Stereo Hardware Troubleshooting Question

[MishaK]

Hey people,

I'm having a little problem with my stereo I hope someone here can help me solve. Following issue:

I have a Technics turntable and a Technics amp/receiver. As of recently, there is no sound coming out of the right speaker when I am using the turntable. I first checked the speaker cables to make sure nothing is wrong there. Everything was fine and CD or tuner produces proper stereo sound. So I checked the wires connecting the turntable to the amp. Turns out, when I attach the L cable from the turntable at the R jack on the amp and vice versa, it's again the right speaker that doesn't work. IOW, by switching the cables, I get the R sound from the turntable out of the L speaker, but the R speaker still doesn't work. That leads me to believe that the problem is with the amp itself, not the wiring, nor the turntable. I bought both pieces of equipment around 2000/2001, so there isn't a shred of manufacturer warranty left, I'm sure. Any ideas what it might be and how to fix it? Thanks in advance.

[Scarpia]

Hey people,

I'm having a little problem with my stereo I hope someone here can help me solve. Following issue:

I have a Technics turntable and a Technics amp/receiver. As of recently, there is no sound coming out of the right speaker when I am using the turntable. I first checked the speaker cables to make sure nothing is wrong there. Everything was fine and CD or tuner produces proper stereo sound. So I checked the wires connecting the turntable to the amp. Turns out, when I attach the L cable from the turntable at the R jack on the amp and vice versa, it's again the right speaker that doesn't work. IOW, by switching the cables, I get the R sound from the turntable out of the L speaker, but the R speaker still doesn't work. That leads me to believe that the problem is with the amp itself, not the wiring, nor the turntable. I bought both pieces of equipment around 2000/2001, so there isn't a shred of manufacturer warranty left, I'm sure. Any ideas what it might be and how to fix it? Thanks in advance.

Your conclusion seems right.  I'd pop the top of the amp and take a look.  If you're lucky you have a broken solder joint and the wire connecting the circuit board to the connector phono connector fell off.  You could solder it back on.  You might also jiggle the various switches, they are usually the first things to fail in a piece of electronic equipment.  Maybe the input selector switch has a bad contact, and could be fixed by working it, or by spraying some contact cleaner in.  If that's not it, probably a transistor or OpAmp failed.  If you don't have familiarity with electronics and test equipment, you're going to have to take it to a repair shop.  Another option would be to buy an external phono amp, which would boost the signal and make it suitable for a free line-level input.

[KevinP]

Does the amp have a dedicated phono input? If not then either the turntable has one built-in (as mine does) or you have an external phono amp.

[MishaK]

Does the amp have a dedicated phono input? If not then either the turntable has one built-in (as mine does) or you have an external phono amp.

Dedicated phono input.

Your conclusion seems right.  I'd pop the top of the amp and take a look.  If you're lucky you have a broken solder joint and the wire connecting the circuit board to the connector phono connector fell off.  You could solder it back on.  You might also jiggle the various switches, they are usually the first things to fail in a piece of electronic equipment.  Maybe the input selector switch has a bad contact, and could be fixed by working it, or by spraying some contact cleaner in.  If that's not it, probably a transistor or OpAmp failed.  If you don't have familiarity with electronics and test equipment, you're going to have to take it to a repair shop.  Another option would be to buy an external phono amp, which would boost the signal and make it suitable for a free line-level input.

Thanks, I'll have to give that a try... next time when the baby isn't sleeping. 

[Daverz]

By coinkadink, I blew a fuse in my big BAT amp over the weekend -- in the right channel.  It then blew the replacement fuse, so it has to go back to the shop.  Hopefully I don't herniate myself moving the thing.  Now I'm wondering why I bought the monster.

[Scarpia]

I understand your frustration.  I have an NAD 2200 power amp with output relays that are a bit the worse for the wear and sometimes make intermittant contact, causing a static sound.  The thing is 25 years old and the relay is no longer made.   However, I managed to find the data sheet for the original relay and it is an automotive relay that was designed to turn the headlights of a car on and off.  So, I ordered automotive relays with more-or-less identical specifications and will be soldering them in.  My plan is that after this operation, the amp will either work perfectly, or explode, allowing me to buy a new one in good conscience.   

[RJR]

Check for bad fuses if there are any in your amp/receiver.

[Archaic Torso of Apollo]

OK, my turn!

I have a problem that has left me somewhat mystified. Recently, when playing LPs, I have noticed a fuzzy, sometimes crackly sound at higher volumes. It is particularly notable when there are sudden jumps in volume (as in orchestral music), and on high piano and violin notes. It is bad enough to spoil the listening experience.

I don't think it's a stylus problem - I have swapped styluses for comparison, same problem on both. It's not a speaker problem - I played some CDs and the speakers sounded fine. I don't think it's a problem with the integrated amp, since that seems to function well. I also checked the cable connections, they seem to be OK.

This leaves the turntable and the pre-amp as potentially guilty parties. My equipment (all bought in 2013) is a Pro-Ject Debut Carbon TT, NAD CD player, amp and pre-amp, and B&W speakers.

What do you think?

[Baron Scarpia]

Pre-amp is a separate unit dedicated to phonograph amplification?

Well, since CDs play fine it could be anything in the phonograph signal chain, the pre-amp, the cartridge itself. Best to start with the simple, inexpensive things. Connectors and switches are usually the first thing to fail. Try jiggling everything. Replace the cables, and check those flakey little connections to the back of the cartridge. Sometimes a cable seems fine but has an internal defect which causes intermittent failure.

[Archaic Torso of Apollo]

Pre-amp is a separate unit dedicated to phonograph amplification?

Yes.

I took your advice to fiddle with the connections. I unplugged the cables between the turntable and pre-amp and then plugged them back in. Playing my test record, everything seemed back to normal, or nearly so. Is it possible there was some un-discharged electricity in there gumming things up, or something like that? (I hadn't touched those cables since first setup, 5 years ago.)

Thanks for the suggestion. Maybe I will unplug the cables again for a longer period of time and see if it makes any difference.

[Daverz]

Removing and replacing the cables probably removed some oxidation.  I would suggest getting some DeOxit for cleaning the connections.

[Baron Scarpia]

Yes.

I took your advice to fiddle with the connections. I unplugged the cables between the turntable and pre-amp and then plugged them back in. Playing my test record, everything seemed back to normal, or nearly so. Is it possible there was some un-discharged electricity in there gumming things up, or something like that? (I hadn't touched those cables since first setup, 5 years ago.)

Thanks for the suggestion. Maybe I will unplug the cables again for a longer period of time and see if it makes any difference.

I don't think static electricity should be able to build up, but anything is possible. I think the issue is that the "RCA connector" is an extremely poor design which has been grandfathered in to audio equipment, despite the fact that much better connectors have been subsequently designed. Probably there was a poor contact, which was resolved when you removed and plugged back in again. The signals that pre-amps, CD players and amps sent back and forth are robust and relatively immune to flakey connections. But the phono cartridge generates a very weak signal that the pre-amp has to amplify with high gain, and is particularly vulnerable to a less-than-ideal connection.

Removing and replacing the cables probably removed some oxidation.  I would suggest getting some DeOxit for cleaning the connections.

Good suggestion.