Re: TDS 640 Noisy Vertical Signal at Fast Horizontal Sweep Rate
Dear Scott,toggle quoted messageShow quoted text
from my experience I can give you the following advice:
The TDS 640 has no FLASH ADC like the TDS 744 or equivalent scope, but
uses an analogue bucket-brigade device like memory (CCD), called the
FISO (Fast in Slow out). It is the rectangular PQFP Chip U850 in the
center of the 4 heatsinked chips (T&H). Under 10 usec/Div the CCD is
bypassing, above it is doing the sampling. I would start to look around
U850, it's power supply, and control signals. Maybe a corroded trace?
Worst case: U850 is dead.
TNX to Hakan again.
br and good luck,
I have a TSD 640 that I recently re-capped. It works fine, but Channel 4 appears to be dead. Looks like the input hybrid on that channel is dead.
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