User manual?

 

hi lojo,
Welcome to AAC.
Check out this link.
E
https://www.allaboutcircuits.com/test-measurement/oscilloscopes/cs-4000-series-4035/manual/

 

hi lojo,
Welcome to AAC.
Check out this link.
E
https://www.allaboutcircuits.com/test-measurement/oscilloscopes/cs-4000-series-4035/manual/

Thanks so much, let's see if adjusting the settings gets me anywhere. Unit powers up, but no trace.

 

Hello,

Here is a link to the service manual of the CS4025.
It could be the 20 MHz version of yours:
https://www.jabse.com/L0tlbndvb2QvQ1M0MDI1LnBkZg

Bertus

 

Hello,

Here is a link to the service manual of the CS4025.
It could be the 20 MHz version of yours:
https://www.jabse.com/L0tlbndvb2QvQ1M0MDI1LnBkZg

Bertus

Thanks, but I got the 4035 owner's manual.

 

The service manual might be needed when something needs to be repaired or internaly adjusted.

Bertus

 

Set both CH1 and CH2 inputs to GND.
Set the MODE to X-Y.
Adjust the INTENSITY control to max.
Adjust both CH1 and CH2 POSITION (possibly to mid position).

Try to find a single dot on the screen.

(Photo shown below is for reference only. It does not represent the settings described above.)

 

Well, following MrChips advice & the user manual, set up everything and - no trace. Unit powers on but no mojo. I don't really need this as I have a digital Hantek, but it was given to me & I thought I might repair it to give away. Where to start? Anybody want it? I'm in Rawdon Quebec Canada.

 

Are you able to take the cover off and have a look at the CRT?
Look at the neck of the CRT where the socket connects to the tube. Look to see if the heater is glowing.
You will have to turn off the room lights in order to see a faint orange glow.

 

Are you able to take the cover off and have a look at the CRT?
Look at the neck of the CRT where the socket connects to the tube. Look to see if the heater is glowing.
You will have to turn off the room lights in order to see a faint orange glow.

Did that today, cover off, I'll do that tomorrow. The CRT is a Panasonic...

 

Hello,

Here is a link to the service manual of the CS4025.
It could be the 20 MHz version of yours:
https://www.jabse.com/L0tlbndvb2QvQ1M0MDI1LnBkZg

Bertus

That turned out to be nothing for CS4025...?

 

Are you able to take the cover off and have a look at the CRT?
Look at the neck of the CRT where the socket connects to the tube. Look to see if the heater is glowing.
You will have to turn off the room lights in order to see a faint orange glow.

Total darkness no glow - this means heater is dead? If it's like any audio tubes I know, no heater no working. I imagine the CRT is unobtanium? I looked for the usual signs of bad components - burnt resistors, swollen caps etc - but all looks good. Still trying to get the online service manual with no success.
Next move?

 

That turned out to be nothing for CS4025...?

After more internet time I did manage to get the service manual, thanks Bertus.

 

Total darkness no glow - this means heater is dead? If it's like any audio tubes I know, no heater no working. I imagine the CRT is unobtanium? I looked for the usual signs of bad components - burnt resistors, swollen caps etc - but all looks good. Still trying to get the online service manual with no success.
Next move?

No glow means one of two things, (1) bad CRT heater, (2) no power to heater.
Check the voltage (AC) going to the heater.
Check the voltage across R52.

Or, with the power off, measure the resistance across R52. If you measure higher than 7.5 Ω, then R52 is bad.

 

Today's update - R52 is 7.6 ohms (thanks for the diagram, hard to find that little bugger)
Didn't do any power on voltage checks.
What i did do was check the circuit diagram & pull off the 6 pin connector that feeds the small board soldered to the CRT.
Pins 5&6 labeled 'H' would seem to be the heater, seems to be NC between one of those pins?
Then presuming I could test the heater from the back of the board, I have open circuit. This means heater is dead?

 

If you measure open circuit across the H pins on the PCB after removing the CRT connector, then assuming R52 is OK and there are no track breaks or open wiring to the transformer, the transformer is open circuit. You can measure across the H pins of the unplugged connector to check the heater resistance of the CRT.

 

If you measure open circuit across the H pins on the PCB after removing the CRT connector, then assuming R52 is OK and there are no track breaks or open wiring to the transformer, the transformer is open circuit. You can measure across the H pins of the unplugged connector to check the heater resistance of the CRT.

What I did was measure the voltage on pins 4,5,6 with the connector removed. Between 4 (ground) & 5 or 6 - 3.8VAC each for a total of 7.6VAC, close enough to the 8VAC spec. So power is there.
Measuring across the H pins reads 18 ohms - but there are a few components on the board soldered to the CRT...
With some difficulty I measured the 2 pins on that board which are soldered to the CRT - open, I guess the heater is fried.
Pity.
Thanks for your help.

 

Remove the neck board from the CRT and measure the resistance of the heater pins directly to check for an open circuit there. If good, it's a problem with either R52, a bad solder joint, or a break in the board somewhere. Check the solder joints on the neck board where they connect to the CRT socket, the heater pins often get dry joints!

 

Remove the neck board from the CRT and measure the resistance of the heater pins directly to check for an open circuit there. If good, it's a problem with either R52, a bad solder joint, or a break in the board somewhere. Check the solder joints on the neck board where they connect to the CRT socket, the heater pins often get dry joints!

Thanks for that advice - I didn't realize the neck board could be removed! So i did that & gave me access to the CRT pins, the heater is open, the unit is a boat anchor.
It's a gold mine of parts but not for me.
Thanks to all for their help!