Old thread, but I thought I'd add a few comments for others who are working on one of these. I just finished cleaning up a VR-5505 and found a few things:
- There are 4 - 2SC458 transistors on the phono preamp. I changed them out for KSC1845s which eliminated noise issues.
- I also replaced the 2 - 2SC458s on the tone board since the ones on the phono board were noisy.
- All 8 of the small indicator lamps for speaker/source were out - they are supposed to be 6V 35mA but I substituted 12V 70mA which are readily available (cheap) and worked well. Bright enough and they draw about 40mA at 6.9VAC which is what I measured for actual voltage.
- Dial lamps were also out. The schematic shows 8V 150mA which are not very common so I used 6.3V 150mA (#40) lamps. I know they won't last as long with the measured 6.9VAC supply, but they are easy to change and readily available.
- The stereo lamp was not working - I replace it with the proper 6V 35mA lamp since that circuit can be a bit sensitive. I also replaced the 4 - 2SC711 transistors in that section of the tuner. One read really low hfe so they all went. I used 2SC945s (KSC945). Worked perfectly.
- Grounding: The grounding in this receiver had me scratching my head for a while. The speaker outputs, the tuner and all of the lamps are shown with chassis grounding points, but the rest of the circuits including amp and power supply don't connect to chassis ground at all according to the schematic. Some resistance measurements seemed to confirm that everything was, in fact, grounded through the chassis, so I added ground straps to various places to ensure good grounding. Not surprisingly, voltage reading that were somewhat erratic when I started working on it all became very stable. The tuner in particular was working intermittently with B+ voltages all over the place - that was resolved with improved grounding.
I suspect the OPs issues with fading output may have been related to the grounding issues I found . . . Maybe not, but something to consider if you work on one of these.
Rich
- There are 4 - 2SC458 transistors on the phono preamp. I changed them out for KSC1845s which eliminated noise issues.
- I also replaced the 2 - 2SC458s on the tone board since the ones on the phono board were noisy.
- All 8 of the small indicator lamps for speaker/source were out - they are supposed to be 6V 35mA but I substituted 12V 70mA which are readily available (cheap) and worked well. Bright enough and they draw about 40mA at 6.9VAC which is what I measured for actual voltage.
- Dial lamps were also out. The schematic shows 8V 150mA which are not very common so I used 6.3V 150mA (#40) lamps. I know they won't last as long with the measured 6.9VAC supply, but they are easy to change and readily available.
- The stereo lamp was not working - I replace it with the proper 6V 35mA lamp since that circuit can be a bit sensitive. I also replaced the 4 - 2SC711 transistors in that section of the tuner. One read really low hfe so they all went. I used 2SC945s (KSC945). Worked perfectly.
- Grounding: The grounding in this receiver had me scratching my head for a while. The speaker outputs, the tuner and all of the lamps are shown with chassis grounding points, but the rest of the circuits including amp and power supply don't connect to chassis ground at all according to the schematic. Some resistance measurements seemed to confirm that everything was, in fact, grounded through the chassis, so I added ground straps to various places to ensure good grounding. Not surprisingly, voltage reading that were somewhat erratic when I started working on it all became very stable. The tuner in particular was working intermittently with B+ voltages all over the place - that was resolved with improved grounding.
I suspect the OPs issues with fading output may have been related to the grounding issues I found . . . Maybe not, but something to consider if you work on one of these.
Rich
I am contemplating maybe going LED but probably just go incandescent. They are pretty small and only two are lit at a time. I got all 8 of the old bulbs unsoldered this morning. The tuner dial bulb is also out so I will need to get one of those. May replace all lights while I am in here.
