29 Jul
2019
29 Jul
'19
6:34 p.m.
I have an ill NLS MS-230 Miniscope.? Is there anyone on list that might
be interested in getting it running for me?? I'm willing pay for the
privilege.? I'd like to see the unit working, but I have no experience
with analog scopes, and I'd rather just entrust it to someone who can
see it to success.? I did replace the batteries and let it charge for
quite a while.? The red LED lights up on the front when on, but no sign
of a trace, even when fed a known good 1kHz wave.? The CRT does not
appear to be on.
Anyone a fan of these units and might be interested in taking a look?
Jim
--
Jim Brain
brain at jbrain.com
www.jbrain.com
29 Jul
29 Jul
7:24 p.m.
On 7/29/19 9:34 PM, Jim Brain via cctalk wrote:
I have an ill NLS MS-230 Miniscope.? Is there anyone
on list that might
be interested in getting it running for me?? I'm willing pay for the
privilege.? I'd like to see the unit working, but I have no experience
with analog scopes, and I'd rather just entrust it to someone who can
see it to success.? I did replace the batteries and let it charge for
quite a while.? The red LED lights up on the front when on, but no sign
of a trace, even when fed a known good 1kHz wave.? The CRT does not
appear to be on.
Anyone a fan of these units and might be interested in taking a look?
Jim
Jim,
I have a MS15 miniscope that has been my backup since '77. Good tool
and I got that one in "not working" condition. I've worked on a few
MS-215s over the years. Right now I'm up to my eyes with stuff to do
but but if no one answers you, maybe in the late fall (after October).
If you don't have the manual its on BAMA and a few other sites.
Since you replaced the batteries did you check the fuse? Also the 4066s
sometimes get cranky and/or the sockets.
The tough fail would be the CRT. Check the heater pins with a multimeter
to see if its open (unplug it as there is a transformer winding across
it). Mine needed one when I got it but they were available then (1977)
from NLS. Side effect of the hammer mechanic owner.
Now it would be a
hunt though old tube brokers.
Allison
7:30 p.m.
On 7/29/2019 9:24 PM, allison via cctalk wrote:
Since you replaced the batteries did you check the fuse?
Yep, good.
Also the 4066s
Hmm, all mine are soldered in.?
Do you suggest I desolder and check?
sometimes get cranky and/or the sockets.
Only
one '00 has a socket.
The tough fail would be the CRT. Check the heater pins with a multimeter
to see if its open (unplug it as there is a transformer winding across
it).
I'll check.
Mine needed one when I got it but they were available
then (1977)
from NLS. Side effect of the hammer mechanic owner. Now it would be a
hunt though old tube brokers.
Yep, I know that'd be the main issue, but I am
hopeful it's something
less problematic.
Allison
--
Jim Brain
brain at jbrain.com
www.jbrain.com
30 Jul
30 Jul
6:22 a.m.
On 7/29/19 10:30 PM, Jim Brain via cctalk wrote:
Check only socketed devices. Do not desolder unless you have good
reason to believe the part is bad.
Hint check for 5-6V on the power pins of the ICs.
IF you have the manual, check for all the voltages.
The only problem with the CRT is finding a replacement. THey may be
more common than thought. Haven't checked in decades.
Allison
On 7/29/2019 9:24 PM, allison via cctalk wrote:
THe batteries are charged? (about 6.6V or more full charge)
Since you replaced the batteries did you check the fuse?
Yep, good. Also the 4066s
Hmm, all mine are soldered in.? Do you suggest I desolder and check?
sometimes get cranky and/or the sockets.
Only one '00 has a socket.
The tough fail would be the CRT. Check the heater pins with a multimeter
to see if its open (unplug it as there is a transformer winding across
it).
I'll check. Mine needed
one when I got it but they were available then (1977)
from NLS. Side effect of the hammer mechanic owner.? Now it would be a
hunt though old tube brokers.
Yep, I know that'd be the main issue, but I am
hopeful it's something
less problematic.
6:23 a.m.
New subject: Ill NLS MS-230 ---manual!
On 7/29/19 10:30 PM, Jim Brain via cctalk wrote:
On 7/29/2019 9:24 PM, allison via cctalk wrote:
Since you replaced the batteries did you check the fuse?
Yep, good.
Also the 4066s
Hmm, all mine are soldered
in.? Do you suggest I desolder and check?
sometimes get cranky and/or the sockets.
Only one '00 has a socket.
The tough fail would be the CRT. Check the heater pins with a multimeter
to see if its open (unplug it as there is a transformer winding across
it).
I'll check.
Mine needed one when I got it but they were
available then (1977)
from NLS. Side effect of the hammer mechanic owner.? Now it would be a
hunt though old tube brokers.
Yep, I know that'd be the main issue, but I am
hopeful it's something
less problematic.
Allison
11:58 a.m.
On 2019-Jul-29, at 6:34 PM, Jim Brain via cctalk wrote:
I have an ill NLS MS-230 Miniscope. Is there anyone
on list that might be interested in getting it running for me? I'm willing pay for
the privilege. I'd like to see the unit working, but I have no experience with analog
scopes, and I'd rather just entrust it to someone who can see it to success. I did
replace the batteries and let it charge for quite a while. The red LED lights up on the
front when on, but no sign of a trace, even when fed a known good 1kHz wave. The CRT does
not appear to be on.
Anyone a fan of these units and might be interested in taking a look?
It's tempting but I'm across the border and some shipping distance away.
Looking at the schematic (readily available online), it's fairly straightforward.
If you're willing to spend a little time on it, you could do the basics and check
for the power supply voltages as listed on the schematic.
The power supply is essentially 3 stages:
1) line -> charging circuit for the batteries,
2) batt -> +5 regulator,
3) +5 -> simple switching supply for +/-7V, +80V, +100V, -720V, 0.5V heater, 12V for
U11.
With nothing on the CRT (esp with the intensity turned full up), suspicion may fall around
the little switching supply.
A key point to note with 'scopes like this is the cathode/heater runs at high negative
voltage relative to GND, rather than the TV/monitor convention of the anode running at
high positive voltage. This is done so the amplifiers to drive the electrostatic
deflection plates can be be operated near GND level rather than having to raise them way
above GND.
So according to the schematic the heater (acting as cathode; either pin) should measure
-720V relative to GND and there should be 0.6V across the two heater pins.
U11 should have 12V across pins 14 & 7, but like the heater, it to is floating at
-720V below GND.
1:17 p.m.
On 7/30/19 2:58 PM, Brent Hilpert via cctalk wrote:
On 2019-Jul-29, at 6:34 PM, Jim Brain via cctalk
wrote:
Read the manual as it has troubleshooting information and test points.
If you follow that it will bring you to the fault very quickly
I've not seen the switching converter fail but there are many parts of
the regulators that can.
Hint do yourself a favor and expand and print the schematic as at least
B if not D size. it will be easier to follow.
Allison
I have an ill NLS MS-230 Miniscope. Is there
anyone on list that might be interested in getting it running for me? I'm willing pay
for the privilege. I'd like to see the unit working, but I have no experience with
analog scopes, and I'd rather just entrust it to someone who can see it to success. I
did replace the batteries and let it charge for quite a while. The red LED lights up on
the front when on, but no sign of a trace, even when fed a known good 1kHz wave. The CRT
does not appear to be on.
Anyone a fan of these units and might be interested in taking a look?
It's tempting but I'm across the border and some shipping distance away.
Looking at the schematic (readily available online), it's fairly straightforward.
If you're willing to spend a little time on it, you could do the basics and check
for the power supply voltages as listed on the schematic.
The power supply is essentially 3 stages:
1) line -> charging circuit for the batteries,
2) batt -> +5 regulator,
3) +5 -> simple switching supply for +/-7V, +80V, +100V, -720V, 0.5V heater, 12V for
U11.
With nothing on the CRT (esp with the intensity turned full up), suspicion may fall
around the little switching supply.
A key point to note with 'scopes like this is the cathode/heater runs at high
negative voltage relative to GND, rather than the TV/monitor convention of the anode
running at high positive voltage. This is done so the amplifiers to drive the
electrostatic deflection plates can be be operated near GND level rather than having to
raise them way above GND.
So according to the schematic the heater (acting as cathode; either pin) should measure
-720V relative to GND and there should be 0.6V across the two heater pins.
U11 should have 12V across pins 14 & 7, but like the heater, it to is floating at
-720V below GND.
1739
days inactive
1739
days old
6 comments
3 participants
participants (3)
-
allisonportable＠gmail.com -
bhilpert＠shaw.ca -
brain＠jbrain.com