TEKTRONIX 2445 150 Mhz SCOPE

[sesosoft]

I recently bought a used TekTronix 2445 150 Mhz scope from a “friend”; he had had this scope in his garage for god knows how long. When we first gave this puppy the smoke test, it worked fine! The trace came on crisp and within focus, all the buttons and dials worked fine, no smoke came out and nothing smelled either. This weekend as I tried it out, connected it to a two 2N3904-transistor flip-flop circuit, on a 15 volts power supply it; it worked fine for about 20 minutes then w/o any warning, complaints or any kind of fuzz at all the trace on all channels simply went off. The “Beam Finder” finds nothing now. All of the LED still work exactly on the settings I left them. The screen illumination works just fine too. But there is no trace at all. No burnt smell, no noise, no rattles. But it still has power. The power light is on along with all of the other LEDS.
Help. 
Thank you very much.

 

[DerStrom8]

Post removed

 

[bountyhunter]

It's almost guaranteed the high voltage supply blew up. All scopes generate an internal voltage rail of several kV by various means to get enough potential to fly electrons from the gun at the back to the screen. And, as is also the case in TV's which use similar circuitry, the HV supplies' components are under a lot of stress and fail with some regularity.

Without a schematic, you have zero hope of fixing it.

 

[KeepItSimpleStupid]

The service manual is available from the BAMA site here: https://bama.edebris.com/manuals/tek/2445 Join the tekscopes yahoo group and then look through the archives. groups.yahoo.com Once you have looked through the archives to see if your problem has been addressed before then you can ask questions. It may take a while to get your membership approved.

Guaranteed one of the first things to do is check the power supply voltages. Some of the TEk stuff is plaqued with bad tantalum capacitors. Leaky electrolyte is a tell-tale sign.