Grizzly Posted April 27, 2017 Share Posted April 27, 2017 So what I thought was a phono stage problem may very well be a cartridge problem instead. Just to isolate the issue I removed the headshell and checked the continuity of the cartridge (multimeter checking resistance between left "hot and earth" and right "hot and earth). Left reads around 11 ohms and right around 210 ohm. The output in the right channel is extremely low level, except for ultra low frequency which seems almost at a much higher level. Left channel appears fine. Oddly I also had a significant pop through the right channel when adjusting one of the loading switches (the other switch worked silently) on my Slee Elevator step up, which was what made me think it was the Slee. Do cartridges suddenly just start exhibiting this sort of behaviour? There has been no force put on the Benz and it was working perfectly just a few days back. Plus it's only done around 140 hours. Link to comment Share on other sites More sharing options...
ophool Posted April 27, 2017 Share Posted April 27, 2017 Have you tried swapping the channels on the input to the Elevator to see if the problem changes side or not. Link to comment Share on other sites More sharing options...
eltech Posted April 27, 2017 Share Posted April 27, 2017 The multimeter probes need to make firm contact with the pins or you can get a false high resistance reading. A bad solder joint from the factory can also cause high resistance. DC offset on the phono stage input can burn out a coil. What resistance is the cartridge meant to have? Link to comment Share on other sites More sharing options...
andrewp Posted April 27, 2017 Share Posted April 27, 2017 Fiddle at your peril.. If you purchased new from a retailer and you suspect issues dont touch it because as soon as you do all warranty will disappear. Might be worth a call to the agent to see what they suggest. All the best. 2 Link to comment Share on other sites More sharing options...
Batty Posted April 27, 2017 Share Posted April 27, 2017 Great advice Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2017 Share Posted April 28, 2017 13 hours ago, ophool said: Have you tried swapping the channels on the input to the Elevator to see if the problem changes side or not. I'll give it a go tonight, and also with another cart. 12 hours ago, eltech said: The multimeter probes need to make firm contact with the pins or you can get a false high resistance reading. A bad solder joint from the factory can also cause high resistance. DC offset on the phono stage input can burn out a coil. What resistance is the cartridge meant to have? Coil resistance is meant to be 12 ohm. Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2017 Share Posted April 28, 2017 12 hours ago, eltech said: The multimeter probes need to make firm contact with the pins or you can get a false high resistance reading. A bad solder joint from the factory can also cause high resistance. DC offset on the phono stage input can burn out a coil. What resistance is the cartridge meant to have? Is it possible to check for DC offset without having to open it up? Would that explain the pop when manipulating the loading switch? Link to comment Share on other sites More sharing options...
eltech Posted April 28, 2017 Share Posted April 28, 2017 1 hour ago, Grizzly said: Is it possible to check for DC offset without having to open it up? Would that explain the pop when manipulating the loading switch? Yes. Disconnect tonearm wires from your preamp. Set your multimeter to the DC voltage setting and put your probes on the RCA input sockets of your phono preamp. Turn preamp on and watch the DC reading. Once on, flick those switches and see if the DC voltage reading momentarily changes. It should be zero at all times, but if you are seeing momentary voltage fluctuations then thats not ideal for an MC cartridge. Link to comment Share on other sites More sharing options...
eltech Posted April 28, 2017 Share Posted April 28, 2017 1 hour ago, Grizzly said: Coil resistance is meant to be 12 ohm. Oh. sounds like one channel of the cartridge is not good. Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2017 Share Posted April 28, 2017 Yes. Disconnect tonearm wires from your preamp. Set your multimeter to the DC voltage setting and put your probes on the RCA input sockets of your phono preamp. Turn preamp on and watch the DC reading. Once on, flick those switches and see if the DC voltage reading momentarily changes. It should be zero at all times, but if you are seeing momentary voltage fluctuations then thats not ideal for an MC cartridge. So probes against "active" and "neutral" of, say, the RH input? Sent from my SM-G930F using Tapatalk Link to comment Share on other sites More sharing options...
eltech Posted April 28, 2017 Share Posted April 28, 2017 2 minutes ago, Grizzly said: So probes against "active" and "neutral" of, say, the RH input? Sent from my SM-G930F using Tapatalk Yes. Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2017 Share Posted April 28, 2017 So, theoretically, the headamp could have gone a bit rogue, causing the output failure. Then while adjusting the loading switches to try and isolate the issue I may have inadvertently sent DC to the cartridge and fried a coil?Sent from my SM-G930F using Tapatalk Link to comment Share on other sites More sharing options...
eltech Posted April 28, 2017 Share Posted April 28, 2017 28 minutes ago, Grizzly said: So, theoretically, the headamp could have gone a bit rogue, causing the output failure. Then while adjusting the loading switches to try and isolate the issue I may have inadvertently sent DC to the cartridge and fried a coil? Sent from my SM-G930F using Tapatalk Perhaps. If your cartridge was OK, up until flicking the DIP switches at which time there was a pop through the right channel, and afterwards the cartridge sounded bad (on the right channel), and you measured it and the right channel reistance is high, then it appears that the phono preamp caused the problem by sending DC voltage out of its right input to your cartridge burning the coil. If you can replicate and measure DC voltage on your phono preamps input on the right channel when flicking the DIP switches then this would be further evidence to support the above theory. If though, you cannot replicate and measure the DC voltage, the first theory is a reasonable, but not 100% proven. checking the schematic of the preamp would allow a qualified person to see if it is even possible for this to happen. In some circuits, it is simply not possible for this to happen. In other circuits it could happen under certain circumstances. Link to comment Share on other sites More sharing options...
andyr Posted April 28, 2017 Share Posted April 28, 2017 3 hours ago, eltech said: Turn preamp on and watch the DC reading. Once on, flick those switches and see if the DC voltage reading momentarily changes. It should be zero at all times, but if you are seeing momentary voltage fluctuations then that's not ideal for an MC cartridge. Mmmm, if that is the case (voltage fluctuations) ... then that is a very good argument for not using dip switches for changing loading. Use a parallel set of RCA sockets - which also allows an infinite range of loading options. Andy Link to comment Share on other sites More sharing options...
eltech Posted April 28, 2017 Share Posted April 28, 2017 1 hour ago, andyr said: Mmmm, if that is the case (voltage fluctuations) ... then that is a very good argument for not using dip switches for changing loading. There is nothing inherently wrong with DIP switches. They are just switches. Potential for problems depends entirely upon the design of the circuit. Link to comment Share on other sites More sharing options...
andyr Posted April 28, 2017 Share Posted April 28, 2017 (edited) 45 minutes ago, eltech said: There is nothing inherently wrong with DIP switches. They are just switches. Potential for problems depends entirely upon the design of the circuit. Absolutely - on the surface! But the fact that some dip-switches seem to have produced a negative effect suggests they are not ideal. Compared to a pair of parallel input RCAs, into which you put 'loaded' RCA plugs - what can possibly go wrong with them? Andy Edited April 28, 2017 by andyr Link to comment Share on other sites More sharing options...
ophool Posted April 28, 2017 Share Posted April 28, 2017 The designer is not unapproachable, enquiring of him as to the (IMO highly unlikely) possibility of creating problems by changing the load switches might obviate most of this speculation. Link to comment Share on other sites More sharing options...
Guest Posted April 28, 2017 Share Posted April 28, 2017 So after a chat with a local guru, it would appear that any artefacts of loading adjustment are more likely symptomatic of the cartridge fault rather than a fault of the headamp. I tried another cart tonight with no issues. Now to determine whether the Benz can be mended and, if not, how to appropriate the funds for a suitable replacement from the treasury.....Sent from my SM-G930F using Tapatalk Link to comment Share on other sites More sharing options...
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