LCD display on exercize bike troubleshooting.
ste...@my-deja.com
any useful usenet search of this newsgroup history. Boy, do I miss
DejaNews! If someone knows of a usable search of
sci.electronics.repair please post it. The google one was pretty
terrible IMHO.
I have a "computer" on a Schwinn exercise bike that the monochrome LCD
is nearly blank. I can see that it is working, but the display is
very light. When I turn it on I can hear the friction control motor
in the bottom of the bike working. That system does seem to work, I
can increase the friction with the buttons on the computer. So
buttons work, display works a little, other functions work.
A single failure in the display circuitry. The problem is just the
display.
This runs on 4 C cell batteries, I did check the voltage on the
batteries and when I press the soft "start" button on the panel the
battery voltage diminishes from over 6V to less than 1V. Something is
dragging it down!
I unplugged the harness from the computer to the rest of the bike,
that didn't change anything. So the short is likely in the computer
related to the LCD display.
Do the driver chips for such a display fail shorted? That seems to be
what I have here.
It seems unlikely to me that this is actually repairable since the
large LCD display probably has integrated drivers in it's module. But
I haven't disassembled it yet.
Is there going to be a whole bunch of driver chips along the edge of
the LCD and something that runs those that has failed shorted?
What should I be looking into?
Meat Plow
If something is dragging the voltage at the batteries down 5 volts that's
going to consume a huge amount of current seeing it's almost a short
circuit. I doubt any of the internals would be able to sustain such a
current draw without making a little smoke. I'd check for a bad
connection within the battery cage itself. Maybe where the contacts are
riveted to a supporting structure. This makes more sense to me.
--
Live Fast, Die Young and Leave a Pretty Corpse
ste...@my-deja.com
<mhy...@yahoo.com> wrote:
>On Thu, 30 Dec 2010 08:48:48 -0800, Ste...@my-deja.com wrote:
>
>> Sorry if this type of problem has been discussed before, I didn't find
>> any useful usenet search of this newsgroup history. Boy, do I miss
>> DejaNews! If someone knows of a usable search of
>> sci.electronics.repair please post it. The google one was pretty
>> terrible IMHO.
>>
>> I have a "computer" on a Schwinn exercise bike that the monochrome LCD
>> is nearly blank. I can see that it is working, but the display is very
>> light. When I turn it on I can hear the friction control motor in the
>> bottom of the bike working. That system does seem to work, I can
>> increase the friction with the buttons on the computer. So buttons
>> work, display works a little, other functions work.
>>
>> A single failure in the display circuitry. The problem is just the
>> display.
>>
>> This runs on 4 C cell batteries, I did check the voltage on the
>> batteries and when I press the soft "start" button on the panel the
>> battery voltage diminishes from over 6V to less than 1V. Something is
>> dragging it down!
>>
>>
>> What should I be looking into?
>
>If something is dragging the voltage at the batteries down 5 volts that's
>going to consume a huge amount of current seeing it's almost a short
>circuit. I doubt any of the internals would be able to sustain such a
>current draw without making a little smoke. I'd check for a bad
>connection within the battery cage itself. Maybe where the contacts are
>riveted to a supporting structure. This makes more sense to me.
Yes, except for the problem didn't occur until I pressed the start
button on the panel. a soft button, btw. That kind of leaves out a
constant short from the battery box.
Ken
Check for a cap that is leaking in the display circuit. It should be
easy to determine, but might require one lead be lifted in order to do so.
Meat Plow
Didn't say a short. I said a poor (bad) connection. Learn the difference.
Charlie
"Ste...@my-deja.com" <ste...@my-deja.com> wrote in message
news:98dph6d0d3oquccn9...@4ax.com...
Before you get all tangled up, try a set of NEW batteries.
If you are testing with a digital meter you are putting essentially no load
on the batteries.
Where in the circuit did you access the voltage reading?
If the batteries are truly good, just probe along the connections from the
batteries to the display to find the high resistance culprit.
Charlie
D Yuniskis
> Sorry if this type of problem has been discussed before, I didn't find
> any useful usenet search of this newsgroup history. Boy, do I miss
> DejaNews! If someone knows of a usable search of
> sci.electronics.repair please post it. The google one was pretty
> terrible IMHO.
>
> I have a "computer" on a Schwinn exercise bike that the monochrome LCD
> is nearly blank. I can see that it is working, but the display is
> very light. When I turn it on I can hear the friction control motor
> in the bottom of the bike working. That system does seem to work, I
> can increase the friction with the buttons on the computer. So
> buttons work, display works a little, other functions work.
>
> A single failure in the display circuitry. The problem is just the
> display.
>
> This runs on 4 C cell batteries, I did check the voltage on the
> batteries and when I press the soft "start" button on the panel the
> battery voltage diminishes from over 6V to less than 1V. Something is
> dragging it down!
Are you looking at the batteries themselves? Or, someplace
else in the circuit? 4 cells won't drop to 1/4V each (on average)
unless they are *shorted* (otherwise, several would have
to be "completely flat" -- in which case, they wouldn't
read as 6V open circuited).
Are the battery terminals corroded?
Steevo
"Charlie" <le...@thestation.com> wrote in message
news:ifimmi$h80$1...@news.eternal-september.org...
>> Before you get all tangled up, try a set of NEW batteries.
> If you are testing with a digital meter you are putting essentially no
> load on the batteries.
> Where in the circuit did you access the voltage reading?
> If the batteries are truly good, just probe along the connections from the
> batteries to the display to find the high resistance culprit.
>
>
> Charlie
I did test at the battery contacts in circuit.
They are new batteries.
I could try some other new batteries but I suspect these batteries should
work.
That said I did plug in an ac adapter, 6v 2A, and it acts the same with or
without the batteries installed.
Steevo
"D Yuniskis" <not.goi...@seen.com> wrote in message
news:ifiogh$p0i$1...@speranza.aioe.org...
>> Are you looking at the batteries themselves? Or, someplace
> else in the circuit? 4 cells won't drop to 1/4V each (on average)
> unless they are *shorted* (otherwise, several would have
> to be "completely flat" -- in which case, they wouldn't
> read as 6V open circuited).
>
> Are the battery terminals corroded?
I checked the voltage at the ends of the set of 4 batteries as installed by
probing the ends of the batteries in circuit.
There is no corrosion. They are new alkaline batteries.
I haven't taken the whole thing apart to get a look at the PCB, the problem
may be evident when I get home and try that.
I liked the leaking cap suggestion from earlier. It could be something like
that.
Meat Plow
Can you insert a DC ammeter in series with the b+ line to the board and
report back as to the current draw?
ste...@my-deja.com
> Check for a cap that is leaking in the display circuit. It should be
>easy to determine, but might require one lead be lifted in order to do so.
I took the whole thing apart.
I found a broken ceramic disk capacitor. Actually broken. Near the
display area. I replaced it, it was a .1 mfd, same as it was.
That didn't help. Inspection didn't reveal anything else obvious.
While I had the LCD out I tried it on the board a little moved it
around. It has those rubber conductive connections. I did get bright
flashes on some parts of the display, the word "AGE" lit up brightly,
so the display works
Jim Yanik
news:98dph6d0d3oquccn9...@4ax.com:
> Sorry if this type of problem has been discussed before, I didn't find
> any useful usenet search of this newsgroup history. Boy, do I miss
> DejaNews! If someone knows of a usable search of
> sci.electronics.repair please post it. The google one was pretty
> terrible IMHO.
>
> I have a "computer" on a Schwinn exercise bike that the monochrome LCD
> is nearly blank. I can see that it is working, but the display is
> very light. When I turn it on I can hear the friction control motor
> in the bottom of the bike working. That system does seem to work, I
> can increase the friction with the buttons on the computer. So
> buttons work, display works a little, other functions work.
>
> A single failure in the display circuitry. The problem is just the
> display.
>
> This runs on 4 C cell batteries, I did check the voltage on the
> batteries and when I press the soft "start" button on the panel the
> battery voltage diminishes from over 6V to less than 1V. Something is
> dragging it down!
a new set of cells? This low V is why your LCD is dim.
>
> I unplugged the harness from the computer to the rest of the bike,
> that didn't change anything. So the short is likely in the computer
> related to the LCD display.
>
> Do the driver chips for such a display fail shorted? That seems to be
> what I have here.
If the display "works",but it's light,the drivers are probably OK.
It might be a bad Vcc regulator IC.
>
> It seems unlikely to me that this is actually repairable since the
> large LCD display probably has integrated drivers in it's module. But
> I haven't disassembled it yet.
>
> Is there going to be a whole bunch of driver chips along the edge of
> the LCD and something that runs those that has failed shorted?
>
> What should I be looking into?
>
>
perhaps bad electrolytic caps? they can be a common failure.
do you have an ESR tester,such as the ANATEK/Dick Smith model?
--
Jim Yanik
jyanik
at
localnet
dot com
Jim Yanik
news:oieqh6dm1e3tq4d8g...@4ax.com:
ah,perhaps you need new rubber connector strips.
where to get them,I don't know.
Maybe MCM,maybe the manufacturer of the exerciser.
D Yuniskis
So, it's drawing (considerably) *more* than 2A (in order to
drag the 6V supply down to 1V)? What exactly *is* it
drawing?
ste...@my-deja.com
wrote:
>It might be a bad Vcc regulator IC.
I don't see an obvious regulator IC, or anything that looks to be
power supply, really. This is a cheaply made chinese board, one ic
under a glob of epoxy connected directly to the LCD. Lots of diodes
and caps. No obvious stuff for making the LCD work, seems integrated
in the one ASIC.
>>
>> It seems unlikely to me that this is actually repairable since the
>> large LCD display probably has integrated drivers in it's module. But
>> I haven't disassembled it yet.
>>
>> Is there going to be a whole bunch of driver chips along the edge of
>> the LCD and something that runs those that has failed shorted?
>>
>> What should I be looking into?
>>
>>
>
>perhaps bad electrolytic caps? they can be a common failure.
>do you have an ESR tester,such as the ANATEK/Dick Smith model?
Only three electrolytic caps on the board. I tested them with an
EDS-88A cap tester. They seem OK.
So I dunno.
William Sommerwerck
> it around. It has those rubber conductive connections. I did
> get bright flashes on some parts of the display, the word
Let's apply Sherlock Holmes' rule about eliminating the obvious.
If the display flashes or briefly displays "something", the problem might be
the contacts.
Try carefully cleaning the contacts on the board. You might also try
cleaning the conductive-rubber contacts on the LCD, but this requires using
a lint-free swab, and "rolling" (rather than rubbing) the swab over the
contact surfaces. Be vewy, vewy kehful.
William Sommerwerck
Duh... I meant impossible.
Wild_Bill
majority of the current is being dissipated.
That may indicate the vicinity of the fault.
If you power the circuit on for 5-10 seconds (with good batteries or AC/DC
adapter) then power the circuit off (disconnect the AC/DC adapter), you may
be able to detect a heated component with your fingertips.
A longer power cycle may be needed, but avoiding excess on-time may be
beneficial.
I only mention this method for this low voltage, battery powered circuit,
because there is essentially zero chance of any electrical shock hazard with
the power turned off, after a brief power-on period.
Feeling around for warm components on any line powered equipment circuit
boards could very likely be hazardous, even with the power off, and should
not be done as a troubleshooting method.
There is a plastic sheet product that indicates thermal changes, but I don't
remember what it's called. The sheet is placed on a circuit board, and warm
areas change color.
If you know anyone with a thermal/Flir scanner-camera, it would likely show
a heated component on the board.
I doubt that an infrared sensitive surveillance-type video camera would be
sensitive enough to spot heated components with, but if you have access to
one, it may be worth a try, with the test area lighting turned off.
--
Cheers,
WB
.............
"Ste...@my-deja.com" <ste...@my-deja.com> wrote in message
news:98dph6d0d3oquccn9...@4ax.com...