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Opening the Valve Junior Combo


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I've taken the screws out of the back, can't get the back off. I've taken the metal corners off, unscrewed the top, grabbed the handle, yanked, can't get that off. How the heck do i get inside the Valve Junior? There's no instructions for actually opening the cabinet! Currently I have all the screws out, I can grab the handle (which is still screwed in) and spin like a top without it coming apart. (don't try)

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I've taken the screws out of the back' date=' can't get the back off. I've taken the metal corners off, unscrewed the top, grabbed the handle, yanked, can't get that off. How the heck do i get inside the Valve Junior? There's no instructions for actually opening the cabinet! Currently I have all the screws out, I can grab the handle (which is still screwed in) and spin like a top without it coming apart. (don't try)[/quote']

 

The screws are all that's holding it in. Perhaps it's a tight fit.

Take the front off, too. Look through it. If you don't see any mishappen gobs of glue.. push the back panel out.

Be sure the screws are out far enough. the wood is good enough that just a thread or two still in the wood will hold the thing on.

 

remove the little black plastic caps and unscrew the bolts that hold the head in.

 

 

be sure you lift on the head, use the PT, and don't bang your tubes around.. while you are unscrewing the bolts.

then slide it gently out.

 

On the speaker cabinet you have to pry the back panel off.. it's a really tight fit.

So, if your back panel screws are out.. prying it would most likely cause you to scratch or tear the tolex.

better to take off the front panel and push the rear panel through.

 

I don't know if you got a new amp or a used one, maybe something has changed.

What did you take the amp corners off for?

 

I mean not to offend.. but are you sure you want to get in there?

You know, it takes a bit of experience to keep from frying your butt, eh?

Removing a panel is the easiest thing on this...

just saying... good luck. take care!

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The back panel's really tight. I took the corners off because the top is screwed down to one corner anchor, and then the other anchor on the metal corner piece is in the side. The front has actually the black plastic stuff going around, to the corners, and ALL THE WAY to the back; there's no real "front panel" to speak of, unless I strip the tolex off. There's seams at the top and bottom, one for lifting out the head and one for I don't know what.

 

It's a V1 valve junior I just bought new (...) and I want to fix the input jack ground.

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try to avoid bending the tube pins.. and look carefully when you put the tubes back in.

dont bend any over when you do.

 

clean the tolex where it was sticky with a slightly damp sponge or cloth. wipe dry before you put it back in, too.

inside the cab, and the panel edges.

 

what are you going to do with it?

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what are you going to do with it?

 

I broke the ground-to-self on the input jack and soldered the ground to where it's shown on valvejunior.com

 

I soldered in 2 100uF 450V caps ($11 each!) in parallel with the first cap in the circuit; unlike valvejunior.com, I paralleled straight across the cap instead of soldering from a diode to the cap.

 

Later I'm dropping in a Hammond 125ESE (not right now), then having the amp rebiased with some JJ tubes in it (my EL84 and my 12AX7 are both Sovtek; yeah, it's a V1).

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11.00? where are you ordering from? Did you try Mouser?

You put in two 100uF on C6?

I have that cap on C6 and C9 on one of mine. On the other I just paralleled the stock caps with the ones I pulled out of the first head.

 

You know, I'm not that up on V1s, since both of mine are V2s, but it seems they have quite a few differences.

 

Did you put a 1M 1W res. in R1?

Also, most people put a 1W res. in R2, values varying down to 10K.

(10K 30K 47K up to the stock 68K)

(marshallized.. 10K)

 

If you're going to use an el84 power tube, the ESE is really spending money on more than you'd need. I'd suggest a DSE or

look on ebay for a used 5K from a V3, or peruse Webers site.. I have a weber in one of mine, it's got all the ooomph and costs less than

the Hammond or Heyboers.

But the savings would be there on the V3 OT off ebay...and you can still tweak for lows etc.

 

You should definately go through the FAQ, there are quite a few ideas in there you can start planning from!

 

TWANG

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11.00? where are you ordering from? Did you try Mouser?

 

I went down the street and bought two. There's one electronics parts store in this town. :|

 

Did you put a 1M 1W res. in R1?

Also' date=' most people put a 1W res. in R2, values varying down to 10K.

(10K 30K 47K up to the stock 68K)

(marshallized.. 10K)

[/quote']

 

I found no literature on that mod. I need to change out R14 eventually for proper bias, I don't know if there's just "a good resistor value" or if I seriously need to get the bias checked out.

 

If you're going to use an el84 power tube' date=' the ESE is really spending money on more than you'd need. I'd suggest a DSE or look on ebay for a used 5K from a V3

 

But the savings would be there on the V3 OT off ebay...and you can still tweak for lows etc.

[/quote']

 

The ESE costs like $5-$10 more than the DSE. V3 OT off ebay is a potential; I'm seeing $11 + $7 shipping on that so far (I haven't bid up) versus like $40 + $10 shipping for the ESE.

 

You should definately go through the FAQ' date=' there are quite a few ideas in there you can start planning from!

[/quote']

 

What FAQ?

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http://forums.epiphone.com/Default.aspx?g=posts&t=7

that should be the second thread at the top of the epi amps forum.

 

the V3 heads have already moved R1 to 1M. This is probably the most significant easy mod to do... and epi copied the modders in V3.

 

the caps should have a been a couple/few bucks each.

try antique radio supply or Mouser online..

R14 will depend on other things, so.. one step at a time!

read that faq material, you'll love it!

(inc. how to bias.. )

just be safe and read first.. save yourself money on components.. get the right mods for the performance you want it to give.

You can do a lot with these, and I'd bet no two modded amps sound all that much alike.

cool beans!

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http://forums.epiphone.com/Default.aspx?g=posts&t=7

that should be the second thread at the top of the epi amps forum.

 

Ah' date=' ok, it's that sticky thread. :P

 

Also, most people put a 1W res. in R2, values varying down to 10K.

(10K 30K 47K up to the stock 68K)

 

I'm seriously thinking about doing a 100k pot here (dial on the back, or inside), possibly in front of a 3k resistor for base value. Don't know if I want 100K of resistance ever, might want to stop at 80k but might not be able to find a pot that size; then again, I could drop a 250k pot in and just never go past 4. Could also push-pull pot the circuit to

 

I've also considered adding the DC rectifier for the filaments as on ValveJunior.com but tying it to a switch (inside or on the back) and using more caps to smooth the voltage (these I'll get for real cheap, they only have to be 16V instead of 450V).

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I'm seriously thinking about doing a 100k pot here
(R2)

 

Why? I can't see that serving any useful purpose.

 

I've also considered adding the DC rectifier for the filaments

 

I'd consider that a must mod on v1.

 

but tying it to a switch

 

Again, why? You want to have the option to make it hum?

 

more caps to smooth the voltage (these I'll get for real cheap

 

I certainly hope so...you paid as much for those two caps as I paid to replace every single component in mine.

 

 

 

I think you need to slow down and start doing some reading, before you grab a drill and soldering iron and start creating frankenstein. Most of the mods that require external add-ons, such as pots for this and that or switches for the other, simply aren't that necessary. The trouble is, if you start right off with these permanent modifications to the chassis, you really don't know which ones you'll later find useful, and which ones you find downright useless, BUT, you'll be left with extra holes that you wouldn't have, if you'd have just been patient and tried mods out BEFORE punching holes in the chassis.

 

The fact is, you're going to find out what mods work for you and what doesn't, by trial and error, and once you find a cap or resistor value that works for you in a given location, you're not going to need a way to switch in and out or dial up or down with it.

 

I personally find that gain control mod useful, though I generally keep it right about at the point where it would be had I just gone with the fixed value resistor in that spot. I still like having the flexibility to increase or decrease the gain with a knob, but in all honesty, it really isn't a necessary mod.

 

I also installed a small switch, to switch C3 (or is it C4?...can't recall offhand) in and out. Useless for me. Yes, it works to dramatically decrease gain, but it also thins the tone, and I figured out about two weeks after I installed it that I really don't care for that cap being lifted. Doesn't matter now...I've got a new hole in the front of the amp that I didn't need.

 

I ESPECIALLY wouldn't even be thinking of any drilling mods before I'd even done the basic, most critical mods, including the OT.

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The comment about using different resistor values on R2 for different sounds as a personal preference makes me think I can get different sounds out by toying with the resistor value. Variable resistor?

 

I personally find that gain control mod useful' date=' though I generally keep it right about at the point where it would be had I just gone with the fixed value resistor in that spot. I still like having the flexibility to increase or decrease the gain with a knob, but in all honesty, it really isn't a necessary mod.[/quote']

 

I'm going to be attempting a three-knob tone stack from the diagram at http://amps.zugster.net/articles/tone-stacks#FMV but it causes 18dB gain loss. I'll have a switch (push-pull pot DPDT on one of the knobs) to 1) break the output; and 2) jump input to output somewhere just past the break. This means when I pull the knob out, I bypass the entire friggin' tone stack; a gain control would be nice.

 

I ESPECIALLY wouldn't even be thinking of any drilling mods before I'd even done the basic' date=' most critical mods, including the OT.[/quote']

 

Currently trying to acquire an Epiphone V3 original OT.

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again.. 18db gain loss is a lot!

imagine if you went from a 100db sens. speaker to one 18db less.. you're going to wind up with tone control over crappy tone, I think.

I hear you.. I know you really beleive that having a tone stack in there is going to be good.. well, if you went with a bigger OT and stuck a 6V6 tube in parallel with the el84, you'd probably be ok.

But everyone I know of who'd tried that with just the el84 hasn't been happy.

 

I'm building a new face plate to cover the extra holes I wound up with.. and I went even slower than you are, but still didn't try some mods before drilling.

No small job getting the amp looking good again.

 

hang in there and you'll be fine!

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If you do add a TMB tone stack, you can eliminate R6 & R7. The are there as a voltage divider circuit to pad down the gain. The EL84 is a very sensitive tube and it doesn't take much signal to turn it on full blast. With the TMB tone stack, you're already eating up a lot of gain, so you don't really need R6 & R7.

 

Take a look at the Blackheart 5W amp schematic:

 

http://www.rowbi.myzen.co.uk/Blackheart/Documents/BH5_schematic%20Rev%2020070611.pdf

 

 

tung

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