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Problems with turntable, stumped

B

Brian Bee

Member
One of my set ups is a classic dj 2 turntable set up. I currently have some KG4s and just recently, got a beautiful little Hafler amp to power them. It's more for social listening and people have a lot of fun with it.

Channel 1 (1st turntable) works perfectly, sounds amazing with the new Hafler!
When I try to play something from channel 2 (2nd) turntable, I only get sound from one speaker. The 2nd speaker is humming, so I know there's power, but no signal.

The amp works perfectly. I have switched the "good" turntable to the other channel, switched wires, switched stylus'... everything is working as it should. I've troubleshot down to the actual turntable and I'm completely stumped.

This was not a problem when I had a different amp attached. Both turntables worked perfectly.

Am I missing something?
Any ideas?

Ty
 
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sfrost said:
Table #2 probably has a bad wire, broken ground in the arm or RCA's in one channel.
Click to expand...
But everything was working perfectly up until I switched amps. I used the set up only a few days ago.

Just to check, I hooked everything back up to the old amp, ran my troubleshoot, and yeah, still one speaker, still the turntable.

Was this just really bad timing for that turntable to have a problem?
 
I agree with the above, sounds like bad wire, cable, or even the had shell possibly where the contacts are.
 
Yep, sooner or later one of those wires goes bad, or a cartridge drops a channel. Try switching the wires on the cartridge just to make sure it's not that, or just switch the cartridges on the two tables to rule out that aspect.
 
sfrost said:
Yep, sooner or later one of those wires goes bad, or a cartridge drops a channel. Try switching the wires on the cartridge just to make sure it's not that, or just switch the cartridges on the two tables to rule out that aspect.
Click to expand...
I switched the cartridges and same problem.
I guess I'm just struggling with the timing of this. The turntable wasn't jostled when I was switching the amps out.

Is it simple as a solder might've come loose somewhere?
 
Usually the wire at the RCA plug has become compromised, shorted out causing hum and no sound. Replacing the RCA interconnects is probably the cure. Which table is it, brand wish.
 
Not a vintage or audiophile brand. :)

It's an audio Technica 1240.
They're built for gigs, but this set stays put which is another reason why I'm so surprised it's probably what you're suggesting.
 
Have you swapped turntables on the Halfer to see if it might be the amp? Sp swap channel one with channel 2
 
kermit z said:
Have you swapped turntables on the Halfer to see if it might be the amp? Sp swap channel one with channel 2
Click to expand...
Yes, one turn table on either channel of the mixer works wonderfully.

Tried different cords, both channels, switched cartridges, tried a different mixer and did same thing all over again.
It's definitely the turntable
 
Grenadeslio said:
It's possibly the headshell contacts where they meet the arm. Have you cleaned the contacts?
Click to expand...
I've swapped the unit out, put in a different head shell and cartridge...
Normally I'm not so patient, but I really went step by step and am pretty certain it's the turntable itself.
 
With the turntable you're having trouble with connected, play a record. Wiggle the interconnects, one side at a time, from one end at a time. You will probably be able to hear where the problem is, either at the turntable end, or the end where the RCA connectors are.

Most likely just need to swap out the interconnects.
 
Before you do anything else, do this. With the problem turntable connected to Channel 2 on the Haffler, reverse the RCA cables left for right and right for left. If the dead channel follows the cable swap to the other channel (left-right, not 1-2) the problem is in the turntable. If it doesn't change channels, then the problem in in the amp.

John
 
What John said. And it sounds to me like one of the RCA plugs on the bad turntable is the culprit. They go bad where the wire connects to the plug itself. It probably was weak before, and when you switched it from one amp to the other, the connection broke inside of the plug. Sometimes wiggling it about will make it come back temporarily for short durations.

If this is the case, then you only need get a new RCA cable if your turntable has RCA outs on the back. If not, your options are twofold. One, you can 'do it right' and take your turntable apart and solder in a new set of cables (make sure that they are shielded and of good quality, not dollar store specials) or you can do it 'half arsed' and cut the bad plug off, cut a plug off of a good set of cables, get some heat shrink tubing, make the splice and solder it, then cover with the heat shrink tubing and shrink. Depends on your ambition and skill level.
 
DustyOldPile said:
What John said. And it sounds to me like one of the RCA plugs on the bad turntable is the culprit. They go bad where the wire connects to the plug itself. It probably was weak before, and when you switched it from one amp to the other, the connection broke inside of the plug. Sometimes wigg

ling it about will make it come back temporarily for short durations.

If this is the case, then you only need get a new RCA cable if your turntable has RCA outs on the back. If not, your options are twofold. One, you can 'do it right' and take your turntable apart and solder in a new set of cables (make sure that they are shielded and of good quality, not dollar store specials) or you can do it 'half arsed' and cut the bad plug off, cut a plug off of a good set of cables, get some heat shrink tubing, make the splice and solder it, then cover with the heat shrink tubing and shrink. Depends on your ambition and skill level.
Click to expand...

Another option is to cut off the plugs and buy and install a new pair of plugs. It's a tidier and better way to do the repair because it doesn't introduce a new failure point in the form of the splice. This, of course, assumes that the failure is, as it often is, at the plug. Another typical failure point for hard wired interconnects is at the strain relief clamp where the wires exit the turntable. Unfortunately, it's virtually impossible to determine at which end the failure occurred unless the cables respond to the Wiggle Test.

John
 
It occurred to me to look to see whether the AT LP1240 has captive or removable ICs. Turns out they're removable. This greatly simplifies the repair if they turn out to be the problem and offers another way to confirm or eliminate the cables as the source of the problem.

Swap cables with the turntable that's got two live channels and see if the problem follows the cables or whether it stays with the turntable.

John
 
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