| Author |
Message |
peter
Guest
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 Posted:
Fri Feb 11, 2005 5:31 pm Post subject:
Telequipment woes |
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Gentlemen,
Please forgive the intrusion.
I have an old Telequipment D755 opt66 that has decided it no longer wants to
display my waveforms.
Everything was going along nicely until it started displaying secondary
waveforms over the top (or underneath) what I wanted to see.
Pic at http://www.purpose.freeserve.co.uk/scerp.jpg
After an hour or so the screen would brightly flicker every five minutes.
Adjusting the intensity pot would have no effect and a while later I had no
screen output.
Does this sound familiar?
Would you scope gurus kindly point me to a culprit.
I'm yet to acquire a schematic, but I promise to stay away from the high
voltages.
Thank you for any and all suggestions.
peter
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Jim Yanik
Guest
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| Posted:
Fri Feb 11, 2005 6:23 pm Post subject:
Re: Telequipment woes |
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"peter" <peter@purpose.freeserve.co.uk> wrote in
news:cui51l$a6u$1@news6.svr.pol.co.uk:
| Quote: | Gentlemen,
Please forgive the intrusion.
I have an old Telequipment D755 opt66 that has decided it no longer
wants to display my waveforms.
Everything was going along nicely until it started displaying
secondary waveforms over the top (or underneath) what I wanted to see.
Pic at http://www.purpose.freeserve.co.uk/scerp.jpg
After an hour or so the screen would brightly flicker every five
minutes. Adjusting the intensity pot would have no effect and a while
later I had no screen output.
Does this sound familiar?
Would you scope gurus kindly point me to a culprit.
I'm yet to acquire a schematic, but I promise to stay away from the
high voltages.
Thank you for any and all suggestions.
peter
|
Sounds like the problem is in the HV area;the CRT grid bias and unblanking
circuit(DC restorer,that xfers the Z-axis unblank signal to the HV levels
the CRT needs.)
--
Jim Yanik
jyanik
at
kua.net |
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peter
Guest
|
| Posted:
Fri Feb 11, 2005 6:59 pm Post subject:
Re: Telequipment woes |
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|
Thanks Jim,
I have absolutely no idea what you're talking about, but hopefully once I
have a schematic available things will fall into place.
Cheers
peter
"Jim Yanik" <jyanik@abuse.gov.> wrote in message
news:Xns95FA4B0F04C81jyanikkuanet@129.250.170.85...
| Quote: | Sounds like the problem is in the HV area;the CRT grid bias and unblanking
circuit(DC restorer,that xfers the Z-axis unblank signal to the HV levels
the CRT needs.) |
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| Back to top |
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Jim Yanik
Guest
|
| Posted:
Sat Feb 12, 2005 6:11 am Post subject:
Re: Telequipment woes |
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|
"peter" <peter@purpose.freeserve.co.uk> wrote in
news:cuia75$e1b$1@news6.svr.pol.co.uk:
| Quote: | Thanks Jim,
I have absolutely no idea what you're talking about, but hopefully
once I have a schematic available things will fall into place.
Cheers
peter
"Jim Yanik" <jyanik@abuse.gov.> wrote in message
news:Xns95FA4B0F04C81jyanikkuanet@129.250.170.85...
Sounds like the problem is in the HV area;the CRT grid bias and
unblanking circuit(DC restorer,that xfers the Z-axis unblank signal
to the HV levels the CRT needs.)
HV= high voltage |
CRT=cathode ray tube,your display.
X-axis= horizontal,generally the sweep,'trace',or baseline displayed on the
CRT.(time per division)
Y-axis= vertical,amplitude displayed on the CRT (volts per division)
Z-axis= intensity control of the CRT,and unblank to display signal,blanks
to hide sweep retrace,developed from sweep ramp.
DC restorer= level shifting circuit to transfer the Z-axis signal(intensity
level plus gate signal from sweep) to the HV levels used by the CRT.
I'd also get a TEK service manual,like for a 465 or other simple scope and
read the circuit description;that will really educate you on how a scope
works,in great detail.
Others here may be able to point you to an on-line copy of a 465 manual.
--
Jim Yanik
jyanik
at
kua.net |
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peter
Guest
|
| Posted:
Sat Feb 12, 2005 8:35 pm Post subject:
Re: Telequipment woes |
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|
Marvellous stuff Jim, thank you very much indeed.
I'll have a service manual with schematics soon, courtesy of N. Cook @
diverse and hope to prove you right in your diagnosis.
Cheers
peter
"Jim Yanik" <jyanik@abuse.gov.> wrote in message
news:Xns95FACFAE03C19jyanikkuanet@129.250.170.84...
| Quote: |
HV= high voltage
CRT=cathode ray tube,your display.
X-axis= horizontal,generally the sweep,'trace',or baseline displayed on
the
CRT.(time per division)
Y-axis= vertical,amplitude displayed on the CRT (volts per division)
Z-axis= intensity control of the CRT,and unblank to display signal,blanks
to hide sweep retrace,developed from sweep ramp.
DC restorer= level shifting circuit to transfer the Z-axis
signal(intensity
level plus gate signal from sweep) to the HV levels used by the CRT.
I'd also get a TEK service manual,like for a 465 or other simple scope and
read the circuit description;that will really educate you on how a scope
works,in great detail.
Others here may be able to point you to an on-line copy of a 465 manual. |
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