Sony HP-810 stereo system has no sound coming out of the record player

[vortalexfan]

Hello, I was given a Sony HP-810 AM/FM Stereo Record player combo receiver from 1972 several years ago by my old landlord and I repaired it and sold it to a friend of mine to give to his son as a birthday gift but then his son moved into a small apartment that he didn't have any room for the stereo in so then I got it back because it actually was having trouble with the record player not working right.

So I got the mechanicals of the record player working but now the electronics aren't working right as there is no sound coming out of the tonearm when you try to play a record, which at first I thought it might of been a failing cartridge because before the audio completely died the audio was distorted and was only coming out of the left channel and the right channel was barely audible which is usually a sign of a dying cartridge.

I then bought a new cartridge an AudioTechnica AT3600T cartridge and hooked up the new cartridge and I still have no audio coming out of the unit.

Any ideas as to what might be causing the phono stage on this stereo to be dead?

Thanks for your help.

[Electronic M]

Touch the signal hot lead or connect a known good audio source to see if it gets through. If it does you've got a dead NOS cartridge (not in heard of at that vintage and somewhat common on 50s-60s carts). The cables don't pass signal, and the radio works fine then something between there and the output of the function switch has failed (dead phono preamp?).

[vortalexfan]

Originally Posted by Electronic M

Touch the signal hot lead or connect a known good audio source to see if it gets through. If it does you've got a dead NOS cartridge (not in heard of at that vintage and somewhat common on 50s-60s carts). The cables don't pass signal, and the radio works fine then something between there and the output of the function switch has failed (dead phono preamp?).

The Radio part works fine, no issues there, but when I touch the tonearm I get a low volume hum out of the speakers (like a groundloop style hum) but nothing when I touch the tip of the needle and touching the wires for the cartridge doesn't do much either. So what I was thinking (and it seems like we might be on the same page here) maybe the phono preamp stage might have some failed capacitors or something like that that might be causing some trouble? It is an early 70s Sony, and I know some of the Japanese capacitors from that time period are now starting to go bad due to age (being that they are over 50 years old now.)

[zeno]

2 ways this can go. If the OEM cart was magnetic or ceramic cart.

1) ceramic has a high output. If you use it on a magnetic input stereo
it will blast you out if the room.
2) magnetics are very low output. Hook it to a ceramic input & you can
barely hear it at all.

SO the mag cart requires an extra amp stage that is NOT used for anything
else to work. BTW I have never seen a phono amp fail !

Try this. Unplug the audio cables from the turn table. Turn up the
stereo just a little & on phono. Touch the center pins & you should get
a loud hum. You are a free signal injector

73 Zeno
LFOD !

[vortalexfan]

Originally Posted by zeno

2 ways this can go. If the OEM cart was magnetic or ceramic cart.

1) ceramic has a high output. If you use it on a magnetic input stereo
it will blast you out if the room.
2) magnetics are very low output. Hook it to a ceramic input & you can
barely hear it at all.

SO the mag cart requires an extra amp stage that is NOT used for anything
else to work. BTW I have never seen a phono amp fail !

Try this. Unplug the audio cables from the turn table. Turn up the
stereo just a little & on phono. Touch the center pins & you should get
a loud hum. You are a free signal injector

73 Zeno
LFOD !

The Original Cartridge was a Sony Branded Cartridge and I was assuming it was a Magnetic Cartridge because it looked just like a 1/2" mount Magnetic Cartridge the way it was built and the way it was mounted, but then I had an old Shure Cartridge that was a Magnetic Cartridge attached to the unit and it was working for a while (albeit without any audio out the right channel and lower volume out the left channel which to me sounded like the symptoms of a failing magnetic cartridge but then when I bought a replacement Magnetic Cartridge (an Audio Technica AT3600) and installed it there was no audio coming out of the speakers at all period not even with the volume turned up full blast (because even if it was meant to have a ceramic cartridge and I had a magnetic cartridge wired up to it, it still should of produced audio even at full blast but it wasn't even doing that.)

The original cartridge that this unit had equipped with it from the factory was a Sony VL-30G Cartridge which I'm pretty sure is a magnetic cartridge from what info I was able to find about it on the internet when I looked it up.

To answer your question, yes everything else on the stereo system works just fine independent of the record player (the tuner works flawlessly and has probably the most sensitive tuner I have heard on an older all-in-one unit) and the tape input works fine, just the phono mode doesn't work, when I touch the tonearm I get a loud hum out of the unit, but nothing when I actually touch the physical wires themselves that go from the cartridge to the RCA Jacks on the underside of the turntable, and nothing when I touch the individual RCA Cables when they are disconnected from the turntable.

So with that in mind, is it possible (even though its rare for it to happen) that the phono preamp stage did indeed die in this stereo system, like perhaps some capacitors may have failed causing an issue with the phono preamp stage of this stereo? It does have some of those old school Elna caps that are notorious for failing in it.

[zeno]

Looked up a few things last night. Set uses a Dual TT so 99.9% sure its a mag cart. Dual is a step up from the usual BSR, VM, Garrard that go either way. Its
German also so pricy & a PIA to work on.
Pre amp usually on a separate little PCB. Be sure its getting B+. Also
check the TT & see if it has audio muting switches. If so
it may have a mech problem like muting stuck on.

Zeno