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Markfothebeast

Spider Valve MKII 112 Bogner - Overheating

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About 2 months ago the amp cut out volume completely during band practice. Immediately, I powered off the amp to let it cool and it worked fine after that. Before buying this amp a couple years ago I'd read about overheating issues.

 

Just yesterday (6/23/18), I was about to power the amp off and I noticed how hot the metal chassis enclosure had gotten. The backside of the chassis was nearly hot enough to burn fingers. If it was manufactured with lead-free solder there's a good chance that it may become hot enough internally to melt solder joints. I will not be using the amp in this state.

 

This is also the first time I've used my new MKII FBV Express pedal with this amp. I also direct output the audio to a mixer and use the amp as a monitor if that has anything to do with it. 

 

I do not plan to send the amp in for repairs. I would like to know what the root cause for these amps to overheat may be. Any input or knowledge of which component is generating this heat would be appreciated. I need the amp for a gig in 3 weeks...

 

-markfothebeast 

 

 

 

 

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Check the power tubes. You might see one tube glowing excessively and getting way too hot. If this is the case, replace both power tubes and check the bias of the new tubes,

 

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I've never changed the tubes in my 2 years of ownership. The tubes are equally as bright as one another. After 30-40 minutes the tubes operating temperatures were anywhere from 350F - 385F (with head unit out of amp). One larger tube was operating 20 to 30 degrees fahrenheit hotter than the other.

 

The inside of the chassis enclosure is nearly sealed off from any air flow. This is not good.

 

The repeat issues I continue to read about on this forum are very similar to other electronic devices that tend to overheat. So I've decided to get a good look inside the amp and measure how much heat it may potentially generate.

 

I recently repaired a solid state bass amp that generated enough heat to melt solder joints. The main cause was a lack of support on the PCB. The board was able to "warp" and the heat generated was enough to loosen the solder joints to the legs of a pot causing all types issues. This amp generated much less heat than my Spider Valve 112.

 

*Test Results*

High Temps after roughly 40 minutes with instrument playing, effects on, and volume at 1/8th turn:

-Tubes: 350F - 385F

-DSP Chip: 120F - 125F

-Capacitors near DSP: 130F - 172F

-Larger Caps near pots: 150F - 190F

 

I'd forgotten the temps of the ceramic resistors but they were definitely getting hot. If I had the amp cranked up in that 40 minutes with the chassis in the enclosure it'd be much, much hotter than I measured. I would not be surprised if the components in the chassis were to exceed 220F+. 

 

The solder joints on the tube sockets look overheated like that of burnt flux. Smaller SMD solder joints, depending on the solder used, can soften or melt around 300F. This has been an issue with some video game consoles.

 

The chassis is definitely in need of a means of air flow. I will be cutting two holes for two AC fans that are about the size of a standard 12V DC fan used in a desktop PC. The fans will be wired to the 120V AC power input with the neutral on the power switch (I think it was a neutral on the switch). And of course, fused. 

 

I will post updates when I complete the fan install.

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Thanks! The names of the Line 6 products are confusing. The manual shows a photo of it and states it's MKII. But that must be incorrect.

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Yours is a MkI. MkII will say "Spider Valve MkII 112" on the front there. 

 

Two years without a tube change out is too long.

5881WXT Matched pairs,... have to be a matched set.

12AX7B China or 12AX7EH is fine for the pre-amp tubes.

 

The heater element are wearing, so there is leakage current between the filaments,

hence the temperature rise.

 

Needs to be put in for servicing at an authorized service center for a full check-out.

Don't do self repairs on this. Too dangerous.

 

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7 minutes ago, psarkissian said:

Yours is a MkI. MkII will say "Spider Valve MkII 112" on the front there. 

 

Two years without a tube change out is too long.

5881WXT Matched quad (aka- quartet),... have to be a matched set.

12AX7B China or 12AX7EH is fine for the pre-amp tubes.

 

The heater element are wearing, so there is leakage current between the filaments,

hence the temperature rise.

 

Needs to be put in for servicing at an authorized service center for a full check-out.

Don't do self repairs on this. Too dangerous.

 

May I ask, what's dangerous about tubes? Do they hold capacitance? I've never changed out tubes but I do understand that they require a "Bias". Is that a different procedure on Line 6 amps vs a standard tube amp?

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Oh geez... That's an easy procedure. I had to look that one up. A simple voltage adjustment. I can handle that in my sleep. I should give it a check. Maybe someone had swapped in tubes without voltage adjustment. Looks like 35mV. I'll have to find the correct voltage for my model amp. Is there a service manual available?

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Capacitors are hefty and hold quite a charge,... those four big ones.

200v if I recall, from the last time got zapped.

 

Yeah, forget those power tubes, factory is Sovtek 5881WXT.

 

+35mV.

 

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I can discharge the caps. How does the "bias" voltage change? Do new tubes have lesser resistance and the voltage increases?

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Okay, so I won't be using AC fans. Apparently the brushes create electrical noise. Plan B. DC fans with a power supply hard wired in to the power input.

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Everything I've managed to gather has basically concluded that this model amp is flawed from the start. The amount of heat rising upward from the tubes directly in to the sealed enclosure is decimating the components. My conclusion comes from any and all tube amps that are designed with the tubes below. But stupidly enough, there's not an ounce of air flow in to this amp.

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Looking at your temperatures, I've never seen them get that hot before and hold together,

except with old tubes about to fail or wrong tubes. Measured 370-ish as I was about to do

a repair on one once.

 

Power tubes measuring 350F - 385F  is way too high, 220-230F is more normal,

308-311F is as high as I've measured when running it hard. Should have a complete check

out on that unit by someone who knows the insides of our product, a Line 6 authorized tech.

 

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For the 1.5 hour drive to the nearest authorized Line 6 tech, the fuel, and service costs, I could purchase another one of these amps used. 

 

In a few minutes I'm going to do a check up on the bias voltage to ensure that it's within range.

 

There seems to be a lot of numbers flying around as far as the temperature of tubes. The infrared thermometer is probably not the most accurate device when pointing at glass or metallic objects. The innards of the tube could be reading these temps. The inside of the tube is probably far hotter than 350F.

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V3 reads 32.7mV and V4 reads 33.2mV. Think I should raise it? Service manual says +/- 2mV. This is after about 1 minute and the reading is steady.

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After about 45 min, it kept slowly creeping up. When it was hot I brought it to 34mV. It went up to 35mV. I came back home from band practice and had zero issues after installing two 12v fans to cool the PCBs. It was as cool as a cucumber and did not pull any odd sound changes on me. The sound had always seemed to erratically change as far as distortion/clean. It operated just fine now.

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Anyway, I went through and played like I typically do through the Spider Valve. Amp keeps a stable sound, as should be. I'd always thought my mind was playing with me when sound levels and effects were unstable. Still playing through the amp right now. No issues. FYI, I recorded the entire scenario for YouTube. But I have yet to determine that everything is still 100% stable. Temps are cool to the touch on the chassis.

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To edit, you need a FBV Shortboard MkII. Not certain how deep you can access a Spider Valve MkI.

I forget what the circuit is, besides, I can't discuss circuit level stuff.

 

 

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Ahh. The circuit disclosure.  Hehehe. Anyway I've read that the Spider Valve MKI is not accessible to edit. It appears true if there's no firmware update available. So it must not be linked through the CAT5E/USB. That's too bad. I was really looking forward to that feature.

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I wired up two 12v DC fans to a 1200mA power supply. One fan sucks in cool air and the other blows it out. Works like a charm. 

 

However, I think it's time for new tubes as mentioned. I don't get a very heavy tone like the solid state Spider III 75 I just picked up. It's as if the sound is temperamental. It might have a nice, heavy tone one day and another day sound like a wet fart. Even after I raised the bias voltage to 34mV.

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I changed the tubes today. I did not use the suggested tubes in the admin post. The service manual states to use 6L6 tubes. It did not specify WGC/GC/WG and so on. It simply stated 6L6 tubes. I needed tubes by Saturday so I had to purchase them locally.

 

Words cannot describe how drastically the sound quality has improved. I've installed "JJ 6L6GC" power tubes and Tong-Sol 12AX7 Pre-Amp tubes. Not even the same amp anymore... It doesn't even seem like I'm playing the same guitar.

 

The 6L6GC tubes are physically longer. I simply had to stretch the springs on the tube brackets about 3/8". These tubes also have a higher max wattage and voltage rating. I'm not sure if that will increase the life expectancy or not. But WOW! I should've installed these a long time ago.

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Just an update on this amp. It's been about 4 months running the JJ tubes I was told not to use. I play the amp for 4 hour performances and 3 hour practices twice a week. The amp has not had any type of issues. Having the fans vent the head unit keeps it cool to the touch and is most likely extending the life of the circuit boards and components. I am still very happy with the sound of the tubes on stage. 

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On 11/11/2018 at 5:59 PM, Markfothebeast said:

Just an update on this amp. It's been about 4 months running the JJ tubes I was told not to use. I play the amp for 4 hour performances and 3 hour practices twice a week. The amp has not had any type of issues. Having the fans vent the head unit keeps it cool to the touch and is most likely extending the life of the circuit boards and components. I am still very happy with the sound of the tubes on stage. 

I already bought a duet Mesa/Boogie 12AX7 Preamp Tube and some Mesa/Boogie 6L6 STR 440 Power Tubes-Matched Duet for my SV MKII, 40. But I confess that I am afraid to make the change because I do not know if they are compatible. And I don't know how to do the Bias.

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