Hifi amp problem.

Budgie

About a month ago my hifi amp developed a fault. From phono there was no sound from the left speaker, from the CD player there is sound from both speakers but really degraded. This was exactly the same when listening to both sources through headphones. Anyway, I sent it to be repaired and have just got it back. Annoyingly, the exact same problem still exists. The repair agents have replaced the pcb and a speaker input and it was tested by the retailer before sending.

I've just called the retailer and am waiting to hear back.

Is there anything that may have caused this to happen from the mains socket or whatever? It seems very odd for the exact same problem to occur.

Gagaryn

Knackered RCA cables and nowt wrong with the amp is my guess

strumjoughlamps

assuming it was repair and tested as ok then it must be another link in the chain, unless it was not properly tested.

which amp is it? does it have L/R fuses?

Budgie

I've swapped the RCA cable from the CD player and the problem persists. I also connected the CD player to another input, exactly the same. I swapped the speaker cables over too and now sound comes out of the other speaker from the turntable. In conclusion, I reckon the amp is not the problem but both the CD player and the turntable... what are the chances.

robgilmo

Could well be, do you have a different source to try?

ICBM

Very simple test - connect just a RCA cable to the amp and touch the tips of the plugs at the far end - start with the amp turned right down and increase volume slowly until you hear a good strong (but not overly loud, you don't want to harm the speakers) buzz when you touch each one. If both left and right give a similarly strong signal, the same on each input channel to the amp and louder on the phono, then it's unlikely there is a fault in the amp.

If one channel is louder than the other, swap the speaker connections. If the fault moves to the other speaker the problem is in the amp. If the amp isn't faulty then it does sound like both the sources are, unlikely though it sounds for both to fail at once in different ways.

robgilmo

Do you have a multimeter? Also, sounds daft but do your pots need cleaning?

robgilmo

What amp is it?

Budgie

@ICBM thanks for the advice. I tried that and both the cd and phono inputs give a good and balanced hum. So, annoyingly, it looks like both the CD player and turntable. The black connection from the turntable seems faulty but the rca is wired directly into the unit (Rega P2).. how much of a task would it be to replace do you think? I suppose it could just be the plug.

I was going to replace the CD player anyway at some point.

@robgilmo the amp is a Yamaha AS501 and it's just over a year old, and probably didn't need repairing at all. Talking to the shop yesterday, they mentioned the repair agents had replaced the pcb as a precaution. Luckily it is still under warranty.

ICBM

It should be fairly easy to replace the RCA cable on the turntable, assuming it isn't a total pig to get into. Check that the little crimp connectors are tight on the cartridge pins first though, if one isn't then one channel won't work. There's almost nothing else to go wrong in a traditional turntable other than the cartridge itself.

Budgie

@icbm cheers. I swapped the small wires connecting the cartridge, white to red, blue to green and the sound still only comes out of the right speaker (the same side as before I swapped the small wires over). Would that indicate a problem with the cartridge rather than any other wiring further along do you think?

ICBM

Assuming that's the right colour coding so you haven't just phase-reversed each channel (I can't remember!), that proves it's the cable - if it was the cartridge, the fault would then move to the other channel.

Budgie

ICBM said:

Assuming that's the right colour coding so you haven't just phase-reversed each channel (I can't remember!), that proves it's the cable - if it was the cartridge, the fault would then move to the other channel.

Thanks again @icbm much appreciated. I think I'm just going to send the arm and wiring off to someone who knows what they are doing to be sorted and upgraded. Cheers

robgilmo

Send it to http://www.audioorigami.co.uk/, from memory the Rega RB250 which I assume your arm is, unless its silver or the newer RB220? Is hardwired, but I could be wrong, Look for a DIN plug on the base of the arm. if it has you can remove just the cable and test it, fingers crossed its just the phono cable, if it is hard wired or if the fault is within the arm its a bit more difficult. Its been years since I looked at a Rega (I restore vintage turntables and some audio as a hobby) but rewiring an arm is pretty straightforward if you know what you are doing.

You could go to https://www.vinylengine.com/turntable_forum/ and enquire about rewiring a Rega arm, or google it, there is lots of info regarding arm rewires,
What you could try is wiggling the wire at the phono plug (gently) to see if the channel comes alive, this will indicate the cable fault at the plug, which is quite common.

boogieman

Can you borrow a source that is known to work? At least that would prove the amp is ok. 

Budgie

@robgilmo thanks for the links, I'll check out the forum you posted too. The arm is a RB251 I think, I'll take a look tomorrow to see how the wiring works, hopefully it's the easier option! I'm woefully non-skilled with electronics, soldering etc.

@boogieman I'll try but everyone seems to just stream. I was going o buy a new CD player at some point anyway, so will see. I am pretty confident now that the amp isn't the fault tbh. It's a pita really!

thermionic

Plug an iPod/phone in through a 3.5mm stereo jack to 2 phono lead.