Testing a completed 18 Watts Amp

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davemojo
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Testing a completed 18 Watts Amp

Post by davemojo »

Hi All,

First of all thanks for all support received on previous topics opened, I had a great help and learnt a tons of stuff.

I have fully completed the 18 Watts amp but I didn't plug it, neither I added the tubes I only put the fuse and plugged all knobs.

At this point the scary part is coming for me, high voltage are lethal and being reading this all over the guides is a warning that makes suspicious, which is a good thing.

I am only planning now as we speak, to add a 220K resistor on the can filter and ground it, to bleed off the charge, so that should make things less dangerous?

I read somethings to check, but would you please list a series of steps of what to do one by one

1) Before plugin in the cable to the outlet what I shall check? Anything with the multimeter before any electricity is on the circuit?
2) Once I power on if nothing is going to exploding, smoke or anything like that :lol: what are the first things to check?
3) I should operate with one hand only and keep the other one behind my back? What else?

Any info are welcome, please be simple :lol: on listening the steps since I am beginner, and of course I don't wanna die lol ….

I am so exited hope it works :D
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Re: Testing a completed 18 Watts Amp

Post by Bieworm »

Lightbulb current limiter.. that's what I do
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Re: Testing a completed 18 Watts Amp

Post by Riffmonster »

I find this start up procedure quite helpful: https://robrobinette.com/Tube_Amp_Startup.htm

Be safe!
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Re: Testing a completed 18 Watts Amp

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Riffmonster wrote:
Fri 03/26/21 12:00 pm
I find this start up procedure quite helpful: https://robrobinette.com/Tube_Amp_Startup.htm

Be safe!
Lightbulb after all that ofcourse...hahaha!
And hightlighter procedure..
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Re: Testing a completed 18 Watts Amp

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Bieworm wrote:
Fri 03/26/21 11:52 am
Lightbulb current limiter.. that's what I do
ok need to understand what that is, I think I have seen a video from TubeDepot after completing the amp, but unsure
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Re: Testing a completed 18 Watts Amp

Post by Bieworm »

davemojo wrote:
Fri 03/26/21 12:12 pm
Bieworm wrote:
Fri 03/26/21 11:52 am
Lightbulb current limiter.. that's what I do
ok need to understand what that is, I think I have seen a video from TubeDepot after completing the amp, but unsure
https://youtu.be/wRFRwOnLsZI

The cr@p about building one is the fact that it's hard to get high wattage bulbs. And that's the key ingredient. I built mine with a 500W halogen lamp that people use to light the yard. Works perfectly!!
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Re: Testing a completed 18 Watts Amp

Post by davemojo »

Bieworm wrote:
Fri 03/26/21 12:28 pm
davemojo wrote:
Fri 03/26/21 12:12 pm
Bieworm wrote:
Fri 03/26/21 11:52 am
Lightbulb current limiter.. that's what I do
ok need to understand what that is, I think I have seen a video from TubeDepot after completing the amp, but unsure
https://youtu.be/wRFRwOnLsZI

The cr@p about building one is the fact that it's hard to get high wattage bulbs. And that's the key ingredient. I built mine with a 500W halogen lamp that people use to light the yard. Works perfectly!!
Indeed I can’t find any high watts bulb complicated.

This is what I have seen on YouTube already but not so practical, I mean is a very good way to test, but not easy to accomplish

I need to figure out how to proceed
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Re: Testing a completed 18 Watts Amp

Post by davemojo »

It is impossible to find a 230 watts bulb light

So I must adopt a different approach

First of all I’m going to check for continuity in some parts of the amp.

I reviewed the work , capacitors are set the correct orientation, resistors are of the correct value I checked 3 times each one of them.

My only doubt is not properly soldered joints on turrets or no properly soldered resistors on pots or the most critical part the tube sockets lugs having issues on lug soldered
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Re: Testing a completed 18 Watts Amp

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davemojo wrote:
Fri 03/26/21 1:30 pm
It is impossible to find a 230 watts bulb light

So I must adopt a different approach

First of all I’m going to check for continuity in some parts of the amp.

I reviewed the work , capacitors are set the correct orientation, resistors are of the correct value I checked 3 times each one of them.

My only doubt is not properly soldered joints on turrets or no properly soldered resistors on pots or the most critical part the tube sockets lugs having issues on lug soldered
I always follow Josh’s advice.. print out the layout and schematic, a few copies. Then compare the build, layout diagram and schematic starting from the input and move on to the output. Highlight ONLY WHEN values, connections and positions are checked. Do this very meticulously and take your time. When everything matches the documents plug the amp into a lightbulb current limiter and fire it up. When the lightbulb doesn't light up it's probably fine to take the bulb out of the circuit. Don't forget to plug in a speaker or dummy load, or you might ruin your output transformer.
Now you can check your voltages. Be aware that the voltages are off with the bulb in the circuit. Bad connections and wiring layout can be adressed now. Read the robrob 1st startup carefully before switching the amp on. I might be forgetting stuff here...
But first build that bulb limiter!!! It's really easy.. take a halogen 500W lamp.. it's good enough. I built mine from an old scrap lamp.
20210326_200457.jpg
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Re: Testing a completed 18 Watts Amp

Post by davemojo »

Yes building the bulb limiter is easy when you have an Hallogen light 500 watts or even 300 watts would work fine, but it gets complicated when you can't find such a bulb light of such a wattage

It may take days for me to arrange that and unsure if I can succeed on finding such a bulb light.

Thanks
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Re: Testing a completed 18 Watts Amp

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davemojo wrote:
Fri 03/26/21 2:58 pm
Yes building the bulb limiter is easy when you have an Hallogen light 500 watts or even 300 watts would work fine, but it gets complicated when you can't find such a bulb light of such a wattage

It may take days for me to arrange that and unsure if I can succeed on finding such a bulb light.

Thanks
They are at every home depot...very common
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Re: Testing a completed 18 Watts Amp

Post by TriodeLuvr »

davemojo wrote:
Fri 03/26/21 1:30 pm
It is impossible to find a 230 watts bulb light
Here in the States, that would be a type ECA photoflood lamp. They're 120V, 250W. Isn't there something equivalent for 230V?

Jack
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Re: Testing a completed 18 Watts Amp

Post by davemojo »

TriodeLuvr wrote:
Fri 03/26/21 11:05 pm
davemojo wrote:
Fri 03/26/21 1:30 pm
It is impossible to find a 230 watts bulb light
Here in the States, that would be a type ECA photoflood lamp. They're 120V, 250W. Isn't there something equivalent for 230V?

Jack
Hi Jack Hi-ya

Yes we actually do, we have those halogen lamps 300W 230v usually for the garden. I ordered one already.

Thanks
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Re: Testing a completed 18 Watts Amp

Post by davemojo »

Hey All,

so I guess I could actually use that isn't?

https://www.ebay.co.uk/itm/Packs-of-Inf ... SwaEhZFWhG

I already prepared the bulb light current limiter
Last edited by davemojo on Sat 03/27/21 6:18 am, edited 1 time in total.
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Re: Testing a completed 18 Watts Amp

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davemojo wrote:
Sat 03/27/21 3:36 am
Hey All,

so I guess I could actually use that isn't?

https://www.ebay.co.uk/itm/Packs-of-Inf ... SwaEhZFWhG

I already prepared the bulb light current limiter
That one should be fine
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Re: Testing a completed 18 Watts Amp

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Re: Testing a completed 18 Watts Amp

Post by ViperDoc »

Here's the one I use. I use 40 watt bulbs.

https://ampgarage.com/forum/viewtopic.p ... 545d4f546d

EDIT: And here's the latest version:

https://ampgarage.com/forum/viewtopic.php?f=6&t=34311
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Re: Testing a completed 18 Watts Amp

Post by TriodeLuvr »

davemojo wrote:
Sat 03/27/21 3:36 am
Hey All,

so I guess I could actually use that isn't?

https://www.ebay.co.uk/itm/Packs-of-Inf ... SwaEhZFWhG

I already prepared the bulb light current limiter
Something like this would be my choice; very easy to see if it's beginning to light up:

https://www.barkerphotographic.ie/no-1- ... o-lighting

Incidentally, when testing an amp for the first time that has a tube rectifier, I always substitute a solid state plug-in for the first run with a variac. The tube rectifier can surprise you when it suddenly reaches the threshold where it begins to deliver current. I would do the same thing with a limiter, just to be sure B+ isn't dependent on the rectifier filament being at full power.

Jack
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Re: Testing a completed 18 Watts Amp

Post by davemojo »

Hey All,

So with few bucks I was finally able to get a 250W 230v bulb light a double outlet some cable with power-cord plug and the bulb plate holder.

I have a piece of square wood like plywood and ready to go next week since I order everything online since here you can't just walk in to a shop and buy what you need , no yet bloody pandemic is limiting freedom... :cry:
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Re: Testing a completed 18 Watts Amp

Post by davemojo »

Here some results

I have connected the bulb light current limiter between the wall receptacle and the Amp.
I put the amp standby switch on and the amp main switch off.
I plugged the amp power cord into the bulb limiter and the bulb light limiter to the wall receptacle, it is actually a lead extention that goes into the wall.

I then at this point kept amp standby switch on and turned on the amp, the amp indicator light turns on but the bulb light didn't go on at all no even for a sec, so either I built the bulb light limiter wrong or something else isn't right. However the amp didn't smell any burned or smoked or anything like that.

The light on the amp was lit red but i switched all of after about 10 secs

The current seems to be flowing to the amp since the amp light is lit, unsure what's wrong with bulb limiter.

In the Netherlands the power cord cable are made with 2 colors brown and blue + ground yellow/green

On the limiter I didn't use any ground I have connected the brown cable from power cord plug to the bulb light holder took another piece of brown that goes from the other side of the connector straight to the outlet where the amp will be connected

The blue cable instead runs directly to the outlet and doesn't engage on the bulb light holder,

Hope my explanation is clear, see photo

Thanks
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