Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old October 1st 15, 08:49 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Nov 2009
Posts: 54
Default old HP1740A o'scope problem

On 09/30/2015 05:19 AM, JC wrote:
On 9/30/2015 12:24 AM, Bill Martin wrote:
Hi,
Anyone have a list of "usual suspects" with this HP1740A scope when
there is no display at all? Front panel lights seem working, but that is
all I find so far. Have not opened the case yet, nothing seems to "smell
bad" so far. I won't be stressed if it can't be fixed, I bought it for
the nice rolling stand it was sitting on...I have another similar,
slightly newer antique scope that is still working that can use that
stand.

TIA,
Bill M

All the interboard connections on these are suspect for dry/bad joints
especially on the power board where you can get a nice burn up from the
arcing. Also the vertical output chip fails so you will get a trace but
no deflection. If you can go over all the joints carefully you might
have an easy repair.


Ok, I opened it up, there do not seem to be any burn marks on anything.
Wiggled the connectors too. Should I be able to see a glow from the ctr
filament without removing the metal shielding? So far I see no light,
nor detect any warming near the neck end of the tube...one additional
data point: the red "reset" led on the front panel is on all the time,
and there is no illumination of the faceplate.



  #2   Report Post  
Old October 1st 15, 09:35 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Dec 2013
Posts: 96
Default old HP1740A o'scope problem


"Bill Martin" wrote in message
...
On 09/30/2015 05:19 AM, JC wrote:
On 9/30/2015 12:24 AM, Bill Martin wrote:
Hi,
Anyone have a list of "usual suspects" with this HP1740A scope when
there is no display at all? Front panel lights seem working, but that is
all I find so far. Have not opened the case yet, nothing seems to "smell
bad" so far. I won't be stressed if it can't be fixed, I bought it for
the nice rolling stand it was sitting on...I have another similar,
slightly newer antique scope that is still working that can use that
stand.

TIA,
Bill M

All the interboard connections on these are suspect for dry/bad joints
especially on the power board where you can get a nice burn up from the
arcing. Also the vertical output chip fails so you will get a trace but
no deflection. If you can go over all the joints carefully you might
have an easy repair.


Ok, I opened it up, there do not seem to be any burn marks on anything.
Wiggled the connectors too. Should I be able to see a glow from the ctr
filament without removing the metal shielding? So far I see no light, nor
detect any warming near the neck end of the tube...one additional data
point: the red "reset" led on the front panel is on all the time, and
there is no illumination of the faceplate.



Do you have a copy of the service manual? Have you checked the power supply
test points? Be careful, there are some points that can bite you.

The screen illumination is done by a flood gun.

Do you have another scope?


Regards,
Tom


  #3   Report Post  
Old October 1st 15, 10:05 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Nov 2009
Posts: 54
Default old HP1740A o'scope problem

On 10/01/2015 01:35 PM, Tom Miller wrote:

"Bill Martin" wrote in message
...
On 09/30/2015 05:19 AM, JC wrote:
On 9/30/2015 12:24 AM, Bill Martin wrote:
Hi,
Anyone have a list of "usual suspects" with this HP1740A scope when
there is no display at all? Front panel lights seem working, but
that is
all I find so far. Have not opened the case yet, nothing seems to
"smell
bad" so far. I won't be stressed if it can't be fixed, I bought it for
the nice rolling stand it was sitting on...I have another similar,
slightly newer antique scope that is still working that can use that
stand.

TIA,
Bill M
All the interboard connections on these are suspect for dry/bad joints
especially on the power board where you can get a nice burn up from the
arcing. Also the vertical output chip fails so you will get a trace but
no deflection. If you can go over all the joints carefully you might
have an easy repair.


Ok, I opened it up, there do not seem to be any burn marks on
anything. Wiggled the connectors too. Should I be able to see a glow
from the ctr filament without removing the metal shielding? So far I
see no light, nor detect any warming near the neck end of the
tube...one additional data point: the red "reset" led on the front
panel is on all the time, and there is no illumination of the faceplate.



Do you have a copy of the service manual? Have you checked the power
supply test points? Be careful, there are some points that can bite you.

The screen illumination is done by a flood gun.

Do you have another scope?


Regards,
Tom


I do have another scope...it is even working. No service manual for this
one, I have the 1743A service manual, which should be "close" at least.
Yeah, I know about being bitten, got 300Vdc from a Klystron plate cap
once. Long ago, but you don't forget. So far all I have done is
superficial, really obvious kind of stuff. Not likely to put a lot of
effort into this, since fixing it could easily cost more than it is
worth...just curious what is ailing. I'm suspicious of the crt itself at
this point. If I can get it working, will likely give it away, to
another "old guy" buddy that could use it.

Bill


  #4   Report Post  
Old October 2nd 15, 12:52 AM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Dec 2013
Posts: 96
Default old HP1740A o'scope problem


"Bill Martin" wrote in message
...
On 10/01/2015 01:35 PM, Tom Miller wrote:

"Bill Martin" wrote in message
...
On 09/30/2015 05:19 AM, JC wrote:
On 9/30/2015 12:24 AM, Bill Martin wrote:
Hi,
Anyone have a list of "usual suspects" with this HP1740A scope when
there is no display at all? Front panel lights seem working, but
that is
all I find so far. Have not opened the case yet, nothing seems to
"smell
bad" so far. I won't be stressed if it can't be fixed, I bought it for
the nice rolling stand it was sitting on...I have another similar,
slightly newer antique scope that is still working that can use that
stand.

TIA,
Bill M
All the interboard connections on these are suspect for dry/bad joints
especially on the power board where you can get a nice burn up from the
arcing. Also the vertical output chip fails so you will get a trace but
no deflection. If you can go over all the joints carefully you might
have an easy repair.

Ok, I opened it up, there do not seem to be any burn marks on
anything. Wiggled the connectors too. Should I be able to see a glow
from the ctr filament without removing the metal shielding? So far I
see no light, nor detect any warming near the neck end of the
tube...one additional data point: the red "reset" led on the front
panel is on all the time, and there is no illumination of the faceplate.



Do you have a copy of the service manual? Have you checked the power
supply test points? Be careful, there are some points that can bite you.

The screen illumination is done by a flood gun.

Do you have another scope?


Regards,
Tom


I do have another scope...it is even working. No service manual for this
one, I have the 1743A service manual, which should be "close" at least.
Yeah, I know about being bitten, got 300Vdc from a Klystron plate cap
once. Long ago, but you don't forget. So far all I have done is
superficial, really obvious kind of stuff. Not likely to put a lot of
effort into this, since fixing it could easily cost more than it is
worth...just curious what is ailing. I'm suspicious of the crt itself at
this point. If I can get it working, will likely give it away, to another
"old guy" buddy that could use it.

Bill



Pretty good copy he
http://www.ko4bb.com/manuals/index.p...0_Oscilloscope

It really is not a bad scope. Good to over 100 MHz, two channel w/ delayed
sweep.

It could be something minor like a bad capacitor in the power supply. Go
check the supplies first.

Also, you will need to figure out how to fab some new feet as the originals
are most likely gone.


Good luck and 73


  #5   Report Post  
Old October 2nd 15, 07:15 PM posted to sci.electronics.repair
external usenet poster
 
First recorded activity by DIYBanter: Nov 2009
Posts: 54
Default old HP1740A o'scope problem

On 10/01/2015 04:52 PM, Tom Miller wrote:

"Bill Martin" wrote in message
...
On 10/01/2015 01:35 PM, Tom Miller wrote:

"Bill Martin" wrote in message
...
On 09/30/2015 05:19 AM, JC wrote:
On 9/30/2015 12:24 AM, Bill Martin wrote:
Hi,
Anyone have a list of "usual suspects" with this HP1740A scope when
there is no display at all? Front panel lights seem working, but
that is
all I find so far. Have not opened the case yet, nothing seems to
"smell
bad" so far. I won't be stressed if it can't be fixed, I bought it
for
the nice rolling stand it was sitting on...I have another similar,
slightly newer antique scope that is still working that can use that
stand.

TIA,
Bill M
All the interboard connections on these are suspect for dry/bad joints
especially on the power board where you can get a nice burn up from
the
arcing. Also the vertical output chip fails so you will get a trace
but
no deflection. If you can go over all the joints carefully you might
have an easy repair.

Ok, I opened it up, there do not seem to be any burn marks on
anything. Wiggled the connectors too. Should I be able to see a glow
from the ctr filament without removing the metal shielding? So far I
see no light, nor detect any warming near the neck end of the
tube...one additional data point: the red "reset" led on the front
panel is on all the time, and there is no illumination of the
faceplate.



Do you have a copy of the service manual? Have you checked the power
supply test points? Be careful, there are some points that can bite you.

The screen illumination is done by a flood gun.

Do you have another scope?


Regards,
Tom


I do have another scope...it is even working. No service manual for
this one, I have the 1743A service manual, which should be "close" at
least. Yeah, I know about being bitten, got 300Vdc from a Klystron
plate cap once. Long ago, but you don't forget. So far all I have done
is superficial, really obvious kind of stuff. Not likely to put a lot
of effort into this, since fixing it could easily cost more than it is
worth...just curious what is ailing. I'm suspicious of the crt itself
at this point. If I can get it working, will likely give it away, to
another "old guy" buddy that could use it.

Bill



Pretty good copy he
http://www.ko4bb.com/manuals/index.p...0_Oscilloscope

It really is not a bad scope. Good to over 100 MHz, two channel w/
delayed sweep.

It could be something minor like a bad capacitor in the power supply. Go
check the supplies first.

Also, you will need to figure out how to fab some new feet as the
originals are most likely gone.


Good luck and 73


Thanks for that, and yes, the feet on both my scopes are falling apart.

Bill


Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Rigol scope LCD problem [email protected] Electronics Repair 5 April 12th 11 03:19 PM
HP1740A Repair ronspencer Electronics Repair 1 March 6th 05 12:27 PM
HP1740a calibration Kevin Carney Electronics Repair 0 March 25th 04 02:16 PM
tek 465b scope problem Aaron Kentucky Electronics Repair 10 March 10th 04 07:30 PM


All times are GMT +1. The time now is 01:48 PM.

Powered by vBulletin® Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright 2004-2019 DIYbanter.
The comments are property of their posters.
 

About Us

"It's about DIY & home improvement"

 

Copyright © 2017