07-19-2014, 10:50 PM
I was going to take this circa 1973 Fisher 170 to Midwest Audiofest last week along with several others to try and sell.
I replaced all of the electrolytic capacitors in the audio section and power supply.
Here's the deal: On headphones, it plays well. But on speakers, it has a lot of distortion.
I made some voltage measurements. Looking at the chart below, notice that I measured voltage with headphones (second column) and with speakers (third column). The fourth column reflects voltages as listed on the schematic.
I measured all four output transistors, plus the two transistors in the power supply, as well as the positive terminal of main filer capacitor C55.
[Image: http://www.philcoradio.com/images/phorum..._chart.jpg]
Here is the audio/power supply schematic. Click the thumbnail to be taken to another page, where you need to click the magnifying glass icon at lower right, then click it again, to see the schematic full size:
[Image: http://www.philcoradio.com/images/phorum..._schem.jpg]
If you look at the full size schematic, you will notice that in some places, two voltages are given. The higher voltages are for Model 180, a receiver that was a step up from the 170. The lower voltages are for the 170.
Your thoughts and suggestions would be most appreciated. I've cleaned this receiver up...it looked like crap when I acquired it and looks a lot better now...I just want it to play as well as it now looks.
Thanks.
I replaced all of the electrolytic capacitors in the audio section and power supply.
Here's the deal: On headphones, it plays well. But on speakers, it has a lot of distortion.
I made some voltage measurements. Looking at the chart below, notice that I measured voltage with headphones (second column) and with speakers (third column). The fourth column reflects voltages as listed on the schematic.
I measured all four output transistors, plus the two transistors in the power supply, as well as the positive terminal of main filer capacitor C55.
[Image: http://www.philcoradio.com/images/phorum..._chart.jpg]
Here is the audio/power supply schematic. Click the thumbnail to be taken to another page, where you need to click the magnifying glass icon at lower right, then click it again, to see the schematic full size:
[Image: http://www.philcoradio.com/images/phorum..._schem.jpg]
If you look at the full size schematic, you will notice that in some places, two voltages are given. The higher voltages are for Model 180, a receiver that was a step up from the 170. The lower voltages are for the 170.
Your thoughts and suggestions would be most appreciated. I've cleaned this receiver up...it looked like crap when I acquired it and looks a lot better now...I just want it to play as well as it now looks.
Thanks.
--
Ron Ramirez
Ferdinand IN