Re: PG506 Repair - I had a Great Day today/

Albert Otten

Just curious I measured in my PG506, B03xxxx.
+5V1 was 4.75 V, for convenience measured between pins 16 and 8 of U673.
+5V was 5.05 V, measured between pins 10 and 5 of U668.
About 0.3 V saturation voltage of Q70 is normal I think.

Even after 2 hours running with the display on the outside of T130 was not hotter than 50 degrees C, while the TM501 transformer is already almost 40 degrees C (measured with cheap IR thermometer). I don't know how much hotter the winding was.


On Sun, May 2, 2021 at 02:44 PM, tek_547 wrote to Michael:

If you have the possibility pls check the 5V1 at the collector from Q70, mine
is 4,75V. For TTL logic (U670, 671, 673 & 675) this is the absolute minimum.
Maybe this is the reason of the problem so I am interested in the value from
your PG506.

And also look that if inside your PG506 T130 in the power supply is about
70°C when the STD AMP switch is activated. So almost not possible to you put
your finger on the windings of it. Is this on yours the same?
Thanks so far and hopefully you have some suggestions, Rene

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