Re: Wacky voltage readings


Charles W. Powell
 

Thanks for the suggestions Alan. I show 19.91K from R2 to ground, and 9.96K for R1 plus 9.95K for R2. C6 shows resistance across it of 9.96K, which it should since it parallels R1, so I do not identify a problem there. I get 3.98V at R2 on one side, and nominally 0.15 volts on the other side. That is also what I show +/- 0.05V at the four points on T1 which is quite low for the published specification of ~2.36V. And I still have the following on IC-5, way out of spec:

pin 1 10.99v (2.64)
pin 2 0.46v (2.46)
pin 3 0.17v (2.26)
pin 4 0.00v (0.00)
pin 5 0.12v (2.28)
pin 6 0.15v (2.46)
pin 7 12.1v (2.44)
pin 8 12.8v (11.67) (input voltage 13.1, bus voltage is 12.8v after the protective diode.)

IC 6 is worse:

pin 1 11v
pin 2 11v
pin 3 11v
pin 4 0.0v
pin 5 11.4
pin 6 11.4
pin 7 11v
pin 8 128v


Is it possible IC-4 is fried and that’s where the voltages or lack there of originate?

73,

Charles

On Jul 11, 2018, at 2:10 AM, Alan G4ZFQ <alan4alan@gmail.com> wrote:


I get normal voltage readings at Clk0 and Clk1. That's where it stops. Voltage readings are very low on the transformer test points (pins 5, 6, 7, 8)
Charles,

Get this right first. It all starts here.
R1/2 soldered, no bridges?
5V on R2?
No short to ground at C6?

73 Alan G4ZFQ

but then I get to the ICs. Almost all of them, instead of
showing ~2.5 - 5 volts on the various pins, show > 11 volts. The really odd thing is that some of these are in the audio chain, and despite that, I at least have sidetone audio and variable hiss with the volume pot. I can't for the life of me figure out why this is so high, nearly across the board. I also know it receives down to at least -73 dBm. Not great, but it's a start.

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