Little/Mini Tube Amps - Reviews? Thoughts?

[Jay]

Those links just go to the main page...

Here are a couple that would do what you needed

http://www.homedepot.com/prel80/HDUS/EN ... 04&pos=n04

Only $10 but never ordered from here...
http://www.multimeterwarehouse.com/MAS830Bf.htm

$25 and auto-ranging so it you don't have to choose a "less then 10v" or "less then 100v" setting on a dial.  Just choose AC or DC or Ohms or whatever.
http://www.multimeterwarehouse.com/MAS830Bf.htm

[davelowell]

Damn that homedepot.  Your link goes to a main page as well.  Thanks for the reply, I have a homedepot credit and can get one there without spending any "money", so I want to go there.

I'll just get one and try it out.  I guess I can always return it...  if I'm still alive!!!

[davelowell]

So, I am going to open up the Valve Jr. today.  Basically, after I drain the caps and check for the voltages, I still don't want to touch them, right? 



And the caps are the five cylinders, correct?

[Jay]

The caps are the 5 cylinders.  Once you've drained all the voltage from the amp AND it's unplugged from the wall.  You are safe to touch anything inside you need to.  But always double check and make sure there is no voltage remaining before going in.  In my case, my meter would read around 1 volt no matter how much I drained and re-drained so it possible you may see a very very slight voltage or that my meter is just poorly calibrated but I wouldn't worry as long as the most you read is around a volt.

[rabidhamster]

I always just leave the alligator clips on there to keep the caps properly drained.  Just remember to take them off afterwards:) 

my favorite thing to do to discharge caps, however, is alligator clip to one of the dropping resistors, then to ground, through my multimeter, and watch the voltage dropping off, and you know precisely when its done. 

[davelowell]

Two questions...

Where do you test the voltages?

Where do you leave the "alligator clips"?

Thanks.

[TheMilford]

Two questions...

Where do you test the voltages?

Where do you leave the "alligator clips"?

Thanks.

clip the negative (black) lead to the chassis (bare metal or a screw)

probe with the hot lead (red) to the positev terminat on each cap. Electrolytics should have a stripe on one side... this is the negative side.

good luck,
David

[Jay]

Here's a schematic...  the junction of R12 and C6 should be an appropriate place.

http://www.euthymia.org/DIY/VJstock.jpg

[davelowell]

Jay, I cannot get to the leads of the caps, they are underneath the board.  Refer to the picture above. 

I read somewhere that if the ground lead of the meter is grounded, the positive can be put on pin 3 of the power tube.  I get little to no reading there.  Does that mean they are drained?  Where else can I check to make sure?

I have everything apart and my meter and solder and I'm ready to go.  Just really want to make sure!

Thanks!

[Jay]

Pin 3 looks like it's provided the bias voltage.  Pin 9 should be a much higher reading with the amp powered up.  You could try there but the leads for R12 are on the top side of the board so quickly check both sides (one will be attached to C6 for sure) and see what you get.

[davelowell]

I get the same very low readings, .001, .002. 

[TheMilford]

you're gonna need to unscrew the board from the chassis.

has the amp been off for a while?

if so you're pobably fine.

besides a pop from one of those caps will probably ony sting a little

[davelowell]

you're gonna need to unscrew the board from the chassis.

has the amp been off for a while?

if so you're pobably fine.

besides a pop from one of those caps will probably ony sting a little

Off for over 12 hours.  Just a sting, huh? 

[TheMilford]

yeah, they'll POP! but they only hold a split second of a charge. and after a while it'll be pretty minimal.

no worse than when you have a static charge walking across the carpet them touching a door knob.

most likely you discharge them across your meter.

[davelowell]

Well, I did it!  Much ado about nothing, really.  It was pretty easy, and the sounds are cool.  The bright switch helps with guitar and the gain switch is fun too.  Also added a standby,  seems like the amp will like it better in the long run !  High gain sounds good with the Bass VI!

Thanks for all the help guys!

Dave