Denon DL103S on MM Input?

[avantbored]

Hey all. Wondering if anyone can shed light on this.

Purchased a Denon DL103S on eBay last weekend; output is 0.3mV, so needed to be into my MC input of my Nakamichi CA7 preamp. Manual says it set to "24" for gain. Cartridge impedence is 100ohm. Pre is factory-set to 100ohm.

Except there's no sound! Just that white noise when the pre gets turned up high (~5:00 position).

I tried the cart on my Yamaha C80 into the MC input, set it to 100ohm. Same thing. No sound (except for crosstalk on the MM input -- but that has happened when I have changed the phono load settings when I have an MM cart playing (I will hear music faintly when set to MC loading).

Anyway, I tested the cartridge with my multimeter. All good. Tightened the leads from headshell to cart. All good.

Last thing to try was the MM input. Produces sound. Since the output of the DL103S is so low, I have to turn the preamp up pretty high for my normal listening level (~11:30 position), but set to MM, it's making sound. Any idea why? I'm really confused. I don't have another MC cart to investigate further.

Specs for the DL103S, and my pre:

DL103S

Output impedance 40 Ω (1 kHz)
Output voltage: 0.3 mv (1 khz, 50mm/s horizontal direction)
Adaptive load impedance 100 Ω or More (Transformer 40 Ω)


Nakamichi CA-7A

 

[BillWojo]

I've always used a SUT (step up transformer) between my Denon DL-103 or 103S carts into a MM stage. Since it works with the MM stage, that proves out the cartridge and all the wiring to the RCA connectors.
The thing that puzzles me is that you get no output at all when using the MC gain stage. Not being adjusted to the optimum setting will still allow you to hear it just fine. Is there a switch setting that might need to be set when going from MM to MC? Did you check your manuals? I'm not familiar with either preamp that your using.

BTW, that's a very nice cart. It's a higher compliance version of the DL-103 with a different stylus. Denon doesn't say exactly what it is but some of us suspect it's a fine line or close to it. They call it a "special elliptical", what ever that means.

BillWojo

 

[avantbored]

I've always used a SUT (step up transformer) between my Denon DL-103 or 103S carts into a MM stage. Since it works with the MM stage, that proves out the cartridge and all the wiring to the RCA connectors.
The thing that puzzles me is that you get no output at all when using the MC gain stage. Not being adjusted to the optimum setting will still allow you to hear it just fine. Is there a switch setting that might need to be set when going from MM to MC? Did you check your manuals? I'm not familiar with either preamp that your using.

I have capacitance and gain settings, as well as a switch to toggle between MM/MC inputs. There are three capacitance and three gain settings; 100, 200, 300 and 24/30/26 respectively. I tried em all! No sound.

Right after I posted, I found this thread and post that described a similar problem to mine. The hypothesis was a dead fuse in the MC section. I have no idea how to check that.

BTW, that's a very nice cart. It's a higher compliance version of the DL-103 with a different stylus. Denon doesn't say exactly what it is but some of us suspect it's a fine line or close to it. They call it a "special elliptical", what ever that means.

BillWojo

My first MC, and I'd been long trying to find a line-contact stylus in my budget. I was really lucky to find it domestically for a nice price. I learned about the DL103S at this very forum!

I wonder if the "special elliptical" is akin to Shure's "hyper elliptical" or even LP Gear's "Vivid Line" series, which some have found to be less sharp than a MicroLine or Shibata, but finer than an elliptical?

 

[Jeff449]

The hypothesis was a dead fuse in the MC section. I have no idea how to check that.

You would have to use your multimeter on the circuit board. If you don't have a schematic, look on the board for a component marked Fxxx, as opposed to Rxxx (resistors) or Cxxx (capacitors), etc.
Check for resistance across each fuse you find. It should be less than an ohm unless it is blown.

 

[avantbored]

You would have to use your multimeter on the circuit board. If you don't have a schematic, look on the board for a component marked Fxxx, as opposed to Rxxx (resistors) or Cxxx (capacitors), etc.
Check for resistance across each fuse you find. It should be less than an ohm unless it is blown.

Cheers, Jeff. I'll open up the cover and see if I can access them. If I have to open up more stuff I'd be hesitant to do so and will likely bring it to my tech. While I'd be bummed I can't listen to my DL103S really, I'm pretty happy with my AT150Sa right now.

 

[BillWojo]

If you can use a meter check the switch contacts on the MM/MC switch. It may have never been used and the MC contacts could be tarnished.

BillWojo

 

[avantbored]

If you can use a meter check the switch contacts on the MM/MC switch. It may have never been used and the MC contacts could be tarnished.

BillWojo

Hmm. Interesting. Could I hit that with DeOxIt?

Ryan

 

[tnsilver]

Hmm. Interesting. Could I hit that with DeOxIt?

It never hurts if you can get the spray inside the pot but I doubt that's the issue. I'm using a CA-5, which is a Nelson Pass design and one of the best phono pre-amps I'd ever had. The CA-7 should be similar, except we need to know if that's a 'CA-7A', 'CA-7E' or just CA-7. When you do open it up, post some pics of the MC head-amp input section. Chances are it's missing the impedance resistors for both channels, has some odd ball value resistors or some other related mess.

 

[avantbored]

It never hurts if you can get the spray inside the pot but I doubt that's the issue. I'm using a CA-5, which is a Nelson Pass design and one of the best phono pre-amps I'd ever had. The CA-7 should be similar, except we need to know if that's a 'CA-7A', 'CA-7E' or just CA-7. When you do open it up, post some pics of the MC head-amp input section. Chances are it's missing the impedance resistors for both channels, has some odd ball value resistors or some other related mess.

Whoops, thought I got the "7A" in the post. It indeed is a CA-7A.

I'll post pics tomorrow, but I'm sure the extra impedence resistors aren't in there. I inherited this rig from the first owner, who kept it in pristine, unmolested condition; the only thing I've done to it is break the plastic crutch that holds the screw above the MM/MC inputs. My tech has used a really small amount of silicon glue to stabilize it. But I'll post pics tomorrow.

 

[tnsilver]

Note the CA-7A phono stage is built like two separate mono phono stages, one per each channel. This duplicates the gain, capacitive loading, and MM/MC cart type selector switches. It only appears like you could have different and separate settings for each channel. In reality you can't and it's really a silly and dangerous arrangement, because different cart type settings (MM and MC), for different channels would activate the MC phono stage, which has a dedicated 9V power supply, along with the MM phono stage, which feeds on the main power supply. That may overload the PS and blow the fuses. The same with different gain and capacitance loading for each channel. Those switches on each channel, must be set to the same value! It's very easy to stick a finger in the back and accidentally flip the wrong switch on the wrong channel and cause damage.

Before you begin trouble shooting this, turn the unit off, pull the plug out of the power socket and verify the PS fuses (F401/F402) with a meter to make sure they're not blown.

 

[avantbored]

Note the CA-7A phono stage is built like two separate mono phono stages, one per each channel. This duplicates the gain, capacitive loading, and MM/MC cart type selector switches. It only appears like you could have different and separate settings for each channel. In reality you can't and it's really a silly and dangerous arrangement, because different cart type settings (MM and MC), for different channels would activate the MC phono stage, which has a dedicated 9V power supply, along with the MM phono stage, which feeds on the main power supply. That may overload the PS and blow the fuses. The same with different gain and capacitance loading for each channel. Those switches on each channel, must be set to the same value! It's very easy to stick a finger in the back and accidentally flip the wrong switch on the wrong channel and cause damage.

Before you begin trouble shooting this, turn the unit off, pull the plug out of the power socket and verify the PS fuses (F401/F402) with a meter to make sure they're not blown.

Hell yeah, thanks for this info! Capacitance settings have always been set to same value, as with the MM/MC settings.

I've got the meter, but still new with using it. Which setting should I use? Volts or ohms?

 

[tnsilver]

Continuity if you have it. That's when the meter buzzes, beeps or lights up with low resistance. Practice on a paper clip. Ohms if you don't have it.

 

[kotofei]

Once I have had the MC stage dead in my CA-7A. It turns out that the preamp has a dedicated power supply, starting from the transformer, for the MC section. All other circuits are powered by another power supply with its own transformer. Some people think that one of the CA-7A power supply is for analog circuits and another for digital one; this is wrong.

In my case, I have had a dead fuse in the MC power section. When I changed it everything went back to normal. That could be your case.

Also, the MC stage of CA-7A is designed in such a way that one can change the loading by soldering a loading resistor into a special socket. I believe (IIRC) that this extra resistor is in parallel to the 100 Ohm one installed permanently; that's why the manual says the preamp is factory set at 100 Ohm. I don't think presence or absence of extra resistors could lead to lack of output.

So most likely it's a burned fuse.

 

[avantbored]

Continuity if you have it. That's when the meter buzzes, beeps or lights up with low resistance. Practice on a paper clip. Ohms if you don't have it.

Just finished testing them. The two bottom fuses beep on Continuity mode, but fuses F401 and F402 are dead.

Once I have had the MC stage dead in my CA-7A. It turns out that the preamp has a dedicated power supply, starting from the transformer, for the MC section. All other circuits are powered by another power supply with its own transformer. Some people think that one of the CA-7A power supply is for analog circuits and another for digital one; this is wrong.

In my case, I have had a dead fuse in the MC power section. When I changed it everything went back to normal. That could be your case.

Also, the MC stage of CA-7A is designed in such a way that one can change the loading by soldering a loading resistor into a special socket. I believe (IIRC) that this extra resistor is in parallel to the 100 Ohm one installed permanently; that's why the manual says the preamp is factory set at 100 Ohm. I don't think presence or absence of extra resistors could lead to lack of output.

So most likely it's a burned fuse.

Andrei kindly replied to my direct message -- thanks Andrei, and for the extra info about the MM/MC section. (BTW, can anyone confirm that John Curl designed this one, and not Pass?).


Anyway, I know now I have to replace the fuses. My tech is busy with rebuilding my crossovers for some KEFs. So:

1. How easy might this be for a novice like me to replace the fuses?

2. I will try to read the schematic to see which fuse I need to buy (I assume on Parts Express?)


Thank you all! Very relieved it may not be a bigger job.


Edit: I figured out to remove the fuse. I see the part number is "314 1/2A 250V". Wondering what would be a suitable replacement. Cheers.

 

[tnsilver]

Good job. Congrats! It's a slow blow (T) 0.5A/250V 32mm glass fuse - like these.

Keep your fingers off the fuse metal ends even when the unit is unplugged. Use some plastic/wood tool (fork, spoon) to extract the old fuses. I'm not sure how hard those relatively small phono stage filter caps can bite, but it's good practice not to test it in person.

BTW: It's kinda common knowledge Nelson Pass had designed the CA-5 (or sections thereof) and licensed it to Nakamichi. Some of their following gear (the series II, for example) strays away quite far from the original design. I'm not sure how (and if) it applies to the CA-7. Audiogon seems to think it was both Pass and Curl who worked on the CA-5. Those two masterminds are probably having a good laugh about the rumors.

 

[avantbored]

Up and running everybody! I have the DL103S mounted on my backup TT, a beat up, but functional, YP-D6. It's less refined than the AT150Sa, but there's something more energetic and coherent than that one. Kind of between the analysis of the nude shibata on the AT150Sa and the energy of my Nagaoka.

Thanks everyone! Massive help.

Good job. Congrats! It's a slow blow (T) 0.5A/250V 32mm glass fuse - like these.

The MM PS fuses are still good, but decided to keep it consistent and switch all of them out. I got the glass ones as suggested; they're like 1mm longer than the original ceramic ones, but fit just fine.

BTW: It's kinda common knowledge Nelson Pass had designed the CA-5 (or sections thereof) and licensed it to Nakamichi. Some of their following gear (the series II, for example) strays away quite far from the original design. I'm not sure how (and if) it applies to the CA-7. Audiogon seems to think it was both Pass and Curl who worked on the CA-5. Those two masterminds are probably having a good laugh about the rumors.

I'd read that the Series II examples stray. What's interesting is that in a thread on diyaudio, Pass says he didn't really contribute to the preamps at all! Maybe he forgot? Ha.

Also learned that it was Nakamichi, when they engaged Pass & Threshold, that introduced him to Toshiba JFETs (relevant post on diyaudio), of which he's really fond of and think has used in his First Watt designs! As far as Curl's contributions, I've only seen those Audiogon rumors.


I have the PA7A II and haven't heard the original, so couldn't compare. I can't read a schematic or understand enough to really know/tell the difference. Generally curious about all things Pass designs, so would love to hear an OG Threshold, Forte Audio, and First Watt amp. There's a Forte Audio phono pre near me, but need to fix some things in the house before I buy any other toys.

 

[Blue Shadow]

Interesting that the lowest level input can be stymied by a fuse. Glad there were knowledgeable folks that could direct you to those fuses. Easier than finding, downloading and figuring out the manual.

 

[tnsilver]

Interesting that the lowest level input can be stymied by a fuse.

Yup. Part of the divide and conquer topology with the high gain MC phono stage feeding on a completely separate 9V power supply section. Dedicated toroidal transformer, separate power supply. Real cost no object, kinda high end design. Neat!!! (and beautiful too).

 

[tnsilver]

The MM PS fuses are still good, but decided to keep it consistent and switch all of them out.

It's actually not just MM, but everything else. My copy of the schematics is so blury, I can't say for sure, but I think fuses 403/404 are 1A fuses, not 0.5. It should say so on the silk screen, so have a good look and put back the original ceramic fuses, if the values of the new ones don't match. Ceramic or glass won't make a difference but half an Ampere might very well do.

 

[avantbored]

It's actually not just MM, but everything else. My copy of the schematics is so blury, I can't say for sure, but I think fuses 403/404 are 1A fuses, not 0.5. It should say so on the silk screen, so have a good look and put back the original ceramic fuses, if the values of the new ones don't match. Ceramic or glass won't make a difference but half an Ampere might very well do.

Will do, will do. I double-checked the good ceramic ones -- you're right! Switching them out right now.