Hello.
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painless2019
- Beginner
- Posts: 3
- Joined: Thu Apr 02, 2020 11:37 am
Hello.
I am going to use the PV-1 I bought in 1978 again for the first time in 40+ years. But I can't fix the 120Hz hum. I came to this site because I need a circuit diagram to study.
Re: Hello.
Welcome to CJO, nice to have you with us.
You can find the schematic to the PV-1 here: https://www.conradjohnsonowners.com/vie ... f=17&t=128
Just out of curiosity, are you sure the hum is 120 Hz (and not 60 Hz)? It's rather unusual to have a 120 Hz hum but very common to have a 60 Hz hum.
You can find the schematic to the PV-1 here: https://www.conradjohnsonowners.com/vie ... f=17&t=128
Just out of curiosity, are you sure the hum is 120 Hz (and not 60 Hz)? It's rather unusual to have a 120 Hz hum but very common to have a 60 Hz hum.
-admin
Home Theater in Member Gallery
Main stereo: ART Amplifier and ET7s2. 2nd stereo: PV-14L and MV-55. Previously Owned: PF2 preamp, Evolution 2000 Amp, PV-12AL preamp, D/A-2b Vacuum-Tube Digital Processor.
Home Theater in Member Gallery
Main stereo: ART Amplifier and ET7s2. 2nd stereo: PV-14L and MV-55. Previously Owned: PF2 preamp, Evolution 2000 Amp, PV-12AL preamp, D/A-2b Vacuum-Tube Digital Processor.
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painless2019
- Beginner
- Posts: 3
- Joined: Thu Apr 02, 2020 11:37 am
Re: Hello.
thank you all.
Unfamiliar with the style of this site, can not download the schematic of PV-1 well. Maybe I'm accessing it on a Mac?
Two players are connected to Phono 1 and 2, respectively. There is a low hum that seems to be 60Hz from both, and a little 120Hz hum is added from one.
It seems that there is poor contact around the ground terminal which seems to occur often. However, besides that, I suspect deterioration of the electrolytic capacitor. After all, it's an amplifier that hasn't been switched on for a long time.
Unfamiliar with the style of this site, can not download the schematic of PV-1 well. Maybe I'm accessing it on a Mac?
Two players are connected to Phono 1 and 2, respectively. There is a low hum that seems to be 60Hz from both, and a little 120Hz hum is added from one.
It seems that there is poor contact around the ground terminal which seems to occur often. However, besides that, I suspect deterioration of the electrolytic capacitor. After all, it's an amplifier that hasn't been switched on for a long time.
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painless2019
- Beginner
- Posts: 3
- Joined: Thu Apr 02, 2020 11:37 am
Re: Hello.
hello again.
I got the schematic of PV-1. Thank you very much!
I got the schematic of PV-1. Thank you very much!
Re: Hello.
Hola and Welcome painless2019,
The hum could be just due to an adjacent AC cable to the signal RCAs cables. Before you do anything, check this possibility.
Of course you have the turntable ground cable connected to the chassis of your preamp, right?
Happy listening!
The hum could be just due to an adjacent AC cable to the signal RCAs cables. Before you do anything, check this possibility.
Of course you have the turntable ground cable connected to the chassis of your preamp, right?
Happy listening!
ML CLX BF-210 Stage X Motion 4. CJ 120SE amp ET7V2 pre, Holo May Kte Dac. Mac Pro. Power Cond. BPT Signature+ 3.5, Gaia II Feet. USB Lush^V3. Nordost SPM IC and Spk. Shun Mook, BCanto CD2 CD3. Linn LP-12/Unitrack tonearm/Denon DL103R MC.
Re: Hello.
Painless2019,
If you want to know if your preamp is causing the hum, use a couple of shorting RCAs and plug them into your phono 1 or phono 2 inputs. Select the one where you are using the shorting plugs and take a listen. If you do have hum, then your pream is causing that hum. If your preamp is clean, then you should track from where the unwanted 60Hz is coming from.
Separated carefully the RCA cables away from any AC cables. This could produce to you an induction of this unwanted hum. Sometimes the pick up pics up a EMI produced by a power transformer, and might cause this induction. Solution? Move the turntable to another place.
Happy listening!
If you want to know if your preamp is causing the hum, use a couple of shorting RCAs and plug them into your phono 1 or phono 2 inputs. Select the one where you are using the shorting plugs and take a listen. If you do have hum, then your pream is causing that hum. If your preamp is clean, then you should track from where the unwanted 60Hz is coming from.
Separated carefully the RCA cables away from any AC cables. This could produce to you an induction of this unwanted hum. Sometimes the pick up pics up a EMI produced by a power transformer, and might cause this induction. Solution? Move the turntable to another place.
Happy listening!
Last edited by roberto on Fri Apr 03, 2020 7:52 pm, edited 1 time in total.
ML CLX BF-210 Stage X Motion 4. CJ 120SE amp ET7V2 pre, Holo May Kte Dac. Mac Pro. Power Cond. BPT Signature+ 3.5, Gaia II Feet. USB Lush^V3. Nordost SPM IC and Spk. Shun Mook, BCanto CD2 CD3. Linn LP-12/Unitrack tonearm/Denon DL103R MC.
Re: Hello.
If it's 60 hz, it most likely is a "ground loop" as others have eluded to. As Roberto has indicated, you have to isolate the components to figure out where exactly it is coming from. I would also recommend using an "RCA ground loop isolator", as it's a cheap and helpful tool to narrow down ground loops.
-admin
Home Theater in Member Gallery
Main stereo: ART Amplifier and ET7s2. 2nd stereo: PV-14L and MV-55. Previously Owned: PF2 preamp, Evolution 2000 Amp, PV-12AL preamp, D/A-2b Vacuum-Tube Digital Processor.
Home Theater in Member Gallery
Main stereo: ART Amplifier and ET7s2. 2nd stereo: PV-14L and MV-55. Previously Owned: PF2 preamp, Evolution 2000 Amp, PV-12AL preamp, D/A-2b Vacuum-Tube Digital Processor.
Re: Hello.
Hola, please tell us how you are doing with your hum? Did you find the culprit?
Happy listening!
Happy listening!
ML CLX BF-210 Stage X Motion 4. CJ 120SE amp ET7V2 pre, Holo May Kte Dac. Mac Pro. Power Cond. BPT Signature+ 3.5, Gaia II Feet. USB Lush^V3. Nordost SPM IC and Spk. Shun Mook, BCanto CD2 CD3. Linn LP-12/Unitrack tonearm/Denon DL103R MC.