Bizzare turntbale problem

My parents preamp on their PM4000 amp didn;t work so I bought a Rotel preamp to try and fix this however I still have the same problem. What is odd is the turntbale worked fine when connected to an old 1984 Sony reciever. However on the PM4000 and Rotel it is single channel only. It works fine for the first 10 minutes or so then goes into mono.

My parents had another turntbale that that did exactly the same thing too.

So two pre amps and two turntbales both developed the same problem. What is going on? The rest of the HIFI works fine.

 

I have just left it playing, turned the balance to the right (its the right channel that does not work) then switched the HIFI of from thje mains but left everything turned on. For a split second the music played from the right. This must surely prove I have a problem with the mains downstairs?

Its working now but I am not sure how long that will last. I do know however there may be damp inside the socket. But whats odd is everything else works fine its always the turntbale that causes this fault.

Any electrical enginners out there that know what is causing this?

 

Are these faults temporary, or permanent? I mean, if you take everything to your house, and reconnect them there, do they work, or not?

Also, try disconnecting completely both speakers, and monitoring with headphones only. Does the fault reproduce itself?

Its extremely unlikely to be the mains, damp inside a mains socket would just trip the fuse in the fusebox. Just to be safe, have an electrician call round to test the earth continuity in your house.

 

The problem just seems to come and go. It was working again before. It is all very strange.

Could it be the speaker causing the problem? The cartirdge is directly underneath the speaker underneath the seperates and the shelf.

 

not the mains mate

if it was then nowt would work, mains goes in as Ac then gets rectified to work on bothe channels for the amp, if it was a mains prob then neither would work.

plug a table lamp in and see if half of it goes out after 10 minutes

 

It must be somthing to do with the speakers then. Ok how do you magneticaly sheild speakers?

 

eh??

er
welcome to try

get another speaker mag and stick it on the back of the driver
dont know why you'd wanna do it tho

 

Obviously try a diffewrent source, If the problem persists you know its not the deck. Otherwise I would suspect a dodgy cartridge, possibly with a dying coil or loose connection.

If the problem is on all sources then you need to start moving through the chain. If its a speaker problem then try swaping the speaers round and see it the problem swaps sides.

 

Aren't we missing the obvious here?

I'm thinking turntable or cartridge is dodgy and perhaps the old Sony was set to mono, so you couldn't tell if there was only one channel coming from the TT.

Have you checked out the cartridge and turntable phono leads for faults? I know you said another TT did the same thing, were you using the same cartridge on both?

When you lose a channel, try swapping the plugs over on the phono input. If the sound stays playing through the same speaker then it's an amp fault, but if you hear sound through the other speaker then the problem is with the TT/cartridge.

Next, give the phono cables a waggle to check for lose connections in the cable and plugs. Finally, check the fly leads at the back of the cartridge. Carefully unplug and then reconnect one at a time.

Good luck

Edit: Damn, don't ya just hate it when someone posts a similar reply just as you are typing yours. Doh!

 

Thats the odd thing. It dosn't matter what turntbale it is, what amps I use or anything. As longs as its in that location this problem persists. I've tried many different cables, amps, turntbables etc now.

 

as gary said

if it shows to be the deck then it could be cart or tone arm wire. You say it cuts after 10 minutes, could be that after 10 minutes play the arm has moved to the position that breaks conection in the wire or cart

 

I've discovered the problem. Basicaly both the turntbales I have tried it must have had the same fault.

When you play the outer tracks it plays fine, but when you play the tracks nearer the spindle the right channel cuts out.

So I am guessing there is a break in the arm cable some where.

That now means I have spent £20 on a duff turntbale (in July) and just spent £20 on a Rotel pre amp.

Howeve does anybody know if the phono stage in the Rotel 830 (I think) pre amp is better quality than the Marantz PM6010 one? I might just buy my parents a new turnbtable for christmas and keep the Rotel for my system.

How difficult are the cables to replace inside a turntable?

 

Fixed it now (well at least for tonight). I just took the cartridge and stylus off. Put them back and it seems to work fine for the moment.

I will probably use the Rotel 870 on my system or just keep quiet and not tell my mother that the box I bought her for christmas is not actually needed.

I guess the preamp section is much better quality than my mothers PM4000 anyway. I just can't help thinking its such a waste of a nice pre amp though.

 

glad it got sorted

 

Rotel make decent phono stages - the one in the lowly 920AX is fairly decent. I'd imagine the one in the Marantz will suck in comparison since it's a modern lower-end amp from when vinyl isn't so much in demand (guessing mind you - it might be brilliant!).

Sounds to me like you've got dirty contacts somewhere on the turntable - it's not one of those ones that mutes the cartridge (via a microswitch) while the arm's lifted up is it? If so, I'd get to work on ALL contacts in the arm/phono plugs/cartridge tags AND any microswitches. If the cable was knackered it wouldn't work at all - the wires coming down the arm tube into the arm base are VERY VERY fine, and if one goes, it goes - there's never anything inbetween IME.

Failing that, your cartridges are on their way out - or the antiskate mech's iffy (more guesswork).

 

I did adjust the antiskate last night it was set at 0. I changed it 0.5. It has one of them ortofon OM series cartridges but has a DUEL badge on it. The tunrtbable in question is a horrible semi automatic Yamaha thing from the 80's. My project Debut sounds so much better in comparsion.

 

as a starting point anti skate should be about the same as tracking weight

 

cant believe nobody said ''its probably the cabling'' !

I dunno, leave you folks alone for a couple of weeks, and you miss the easy ones...