Tektronix 2335 oscilloscope No Power

[radioman56]

Hello Guys I Have a Question on my Tektronix 2335 oscilloscope That has No power.
I've never repaid one of these but price was cheep on ebay
a few days ago found a owners/Repair manual but not quite understanding it.has any one repaired these to bring it back to life
Much Thanks from Bill

[alm]

Plug in the power cord? Check the fuse? There is no way to tell with the extremely limited information that you provide.

This document may provide some guidance:
http://sphere.bc.ca/test/tek-parts/troubleshooting-scopes.pdf

[ivi_yak]

send me pcb photo

[tguillaume]

Hi I repaired a 2236 a while back.   It is similar.   The PSU is a switching power supply so very dangerous,  high voltage all over so be very careful!  First of all download the service manual and follow step by step.   There is also a tek scope repair guide which is great help.  On the PCB  there are a few jumper wires very useful to isolate the power supply from the rest of the circuit.  Get a variac to be able to progressively ramp up the power.  Without that you will end up blowing up components by the dozens.   A 75w lights bulb in series with the main power line can help if you don't have a variac.  Good luck!

Sent from my SM-G950F using Tapatalk

[tggzzz]

Hi I repaired a 2236 a while back.   It is similar.   The PSU is a switching power supply so very dangerous,  high voltage all over so be very careful!  First of all download the service manual and follow step by step.   There is also a tek scope repair guide which is great help.  On the PCB  there are a few jumper wires very useful to isolate the power supply from the rest of the circuit.  Get a variac to be able to progressively ramp up the power.  Without that you will end up blowing up components by the dozens.   A 75w lights bulb in series with the main power line can help if you don't have a variac.  Good luck!

Caution with using a variac with an SMPS. Join TekScopes and read
https://groups.yahoo.com/neo/groups/TekScopes/conversations/topics/139963 especially message 6
to understand why that can damage the scope

Caution with using a light bulb with an SMPS.
https://youtu.be/9jd9idAlXDY

[bd139]

This. Really annoys me that debug approach.

For those who can't be arsed to read that:

1. Watts in is relatively constant in and out of the SMPS. However as P=IV, lower voltage = more input current = more stress and more violent explosions.
2. Lamp is a non linear V-I device. This turns it in an oscillator as the source impedance changes as it warms up.

Use this rather stupid old tech with linear supplies only and even then I question the value other than for dropout tests and then only the variac. A lamp test is stupid when you can pretty much test all the likely problems away independently with a DMM BEFORE you have to even apply power.

[oldway]

It is a 2335, not a 2235......
2335 has only linear power supplies....