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Old 19th Oct 2020, 5:24 pm   #17
ColinTheAmpMan1
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Join Date: Jan 2012
Location: Wimbledon, London, UK.
Posts: 1,362
Default Re: Tektronix 7623A poser

Quote:
Originally Posted by tony brady View Post
Colin, did you see that C1193, C1198 & Q1195 all have a triangular symbol for ground? this goes back via pin 3 of the connector P1185, pin 3 of P1195 and pin 1 of P1180 to the power supply connector P870.

be careful that the connector P870 is correct because there is a mistake in the pdf of the manual that I Have where pins 1 & 2 both appear to be +15V unreg depending on which end you look. ( on diagram 7 pin 2 of P870 is +15V unreg whereas on diagram 8 pin 1 is shown as +15V unreg from the fuse). so check the orientation of P1180 and buzz the unreg +15V from the fuse to L1198 and the 0V from the psu to the triangle marked grounds on Q1195 etc
Many thanks for that, Tony. I did notice the triangular symbols on those three components, but not on P1195. I just thought that Tek had got a bit lazy and used the normal chassis symbols and the triangles to mean the same thing, but it was me who was the lazy one! I will check all that stuff out; maybe the board isn't damaged - it certainly doesn't have any burn-mark evidence from the top. It would be nice if this can be repaired with just two new components. The ones that I have on order are off eBay, but the capacitors are Vishay-BC, even though only 85 degrees, unfortunately (I would have preferred 105 degrees). The inductors are Fastron and are capable of 2.5A, so might give a little more leeway (they are 77A-800M-00).

Colin.
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