Given:
Victor TT-71, neon lamp does not light, speed is lower than normal. This is subsequent some short circuit the owner does inside the device. No further details.
I found out the VICTOR QL7 have the same motor driver amd I downloaded the service manual that I attached here in case this manual is not already uploaded.
Looking at the diagrams I found out that at TP3 (same with pin5 of IC803) instead if that rectangular signal, I have nothing but 5VDC and a negative or positive short spike whenever I'm starting or stopping the motor and
Under the circumstances I suspect IC803 is defective. The bad thing, IC803 is NPC SC8043. Also I wonder if the crystal is fine (except that I wonder what can be wrong with a crystal after some short circuit).
Does anybody have any more suggestion?
Also, where can NPC SC4043 be sourced? Also, a crystal 9.054MHz?
Thanks in advance,
Corneliu
Hi!
Before suspecting any component, be sure to check whether all the (supply) voltage values that can be read on the schematic diagram are present.
Gábor
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Checked. The main voltage is a little bit higher, but the 5V for the oscillator is exactly what it should be.
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http://amp8.com/amp-etc/record/victor/tt-71.htm
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Yes, this is the next action if repair succeed (recapping). And yes, I know the variable resistors (VR) are a weak spot for this board, but here is not the case I think... because on IC803, between pin8 or pin7 which is V+ and pin5 which is an output there is a fixed value of 22ohms and I don't think this is the normal behaviour.
Corneliu
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hello:
https://www.utsource.net/pro/SC3043.html
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Thanks, but that link goes to the "Inquiry" action. Anyway I made an inquiry for this part. Also I did this on the SEIKO NPC page...
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