamp.
> use it in place of the fuse that blows. start disconnecting
> things until the lamp glows dim or not at all.
> this will allow you to keep the circuit on, you can then
> track down some heat traces which won't be much..
> actually, you'll be able to do a volt tracking using that
> method..
> You might have some logic issues that is causing current
> to exist only when the circuit is fired up.
>
ok Jamie i tried this idea with a few compromises and tangents
I only had 110 v bulbs and lattern light bulbs (~ 6V) so i used
my lattern lightbulb and the lattern battery (showing 5.2 Volts)
as my power source
no components or tracks were wam enough to discern a change
after several applications of power with increasing time ....
so i inserted the milliAmp meter (the DMM) and that showed ~160
mA with the 6V bulb in series and note the bulb was not shinning
as bright as it could.
so i removed the bulb and i get ~428 mA without the bulb and the
only thing that gets noticeably warm (*but* no more than prior to
the ZAP) is the 8051 procesor
this same result occurs no matter where along the 5V rail i
apply/inject the 5V ....
so i am not sure what this means, maybe good news ??
thanks for any help,
robb
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Author: robbDate: 01:22 08-11-07
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"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
message news:473243FC.6DF1C352@hotmail.com...
>
>
> tonym924@gmail.com wrote:
>
> > "robb" <s...@where.on.net> wrote:
> > >
> > > no shorts on any of the power regulator chips 5v L387 or
the L298s
> > >
> > > and still get 76 ohm continuity between 5v an 0v ref.
> >
> > Ummm, what's wrong with that? I = E/R: 66mA. This
> > (static) current isn't blowing the fuse.
>
> Yes.
>
> I thought it was a SHORT ! Not 76 ohms ! Looks like there may
be hope yet.
>
well i tried the light bulb load ( using a 6v lantern flashlight
bulb) and using a lattern battery as power source.
i could not find anything warmed and the DMM milliAmp meter shows
~ 138 mA
i get ~438 mA when i disconnect the light bulb ???
and the 8051 IC is the only thing that is warmed but no nore than
it warmed before the 32v rail mixing with the 5v
i do not know what this means , hopefully something good
robb
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Author: James SweetDate: 02:50 08-11-07
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"robb" <some@where.on.net> wrote in message
news:13j5ap2fmnfvb96@corp.supernews.com...
>
> "Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
> message news:473243FC.6DF1C352@hotmail.com...
>>
>>
>> tonym924@gmail.com wrote:
>>
>> > "robb" <s...@where.on.net> wrote:
>> > >
>> > > no shorts on any of the power regulator chips 5v L387 or
> the L298s
>> > >
>> > > and still get 76 ohm continuity between 5v an 0v ref.
>> >
>> > Ummm, what's wrong with that? I = E/R: 66mA. This
>> > (static) current isn't blowing the fuse.
>>
>> Yes.
>>
>> I thought it was a SHORT ! Not 76 ohms ! Looks like there may
> be hope yet.
>>
>
> well i tried the light bulb load ( using a 6v lantern flashlight
> bulb) and using a lattern battery as power source.
> i could not find anything warmed and the DMM milliAmp meter shows
> ~ 138 mA
>
> i get ~438 mA when i disconnect the light bulb ???
>
> and the 8051 IC is the only thing that is warmed but no nore than
> it warmed before the 32v rail mixing with the 5v
>
> i do not know what this means , hopefully something good
> robb
>
The 8051 was getting warm? I didn't think those produced enough heat to
feel?
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Author: Arfa DailyDate: 04:49 08-11-07
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"robb" <some@where.on.net> wrote in message
news:13j59meqnhgrkb6@corp.supernews.com...
>
> "Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote
> in message news:KqsYi.131$5R7.3@newsfe02.lga...
>> robb wrote:
>>
>> I have an idea for you.
>> get your self a low voltage auto tail light lamp.
>> use it in place of the fuse that blows. start disconnecting
>> things until the lamp glows dim or not at all.
>> this will allow you to keep the circuit on, you can then
>> track down some heat traces which won't be much..
>> actually, you'll be able to do a volt tracking using that
>> method..
>> You might have some logic issues that is causing current
>> to exist only when the circuit is fired up.
>>
>
> ok Jamie i tried this idea with a few compromises and tangents
>
> I only had 110 v bulbs and lattern light bulbs (~ 6V) so i used
> my lattern lightbulb and the lattern battery (showing 5.2 Volts)
> as my power source
>
> no components or tracks were wam enough to discern a change
> after several applications of power with increasing time ....
>
> so i inserted the milliAmp meter (the DMM) and that showed ~160
> mA with the 6V bulb in series and note the bulb was not shinning
> as bright as it could.
>
> so i removed the bulb and i get ~428 mA without the bulb and the
> only thing that gets noticeably warm (*but* no more than prior to
> the ZAP) is the 8051 procesor
>
> this same result occurs no matter where along the 5V rail i
> apply/inject the 5V ....
>
> so i am not sure what this means, maybe good news ??
>
> thanks for any help,
> robb
>
Well, I would have to say that it certainly indicates that you are not
chasing down any kind of permanent 'short' on your 5v rail. So now that you
know where the 5v rail comes off the end of the LM317 (was it ?), can you
disconnect it from that point, leave the fuses out of the 12 and 30v feeds,
and hook the unit back to line power, with a 5v fuse in place ? Measure the
IN, SET and OUT pins of the '317 to see what you get, and if you get a
correct 5v on the OUT pin, then hook it back to the rail that you
disconnected, which is then just the same as hooking your battery to it. I
would expect all to be well, and you to get exactly the same result as with
your battery.
Once you've established that the 5v is ok, take it's fuse back out, figure
where the 12v rail is regulated, and disconnect it in the same way. With a
fuse in the 12v feed, apply line power, and measure the regulator pins. This
may be another '317 set for 12v, or might be a 7812. If you have 12v
correctly on the output of the regulator, then connect it back up and see
what happens. If it stays ok, then put the fuse back in the 5v, and measure
both rails. Repeat it again for the 30v rail, which probably isn't
regulated. You will have to locate it's smoothing cap, find the piece of
print that carries the 30v away from this point, and into the board's
circuitry (clue : I wouldn't expect this rail to go anywhere other than to
the driver chips that you mentioned previously), and either find a link on
it that can be removed, or put a scalpel through it. Once it has been thus
disconnected, apply power with the 5 and 12v fuses removed, and measure the
30v at its smoothing cap. If it's there ok, refit the 12v fuse, and check
both rails again. If ok, fit 5v fuse and check all three rails.
Now assuming that you really do have a problem, at some point this test
procedure will go off the rails, and that's the point that we need to know
to be able to offer any *proper* fault-finding advice. How far had you got
when everything was proceeding to plan? What happened then ... ?
Finding faults on electronic equipment is something of an 'art', much like
any other trade or skill, but it is based on firm principles, and these
*must* follow a logical sequence (no pun intended - well, maybe a bit ;-} )
If you take time to stop and think about what the problem *is*, not what you
*think* it is, then a logical test sequence will usually suggest itself to
you. If you then follow that sequence religiously, and whilst you are still
learning, write down the results, it should guide you slowly and surely to
an end result, as your tests suggest dead ends and new branches. With
experience, that part of the procedure goes on in your head.
So just take a minute to STOP and then THINK. Try the sequence that I
suggested, and then STOP again, and EVALUATE what you have found. Good
luck with it d;~}
Arfa
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Author: EeyoreDate: 06:35 08-11-07
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robb wrote:
> well i tried the light bulb load ( using a 6v lantern flashlight
> bulb) and using a lattern battery as power source.
Lucky that 6V is *just* acceptable.
> i could not find anything warmed and the DMM milliAmp meter shows
> ~ 138 mA
>
> i get ~438 mA when i disconnect the light bulb ???
You mean when you apply the battery directly to the 5V line ?
> and the 8051 IC is the only thing that is warmed but no nore than
> it warmed before the 32v rail mixing with the 5v
>
> i do not know what this means , hopefully something good
> robb
It means that the power consumption looks to be in the normal range.
Replace the 5V regulator (with a known good working one or test the one you have
but best a new one) and power the board up on AC (but with the power peripherals
unpowered - remove the fuse suppling power to those parts).
Graham
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Author: EeyoreDate: 06:37 08-11-07
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James Sweet wrote:
> The 8051 was getting warm? I didn't think those produced enough heat to
> feel?
I seem to recall that the NMOS versions (which he has) draw a little over 100mA.
Graham
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Author: robbDate: 09:18 08-11-07
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"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
message news:4732F4E0.89AF864A@hotmail.com...
>
>
> James Sweet wrote:
>
> > The 8051 was getting warm? I didn't think those produced
enough heat to
> > feel?
>
> I seem to recall that the NMOS versions (which he has) draw a
little over 100mA.
>
> Graham
>
>
the datasheet says 125 mA dissipates 1W
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Author: EeyoreDate: 09:48 08-11-07
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robb wrote:
> "Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote
> > James Sweet wrote:
> >
> > > The 8051 was getting warm? I didn't think those produced
> > > enough heat to feel?
> >
> > I seem to recall that the NMOS versions (which he has) draw a
> > little over 100mA.
>
>
> the datasheet says 125 mA dissipates 1W
125 mA sounds about right. That's 625mW not 1W though. The datasheet value for
dissipation is almost certainly the maximum theoretical allowed value.
Graham
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On Nov 8, 4:49 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
> Well, I would have to say that it certainly indicates that you are not
> chasing down any kind of permanent 'short' on your 5v rail. So now that you
> know where the 5v rail comes off the end of the LM317 (was it ?), can you
> disconnect it from that point, leave the fuses out of the 12 and 30v feeds,
> and hook the unit back to line power, with a 5v fuse in place ? Measure the
> IN, SET and OUT pins of the '317 to see what you get, and if you get a
> correct 5v on the OUT pin[...]
If the voltage isn't correct (e.g. 4.8-5.2V) at that point (but the
fuse isn't
blown) tack a 470 ohm resistor from the OUT pin to GND. The LM317
has
a load regulation spec of 10 mA, and a minimum operating current of
~1mA
(for low Vi-Vo); the adjust resistors may not be small enough to draw
this
much. And don't isolate the regulator by lifting the OUT pin, or
you'll lose
the adjust resistors.
TM
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Author: robbDate: 11:18 08-11-07
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"Eeyore" <rabbitsfriendsandrelations@hotmail.com> wrote in
message news:4732F496.F552D50E@hotmail.com...
>
>
> robb wrote:
>
> > well i tried the light bulb load ( using a 6v lantern
flashlight
> > bulb) and using a lattern battery as power source.
>
> Lucky that 6V is *just* acceptable.
>
:)
hi Graham, now i have learned a wee bit
I pre-checked battery it was slightly drained and only showing
5.2 volts but still lighting the bulb ok so i thought that was
close enough otherwise i would have found something as close to
5V as i could or even put a 5V regulator on a bread board
>
>
> > i could not find anything warmed and the DMM milliAmp meter
shows
> > ~ 138 mA
> >
> > i get ~438 mA when i disconnect the light bulb ???
>
> You mean when you apply the battery directly to the 5V line ?
>
yes, that is more precise statement , i connected battery
directly to 5V line
to be clear about what i did do
First Test
- i connected the negative battery terminal of battery to the PCB
0v rail
- i connected the positive battery terminal to bulb lead (bulb in
series)
- i connected DMM mA meter (in series) connect red lead to the
free bulb connection
- i connected the other free DMM lead of the DMM to the 5V rail
of PCB
that completed the circuit
||====================(138 mA)================.||
||=(5v)PCB(0v)==(-)Battery(+)==()Bulb()==(+)DMM mA(-)=||
No heating noticed
Second Test
i removed the bulb from the circuit (essentially bypas te bulb
and that gave a ~438 mA reading on the DMM mA meter
noticed that the IC-CPU 8051 was a little warm and no other
components or traces seemed to be seemed to be warming
>
> > and the 8051 IC is the only thing that is warmed but no nore
than
> > it warmed before the 32v rail mixing with the 5v
> >
> > i do not know what this means , hopefully something good
> > robb
>
> It means that the power consumption looks to be in the normal
range.
>
> Replace the 5V regulator (with a known good working one or test
the one you have
> but best a new one) and power the board up on AC (but with the
power peripherals
> unpowered - remove the fuse suppling power to those parts).
>
that is what i will do next , as it seems the 30 volt or 16 v out
of rectifiers is what feeds the 5v regulator so i will need to do
something about that
thanks again for all your time and help,
robb
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Author: EeyoreDate: 11:24 08-11-07
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tonym924@gmail.com wrote:
> On Nov 8, 4:49 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
> > Well, I would have to say that it certainly indicates that you are not
> > chasing down any kind of permanent 'short' on your 5v rail. So now that you
> > know where the 5v rail comes off the end of the LM317 (was it ?), can you
> > disconnect it from that point, leave the fuses out of the 12 and 30v feeds,
> > and hook the unit back to line power, with a 5v fuse in place ? Measure the
> > IN, SET and OUT pins of the '317 to see what you get, and if you get a
> > correct 5v on the OUT pin[...]
>
> If the voltage isn't correct (e.g. 4.8-5.2V) at that point (but the
> fuse isn't blown) tack a 470 ohm resistor from the OUT pin to GND. The LM317
> has a load regulation spec of 10 mA, and a minimum operating current of
> ~1mA (for low Vi-Vo); the adjust resistors may not be small enough to draw
> this much. And don't isolate the regulator by lifting the OUT pin, or
> you'll lose the adjust resistors.
It's not an LM317 though, it's some funny STM part, an L387.
Graham
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Author: robbDate: 11:27 08-11-07
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"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:UYAYi.19410$6v.13525@newsfe2-gui.ntli.net...
>
> "robb" <some@where.on.net> wrote in message
> news:13j59meqnhgrkb6@corp.supernews.com...
> >
> > "Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net>
wrote
> > in message news:KqsYi.131$5R7.3@newsfe02.lga...
> >> robb wrote:
> >>
> >> I have an idea for you.
> >> get your self a low voltage auto tail light lamp.
> >> use it in place of the fuse that blows. start disconnecting
> >> things until the lamp glows dim or not at all.
> >> this will allow you to keep the circuit on, you can then
> >> track down some heat traces which won't be much..
> >> actually, you'll be able to do a volt tracking using that
> >> method..
> >> You might have some logic issues that is causing current
> >> to exist only when the circuit is fired up.
> >>
> >
> > ok Jamie i tried this idea with a few compromises and
tangents
> >
> > I only had 110 v bulbs and lattern light bulbs (~ 6V) so i
used
> > my lattern lightbulb and the lattern battery (showing 5.2
Volts)
> > as my power source
> >
> > no components or tracks were wam enough to discern a change
> > after several applications of power with increasing time
....
> >
> > so i inserted the milliAmp meter (the DMM) and that showed
~160
> > mA with the 6V bulb in series and note the bulb was not
shinning
> > as bright as it could.
> >
> > so i removed the bulb and i get ~428 mA without the bulb and
the
> > only thing that gets noticeably warm (*but* no more than
prior to
> > the ZAP) is the 8051 procesor
> >
> > this same result occurs no matter where along the 5V rail i
> > apply/inject the 5V ....
> >
> > so i am not sure what this means, maybe good news ??
> >
> > thanks for any help,
> > robb
> >
> Well, I would have to say that it certainly indicates that you
are not
> chasing down any kind of permanent 'short' on your 5v rail. So
now that you
> know where the 5v rail comes off the end of the LM317 (was it
?), can you
> disconnect it from that point, leave the fuses out of the 12
and 30v feeds,
> and hook the unit back to line power, with a 5v fuse in place ?
Measure the
> IN, SET and OUT pins of the '317 to see what you get, and if
you get a
> correct 5v on the OUT pin, then hook it back to the rail that
you
> disconnected, which is then just the same as hooking your
battery to it. I
> would expect all to be well, and you to get exactly the same
result as with
> your battery.
>
> Once you've established that the 5v is ok, take it's fuse back
out, figure
> where the 12v rail is regulated, and disconnect it in the same
way. With a
> fuse in the 12v feed, apply line power, and measure the
regulator pins. This
> may be another '317 set for 12v, or might be a 7812. If you
have 12v
> correctly on the output of the regulator, then connect it back
up and see
> what happens. If it stays ok, then put the fuse back in the 5v,
and measure
> both rails. Repeat it again for the 30v rail, which probably
isn't
> regulated. You will have to locate it's smoothing cap, find the
piece of
> print that carries the 30v away from this point, and into the
board's
> circuitry (clue : I wouldn't expect this rail to go anywhere
other than to
> the driver chips that you mentioned previously), and either
find a link on
> it that can be removed, or put a scalpel through it. Once it
has been thus
> disconnected, apply power with the 5 and 12v fuses removed, and
measure the
> 30v at its smoothing cap. If it's there ok, refit the 12v fuse,
and check
> both rails again. If ok, fit 5v fuse and check all three rails.
>
> Now assuming that you really do have a problem, at some point
this test
> procedure will go off the rails, and that's the point that we
need to know
> to be able to offer any *proper* fault-finding advice. How far
had you got
> when everything was proceeding to plan? What happened then ...
?
>
> Finding faults on electronic equipment is something of an
'art', much like
> any other trade or skill, but it is based on firm principles,
and these
> *must* follow a logical sequence (no pun intended - well, maybe
a bit ;-} )
> If you take time to stop and think about what the problem *is*,
not what you
> *think* it is, then a logical test sequence will usually
suggest itself to
> you. If you then follow that sequence religiously, and whilst
you are still
> learning, write down the results, it should guide you slowly
and surely to
> an end result, as your tests suggest dead ends and new
branches. With
> experience, that part of the procedure goes on in your head.
>
> So just take a minute to STOP and then THINK. Try the sequence
that I
> suggested, and then STOP again, and EVALUATE what you have
found. Good
> luck with it d;~}
>
> Arfa
>
>
Wow Arfa thanks for all the great advice and feedback.
it will take me several reply posts to address all your
information
the 5v regulator used is the L387 as it turns out it is powered
by a feed from the 30 or 16 volt line which is my latest attempt
to track. so i need to fnd if there is away to disconnect the 30v
and 16 v feeds to other parts of the board to try your tests.
still need to create a print out of the board as all this
tracking is driving me bannanas
thanks again for your ideas and help i will try and incorporate
what i can nad see what results i can achieve ,
thanks,
robb
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Author: ian fieldDate: 11:46 08-11-07
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"robb" <some@where.on.net> wrote in message
news:13iv5djrkhk1u04@corp.supernews.com...
>i have a micro-controller board with 3 big 40DIP ICs, 10 or so 16
> DIP support ICs. with 32v/8v/5v transformer supply that connects
> to two bridge rectifiers {32v, 8v}a fuse links sit between
> transformer and rectifiers, no schematic.
>
> i believe the 32v shorted with 5V line and it blew one fuse
> link. the fuse link was replaced with same and when powered all
> three fuses blown.
>
> So....where does one start to diagnose such a *big* problem ?
>
>
> .
> Only thing working is transformer outputs and it seems like i get
> continuity hits everywhere i check
> the board was built about 1985 (no SMT) it is about 14" x 5" has
> 3 x 40 DIP ICs and 10 or so 16 DIP support ICs, handful of
> transistors many resistors,diodes etc,
>
> ideas and help would be greatly appreciated :)
> robb
>
>
Its phutted!
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Author: Arfa DailyDate: 12:50 08-11-07
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<tonym924@gmail.com> wrote in message
news:1194538067.753943.90950@e9g2000prf.googlegroups.com...
> On Nov 8, 4:49 am, "Arfa Daily" <arfa.da...@ntlworld.com> wrote:
>> Well, I would have to say that it certainly indicates that you are not
>> chasing down any kind of permanent 'short' on your 5v rail. So now that
>> you
>> know where the 5v rail comes off the end of the LM317 (was it ?), can you
>> disconnect it from that point, leave the fuses out of the 12 and 30v
>> feeds,
>> and hook the unit back to line power, with a 5v fuse in place ? Measure
>> the
>> IN, SET and OUT pins of the '317 to see what you get, and if you get a
>> correct 5v on the OUT pin[...]
>
> If the voltage isn't correct (e.g. 4.8-5.2V) at that point (but the
> fuse isn't
> blown) tack a 470 ohm resistor from the OUT pin to GND. The LM317
> has
> a load regulation spec of 10 mA, and a minimum operating current of
> ~1mA
> (for low Vi-Vo); the adjust resistors may not be small enough to draw
> this
> much. And don't isolate the regulator by lifting the OUT pin, or
> you'll lose
> the adjust resistors.
>
> TM
>
Yes, good advice. Looking again, it seems it is an L387 regulator. I'll have
to look that one up. It's so hard to cover all bases with someone who's at
the 'practice' level. Things like making sure that the V-set resistors are
still connected, is second nature when you do this sort of stuff all the
time ...
Arfa
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