I'm not stupid: Not getting 5.333V
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I'm not stupid: Not getting 5.333V

by janvanvolt on Tue Dec 25, 2012 11:15 pm

Hi,

i've (more or less) succeeded in making another x0xbox, however i am stuck with the PSU and i've nearly exchanged all parts and
still have the problem.

My readings are:

-AC Input = 10.74V
-Volt C3 = dc 14,11v
-Volt C5 = dc 13,62v
-dc total = 27,7V
-7805pin = 5V
-C1= 5.92
-Trim= 4.93 to 5.27V
-J4 12V= 10.97V

d44 d45 juncture = 0.52V
d45 r5 juncture = 1,03v
r5 tm6 juncture = 1,72v
tm6 r4 juncture = 2,29v
r4 d46 juncture = 3,88v
d46 d47 juncture = 4,40V
d47 r3 juncture = 4,74V
r3 r2 juncture = 24,7v
r2 r1 juncture = 27,7V

Anybody got an idea ? PSU is a Doepfer PSU with 9VAC 500mA, but i tried various AC PSUs (up to 12V 1500mA) - but still
the same readings on the TRIM.

Any help appreciated.
janvanvolt
 
Posts: 17
Joined: Fri May 23, 2008 8:08 pm

Re: I'm not stupid: Not getting 5.333V

by MMM on Thu Dec 27, 2012 5:56 pm

Check at J4; also check the supply under load.

It has been observed that the internal impedance of the meter can mess up the measurements significantly. For example, I'm usually getting different readings on pin 5 and pin 7 of IC23 (which should actually be identical).
MMM
 
Posts: 431
Joined: Tue Apr 24, 2012 12:51 am