I took the power supply out to look at it again so didn't check the voltage across it, but it is testing as 10.5ohm, so should be good. The other resistors look to be testing at the correct ohms as well.
Chris
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--- In TekScopes@..., "Tom Miller" <tmiller11147@...> wrote:
Those unregulated supplies all look good. I would concentrate on the +87 first since all the others are dependant on it. You might check the drop across R1221, the current limit shunt. At least check the resistance.
Tom
----- Original Message -----
From: Chris
To: TekScopes@...
Sent: Sunday, February 17, 2013 8:39 PM
Subject: [TekScopes] Re: Tektronix 2465 capacitors etc.
All voltages measured in the scope with everything hooked up. I just got done checking the voltages pre-regulator.
At J233A I get:
pin 5 (87v unregulated) 97.6v
Pin 3 (42v unregulated) 49.0v
And at J234A I get:
pin 5 (15v unregulated) 18.94v
Pin 4 (5v unregulated) 6.64
Pin 2 (-5v unregulated) -6.92v
Pin 1 (-15v unregulated) -18.54v
Based on the unregulated values, I believe the issue must lie in the regulator portions, and since I'm getting the 97.6v pre-regulated it would seem to me the voltage doubler is working. I also double checked and verified the 10v reference voltage at the test point on the main board as well as the J121 connector that feeds the main board. (I figured this was important to double check as the regulators all are based off the 10v reference as I read it). Of course this is where I wish to learn more - I understand what the individual components do but I still somewhat struggle to see what the assembly as a whole is doing, which is why I'm trying to get into all this, so maybe my understanding is skewed. :)
At any rate, it would seem to me that with the unregulated voltages where they're at, that the issue would have to lie within the follow area:
Yes? No? I mean I have the correct voltages on the left side of those three groups, and the wrong voltages on the right side, so it would seem that's where I should look next?
Thanks for helping this newb out!
Chris
--- In TekScopes@..., "Tom Miller" wrote:
>
> The +87 is from a doubler and added to the +42. I would take a close look at the three 10 uF caps and all the diodes in that area. Be sure to only use fast diodes for any replacements.
>
> Since you recapped this unit, don't overlook the fact that bad capacitors can come from the factory new. Did you measure all these voltages in the scope or on an external load?
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> Regards,
> Tom
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