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External
Since: Nov 18, 2008
Posts: 8
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(Msg. 1) Posted: Fri Jul 03, 2009 6:43 pm
Post subject: NEED HELP in South Jersey: monitor troubleshooting
Archived from groups: rec>games>video>arcade>collecting (more info?)
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Drop me a line if you can fix this (I will pay)
I have a 27" neotec 2701 monitor from a san francisco rush that is
dead. It makes a beeping sound and has no picture. I found the HOT
shorted so I replaced that and thought all would be well, but it is
still exhibiting the same problem. I have no schematics and am at the
end on my ability. I believe there is a problem somewhere in the B+
portion of the circuit. The flyback looks immaculate so I do not
suspect that. I pulled it back out and the HOT wasn't blown.
I am hoping there is an expert local to me that will contact me
(preferably this weekend). If I can't get it fixed fairly soon I am
just going to get a new monitor, but it is a shame to do that when it
is probably something small.
Jim (609 617 2177) |
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External
Since: Nov 18, 2008
Posts: 8
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(Msg. 2) Posted: Sat Jul 04, 2009 7:04 pm
Post subject: Re: NEED HELP in South Jersey: monitor troubleshooting [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On Jul 4, 6:02 pm, JD <None@*verizon.net> wrote:
> > Drop me a line if you can fix this (I will pay)
> > I have a 27" neotec 2701 monitor from a san francisco rush that is
> > dead. It makes a beeping sound and has no picture. I found the HOT
> > shorted so I replaced that and thought all would be well, but it is
> > still exhibiting the same problem. I have no schematics and am at the
> > end on my ability. I believe there is a problem somewhere in the B+
> > portion of the circuit. The flyback looks immaculate so I do not
> > suspect that. I pulled it back out and the HOT wasn't blown.
>
> Check the orange caps by the HOT, one of them
> usually shorts.
There are 3 possible caps there, c419, c420, and c421, but on my board
there is only 1, c421. It is not shorted. Where c420 goes there are
2 jumper wires that jumper the voltage to the pin cushion board. I
checked all the caps on that board and none are shorted.
I should have said before that I had checked all the electrolytic caps
up front. I replaced all the ones that I had spares for and
desoldered and checked the ones I didn't (my fluke has a cap scale on
it). I did find one of them open, c501. But swapping that out didn't
fix anything.
when I measure ohms from the HOT collector to ground I don't read
short anyway (like 6 meg). base to ground measures .5 ohms which does
seem low to me, but I am not sure what it should be.
not really sure what to do next. Any other suggestions?
thanks in advance |
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External
Since: Mar 31, 2008
Posts: 40
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(Msg. 3) Posted: Sat Jul 04, 2009 7:25 pm
Post subject: Re: NEED HELP in South Jersey: monitor troubleshooting [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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> Drop me a line if you can fix this (I will pay)
> I have a 27" neotec 2701 monitor from a san francisco rush that is
> dead. It makes a beeping sound and has no picture. I found the HOT
> shorted so I replaced that and thought all would be well, but it is
> still exhibiting the same problem. I have no schematics and am at the
> end on my ability. I believe there is a problem somewhere in the B+
> portion of the circuit. The flyback looks immaculate so I do not
> suspect that. I pulled it back out and the HOT wasn't blown.
Check the orange caps by the HOT, one of them
usually shorts. |
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External
Since: Jul 05, 2009
Posts: 18
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(Msg. 4) Posted: Sun Jul 05, 2009 3:04 pm
Post subject: Re: NEED HELP in South Jersey: monitor troubleshooting [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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james cardona wrote:
> Drop me a line if you can fix this (I will pay)
> I have a 27" neotec 2701 monitor from a san francisco rush that is
> dead. It makes a beeping sound and has no picture. I found the HOT
> shorted so I replaced that and thought all would be well, but it is
> still exhibiting the same problem. I have no schematics and am at the
> end on my ability. I believe there is a problem somewhere in the B+
> portion of the circuit. The flyback looks immaculate so I do not
> suspect that. I pulled it back out and the HOT wasn't blown.
>
> I am hoping there is an expert local to me that will contact me
> (preferably this weekend). If I can't get it fixed fairly soon I am
> just going to get a new monitor, but it is a shame to do that when it
> is probably something small.
>
> Jim (609 617 2177)
The sound you hear is the power supply starting up, detecting an
overload and shutting down, then repeating.
Pull the HOT and apply power, if you still get the chirping, which I'm
guessing you will, then you have a short elsewhere. Follow the trace
back from the collector of the HOT and check any diodes you come across
in that path. Often this sort of thing will be caused by a shorted diode
in the output side of the power supply. I'm not local to you but I'd be
happy to guide you through fixing this thing if you can do a bit of
troubleshooting and post the results. Even better than the money you
save is the education gained from the experience. It gets easier every time. |
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External
Since: Jul 05, 2009
Posts: 18
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(Msg. 5) Posted: Sun Jul 05, 2009 3:09 pm
Post subject: Re: NEED HELP in South Jersey: monitor troubleshooting [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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james cardona wrote:
> On Jul 4, 6:02 pm, JD <None@*verizon.net> wrote:
>>> Drop me a line if you can fix this (I will pay)
>>> I have a 27" neotec 2701 monitor from a san francisco rush that is
>>> dead. It makes a beeping sound and has no picture. I found the HOT
>>> shorted so I replaced that and thought all would be well, but it is
>>> still exhibiting the same problem. I have no schematics and am at the
>>> end on my ability. I believe there is a problem somewhere in the B+
>>> portion of the circuit. The flyback looks immaculate so I do not
>>> suspect that. I pulled it back out and the HOT wasn't blown.
>> Check the orange caps by the HOT, one of them
>> usually shorts.
>
> There are 3 possible caps there, c419, c420, and c421, but on my board
> there is only 1, c421. It is not shorted. Where c420 goes there are
> 2 jumper wires that jumper the voltage to the pin cushion board. I
> checked all the caps on that board and none are shorted.
>
> I should have said before that I had checked all the electrolytic caps
> up front. I replaced all the ones that I had spares for and
> desoldered and checked the ones I didn't (my fluke has a cap scale on
> it). I did find one of them open, c501. But swapping that out didn't
> fix anything.
>
> when I measure ohms from the HOT collector to ground I don't read
> short anyway (like 6 meg). base to ground measures .5 ohms which does
> seem low to me, but I am not sure what it should be.
>
> not really sure what to do next. Any other suggestions?
> thanks in advance
Base to ground will normally read low in circuit because you are
measuring across the secondary of the horizontal drive transformer,
which being a high frequency part will have a low impedance.
With the HOT removed, there is normally no load on the B+ supply. If the
supply has other outputs, an overload on one of them can cause the same
shutdown problem. Sometimes it helps to disconnect sections to isolate
the fault, sometimes this can be done easily by removing a component or
jumper, but occasionally I've had to resort to cutting a trace on the
PCB and then bridging it later. I try to avoid that though. |
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External
Since: Nov 18, 2008
Posts: 8
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(Msg. 6) Posted: Sun Jul 05, 2009 7:16 pm
Post subject: Re: NEED HELP in South Jersey: monitor troubleshooting [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On Jul 5, 6:09 pm, James Sweet <jamesrsw....RemoveThis@gmail.com> wrote:
> james cardona wrote:
> > On Jul 4, 6:02 pm, JD <None@*verizon.net> wrote:
> >>> Drop me a line if you can fix this (I will pay)
> >>> I have a 27" neotec 2701 monitor from a san francisco rush that is
> >>> dead. It makes a beeping sound and has no picture. I found the HOT
> >>> shorted so I replaced that and thought all would be well, but it is
> >>> still exhibiting the same problem. I have no schematics and am at the
> >>> end on my ability. I believe there is a problem somewhere in the B+
> >>> portion of the circuit. The flyback looks immaculate so I do not
> >>> suspect that. I pulled it back out and the HOT wasn't blown.
> >> Check the orange caps by the HOT, one of them
> >> usually shorts.
>
> > There are 3 possible caps there, c419, c420, and c421, but on my board
> > there is only 1, c421. It is not shorted. Where c420 goes there are
> > 2 jumper wires that jumper the voltage to the pin cushion board. I
> > checked all the caps on that board and none are shorted.
>
> > I should have said before that I had checked all the electrolytic caps
> > up front. I replaced all the ones that I had spares for and
> > desoldered and checked the ones I didn't (my fluke has a cap scale on
> > it). I did find one of them open, c501. But swapping that out didn't
> > fix anything.
>
> > when I measure ohms from the HOT collector to ground I don't read
> > short anyway (like 6 meg). base to ground measures .5 ohms which does
> > seem low to me, but I am not sure what it should be.
>
> > not really sure what to do next. Any other suggestions?
> > thanks in advance
>
> Base to ground will normally read low in circuit because you are
> measuring across the secondary of the horizontal drive transformer,
> which being a high frequency part will have a low impedance.
>
> With the HOT removed, there is normally no load on the B+ supply. If the
> supply has other outputs, an overload on one of them can cause the same
> shutdown problem. Sometimes it helps to disconnect sections to isolate
> the fault, sometimes this can be done easily by removing a component or
> jumper, but occasionally I've had to resort to cutting a trace on the
> PCB and then bridging it later. I try to avoid that though. |
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External
Since: Nov 18, 2008
Posts: 8
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(Msg. 7) Posted: Sun Jul 05, 2009 7:34 pm
Post subject: Re: NEED HELP in South Jersey: monitor troubleshooting [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On Jul 5, 6:09 pm, James Sweet <jamesrsw... DeleteThis @gmail.com> wrote:
> james cardona wrote:
> > On Jul 4, 6:02 pm, JD <None@*verizon.net> wrote:
> >>> Drop me a line if you can fix this (I will pay)
> >>> I have a 27" neotec 2701 monitor from a san francisco rush that is
> >>> dead. It makes a beeping sound and has no picture. I found the HOT
> >>> shorted so I replaced that and thought all would be well, but it is
> >>> still exhibiting the same problem. I have no schematics and am at the
> >>> end on my ability. I believe there is a problem somewhere in the B+
> >>> portion of the circuit. The flyback looks immaculate so I do not
> >>> suspect that. I pulled it back out and the HOT wasn't blown.
> >> Check the orange caps by the HOT, one of them
> >> usually shorts.
>
> > There are 3 possible caps there, c419, c420, and c421, but on my board
> > there is only 1, c421. It is not shorted. Where c420 goes there are
> > 2 jumper wires that jumper the voltage to the pin cushion board. I
> > checked all the caps on that board and none are shorted.
>
> > I should have said before that I had checked all the electrolytic caps
> > up front. I replaced all the ones that I had spares for and
> > desoldered and checked the ones I didn't (my fluke has a cap scale on
> > it). I did find one of them open, c501. But swapping that out didn't
> > fix anything.
>
> > when I measure ohms from the HOT collector to ground I don't read
> > short anyway (like 6 meg). base to ground measures .5 ohms which does
> > seem low to me, but I am not sure what it should be.
>
> > not really sure what to do next. Any other suggestions?
> > thanks in advance
>
> Base to ground will normally read low in circuit because you are
> measuring across the secondary of the horizontal drive transformer,
> which being a high frequency part will have a low impedance.
>
> With the HOT removed, there is normally no load on the B+ supply. If the
> supply has other outputs, an overload on one of them can cause the same
> shutdown problem. Sometimes it helps to disconnect sections to isolate
> the fault, sometimes this can be done easily by removing a component or
> jumper, but occasionally I've had to resort to cutting a trace on the
> PCB and then bridging it later. I try to avoid that though.
I appreciate the offer of help. I did as you said and desoldered the
HOT and repowered up and NO BEEP!
As you said the B+ was unloaded so it was slow to adjust but I set it
for 120v and waited a while and it was stable no problem. Then a
weird thing happened. I put the HOT back in the circuit and NO BEEP!
I have no explanation for that. I adjusted B+ to 120v again and it
was stable. I have neck glow also but still no picture on the tube.
By the way I did try the game board output on a spare monitor
previously and it is good so I am sure it is monitor only - rest of
game works 100%. I am guessing the next thing to check is sync?
agian thanks for the help. |
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External
Since: Nov 18, 2008
Posts: 8
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(Msg. 8) Posted: Tue Jul 07, 2009 4:37 am
Post subject: Re: NEED HELP in South Jersey: monitor troubleshooting [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)
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On Jul 5, 10:34 pm, james cardona <JAMES.CARD... DeleteThis @PSEG.COM> wrote:
> On Jul 5, 6:09 pm, James Sweet <jamesrsw... DeleteThis @gmail.com> wrote:
>
>
>
>
>
> > james cardona wrote:
> > > On Jul 4, 6:02 pm, JD <None@*verizon.net> wrote:
> > >>> Drop me a line if you can fix this (I will pay)
> > >>> I have a 27" neotec 2701 monitor from a san francisco rush that is
> > >>> dead. It makes a beeping sound and has no picture. I found the HOT
> > >>> shorted so I replaced that and thought all would be well, but it is
> > >>> still exhibiting the same problem. I have no schematics and am at the
> > >>> end on my ability. I believe there is a problem somewhere in the B+
> > >>> portion of the circuit. The flyback looks immaculate so I do not
> > >>> suspect that. I pulled it back out and the HOT wasn't blown.
> > >> Check the orange caps by the HOT, one of them
> > >> usually shorts.
>
> > > There are 3 possible caps there, c419, c420, and c421, but on my board
> > > there is only 1, c421. It is not shorted. Where c420 goes there are
> > > 2 jumper wires that jumper the voltage to the pin cushion board. I
> > > checked all the caps on that board and none are shorted.
>
> > > I should have said before that I had checked all the electrolytic caps
> > > up front. I replaced all the ones that I had spares for and
> > > desoldered and checked the ones I didn't (my fluke has a cap scale on
> > > it). I did find one of them open, c501. But swapping that out didn't
> > > fix anything.
>
> > > when I measure ohms from the HOT collector to ground I don't read
> > > short anyway (like 6 meg). base to ground measures .5 ohms which does
> > > seem low to me, but I am not sure what it should be.
>
> > > not really sure what to do next. Any other suggestions?
> > > thanks in advance
>
> > Base to ground will normally read low in circuit because you are
> > measuring across the secondary of the horizontal drive transformer,
> > which being a high frequency part will have a low impedance.
>
> > With the HOT removed, there is normally no load on the B+ supply. If the
> > supply has other outputs, an overload on one of them can cause the same
> > shutdown problem. Sometimes it helps to disconnect sections to isolate
> > the fault, sometimes this can be done easily by removing a component or
> > jumper, but occasionally I've had to resort to cutting a trace on the
> > PCB and then bridging it later. I try to avoid that though.
>
> I appreciate the offer of help. I did as you said and desoldered the
> HOT and repowered up and NO BEEP!
> As you said the B+ was unloaded so it was slow to adjust but I set it
> for 120v and waited a while and it was stable no problem. Then a
> weird thing happened. I put the HOT back in the circuit and NO BEEP!
> I have no explanation for that. I adjusted B+ to 120v again and it
> was stable. I have neck glow also but still no picture on the tube.
> By the way I did try the game board output on a spare monitor
> previously and it is good so I am sure it is monitor only - rest of
> game works 100%. I am guessing the next thing to check is sync?
> agian thanks for the help.- Hide quoted text -
>
> - Show quoted text -
OK I got a picture last night. Everything but green gun - that part
should be easy for me. So I want to thank you both for your
suggestions. This was my first monitor repair and I am jumping out of
my skin happy that I actually got it! And you are right I did learn a
lot. Thanks again. |
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