Tektronix 465 298xxx serial,  trace not centered - Page 1
Forum section: electronics / repair

author: yo0
author_rank: Regular Contributor
timestamp: January 17, 2019, 03:47:19 am
content: hello from Mexico, i have a tek 465 with trace not centered in the screen, it moves up and down when change volt/div knob, i need readjust with the vertical adjust knob, this is worst in channel 2, in some settings it dissapears up or down in the visible screen area and in others moves and still visible, i need to readjust the vertical position for see and/or center it again.any suggestion or idea?best regards.Pio

author: particleman
author_rank: Regular Contributor
timestamp: January 17, 2019, 03:57:51 am
content: Get the manual. There are adjustments to correct that.

author: med6753
author_rank: Super Contributor
timestamp: January 17, 2019, 07:35:28 pm
content: The DC balance for both channels on the Invert Balance for channel 2 need to be adjusted. They are located on the vertical board.Do you have a service manual?

author: yo0
author_rank: Regular Contributor
timestamp: January 17, 2019, 08:28:58 pm
content: thanks to both. yes, i have the sm for >250000 serial, any precaution or advice in the stated procedure?by the way if i center the trace in channel 1 and 2... just in 10mv 0.1v, 1v, 10v settings the trace remains centered. the variation in the trace in other settings is worst in channel 2.best regards.Pio

author: tggzzz
author_rank: Super Contributor
timestamp: January 17, 2019, 09:30:30 pm
content: Have you followed the faultfinding procedures in your copy of the service manual?

author: yo0
author_rank: Regular Contributor
timestamp: January 17, 2019, 09:39:22 pm
content: Quote from: tggzzz on January 17, 2019, 09:30:30 pmyes and i can´t find something related, do you think is a failure instead adjustment related?best regards.Pio

author: Paul Moir
author_rank: Frequent Contributor
timestamp: January 17, 2019, 11:20:26 pm
content: Are the signal attenuations correct at low frequencies, or is it just a DC offset? Cracked solder joints in the attenuator modules were pretty common in the early models. Caution for repair: they were soldered with a special silver solder.

author: yo0
author_rank: Regular Contributor
timestamp: January 17, 2019, 11:42:32 pm
content: Quote from: Paul Moir on January 17, 2019, 11:20:26 pmthank you, i think yes, for example the calibration signal at 1 khz is measured correctly, in the past i had a tek 475 with a problem in one of the modules (one of the volt/div setting was low and distorted but in correct position), just made a reflow at the four pins with a very thin soldering tip ( no damage to the plastic boxes ) and all ok, so i think dc offset issues onlyPio

author: rf+tech
author_rank: Frequent Contributor
timestamp: January 18, 2019, 12:51:17 am
content: QuotePerforming Vertical Adjustments steps 7 through 14 should resolve this very problem.Once these alignment steps have been performed, the trace should remain where it is placed vertically, when the Volts/div knob is turned *and* when the vernier knob is turned.Some repetition is required, as the optimum adjustment point can be quite sensitive, to obtain zero shift.RF+ Tech

author: yo0
author_rank: Regular Contributor
timestamp: January 18, 2019, 01:01:25 am
content: Quote from: rf+tech on January 18, 2019, 12:51:17 amThank you!Best regards.Pio

author: yo0
author_rank: Regular Contributor
timestamp: January 19, 2019, 11:49:39 pm
content: Quote from: rf+tech on January 18, 2019, 12:51:17 amAlready adjusted, thank you very much.Best regards.Pio