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No sound one channel


Sam S.
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Trying to diagnose this and looking for suggestions. Have Black Ice (Jolida) F22 integrated. No sound from one speaker. All preamp tubes light up. However, out of the 4 EL34s, V1 and V2 don’t light up (guessing this is the no sound channel). I swapped the EL34s (moved V1 and V2 to V3 and V4) and they lit up in V3 and V4, so seems like it isn’t the tubes. Any ideas? Maybe open it up and check fuses? If so, the next question is what the cause is if blown. Thanks!

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Can you open the amp up and take some pictures of the internals?

 

I believe those share a power transformer but each channel has their own transformer winding. The two wires for each channel go from the power transformer to one socket, then they daisy chain from that connection to the other EL34 socket with two more twisted wires. The heaters do not have a fuse.

 

Either the two wires going to the socket on that channel has a bad connection or the winding failed and you will need a new power transformer. If you post pictures I can annotate them in editing software to show you what connections and wires to look at and test.

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Fuses don't blow for no reason.

Short in the speaker or wires could blow the fuse.

 

Inspect the pre amp tube, maybe a new one is in order.

Open the unit first and look for brown spots, melted insulation, lose connectors or wires etc.

ensure the solder joints are good and no capacitor leaks or shorts between components from extra solder.

 

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41 minutes ago, Bubo said:

Fuses don't blow for no reason.

Short in the speaker or wires could blow the fuse.

 

Inspect the pre amp tube, maybe a new one is in order.

Open the unit first and look for brown spots, melted insulation, lose connectors or wires etc.

ensure the solder joints are good and no capacitor leaks or shorts between components from extra solder.

 

 

The power tube heaters for the dead channel do not light up. I'm pretty certain the heater circuit would be the best place to start troubleshooting.

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Thanks. Pics were too large so I emailed those to @captainbeefheart. No fuses are visible—likely a more complex issue (did a few tests at his recommendation) so I’ll be sending it off for service. I’m happy to report back on results at a later date. I should say thanks for the suggestions and help. Having forum members available with wide swaths of experience is a godsend.

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Each channel's pair of EL34's has their own 6.3v winding. I had him measure filament voltage, he has correct voltage on the channel that works and the dead channel has nothing from it's winding. From pictures the wiring goes down under the PCB and into the power transformer, no visible fuses for the filaments and most likely needs a new power transformer.

 

We stopped further testing because the unit is under warranty and so he is going to send it back to get it fixed with just cost of shipping hopefully.

 

I am trying to talk the OP out of doing their "upgrade packages deals" which in my opinion are not actual performance upgrades but more snake oil based. First stage is they replace coupling caps, tubes, diodes, resistors, with name brand boutique types.

 

Second stage was in/out jack upgrades which isn't going to yield sound improvement but nice jacks that hold tight can be nice. The original stuff on the amp is just fine in my opinion.

 

Third stage is getting to the real snake oil stuff, they add those bybee quantum purifiers which are just a low value inductive resistor in a molded body. How do I know? I'm not the only person to cut one open. I would never purchase one but a group of us pitched in enough to get one to test and cut open. What a disappointment but to be honest not a surprise from the world of "hifi upgrade" market.

 

Fourth stage is they rewire the amp with some expensive wire. For those of you out there that change your internal wiring with your amplifiers do you also measure phase shift before and after? I doubt it. At the very least maybe some square wave tests would be nice to see if anything has changed enough to be audible. It's really not the wire making the sonic difference, it's the layout and slight differences in parasitic capacitance. The Black Ice F22 doesn't have much open loop gain even though they have two 12AX7's per channel, that's four high mu triodes yet they only use 4.5db of feedback. It's a two stage amplifier for those that don't know. Yes that's right, only two stages with 4 front end triodes. They call it "Odyssey circuit technology" or something like that. Nothing new here, just long tail pairs in the front end with a new name. It's funny they say the lower gain has lower distortion because of the lower negative feedback. It's actually the opposite, gain is easy to achieve even with two stages and higher amounts of feedback will give lower distortion and lower noise. At 50 watts it produces 1% THD. All this "new" technology they claim and my old Fisher 200a amps from the 1950's better it by a huge margin. They produce 60 watts from a pair of EL34's at .1%THD. That's 10x lower distortion with more power with "old" technology lol. And no bybees required :D

 

All of these "upgrades" ring in at $800, which is crazy money and they don't even show any before and after measurements to show what was improved upon - only subjective terms are used of course from only listening tests.

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Do NOT do anything inside the amplifier unless you have experience.    Please believe that it's possible to get a bad shock, even if your amp is powered down and unplugged.  If you're sending it out for help -- that is a smart move.  I've seen all too often here over many years when members are told to look at this, or look at that -- or test this or that -- without telling the owner of the component that it can be extremely dangerous to mess around with vacuum tube stuff where high voltages are present.  Looking out for HT is good advice, which, BTW, has nothing to do with Home Theater.

 

Happy Thanks giving, erik

 

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