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Mod difficulty level


Cole

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I want to mod my valve jr. head when i sell my combo and get it. I first plan to change

tubes which i understand is pretty easy. I want to try a bitmo mod but am scared off

by all the people on here saying beware of dangerous voltages. I have done the

electronics in my guitar so i can solder pretty decently. I was still wondering how

difficult mods are to do without killing yourself. I was thinking of trying a bitmo mod,

possibly the TRIO mod so i'm wondering if i would be completely overwhelmed trying to

mod it or if its not that bad.

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Since version 2, the VJ has had a bleeder resistor in the power supply. It will drain the power supply caps once the amp is turned off. To be sure, unplug the amp and wait about 15 minutes or so. You will also want to verify that the amp is safe to work on by measuring the voltages in the amp with a mulitmeter.

 

I've never done any of the BitMo mods, but from what I understand, they have good instructions with them, so it probably shouldn't be too hard for a beginner to successfully complete them.

 

tung

 

I want to mod my valve jr. head when i sell my combo and get it. I first plan to change

tubes which i understand is pretty easy. I want to try a bitmo mod but am scared off

by all the people on here saying beware of dangerous voltages. I have done the

electronics in my guitar so i can solder pretty decently. I was still wondering how

difficult mods are to do without killing yourself. I was thinking of trying a bitmo mod' date='

possibly the TRIO mod so i'm wondering if i would be completely overwhelmed trying to

mod it or if its not that bad.[/quote']

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If i don't have a multimeter should it still be safe after 15 minutes or should i

fint somone with a multimeter to be safe.

 

If you can borrow a DMM, I would. You will need it for modding in addition to checking the voltage. You also might look into buying one. Radio Shack used to run pretty good deals on inexpensive meters. Sears ran a pretty good deal a while on their made in China meter.

 

Look for one that reads at least 600V DC and 1,000V AC. A set of retractable test clips is a nice addition.

 

tung

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This is your life on the line here. Never trust your life to a 20 cent resistor. Be safe. Get a digital multimeter. Learn to use it. THEN check for voltages and dive in. Do a BitMo mod or two. Hey, that's what got me started. But be warned. Once you realize how easy it can be to make such dramatic improvement to your tone, you'll be hooked. And trust me, modding amps can lead to stronger stuff... like... building amps from scratch. #-o It is known to be highly addictive. 8-[

 

Gil...

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Cole,

 

Seriously, what Gil said.

 

tung

 

 

This is your life on the line here. Never trust your life to a 20 cent resistor. Be safe. Get a digital multimeter. Learn to use it. THEN check for voltages and dive in. Do a BitMo mod or two. Hey' date=' that's what got me started. But be warned. Once you realize how easy it can be to make such dramatic improvement to your tone, you'll be hooked. And trust me, modding amps can lead to stronger stuff... like... building amps from scratch. #-o It is known to be highly addictive. 8-[

 

Gil...

 

[/quote']

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Gil... Can you telll me where the bleeder resistor is on the VJs schematic, and could this be added to any tube amp?

I also have a peavey classic 30 that I'd like to add a bleeder to. I get real nervous holding the resistor with insulated pliers for 30 to 40 seconds every time I get inside the amp. I'm curious to know what type of resistor and value it is.

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The usual value seems to be 220k, 3w metal oxide. Just solder it accross the first cap in the power supply. I have some 200k metal oxide resistors that I use, they work just fine.

 

tung

 

Gil... Can you telll me where the bleeder resistor is on the VJs schematic' date=' and could this be added to any tube amp?

I also have a peavey classic 30 that I'd like to add a bleeder to. I get real nervous holding the resistor with insulated pliers for 30 to 40 seconds every time I get inside the amp. I'm curious to know what type of resistor and value it is.[/quote']

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I want to mod my valve jr. head when i sell my combo and get it. I first plan to change

tubes which i understand is pretty easy. I want to try a bitmo mod but am scared off

by all the people on here saying beware of dangerous voltages. I have done the

electronics in my guitar so i can solder pretty decently. I was still wondering how

difficult mods are to do without killing yourself. I was thinking of trying a bitmo mod' date='

possibly the TRIO mod so i'm wondering if i would be completely overwhelmed trying to

mod it or if its not that bad.[/quote']

 

I used the sovteks it came with unitl the mods were done. No sense abusing the good ones.

(though I did try them a couple of times, when I knew things were ok.. and even then I was sure I'd ruined one or two.. but didn't!)

If you have a V1/2 or V3 it makes a difference in which mods need to be done.

 

The bleeder resistor in my V2s never failed.. I checked with DMM and bled caps a lot before I got it.

 

I'm not sure what the trio mods are.. but in any case, a meter will tell you what your voltages are.. and that's unavoidable knowledge.

 

Coupling caps, like C1 and C2 can be swapped out no problem. Resistors won't bite.

The big caps, you want to be sure of.

 

If you read the faq, proceed slowly, and ask questions.. you should be fine.

I thought my soldering technique was good.. but I've had to resolder many times!

 

I did nearly blow a cap.. it swelled but didn't pop, whew!

and I fried one resistor.

The amps have survived some pretty clumsy errors on my part with nary an eyebrow removal.

 

It's only going to be hard if you rush...

 

TWANG

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The bleeder resistor is R11 on the schematic. On the printed circuit card, you'll find it sitting right next to R10. Check the FAQ's for annotated photos. R11 is 220k/3W, but you can use pretty much anything from 1w on up. 3w metal oxide resistors would be the safer choice and a bleeder resistor as high as 220k on the B+ rail won't interfere with the general operation of the amp.

 

If you're in a hurry, try a 10k/5w resistor on a jumper wire with insulated alligator clips. You'll have to be very careful when attaching it though, but it will bleed off the charge in about a minute or two.

 

Gil....

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Yeesh guys. I added extra caps to mine and I tend to just unplug the amp straight (tubes are really hot, if I have to remove the board I gotta wait but I usually don't pull the board...) and assume it's safe. I've soldered around in there like 5 times now. :|

 

Apparently nobody should be paying attention to me because I'm definitely doing something wrong. :-; I'll keep my meter handy next time I go inside the thing, to test cap voltages.

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you soldered in caps without removing the board?

Or do you mean you left it wired in but unscrewed it from the chassis then put in new caps?

Assumptions are the thing here.. I decided the best advice was to test the caps, or bleed them, just to be safe, and if it was a

waste of time, at least I developed a good habit and healthy respect for V!

I had a cap swell.. I was lucky it didn't blow. It wouldn't have killed me or anything nasty even.. but it sure would have scared the bejebus out of me, and probably not done that pcb any good.

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Caps blowing can cause eye damage if you don't wear goggles.

 

My caps are soldered to the leads off C6, not under the board. 200uF 450V in parallel with C6, so it was all still in the amp at the time.

 

Bleeding the caps is GOOD advice, I just hadn't thought about it and haven't actually been doing it. :s

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