Valveking Mark II 50 watt combo TSI warning after tube swap?

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elrrek
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Valveking Mark II 50 watt combo TSI warning after tube swap?

Post by elrrek » Fri Oct 22, 2021 2:49 am

Hi folks

As mentioned in the title, I have a Valvkeking MKII 50 watt combo and the TSI is coming on after 1 hour of playing.

I have had the amp for many years (2015) and never had any problems with it before. It'S never had a tube swap before now, it doesn't get used enough to warrant one before now. I was using it in rehearsals last month and the TSI came on during playing, the lights went red and the amp went silent.
I turned the amp to standby, gave it a few minutes to calm down, the lights went from red to green.
Switched the amp back to ON and payed for a few more minutes before the lights went to red again.
Stopped playing, turned off, packed up, went home.
Same procedure the next week, did some reading, decided it was time for a tube swap. The amp went into the shop on the assumption it needed the tube swap, got 2 new 6L6s tube and a new pre-amp tube, the guys in the shop said they had it ON for 2 hours with no issues.

At the weekend we did some recording, the amp was used for some re-amping and basically ON for 2 or 3 hours, it worked just fine, but we had it switched to STAND-BY when we were not feeding it a signal.

This week it was back to a full on rehearsal, 1 hours of continuous playing and the TSI kicked in again.

So, I guess it is going back into the shop, does anyone have any "tips or tricks" I can feed to the guys in the shop? They're not a Peavey dealer, finding one of those where I am in Europe is basically a nightmare.

Thanks for any help offered!

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JamesPaul
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Re: Valveking Mark II 50 watt combo TSI warning after tube swap?

Post by JamesPaul » Fri Oct 22, 2021 5:42 pm

Provided the new power tubes are good, as sometimes even new tubes can be bad, I would guess that the tubes are biased a little too hot for what the TSI circuit is expecting. Peavey amplifiers tend to have their tubes biased colder than the "average" bias for other amplifiers. If your shop is not a Peavey Authorized Service Center, they mght not know this, and they just biased the power tubes to max power dissipation or their favorite bias point. Ask your shop if they can confirm with Peavey what the bias should be.
Enzo wrote:I find if the amp is working, that is a good point to stop fixing it.
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elrrek
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Re: Valveking Mark II 50 watt combo TSI warning after tube swap?

Post by elrrek » Sat Oct 23, 2021 6:32 am

Thanks JamesPaul, I will mention this.

I have read in another thread about "red platting" in tubes, what does this mean? As far as I know it's perfectly natural for tubes to glow when they are on, but is there a sign that something is wrong for a particular type of glow?

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JamesPaul
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Re: Valveking Mark II 50 watt combo TSI warning after tube swap?

Post by JamesPaul » Mon Oct 25, 2021 6:10 pm

Tubes will have an orange glow from the heater/filament, which is expected. The heater is typically a relatively small coiled wire, which looks similar to an incandescent light bulb filament.

Red plating occurs when there is too much current flowing through the power tube(s). This can be from the tube being biased too hot, an issue with the bias circuit or components, and occasionally a bad tube. When this happens the large gray or black anode "plate" in the tube will overheat and glow red. If you search the Internet, there are images and videos of red plating tubes available. Seeing it is likely better than a description of what it looks like.
Enzo wrote:I find if the amp is working, that is a good point to stop fixing it.
James Paul's Peaveys
Decade, Classics, Ecoustic, Windsors, VYPYR, Triple XXX, XXL, VKs, Bandit, JSXs, VIP, Piranha and a Penta.

elrrek
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Re: Valveking Mark II 50 watt combo TSI warning after tube swap?

Post by elrrek » Thu Oct 28, 2021 4:04 pm

Well, I was in the rehearsal basement again tonight and managed to get 2 hours play out of the amp again before the TSI kicked in once more.

I had a look at the tubes while the amp was on before the TSI kicked in and they looked very orange but not like they were "red plating".

Back to the shop on Saturday :/

elrrek
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Re: Valveking Mark II 50 watt combo TSI warning after tube swap?

Post by elrrek » Fri Nov 05, 2021 11:03 am

So, Mr Tech in the shop seems to think the TSI circuitry has "burnt out".

Has anyone heard of this happening?

Did I read somewhere else on the forum that you can by-pass the TSI?

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