How much would you pay for a non-functioning tube head without knowing the issue?

[Adieu]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Definitely use a resistor. I'm saying this because I like you, but you don't seem to have a 100% grasp on what you are doing, so I'd suggest at least a couple of days of research before you go prodding around too deep into that thing. Death is a serious risk that must be considered when working on the circuitry of an amp. If you don't know what you're looking for or how to safely handle it, it's best to avoid doing so.

Well my research keeps running into claims that the Marshall TSL design has self-bleeding resistors wired to the caps... but, then again, if an amp don't work, how do you tell if that part isn't affected as well??

[NegativeEase]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Well my research keeps running into claims that the Marshall TSL design has self-bleeding resistors wired to the caps... but, then again, if an amp don't work, how do you tell if that part isn't affected as well??

Indeed. You can't assume the amp's safety features are functional.

[Adieu]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Hmmm.... I found a (the?) culprit



Blown HT fuse... do I understand correctly that it MAY be just from somebody trying to run the amp without a speaker load or a mains power surge, and swapping the lil thing COULD resolve all problems?

Or does it mean that there's almost certainly something else wrong and the replacement will cook as well? Also, IF that is the case, am I risking further damage by just trying to replace the fuse first?

[NegativeEase]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Hmmm.... I found a (the?) culprit
[ATTACH=CONFIG]95361[/ATTACH]


Blown HT fuse... do I understand correctly that it MAY be just from somebody trying to run the amp without a speaker load or a mains power surge, and swapping the lil thing COULD resolve all problems?

Or does it mean that there's almost certainly something else wrong and the replacement will cook as well? Also, IF that is the case, am I risking further damage by just trying to replace the fuse first?

So all of your pre amp and the 4 power tubes were coming on and glowing red even though the HT fuse is cooked? How many fuses does a TSL have? one preamp and one HT fuse? wouldn't the power tubes be off if the HT went?

Also, HT fuse is easy to blow disappating a caps incorrectly -did you maybe blow this after you got home?

[Lake Placid Blues]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Make sure you replace the fuse with the proper value and type. Should be a slow blow. A Slow Blow fuse has a T subfix on the part number. A bad tube could have caused it. If so it will do it again. Get a few fuses. Tubes lighting up means nothing. That's just the heaters. On the other hand with a new fuse in there, if one the plates inside the tube start glowing cherry red-shut it down!

On another note you can drain the caps by running a jumper from one the preamp tube plates to the chassis. You don't need a big resistor or anything. It will drain slowly through the plate resistor.

[Adieu]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

So all of your pre amp and the 4 power tubes were coming on and glowing red even though the HT fuse is cooked? How many fuses does a TSL have? one preamp and one HT fuse? wouldn't the power tubes be off if the HT went?

Also, HT fuse is easy to blow disappating a caps incorrectly -did you maybe blow this after you got home?

Nope I only got around to getting the guard grate off and trying to heat the tubes via normal operation...then went to grab some dinner while reading up on possible issues and contemplating whether to trust Marshall's bleeder resistors

Then checked fuses, found a fried one, and went to the electronics store and picked up a baggie of replacements....as well as, don't worry, insulated 16 gauge alligators and a 200k ceramic resistor in a whopping 10w (Marshall forum suggested 2w, but that's all the shop could find 5 minutes before closing, and assured me it'd be ok) just in case

[Adieu]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Make sure you replace the fuse with the proper value and type. Should be a slow blow. A Slow Blow fuse has a T subfix on the part number. A bad tube could have caused it. If so it will do it again. Get a few fuses. Tubes lighting up means nothing. That's just the heaters. On the other hand with a new fuse in there, if one the plates inside the tube start glowing cherry red-shut it down!

On another note you can drain the caps by running a jumper from one the preamp tube plates to the chassis. You don't need a big resistor or anything. It will drain slowly through the plate resistor.

Yeah I got a baggie with like 5 fuses in the matching T1A 250v slow blow... if they cook again, gonna start by pulling power tube pairs, and if that doesn't do the trick, hitting the sockets with Deoxit

And only if that fails will I actually dig in and open her up.... although I've done it before on a TSL to switch it to Euro voltage (stupid switching is inside chassis, probably to idiot proof the thing?)

[Securb]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

You got this brother I think you are headed in the right direction.

[Adieu]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Well I'll be...

$0.80 FUSE SWAPPED & SO FAR SO GOOD

All channels work, sounds grrreat and hella raunchy through my ol g12-65/k85 Carvin 4x12 , even the volume is manageable from quiet to deafening... kinda makes me wonder if I shouldn't forgo flipping this for a quick $400-500 profit, and instead chuck my 2-day-old Mesa Boogie F100 back on craigslist

[Gtrjunior]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Well I'll be...

$0.80 FUSE SWAPPED & SO FAR SO GOOD

All channels work, sounds grrreat and hella raunchy through my ol g12-65/k85 Carvin 4x12 , even the volume is manageable from quiet to deafening... kinda makes me wonder if I shouldn't forgo flipping this for a quick $400-500 profit, and instead chuck my 2-day-old Mesa Boogie F100 back on craigslist

ATTA BOY!!!!

[Adieu]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

ATTA BOY!!!!

Thx

Damn this thing is fun with a strat...

I think I now officially own the world's most monstrous sub-$400 halfstack:
Marshall JCM2000 TSL100 $200.80
Carvin 412 v/ Rola Celestion g12-65 + g12-k85 $179.95

[NegativeEase]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

You struck gold -for a place to sell not knowing the fuse is blown -wow.

You should go there ALL the time and check their inventory of used and broken gear.

I'd buy a EL34 bias probe or take it in and get it the bias check and a once over -and then set the bias for just slightly caliente' lol

[Adieu]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

You struck gold -for a place to sell not knowing the fuse is blown -wow.

You should go there ALL the time and check their inventory of used and broken gear.

I'd buy a EL34 bias probe or take it in and get it the bias check and a once over -and then set the bias for just slightly caliente' lol

People, not places

Heads and guitars, the better deals are on Craigslist... although you can get fun deals from GC on cabs if they have no clue what speakers are inside (they never check, so Carvin and Peavey are always dirt-cheap, even when it's by far the best cab and speakers in the building)... and on guitars and basses, when they misidentify 80s-90s Japan as 2000's indochina or korea

[Adieu]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

I'd buy a EL34 bias probe or take it in and get it the bias check and a once over -and then set the bias for just slightly caliente' lol

Something like this?

https://www.amazon.com/Eurotubes-Bias-Probe-Octal-Tubes/dp/B019PAVXPG

Any advice on what to get or avoid? Tube bias is new territory for me

PS seems there's "plate" and "cathode" probes, which do I need? Thx

[Gtrjunior]

Re: How much would you pay for a non-functioning tube head without knowing the issue?

Something like this?

https://www.amazon.com/Eurotubes-Bias-Probe-Octal-Tubes/dp/B019PAVXPG

Any advice on what to get or avoid? Tube bias is new territory for me

PS seems there's "plate" and "cathode" probes, which do I need? Thx

That would work but this is the one I have....it’s foolproof. It’s not cheap but it is well worth it.

https://www.eurotubes.com/store/pc/Eurotubes-Pro-One-Bias-Probe-for-octal-power-tubes-p144.htm

I got mine on Reverb.com for a little less than this.