My Overtone will be complete by tommrow.......

[Seemoore]

What voltages do I check for and where.

I got an e-mail from Nik about B+= 440-460, if I knew where B+ was.

Yes, I'm a noob..

[briane]

Honestly thats a bit dangerous to go measuring if you dont know what it is or how to do it. That said once you know what your doing, its not that difficult.

Should do some reading up on safety first.

B+0 is directly off the rectifier.

I suspect if nik assembled it all would be fine without checking.

[Seemoore]

Honestly thats a bit dangerous to go measuring if you dont know what it is or how to do it. That said once you know what your doing, its not that difficult.

Should do some reading up on safety first.

B+0 is directly off the rectifier.

I suspect if nik assembled it all would be fine without checking.

I built it from a Package 2 kit, it the second amp I've built but the first one, an 18 watt, was not nearly as difficult and had detailed instructions on how to do a safe startup.

I've checked and rechecked all the connections, everything is solid so far, just have to install the PT and it's done. It's been fun and nerve rackin' at the same time.

[briane]

Yes, then follow the same instructions for a safe startup.

what I do:
(NOTE: I fire up prior to completion as well, when the power section is installed, to do the headphone trick....too late for this)

Obviously you need to keep your hands out of the amp when doing measurements. Only ever reach in with one hand.

1) massive visual inspection. Individually inspect every solder joint.
2) do some continuity measurements with VM. make sure grounds are grounded, and HT points are not. Amp unplugged
3) startup with current limiter light bulb trick.
4) make sure amp works, and amp not shorted out
5) remove lightbulb current limiter, fire up for real.
6) listen
7) check voltages. Set VM to volts DC, then very carefully measure. These measurements are taken down the power drop string, starting at the rectifier diodes, working your way towards the V1 plate resistors.

I'll mention I do use a variac and isolation xformer, though those are not required, just additional measures.

I recall norm had some great instructions on his repository, within the dlite build instructions. Dont have the url handy, but you might want to take a read through those.

[Structo]

http://bad-domain/DumbleLite/BuildersGu ... 0Guide.htm

If you don't have a variac you should build a light bulb current limiter.

It can save the transformers if something is haywire.

Instructions are in the guide.
Also follow the start up procedure in the guide I posted.

[M Fowler]

To late now but I always build my power supply first and test that, then go from there.

Keep us informed on your initial powerup.

Mark

[Seemoore]

Power-up succesful No odd noise/smells/lights/meltdowns..Looks good and sounds very good.

Cleans are clean and overdrive is sexy/creamy/elastic/growls like a dog protecting his food.

Tone controls work as they should as well as the mini toggles.

I think I have a good build, and I see (hear) why these amps cause such a ruccus.

[M Fowler]

Well that is over, whew

Nothing like bring life to a new amp huh. Now when you go messing around back in that chassis remember to discharge those caps using a resistor connected to two insulated aligator clips, RIGHT!

Take your measurments and report back to the Dumble experts here, I don't know anything about Dumbles.

Mark

[Structo]

The OTS has balancing resistors (220K) across the two 100uf filter caps.

These also function as bleeder resistors.

I like to hook a DC voltmeter from the + end to ground and watch the voltage drain down.

It is usually to a safe value in less than a minute.

But I also want to warn Seemoore that this is more the exception than the rule with guitar amps so, don't depend on the voltage to drain on it's own.
Always check the voltage on the filter caps by clipping the black lead to chassis ground and the red probe to the + side of the cap(s).

If the amp does not have the bleeders, a good way to discharge the caps is to take a test lead with alligator clips and clip one end to a preamp tube plate resistor between the tube and the resistor and the other clip to ground.
As before always check the voltage with the meter before sticking your hands inside.

Always unplug the amp as well. Be it an IEC connector or a cord and plug.

120v still hurts like the dickens if you touch it.

[Structo]

Seemoore, another trick that I borrowed from Mil Spec wiring (think Hiwatt), is to take a red Sharpie marking pen, and as you inspect solder joints, mark it with the red pen.
It's easier to keep track of what you have inspected and also looks cool.

Plus it will show someone that is buying the amp down the road that it has been gone over and everything is right.

[Seemoore]

Thanks for the replies, good and useful info here.

I built a simple cab for the head untill I can order something nice.

I'm done working on the insides, now I'm just gonna play the thing.