Author Topic: Tektronix 2335 oscilloscope No Power  (Read 1344 times)

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Offline radioman56

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Tektronix 2335 oscilloscope No Power
« on: July 27, 2017, 08:04:51 pm »
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
 

Offline alm

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Re: Tektronix 2335 oscilloscope No Power
« Reply #1 on: July 27, 2017, 08:27:17 pm »
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
 

Offline ivi_yak

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Re: Tektronix 2335 oscilloscope No Power
« Reply #2 on: July 28, 2017, 12:52:47 am »
send me pcb photo
eevblog
 

Offline tguillaume

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Re: Tektronix 2335 oscilloscope No Power
« Reply #3 on: September 04, 2017, 03:42:56 am »
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

 

Offline tggzzz

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Re: Tektronix 2335 oscilloscope No Power
« Reply #4 on: September 04, 2017, 09:22:58 am »
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
There are lies, damned lies, statistics - and ADC/DAC specs.
Glider pilot's aphorism: "there is no substitute for span". Retort: "There is a substitute: skill+imagination. But you can buy span".
Having fun doing more, with less
 

Offline bd139

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Re: Tektronix 2335 oscilloscope No Power
« Reply #5 on: September 04, 2017, 09:31:32 am »
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.
 

Offline oldway

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Re: Tektronix 2335 oscilloscope No Power
« Reply #6 on: September 04, 2017, 01:07:03 pm »
It is a 2335, not a 2235...... :scared:
2335 has only linear power supplies.... |O
 


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