Topics

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

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



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

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


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

johncharlesgord
 

Bob,
The motor speed is temperature dependent (via RT8038), so the motor might not start right away when the circuit is cold. Try warming the thermistor RT8038 a bit to see if it starts without delay.
--John Gord

On Fri, Oct 11, 2019 at 09:51 PM, Robert Simpson wrote:


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

greenboxmaven
 

Great news! Check diode CR-8066 and it's connections to the rest of the circuit, it helps to dump the charge in the condenser when the power is shut off. R8058 is important because it is the key part of current limiting in the motor and should be fairly close to 15 ohms. It is possible it was damaged by the motor stall and has become intermittent, helping cause the balky starts. I think using a film resistor would be fine. Tektronix used the same sort of "kick starter" condenser in the power supplies of studio video waveform monitors and vectorscopes, and failures were common once they were 10 years or so old.

Bruce, KA2IVY

On 10/12/19 12:51 AM, Robert Simpson via Groups.Io wrote:
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


Chuck Harris
 

Silicon oil? That seems like a gritty thing to use.

Perhaps you mean silicone oil?

What would make you think that silicone oil is suited
for this application?

Educate me please!

-Chuck Harris

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

 

Silicon oil? That seems like a gritty thing to use.
It’s the latest thing in the world of ceramic grease.

Raymond

 

It’s the latest thing in the world of ceramic grease.
Nifty stuff.

Raymond

Abc Xyz
 

Bruce,

Great information on the 465B Fan! My 465B has Traces that are too Short
and cannot be Positioned all the way left!?
Fan works good though...lol
JR

On Fri, Oct 11, 2019, 8:42 PM greenboxmaven via Groups.Io <ka2ivy=
verizon.net@groups.io> wrote:

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






Robert Simpson
 

Chuck, yes Silicone Oil. Late evening typing has its risks. As to why that product, years ago I wanted to fix some sleeve bearing house fans. After some research, tried Silicone oil which has worked fine, and is working at the moment in this fan motor. Is there some long term reason that might be a problem?

Also, oh no, RT8038 is missing! I didn't remove it, somebody must have tried something. Looks like another part to order. Kind of good news in a way as the motor seems to be OK. Amazing its works at all.
Bob

greenboxmaven
 

First, be sure the connections to the pins on the side of the CRT are good. It takes both deflection plates to move the trace it's full range.If you don't find anything loose, the problem is probably in the horizontal output amplifier circuit. You can get a better idea by first checking that both channels have full (vertical) positioning range in normal operation mode. Now, refer to the manual for instructions to put the scope into X-Y mode. This disconnects the sweep generator circuits from the horizontal output amplifier and connects the Channel 1 vertical preamp in it's place. If the position control on CH 1 can move the dot fully across the screen, the problem is likely in the sweep generator circuit. If the CH 1 position control only has limited effect or can't pull the dot onto the screen, the horizontal output amplifier is where to look. Once you get past the paraphrase or phase inverter circuit at the beginning of the signal chain, everything else is push-pull to the deflection plates. The deflection amplifier output transistors or ICs tend to get warm in operation, the dead fan may have allowed destructive heating to happen.

Bruce, KA2IVY

On 10/12/19 11:15 AM, Abc Xyz wrote:
Bruce,

Great information on the 465B Fan! My 465B has Traces that are too Short
and cannot be Positioned all the way left!?
Fan works good though...lol
JR

greenboxmaven
 

Is there a chance someone moved RT 8038 to another place to better sense the temperature? Bruce, KA2IVY

On 10/12/19 1:23 PM, Robert Simpson via Groups.Io wrote:
Chuck, yes Silicone Oil. Late evening typing has its risks. As to why that product, years ago I wanted to fix some sleeve bearing house fans. After some research, tried Silicone oil which has worked fine, and is working at the moment in this fan motor. Is there some long term reason that might be a problem?

Also, oh no, RT8038 is missing! I didn't remove it, somebody must have tried something. Looks like another part to order. Kind of good news in a way as the motor seems to be OK. Amazing its works at all.
Bob


Robert Simpson
 

A careful check shows only the other resisters. Does anyone know the operating parameter of this part (1D1618, tek 307-124-00) ?

Chuck Harris
 

Hi Robert,

There are quite a few different varieties of silicone oil,
but one thing they all seem to have in common is they like
to creep. This time next year, you will probably find the
oil has coated the entire front and back ends of the motor,
and the circuit board. Not a big problem, except that it
attracts dust, and won't be in the bearing anymore.

Watchmakers had this problem with some of synthetic oils
that were used in lubricating watches. They had to dip the
various parts in steric acid to give them a coating that
would stop the oil's migration.

As an example, I have to keep my silicone oil based heatsink
compound in a double plastic zip lock bag. It is in a screw
top jar, but the oil creeps past the cardboard seal in the lid,
over the threads, and leaves oil rings on whatever surface
the jar is sitting upon. I don't like that in an oil.

Synthetic petroleum based oils last virtually forever, and
stay put in the bearing much better than silicone oils.

-Chuck Harris

Robert Simpson via Groups.Io wrote:

Chuck, yes Silicone Oil. Late evening typing has its risks. As to why that product, years ago I wanted to fix some sleeve bearing house fans. After some research, tried Silicone oil which has worked fine, and is working at the moment in this fan motor. Is there some long term reason that might be a problem?

Also, oh no, RT8038 is missing! I didn't remove it, somebody must have tried something. Looks like another part to order. Kind of good news in a way as the motor seems to be OK. Amazing its works at all.
Bob



Robert Simpson
 

Chuck,
What oil do you recommend? I would like to try some.
Bob

Robert Simpson
 

Ken Eckert
 

I have used a lubricant by Nye Lubricants. It was a watchmakers lubricant.
Nye is still in business

On Saturday, October 12, 2019, Chuck Harris <cfharris@...> wrote:

Hi Robert,

There are quite a few different varieties of silicone oil,
but one thing they all seem to have in common is they like
to creep. This time next year, you will probably find the
oil has coated the entire front and back ends of the motor,
and the circuit board. Not a big problem, except that it
attracts dust, and won't be in the bearing anymore.

Watchmakers had this problem with some of synthetic oils
that were used in lubricating watches. They had to dip the
various parts in steric acid to give them a coating that
would stop the oil's migration.

As an example, I have to keep my silicone oil based heatsink
compound in a double plastic zip lock bag. It is in a screw
top jar, but the oil creeps past the cardboard seal in the lid,
over the threads, and leaves oil rings on whatever surface
the jar is sitting upon. I don't like that in an oil.

Synthetic petroleum based oils last virtually forever, and
stay put in the bearing much better than silicone oils.

-Chuck Harris

Robert Simpson via Groups.Io wrote:
Chuck, yes Silicone Oil. Late evening typing has its risks. As to why
that product, years ago I wanted to fix some sleeve bearing house fans.
After some research, tried Silicone oil which has worked fine, and is
working at the moment in this fan motor. Is there some long term reason
that might be a problem?

Also, oh no, RT8038 is missing! I didn't remove it, somebody must have
tried something. Looks like another part to order. Kind of good news in a
way as the motor seems to be OK. Amazing its works at all.
Bob





Chuck Harris
 

I tend to use a couple of lubricants for this purpose.
Either Mobil 1, 5W30, or a turbine lube made by MARS,
which stands for "Motors and Armatures, Inc."
Mars 93240, in the "Zoom Spout" container.

I can't tell any difference in performance between
the two.

-Chuck Harris

Robert Simpson via Groups.Io wrote:

Chuck,
What oil do you recommend? I would like to try some.
Bob