Date   
Re: 465B fan question

Robert Simpson
 

Wu Who! (yeah). Success, C8064 was bad. I only had 10uf 50V, but it worked. Started right away. One note. I tried it several times and found I need to wait 20-30 seconds or it doesn't start. But if I wait briefly after turning the scope off, it does self start. (cap has to discharge?) This is a lot better than replacing the motor.
Note, I had previously checked R8058 and found it slightly high value at 16.5 ohms. I tired paralleling in 180 ohms which gets it to about 14.9 ohms before changing the cap. Changing resistance wouldn't do it. I will still need to get a 15 ohm resistor.
Which brings me to another question. I haven't found a source for 15 ohm carbon at 5 watts. I am afraid to use wire wound as inductance might affect the pulse circuit. Would thin film or thick film be OK?

Thanks, Bob

Re: 465B fan question

greenboxmaven
 

I have looked at the schematic and can suggest some things to check. First, replace condenser C8064. If it is bad, transistor Q 8067 will not get a pulse to "kick start" the circuit and motor. If the motor still will not start unaided, shut the power off and measure the resistance between pins 3,5,10, and 12 on the IC. They should all read zero ohms between each other. If not, find the broken connection and fix it. Check for about 15 ohms between each of those pins to ground. If the resistance is drastically different, check resistor R 8058. It may have been damaged. Measure the resistance from motor terminals 1 and 5 to ground. It should be about 43 ohms. If not, check R 8065 and all of the connections. If all of these things check out and the motor runs at a reasonable speed when you push start it, chances are either one of the Hall Effect sensors in the motor has failed or a winding has fried. Measure the voltage between motor terminals 10, 11, 13, and 14 and ground one at a time while turning the fan slowly by hand. The voltage should be changing from near 15 volts to about 8 volts or less. The change is the most important thing, it indicates the switching transistors in the IC are working. If one of these is not changing or is very low, the motor winding may be fried. Shut off the power and meter the resistance from motor terminal 9 to terminals 10,11, 13, and 14 one at a time. The resistances should be very close. If they are'nt, the motor is likely bad. If the motor windings look good, measure the voltage on motor terminals 3 and 7 with the motor running. They should be close to each other. If they are substantially different, shut off the power and check the 280 ohm resistors that go to motor terminals 3 and 7. If they are good, turn the power back on and measure the voltage between motor terminals 2,4,6,and 8 one at a time and pin 10 of the IC while turning the motor slowly. The voltage should be switching between almost zero and about .6 to.8 volt. If one of these is not changing, a Hall Effect sensor in the motor is likely to be bad. I hope you will find a bad condenser, resistor or a broken connection or circuit board path. Good luck!

Bruce Gentry, KA2IVY

On 10/11/19 10:11 PM, Robert Simpson via Groups.Io wrote:
Trying to get the fan in a 465B working. Initially I noticed the PCB under the IC was dark brown as if the IC had overheated. So I replaced both the IC and the transistor, just in case. Also, the fan motor didn't spin freely, so I also pulled the fan motor, cleaned and lubricated the bearings with Silicon Oil. The fan motor now spins freely. I also checked the diodes with fan off the PCB and they seemed OK (forward reverse Ohm check).
However, The motor won't start turning on its own. If I manually spin it a couple of times, it will then keep spinning until I turn the power off. The fan will only spin if I start it manually.
Does indicate a problem with the motor, like, say, a bad winding thus not enough starting torque?
Bob


2465A Repair Question

Matthew Wilson
 

A friend of mine gave me his old 2465A scope, which he said was working (as of a few years ago when he last turned it on).

When I turned it on, nearly all the button lights come on and I see a bright dot on the CRT, but none of the controls do much at all. Focus control will focus and unfocus the dot, and "beam find" button brings the dot the center of the screen, but the other functions do not seem to have any effect. All of the button lights stay on no matter what. No text appears on the screen.

Thought I'd check the low voltage power supply voltages so here's what I got from J1119:

Pin Spec Measured
1 -15v -17.6v
2 +5v 4.25v
4 +10v 10.01v
5 -5v -5.8v
6 +15v 14v
8 +87v 79.9v
9 +42.4v 39.2v
11 -8v -8.25v
12 +5v 4.98v

Seemed a little off - and after reading some posts on this forum and others, I decided to try to recap the two power supply boards (A2A1 and A3). I know I should have done some troubleshooting to find the problem rather than shotgunning, but I figured I'd want to do that anyway at some point. At any rate, I recapped the two boards using the recommended list of Nichicon electrolytics, film safety caps, and the few resistor upgrades.

The good news is that it appears that I did a decent job and didn't screw anything up further.
The bad news is that I didn't fix the problem: scope operates the same (all buttons light up, no functions) and the power supply voltages, though they shifted to a very minor degree (-5.81v to -6.05v, for example), have not really changed that much. They're still off.

Where do I start from here? What can I test that will help me isolate the stage and then component?

I've worked on simple tube scopes and successfully restored a Heathkit IO--102 - nothing this complex though. I have the service manual.

Any advice?

Re: ths730a battery cover stuck

Craig Cramb
 

The problem is the cover is in the closed locked position and it will not rotate, the o-ring might be broken down and is sticking, not sure.

Your at the point of disassembly. 15 torx screwdriver. Lay on its face on surface that won’t scuff the front. Remove the 4 screws. Hold scope front and back and turn back over onto its back. Then separate the two pieces apart front from back. This will get you to the parts that are stuck together.

Re: 465B fan question

Robert Simpson
 

Ah, Interesting, thank you for the reply. Had not thought of that. Unfortunately that doesn't sound fixable (at least not by Me). Looks like some kind of replacement. In researching 465B fans, Walter Shawlee had a method..
Bob

Re: 465B fan question

Abc Xyz
 

Weak Magnets

On Fri, Oct 11, 2019, 7:11 PM Robert Simpson via Groups.Io <go_boating_fast=
yahoo.com@groups.io> wrote:

Trying to get the fan in a 465B working. Initially I noticed the PCB
under the IC was dark brown as if the IC had overheated. So I replaced
both the IC and the transistor, just in case. Also, the fan motor didn't
spin freely, so I also pulled the fan motor, cleaned and lubricated the
bearings with Silicon Oil. The fan motor now spins freely. I also checked
the diodes with fan off the PCB and they seemed OK (forward reverse Ohm
check).
However, The motor won't start turning on its own. If I manually spin it a
couple of times, it will then keep spinning until I turn the power off.
The fan will only spin if I start it manually.
Does indicate a problem with the motor, like, say, a bad winding thus not
enough starting torque?
Bob



465B fan question

Robert Simpson
 

Trying to get the fan in a 465B working. Initially I noticed the PCB under the IC was dark brown as if the IC had overheated. So I replaced both the IC and the transistor, just in case. Also, the fan motor didn't spin freely, so I also pulled the fan motor, cleaned and lubricated the bearings with Silicon Oil. The fan motor now spins freely. I also checked the diodes with fan off the PCB and they seemed OK (forward reverse Ohm check).
However, The motor won't start turning on its own. If I manually spin it a couple of times, it will then keep spinning until I turn the power off. The fan will only spin if I start it manually.
Does indicate a problem with the motor, like, say, a bad winding thus not enough starting torque?
Bob

Re: Looking for 7104 crt , trade

oliver johnson
 

I an in the US, New York 11553 zip . I did get a crt shipped to me before , as long as its packed in multiple boxes , one larger than the other i should be fine . Let me know if you can 
Do a shipping. 
On Fri, Oct 11, 2019 at 1:11 PM, Steve Wiseman<sjwiseman@...> wrote: > I have a 7103 rack mount scope , my crt is bad and would like to replace
it with a good working crt . I would like to trade someone that has crts
and may want one that i have , i have some 5 series 4 series 7 series  and
other tek crt , in addition to that i have some hp and leader crt , if you
are  looking for something specific let me know and maybe we can help each
other .
I've got a 7103 with a pristine tube (no burn in visible at all, nice and
bright) but otherwise a bit battered. You don't say where you are - and
shipping's going to be the issue... I'm in Cambridge, England. Interested,
or not?

Steve

Re: Looking for 7104 crt , trade

Steve Wiseman
 

I have a 7103 rack mount scope , my crt is bad and would like to replace
it with a good working crt . I would like to trade someone that has crts
and may want one that i have , i have some 5 series 4 series 7 series and
other tek crt , in addition to that i have some hp and leader crt , if you
are looking for something specific let me know and maybe we can help each
other .
I've got a 7103 with a pristine tube (no burn in visible at all, nice and
bright) but otherwise a bit battered. You don't say where you are - and
shipping's going to be the issue... I'm in Cambridge, England. Interested,
or not?

Steve

Re: AM700

Giampi Redmond
 

Hi,
I have just posted the v1.05 firmware on the ko4bb website (www.ko4bb.com).
It will take a few days for it to be downloadable.
There are also the two boot roms I had posted some time ago.
The 8MBytes Simm Flash modules are still found on eBay although not of the same model mounted on the AM700.

Re: ths730a battery cover stuck

Scott Adams
 

The problem is the cover is in the closed locked position and it will not rotate, the o-ring might be broken down and is sticking, not sure.

Re: ths730a battery cover stuck

doyle.paul48
 

G'day Zenith,
The battery compartment relies on having a battery inserted to give enough
spring pressure to pop the cover off when it is rotated.
I use a medium sized bull nosed pliers to rotate the cover then pull it up.
Try not to pry it up with a sharp leaver you could crack it.
Paul Doyle
CRO-TEK

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Re: ths730a battery cover stuck

 

On Thu, Oct 10, 2019 at 09:42 PM, Scott Adams wrote:


I do not want to break anything so any ideas on how to remove the cover so I
can check the battery condition.
The normal way to open is to turn the cover 1/4 turn CCW and the cover should
come off. However there is a small o-ring on the cover which may make the cover
stick to the case especially if it hasn't been opened for a long time. Just try to
carefully pull and/or wiggle the cover in the open position and eventually it will come off.

/Håkan

ths730a battery cover stuck

Scott Adams
 

I just got a ths730a and it works fine, but the battery cover is frozen stuck. I do not want to break anything so any ideas on how to remove the cover so I can check the battery condition.

Re: In search of Impeller Fan Fastener For Tek 2465 - Part # 243104001

EricJ
 

Good question. I think probably Chuck was going off memory when he mentioned 6-32. I didn't even look at the print, just ran with it. 8-32 is likely correct.

--Eric

On Oct 9, 2019 4:15 PM, Paul Amaranth <paul@...> wrote:




The print in the files section shows 8-32, is that a mistake?

On Wed, Oct 09, 2019 at 11:40:40AM -0500, EricJ via Groups.Io wrote:
Chuck, the 6-32 thread won't be any stronger in brass than in aluminum -
in fact most likely weaker. Two benefits to brass as I see it are easier
machining and less likely to corrode and seize the thread - the likely
culprit if aluminum ones are breaking. What material are they screwed
into?

--Eric

On Oct 9, 2019 10:25 AM, Chuck Harris <cfharris@...> wrote:




Tom Jobe's were made of brass.

The collet is made from billet (eg solid rod).  If you
use aluminum, you are going to have trouble threading the
6-32 section without breaking it.  And, some future user
is likely to twist it off, or break the screw slot, when
they guess wrongly that the screw is turned to remove the
fan.

I would use brass or steel.

-Chuck Harris



EricJ via Groups.Io wrote:
Hi Chuck,

Found it. Slight discrepancy though - you mentioned these were made
of
brass and the print says 6061 (aluminum). Which is preferable for
these?

--Eric

On Oct 9, 2019 9:15 AM, Chuck Harris <cfharris@...> wrote:




Hi Eric,

There is already a blue print for the collets
in the files section of this group.  I have a
copy if you can't find it.







!DSPAM:5d9e469095791713744598!
--
Paul Amaranth, GCIH             | Manchester MI, USA
Aurora Group of Michigan, LLC   |   Security, Systems & Software
paul@...              |   Unix & Windows





Re: In search of Impeller Fan Fastener For Tek 2465 - Part # 243104001

Chuck Harris
 

It isn't a fan, per sei, but rather a squirrel cage blower.

Why reinvent the wheel? I could make this collet with a drill
press, slitting saw, and a file.

-Chuck Harris

Phil Wong via Groups.Io wrote:

Looking at it from another perspective: Are there currently available fans that would fit right into the drive shaft of the Siemens motor?


-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of EricJ via Groups.Io
Sent: Wednesday, October 09, 2019 12:41 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] In search of Impeller Fan Fastener For Tek 2465 - Part # 243104001

Chuck, the 6-32 thread won't be any stronger in brass than in aluminum - in fact most likely weaker. Two benefits to brass as I see it are easier machining and less likely to corrode and seize the thread - the likely culprit if aluminum ones are breaking. What material are they screwed into?

--Eric

Re: In search of Impeller Fan Fastener For Tek 2465 - Part # 243104001

Chuck Harris
 

Mine, follow the plan.

-Chuck Harris

Paul Amaranth wrote:

The print in the files section shows 8-32, is that a mistake?

On Wed, Oct 09, 2019 at 11:40:40AM -0500, EricJ via Groups.Io wrote:
Chuck, the 6-32 thread won't be any stronger in brass than in aluminum - in fact most likely weaker. Two benefits to brass as I see it are easier machining and less likely to corrode and seize the thread - the likely culprit if aluminum ones are breaking. What material are they screwed into?

--Eric

Re: In search of Impeller Fan Fastener For Tek 2465 - Part # 243104001

Chuck Harris
 

As an engineer who is very comfortable in the machine shop,
(I won't say I'm a machinist), I agree, but brass is still
better.

My reasoning is that any brass you find will be very good
for machining, and adequate for strength. I can't say the
same about any aluminum you find.... imagine the recycled
chewing gum they sell as aluminum stock in the hardware store.

If you really use 6061, and especially T6061, you will have
a working collet when you are done.

The original was a plastic collet with a 6-32 screw molded
into the plastic. So overall strength is not much of an issue.

I don't think it very much matters what you make it out
of... even some plastics would be fine, if you can cut the
threads to size.

The collet doesn't screw into anything. The threads are used
as the collet closer, and are pulled with an ordinary nut.
The collet's tapered cone is inside of the fan's hub.

-Chuck Harris


EricJ via Groups.Io wrote:

Chuck, the 6-32 thread won't be any stronger in brass than in aluminum - in fact most likely weaker. Two benefits to brass as I see it are easier machining and less likely to corrode and seize the thread - the likely culprit if aluminum ones are breaking. What material are they screwed into?

--Eric

On Oct 9, 2019 10:25 AM, Chuck Harris <cfharris@...> wrote:




Tom Jobe's were made of brass.

The collet is made from billet (eg solid rod). If you
use aluminum, you are going to have trouble threading the
6-32 section without breaking it. And, some future user
is likely to twist it off, or break the screw slot, when
they guess wrongly that the screw is turned to remove the
fan.

I would use brass or steel.

-Chuck Harris



EricJ via Groups.Io wrote:
Hi Chuck,

Found it. Slight discrepancy though - you mentioned these were made of
brass and the print says 6061 (aluminum). Which is preferable for these?

--Eric

On Oct 9, 2019 9:15 AM, Chuck Harris <cfharris@...> wrote:




Hi Eric,

There is already a blue print for the collets
in the files section of this group. I have a
copy if you can't find it.




Re: In search of Impeller Fan Fastener For Tek 2465 - Part # 243104001

Phil Wong
 

Looking at it from another perspective: Are there currently available fans that would fit right into the drive shaft of the Siemens motor?

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of EricJ via Groups.Io
Sent: Wednesday, October 09, 2019 12:41 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] In search of Impeller Fan Fastener For Tek 2465 - Part # 243104001

Chuck, the 6-32 thread won't be any stronger in brass than in aluminum - in fact most likely weaker. Two benefits to brass as I see it are easier machining and less likely to corrode and seize the thread - the likely culprit if aluminum ones are breaking. What material are they screwed into?

--Eric

On Oct 9, 2019 10:25 AM, Chuck Harris <cfharris@...> wrote:




Tom Jobe's were made of brass.

The collet is made from billet (eg solid rod). If you use aluminum,
you are going to have trouble threading the
6-32 section without breaking it. And, some future user is likely to
twist it off, or break the screw slot, when they guess wrongly that
the screw is turned to remove the fan.

I would use brass or steel.

-Chuck Harris



EricJ via Groups.Io wrote:
Hi Chuck,

Found it. Slight discrepancy though - you mentioned these were made
of
brass and the print says 6061 (aluminum). Which is preferable for these?

--Eric

On Oct 9, 2019 9:15 AM, Chuck Harris <cfharris@...> wrote:




Hi Eric,

There is already a blue print for the collets in the files section
of this group. I have a copy if you can't find it.




Re: In search of Impeller Fan Fastener For Tek 2465 - Part # 243104001

Paul Amaranth
 

The print in the files section shows 8-32, is that a mistake?

On Wed, Oct 09, 2019 at 11:40:40AM -0500, EricJ via Groups.Io wrote:
Chuck, the 6-32 thread won't be any stronger in brass than in aluminum - in fact most likely weaker. Two benefits to brass as I see it are easier machining and less likely to corrode and seize the thread - the likely culprit if aluminum ones are breaking. What material are they screwed into?

--Eric

On Oct 9, 2019 10:25 AM, Chuck Harris <cfharris@...> wrote:




Tom Jobe's were made of brass.

The collet is made from billet (eg solid rod).  If you
use aluminum, you are going to have trouble threading the
6-32 section without breaking it.  And, some future user
is likely to twist it off, or break the screw slot, when
they guess wrongly that the screw is turned to remove the
fan.

I would use brass or steel.

-Chuck Harris



EricJ via Groups.Io wrote:
Hi Chuck,

Found it. Slight discrepancy though - you mentioned these were made of
brass and the print says 6061 (aluminum). Which is preferable for these?

--Eric

On Oct 9, 2019 9:15 AM, Chuck Harris <cfharris@...> wrote:




Hi Eric,

There is already a blue print for the collets
in the files section of this group.  I have a
copy if you can't find it.







!DSPAM:5d9e469095791713744598!
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix & Windows