Loud hum coming from pre-amp

remoteboy

Hi, 

Hoping you can offer some advice. I have a Pro Ject phono box V usb (this guy -https://www.richersounds.com/hi-fi/hi-fi-accessories/turntable-pre-amps-accessories/project-phonobox-usb-variable-soc.html) that I bought from you guys a few years back. It's connected to a Pro Ject Essential 2 turntable. Recently it has started making a loud hum and I can't hear any music coming out of the amp. 

I don't think it's an issue with the turntable because If I bypass the pre amp I can hear audio through the amp but obviously I have to ramp up the volume on the amp to hear anything.

I've tried a variety of phono cables but they haven't made any difference. I've pressed all the buttons all the ways - Line In on / Line in out / MM / MC. The only difference they make is that the hum gets louder / quieter / changes in pitch. 

I'm not sure what else I can do. I've read a few sources online that suggest it's either a board gone in the pre-amp, or the power supply is malfunctioning. Any bright ideas?

Thanks.

Michael

Richersounds.ie: DavidS

Hi

While the hum may be due to a faulty phono stage there are a few things you can try first.  A hum from a turntable is usually due to a grounding issue.

Have you the earthing wire connected from the turntable to the phono stage securely? 

Have you the phono stage power adaptor plugged into a plug adaptor or trailing socket?  If so try plugging it directly into the socket on the wall

If you could check there couple of things and let me know how you get on

Regards Stephen

remoteboy

Hi, 

I get the hum regardless of whether the turntable is connected to the pre-amp. I can connect the turntable directly to the amp and it works fine (just very quiet). So I don't think it's a grounding issue with the turntable. 

I've made sure the power adapter is going straight into a wall socket and not an extension board but that's made no difference.

I've tried it with two different amps - a marantz and a yamaha. I've tried multiple sets of phono cables of varying lengths. 

At this point I figure it's either the power supply or the entire unit. I know which one is cheaper to replace, so I'm hoping it's the power supply.

Thanks.

Michael

Richersounds.ie: DavidS

remoteboy wrote: »

Hi, 

I get the hum regardless of whether the turntable is connected to the pre-amp. I can connect the turntable directly to the amp and it works fine (just very quiet). So I don't think it's a grounding issue with the turntable. 

I've made sure the power adapter is going straight into a wall socket and not an extension board but that's made no difference.

I've tried it with two different amps - a marantz and a yamaha. I've tried multiple sets of phono cables of varying lengths. 

At this point I figure it's either the power supply or the entire unit. I know which one is cheaper to replace, so I'm hoping it's the power supply.

Thanks.

Michael

Hi Michael,

We can certainly have it tested in store however as it is a few years old it will be outside of warranty and the repair would be chargeable. It would be a £40 estimate fee to have it sent to our repair agents and then whatever the repair would cost on top of that.

Let me know what you think.

Kind regards

David

remoteboy

Richersounds.ie: DavidS wrote: »

Hi Michael,

We can certainly have it tested in store however as it is a few years old it will be outside of warranty and the repair would be chargeable. It would be a £40 estimate fee to have it sent to our repair agents and then whatever the repair would cost on top of that.

Let me know what you think.

Kind regards

David

Hi David,

Thanks for all the help with this. It sounds like it would be cheaper just to replace the unit. I’ll try sourcing an alternate power supply first though. Hopefully that’s all it is.

Kind regards

Michael

Richersounds.ie: Kenny

remoteboy wrote: »

Richersounds.ie: DavidS wrote: »

Hi Michael,

We can certainly have it tested in store however as it is a few years old it will be outside of warranty and the repair would be chargeable. It would be a £40 estimate fee to have it sent to our repair agents and then whatever the repair would cost on top of that.

Let me know what you think.

Kind regards

David

Hi David,

Thanks for all the help with this. It sounds like it would be cheaper just to replace the unit. I’ll try sourcing an alternate power supply first though. Hopefully that’s all it is.

Kind regards

Michael

Hi Michael.

No problem at all.

Let us know if we can help in any way in future.