Re: Tek 2465B scope help needed

Paul Amaranth
 

Maybe use some of the low strength wicking blue 220 after assembly.
That's a perfect application for that. No worries about it getting
to the bearings and it doesn't require a high shear force to break
it loose if you have to get the screw out again.

Paul

On Wed, Apr 03, 2013 at 06:41:36PM -0000, machineguy59 wrote:
I ask politely: "Why not Locktite?" I ask because I use it often and maybe too often if there is something I need to learn here. So my general question: "Why not Locktite?"

But in this case, it shall be wax (If I can hit the hole, lol).

--- In TekScopes@..., "Tom Miller" <tmiller11147@...> wrote:

Don't put locktite in that hole.
At best, maybe melt some wax in there with the tip of your iron.



----- Original Message -----
From: machineguy59
To: TekScopes@...
Sent: Wednesday, April 03, 2013 2:13 PM
Subject: [TekScopes] Re: Tek 2465B scope help needed



IT WORKS!!!!
The fan motor on my 2465 is quiet as a mouse, maybe more quiet than that. On 12 volts (I don't have 15 volts unregulated ATM) I have to feel the shaft to make sure it is running. Success. Here is what happened.

Based on advice from this forum I opened up a hole I found in the PCB mounted to the fan. There was a bit of dust inside the hole but it cleaned easily and I was able to remove the set screw that is in the rear of the motor and fish it out through the hole. A hypodermic needle with oil was inserted into the rear of the motor and a few drops of oil pushed in (working blind its hard to tell how much oil but a hypodermic needle and oil makes it slow so a few drops is most likely). I then fished the screw back into the hole and into place at the rear of the motor. I tightened the screw until it was hard to turn the motor shaft and then backed off 1/4 turn so the shaft turns freely. Another drop of oil on the front bearing, some rotations by hand to work the oil in and it was done. I powered it up with a 12 volt regulated bench supply and thought at first I had broken it!!! But it was turning so silently it didn't even vibrate on the bench. It starts every time and runs like new.

I plan to drip a bit of Locktite down that hole to hold the set screw.

Thanks guys, especially Tom for your help and advice.

Now back to helping the OP with his motor and error messages.

--- In TekScopes@..., "Tom Jobe" <tomjobe@> wrote:
>
> I may have those PCB's confused as to which is used in the early 24x5 scopes, so double check anything I say for accuracy. (I'm almost 73 years of age, so be careful!)
> In the center of the darker squarish PCB there is nothing to stop you from opening the hole up a bit. I can take a picture of it with some strong light on the back so you can see what trace is where, if you think it would help.
> tom jobe...
>
>
>
>
> ----- Original Message -----
> From: machineguy59
> To: TekScopes@...
> Sent: Tuesday, April 02, 2013 6:35 PM
> Subject: [TekScopes] Re: Tek 2465B scope help needed
>
>
>
> Thanks Tom for those pictures. I have the squarish PCB with the hole already marked by a solder blob. I thought the solder blob was just a marker but maybe it is plugging a hole already drilled. I will touch it with a solder iron later tonight and see if the hole is already there. But, alas, I am forewarned that the hole may not be large enough to remove the screw.
>
> I don't get much time to work on things right now so progress comes in fits and spurts. Its frustrating but I do believe I can repair this motor. It looks to be in good condition except it has worn enough there is too much end play in the thrust bearing.
>
> --- In TekScopes@..., "Tom Jobe" <tomjobe@> wrote:
> >
> > Your plan of drilling a hole in the PCB seems fairly doable, but if you do decide to go that way, don't make the same mistake they made on the 4xx PCB.
> > The 4xx PCB has a hole so you can reach in and set the motor's end play, but as I remember the hole is too small for the screw to come out, so you still can't oil the rear bearing properly.
> > In the attached picture, the 4xx PCB is the smaller, darker colored, squarish one, and the 24x5 PCB is the wider, lighter colored one.
> > Those four components on the 24x5 PCB could get reattached to the motor pins more directly to give you the room to make your modification. There is only one trace on the backside of the 24x5 PCB you will have to be careful of near the center of the motor, and another picture of the backside of the 24x5 PCB is attached.
> > tom jobe...
> >
> >
> >
> > ----- Original Message -----
> > From: machineguy59
> > To: TekScopes@...
> > Sent: Tuesday, April 02, 2013 5:00 PM
> > Subject: [TekScopes] Re: Tek 2465B scope help needed
> >
> >
> >
> > Thanks very much Tom and Tom. I haven't started on the rebuild yet so I will take your advice. My motor seems to be in pretty good shape. Just noisy.
> >
> > I had thought about drilling a hole in the PCB to access the set screw but was afraid to damage the PCB. Might try it now. thanks.
> >
> > --- In TekScopes@..., "Tom Jobe" <tomjobe@> wrote:
> > >
> > > As Tom says, do not pry open the 24x5 fan motor!
> > > Attached are some pictures to show you the back end of the fan motor. The screw in the center that sets the end play of the motor gets removed to oil the back bearing.
> > > If you stand the motor up, and use a piece of wire to stick down into the bearing, you can put some oil on the wire and it will travel down the wire without oiling up the plastic threads the set screw needs to have some friction with. The original motor had the threads locked with some sort of liquid that dried to hold the motor end play adjustment.
> > > tom jobe...
> > > PS Some of the 4xx scopes (465, 475, etc.) use the same exact fan motor, but used a different circuit board and mounting scheme.
> > >
> > >
> > >
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: Tom Miller
> > > To: TekScopes@...
> > > Sent: Tuesday, April 02, 2013 3:06 PM
> > > Subject: Re: [TekScopes] Re: Tek 2465B scope help needed
> > >
> > >
> > >
> > >
> > > Don't pry open the rear endbell. There are many fine wires to the stator coils.
> > >
> > > If you remove the pc board, you will see in the center a plugged hole. Dig out the material until you see a slotted adjusting set screw. Unscrew the setscrew and remove it. Now you can drip some thin oil down the hole and it should lube the bushing. It uses a sintered bronze bearing.
> > >
> > > Now replace the setscrew and adjust it to remove almost all the end play. Keep a few thousands clearance so it does not bind up.
> > >
> > >
> > > HTH,
> > > Tom
> > >
> > >
> > > ----- Original Message -----
> > > From: machineguy59
> > > To: TekScopes@...
> > > Sent: Tuesday, April 02, 2013 5:51 PM
> > > Subject: [TekScopes] Re: Tek 2465B scope help needed
> > >
> > >
> > >
> > >
> > > I am also a proud owner of a 2465 and in the process of replacing capacitors. I also have a noisy fan and have learned it is a common problem with these scopes. If you use the Advanced Search function with the terms +2465 +fan +noisy you will find some of the best explanations of the repairs done by other owners. If you have lots of time you can search +fan +noisy and read what others have done for other scopes.
> > >
> > > Based on my reading, there are two schools of philosophy of repair for the fan:
> > > 1. Restore the original parts if at all possible.
> > > 2. Give up and modify the case to accept a computer style muffin fan.
> > >
> > > I chose option 1, restore the existing fan. The motor and squirrel cage are almost non-existent today but both "might" be repairable. There are excellent explanations of motor repair by several members. One smart guy (Dave) added a tiny ball bearing to the front case of the fan.
> > >
> > > In my case, I will need to unsolder the motor from the control board and pry open the aluminum case. Then, hopefully, lubricate the rear bearing and repair or replace the front bearing. If I fail, I plan to go for option 2.
> > >
> > > --- In TekScopes@..., "wallace.gibbons" <wally.gibbons@> wrote:
> > > >
> > > > Hi,
> > > > I just joined the group. I love these old scopes. I have three 310's, a 317, and two 321's. One with the nuvistor and one with the fet front end. Use em all from time to time.
> > > >
> > > > I just picked up a very nice 2465 with the DMM option. It's got two problems. First is the fan is terribly noisy. I removed the covers, and found the squirrel cage shaft broken. I glued it back together and put it back on the motor shaft. Still very noisy. All the documents I've found show a different fan that the one in my scope. Anyone been able to quiet one of these down? I can't see how to get into the dang fan motor rear to lube it.
> > > >
> > > > Second problem, the backup battery was dead. I've replaced it but I get the message that means the checksum on the memory is invalid. When I push the A/B Trig the scope works ok but I know the calibration is off. Is there a "quick and dirty" way to get past the error message until I can go through the procedure to re-calibrate it?
> > > >
> > > > Thanks so much.
> > > >
> > > > Wally Gibbons
> > > > North Logan, Utah
> > > >
> > >
> >
>
--
Paul Amaranth, GCIH | Rochester MI, USA
Aurora Group, Inc. | Security, Systems & Software
paul@... | Unix & Windows

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