Preparing to rebuild a Tek 2445 Power Supply - Any Advice?


Bru H
 

Hi all,
I have a Tek 2445 (Not 2445A or B).
Someone worked on the Power Supply before me and installed standard film caps in the Safety cap locations.
Plus the PS has the original electrolytic caps, so I will rebuild the whole thing.

I have Options:
01 DMM Option
05 TV Option
06 Counter Option
09 CTT, plus a 17-bit P6407 word recognizer probe

The Power Supply Voltages are all very good.

I would like open (not easy) the Siemens Hall Effect Sensor Controlled Fan and lubricate the sintered bearings, any advice?

As far as I can tell there is no memory battery in the 2445, Tek only had a battery on the higher 24XX models, is this true?

Any Heads Up before I go in?
Is there any record of the calibration that I can save before I rebuild?
Will I loose the calibration on the scope due to the PS rebuild?

I am looking for a Knob for the Scale Illum knob (For example)

Thank you!


Bob Koller <testtech@...>
 

There is no battery on the 2445, it has an EAROM chip instead.

The fan motor can be lubricated after removal from the PCB, by placing a drop of oil or two on the shaft, and allowing it to stand vertical overnight. Also, on the terminal end, in the center there is a small screw that adjusts the armature end play. You dig out the sealant, remove the screw, and again a drop or two of oil, and vertical storage to allow the oil to creep into the bearing. Replace the screw, and carefully adjust for a little end play of the armature.

It is almost certain that in removal of the fan impeller the collet will break. This is a constant problem with Siemens fan units. There are several ways to fix it. A search of the Forum should provide insight.

No worry about loss of the cal with any of this. No easy way to save the constants, don't worry, you don't need to.

Good Luck!


Tom Gardner
 

Be aware that on the silk screen two caps are reversed relative to the schematic and parts list. This is well documented elsewhere.

Simple course of action is to remove and replace one capacitor before moving onto the next.

I don't think a 2445 will lose its calibration constants. Having said that, I've pointed a video camera at the CRT while I cycled through the cal constants using the exer routines. If I lose the cal I'll go backĀ  and recreate the values from the video.

On 04/07/19 21:16, Bru H via Groups.Io wrote:
Hi all,
I have a Tek 2445 (Not 2445A or B).
Someone worked on the Power Supply before me and installed standard film caps in the Safety cap locations.
Plus the PS has the original electrolytic caps, so I will rebuild the whole thing.

Any Heads Up before I go in?
Is there any record of the calibration that I can save before I rebuild?
Will I loose the calibration on the scope due to the PS rebuild?


Chuck Harris <cfharris@...>
 

You won't break the collet if you don't turn the slotted
screw! The slot is there so you can loosen the nut without
turning the slotted screw (and breaking the collet).

Simply put a screwdriver in the slot, using an open end wrench,
loosen the nut until it is flush with the slot, and give the
nut a tap, while holding the fan impeller. The collet will
instantly release... remove the nut, and pull the collet (still
on the shaft) out of the impeller, and once you have done that,
use the screwdriver, if necessary, to pry the collet off of
the shaft. Prying is usually not necessary.

-Chuck Harris

Bob Koller via Groups.Io wrote:

There is no battery on the 2445, it has an EAROM chip instead.

The fan motor can be lubricated after removal from the PCB, by placing a drop of oil or two on the shaft, and allowing it to stand vertical overnight. Also, on the terminal end, in the center there is a small screw that adjusts the armature end play. You dig out the sealant, remove the screw, and again a drop or two of oil, and vertical storage to allow the oil to creep into the bearing. Replace the screw, and carefully adjust for a little end play of the armature.

It is almost certain that in removal of the fan impeller the collet will break. This is a constant problem with Siemens fan units. There are several ways to fix it. A search of the Forum should provide insight.

No worry about loss of the cal with any of this. No easy way to save the constants, don't worry, you don't need to.

Good Luck!




Bru H
 

Great advice on the lubrication.
Yes, the Fan is really delicate and I do not look forward to the removal procedure!


Bru H
 

I went through the Diagnostic Routines and came up with the following tests:
(Note that some of the tests pertain to the TV Option
All 00 - PASS
TEST 01 - PASS
TEST 02 - PASS
TEST 03 - PASS
TEST 04 - PASS
TEST 05 - PASS
BU TEST F1 - PASS
EXER 01 - 00 C1 00 C1
EXER 02 - 00 2048
EXER 03 - no code generated
EXER 04 - 417B 1997 07 8000
TV EXER 61 - LINE 1 COINCIDENT WITH FLD SYNC & LINE 1 OCCURS PRIOR TO FLD SYNC
(in the above I get the two statements by pushing the COUPLING switch up)

TV EXER 62 - LINE NO RESETS ON FLD1 ONLY & LINE NO RESETS ON EACH FLD
(in the above I get the two statements by pushing the COUPLING switch up)

BU EXER F1 - TV BU
BU EXER F2 - no code generated

It will be interesting to see if these codes change with the PS Rebuild. At least I have the data.


Bru H
 

Thank you for all of the Help!


 

Hmm, well the 2465s I have had a battery backup that I upgraded after doing the PSU recapping and fan lubrication as well as a custom heatsink for the U800 display driver.
Here's some pics etc.
https://hackaday.io/project/163890-tektronix-2465-series-servicing


Chuck Harris <cfharris@...>
 

2445 and 2465 are quite a bit different than the 2465A...
particularly in the controller department.

No battery, but rather an EAROM. No muffin fan, but rather
a siemens motor with a squirrel cage fan.

-Chuck Harris

Ancel wrote:

Hmm, well the 2465s I have had a battery backup that I upgraded after doing the PSU recapping and fan lubrication as well as a custom heatsink for the U800 display driver.
Here's some pics etc.
https://hackaday.io/project/163890-tektronix-2465-series-servicing