#1
to start off, i traded a randall combo for the VK50 combo.

it is 220v and i am in the US for 120V. i have the proper stepdown/stepup transformer. 120 going in, 220 going out. not an issue until NOW.

i just finished off my last phase of the basic mods (marshall mod) and it isn't working. not a big deal i will go back and check things over.

first i was a dumbass and forgot to get the stepdown/step up (i always get the name messed up). so it ran at 120V. tubes weren't heating and wasn't making much sound. i don't believe that harmed anything

then i was like duh, i need it to run at 220v.

i hook it up, tubes warmed up and there was a hiss, like you would expect to hear on an amp. then it cut off. i was thinking like oh shit i blew something. smelled around and nothing was hot near the amp, GOOD.

i look at the stepup/down transformer and there is no power. checked the fuse (with a meter( and it was blown. i head to radioshack and buy some more fuses. not a big deal.

then i blew through three more fuses.

the transformer had never had issues powering the amp prior to mods. so something is up with the amp i am assuming.


i put my last on in and i tested at 120v in/120v out and hooked up a table lamp. its fine. it hasn't blown. the lamp is on.

so the amp must be drawing way too much current form the amp i suppose and overloading the fuse?

thoughts?
WTLT 2014 GG&A

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Last edited by trashedlostfdup at Feb 10, 2017,
#2
First up, make sure you have the right fuses. You may need slo-blo type fuses.
After the fuse where you plug an amp in (The mains fuse), the next fuse you come to is usually a slo-blo fuse (It may have something else written on it like "Timed" or just a "T" or other word to indicate that it won't blow immediately).
Those type can handle an over voltage condition for a brief period (like in milliseconds) before they blow.
Putting to little voltage into an amp (like 120 into one set up for 220) won't harm the amp, it just won't work.
Could be that the amp needs more current (Amperage) than the stepdown/stepup transformer is capable of providing.

Cath has way more experience with setpdown/stepup transformers than I do (I have none), but my guess is that with 120 going into that transformer, you have taps that put out 120v and taps that put out 220v.
Those would likely use different windings on the transformer, one for each voltage level.
Sounds like the 120 is fine but the 220 may not be.

So its possible that the transformer is hosed, but I would wait for Cath to speak up.
#3
Derek, how much wattage is your transformer good for?

For example, a tech recommended at least twice the power than you need; for a 100W amp, he recommended at least 400W, higher is better. 

edit: Also, don't buy the cheap Amazon ones, go to an actual audio/video store.
#4
Quote by CodeMonk
First up, make sure you have the right fuses. You may need slo-blo type fuses.
After the fuse where you plug an amp in (The mains fuse), the next fuse you come to is usually a slo-blo fuse (It may have something else written on it like "Timed" or just a "T" or other word to indicate that it won't blow immediately).
Those type can handle an over voltage condition for a brief period (like in milliseconds) before they blow.
Putting to little voltage into an amp (like 120 into one set up for 220) won't harm the amp, it just won't work.
Could be that the amp needs more current (Amperage) than the stepdown/stepup transformer is capable of providing.

Cath has way more experience with setpdown/stepup transformers than I do (I have none), but my guess is that with 120 going into that transformer, you have taps that put out 120v and taps that put out 220v.
Those would likely use different windings on the transformer, one for each voltage level.
Sounds like the 120 is fine but the 220 may not be.

So its possible that the transformer is hosed, but I would wait for Cath to speak up.


well here i go. the transfomer was working fine before the mods. i am positive that it was working before the modding. it was fine.

right before it blew the second fuse, everything sounded great. for a minute, exactly how i was epecting to hear from the mods.

i am not sure about the output voltage (50w amp), but yet again before i modded it it was fine.

i know the fuses are correct. the 120v line is perfect, i tested it with a lamp that had three 60 watt bulbs. but yeah, maybe i did toast the 220v windings. but i don't know.

Quote by Ippon
Derek, how much wattage is your transformer good for?

For example, a tech recommended at least twice the power than you need; for a 100W amp, he recommended at least 200W, higher is better.


i am pretty sure that the transformer could handle it.
WTLT 2014 GG&A

Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/
#5
another fuckup, i thought it may have been the power tubes, so i swapped them for fresh ones, it did the same thing.

however for a brief moment i turned the amp on without the power tubes in could have that killed it?

and also i just took the chassis out of the box and used a meter to test the internal fuses and they (all three i could find) were perfectly fine.
_____

the light goes on but the tubes don't heat up. which lead me to checking the internal fuses epecting to have a blown HT fuse or something.
WTLT 2014 GG&A

Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/
#6
another update, the amp sounded perfect for a few minutes, then i put it into the cab and then no sound.

i did hear humming from the speaker when it was working too.

no noise now but it lights up.

sorry for my scattered thoughts.
WTLT 2014 GG&A

Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/
#7
First thing: Measure what voltage is coming out of the step up transformer unloaded.
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