Hellfire Amp Build-along - first build

[randelli]

Good point on utilizing the posts and the center holes of the turrets. But since he has it all ready to solder he should not rework it at this point.

[bilbarstow]

Man, I hate it when mom and dad fight ...

Lyle, I knew that if I gave it a little time, you would be able to provide me with another of your best practice gems. I really appreciate it and it is a great lesson for others that are following this thread. I understand what you are saying about needing to be able to replace the Caps. Serviceability is always a plus. And I will take that into consideration on my next build (because, we all know there WILL be a next one - this is addictive).

But ... as Randelli has said, I'm sort of ready to move forward on the soldering, and I'm itching to get to the testing phase. If what I've done ends up not working, then I'm sure that I'll look back and say "I wish I'd listened to Lyle". But at that point, I'll probably be having to unsolder more than one thing, so ...

[Lyle Caldwell]

The next guy/gal doing a build will see that and save some headdesking at least.

The earlier resistors/shielding were crucial. This last stuff is almost purely cosmetic, though looking towards the future it's easier to service.

[randelli]

which one is mom?????

[Lyle Caldwell]

You are totally Mr. Mom.

[bilbarstow]

Much as you are going to hate this ... randelli you are Mom, because you gave birth to this project in the first place

And Lyle, you are right - the next person (and me next time) will certainly benefit from your suggestions.

[randelli]

Go to your room!

Wait till your father gets home!









Did I leave anything out?

[bilbarstow]

OK - I went to my room and progress ensued :

I got the components soldered to the Turret board :



Where I was complaining about the single Turret being too small, I took a page out of Lyle's book - used his suggestion to create pigtails for connecting offboard resistors - and took a spare piece of resistor wire and created a ring large enough to accomodate the 4 connections, then soldered them all in place :



And just to make sure, I redid the resistors using the same suggestion, shield brought as far down to the resistor to provide maximum shielding :



And finally, I got the board in place and started soldering the connections, including ground, power, choke, and Tight/loose switch. (sorry, this one's a little blurry) :



I thought it was a pretty good evening's work. I hope to get rest of the connections done today and ready for testing.

Thanks for the continuing support and encouragement to both Randelli and Lyle - you are both helping and teaching me soooo much

[randelli]

You are doing a nice job with this build! Hard to believe this is your first time - where are all the solder puddles and melted insulation? I really like how you utilized Lyle's approach for that turret

It looks like you hust have to wire the pots to finish. What else is not connected?

[bilbarstow]

Originally Posted by randelli

where are all the solder puddles and melted insulation?

It looks like you hust have to wire the pots to finish. What else is not connected?

Crafty photography hides a lot of sins !

Master Volume, 1 connection to Volume, 3 Star gnds from the board, and the pre-amp socket and power socket connections from the board, plus the shielded wire from V2, pin 2 to the board.

Not a lot, but I want to do a good job dressing the wires in place, and I was out of time last night.

Which source did you use for the 500 R 5 W ? I can't believe I have to order 1 Resistor.

[randelli]

I ordered through Watts Tube Audio ~ Everything Tube Amps!

You can fire it up and enjoy it until the new resistor comes in - it won't hurt anything. If you order today you should have it by Friday.

[bilbarstow]

WGS tells me that my speaker has shipped. Ordered an Invader 50 12" @ 8 Ohm to put into my VJr Speaker cab initially, until I can build a 2x Cab. That will require additional speaker(s) - still thinking about either 2 x 10" or 10" + 12". That decision will wait on hearing the amp and the Invader.

[hipofutura]

Originally Posted by randelli

I ordered through Watts Tube Audio ~ Everything Tube Amps!

That's where I get my chassis. Best quality I've seen yet.

[bilbarstow]

You know how you can't eat just 1 potato chip ? Well ... you can't just order 1 resistor, or at least I can't.

Ordered enough stuff frome Watts to be a good way down the road on the second build. See - I told you it was addictive.

[bilbarstow]

Here's today's progress - I think that it is all wired up ! I'm still going to step back and re-run all the connections, but I've checked them once, and it looks like everything is right. I marked off each connection on the circuit diagram, so I did not miss any.

Here is the front panel wiring completed :



This shows how I routed the front batch of wires:



Here's the socket wiring dress :



And the sockets from above:



Soldering on the sockets is an exercise in patience - it is a little close in there !

I welcome any comments - I can still re-do it if need be

I hope that these pictures help someone else to see how easy this is to do and inspires them to tackle this project. I'll keep reporting the progress through the testing and play. The process of documenting this has been very helpful to me just in terms of keeping me focused on the details - I know it will help me to do it again !

[randelli]

Nicely done Bill - can't wait to hear your first impressions!

Did the resistors get wet? They look a little swollen......

[Lyle Caldwell]

Looks really really really good (seriously, well done), but you'll get less noise if you move the output tube grid resistors to the socket (off board).

[bilbarstow]

Originally Posted by randelli

Did the resistors get wet? They look a little swollen......

No... no wetness involved. I think that what you are referring to is the fact that I changed from the specified 1/2 watt resistors to 1 watt resistors, at Lyle's suggestion. Yeah, they are a little bigger, but hopefully, bigger is better.

And Lyle, thanks for your compliments - high praise indeed. As for moving the grid resistors, I'm going to leave it as designed for now. Besides, it is dead silent - at least until I plug it in

Smoke test today - I'll report back with voltages and results. Or, if not, I probably touched the wrong thing and am dead ...

[randelli]

Geez, c'mon Bill, you're draggin this out like a prom date

I can't take it - the anticipation is killing me - like that old ketchup commercial LOL!!

Late 1970s Heinz Ketchup Commercial "Anticipation" - YouTube

Late 1970s Heinz Ketchup Commercial "Anticipation" - YouTube

[bilbarstow]

Randelli, from back at post 32 of this thread, you said :

Originally Posted by randelli

Don't rush it - you are in no hurry or under a deadline - soon enough you will be done and wish you still had more to do. Savor it, enjoy every moment, chew 30 times etc.

But now you say:

Originally Posted by randelli

Geez, c'mon Bill, you're draggin this out like a prom date

I can't take it - the anticipation is killing me - like that old ketchup commercial LOL!!

You can't have it both ways. And I chew slowly. And my prom dates WERE a drag.

[randelli]

It is OK for you to take your time and learn with the build. You have most likely noticed by now that I have a hard time sitting still. I think I must have AD ooooh shiney!

[randelli]

Originally Posted by bilbarstow

my prom dates WERE in drag.

FIXED it for ya

I am so excited!! I think I will go outside and run around the block a few times

[bilbarstow]

Didn't even get to the smoke test, and I found a problem... <doh !>

Shorted between shield and signal on the shielded wire from the input to V1, pin 2 (68K resistor). I get to redo a shielded wire. Yippee !

Continuity checks are your friend ...

[randelli]

I had that exact problem on my build too! It must be fate.

Remember to follow all those steps for the fire up

[bilbarstow]

Originally Posted by randelli

Remember to follow all those steps for the fire up

Do you mind if I publish the steps here ? May be helpfull for the next person.

And what were you doing looking at my prom pictures ? (one is really scary - I have white guy Afro perm - what was I thinking ? man, the 70's were a stupid decade)

[randelli]

That would be great Bill - maybe someone will chime in and add some steps if I left any out. The start up is very important; and if not done right could damage the amp or hurt the builder. Too many people just flip the switch and blow a tube, or transformer.

[mudfinger]

Wow. What a great thread. Thanks to Randy, Bilby, and Lyle for the education and entertainment.

[bilbarstow]

OK - here are the steps for power-up testing, as suggested by Randelli :

For first power up I would do this:

1) visually inspect all connections and test for continuity where possible to verify all wires are connected.
2) test all ground connections for continuity, again......
3) with NO tubes in, turn on power switch and test wall voltage, heater voltage at the lamp, B+ voltage where it hits the diodes, and B1 at the first filter cap. The values on the heater, B+, and B1 could be 40% high as there is no load.
4) still NO tubes, turn off standby and check voltages at B2, B3, and B4.
5) check voltages at power tube sockets (pin 4), preamp (pin 1-6), and phase inverter (pin 1 and pin 6)

So what we have done is verify that power is flowing where it needs to go with no tubes to damage in case you bozo'd the layout (technical term). The voltages will not match the schematic because there is no load, so the dropping resistors do not decrease voltage. You will have about the same voltage at every point. IF AFTER INSTALLING THE TUBES there is no voltage drop that means the tubes are not glowing and pulling amps.

OK, moving on:

6) turn off amp
7) install the preamp and PI tubes, turn on power, wait, turn off standby and check voltage at preamp (pin 3-8) and PI (pin 3-8) Should be 1.5 - 2 volts here.
8) turn off amp
9) install the power tubes, plug in 8ohm speaker, turn ALL knobs to (1), turn on power, wait, turn off standby and check voltage at power tubes (pin 8).

Now we know that the tubes are working

10) turn ALL knobs to see if there is any hum with the guitar unplugged from the amp. If so check the 1M at the input jack, use a chopstick to move wires around to see if there is any wires that need to be moved.
11) plug in guitar and lightly strum, smile

If you got this far congratulations are in order. I assume that there may be issues you discover at each or some of these steps. Hopefully you followed the layout and made good connections and you will progress all the way to 11 with no snags!!!

Ok ... so I got stuck by step 1. After I fix that shielded wire, I'll be back.

Oh, yeah ... remember to put in the fuse and the lamp first.

[bilbarstow]

OK, now I really feel dumb.

The input jack is a shorting type ...

What I was reading as shorted continuity on Pin 2 of V1 was caused by there being no plug inserted into the jack.

Of course I find this out after I pull out the wire and re-test it outside the chassis. Then re-test at the jack without the wire. Then serious face-palm.

Laugh all you like, I'm sure that I'm not the first ...

[Lyle Caldwell]

Doh! I was about to post "make sure a plug is in the jack before you measure"!

No, you are far from the first guy to run into that. I still sometimes forget and get that momentary heart attack.

Moving the grids to the tube socket pins doesn't just lower noise as in "I don't hear hiss". It also greatly reduces parasitic oscillations, the kind you don't really hear until they are gone (but you can see on a scope). Greater sustain, more natural decay, sweeter attack, more string to string definition.

It's the little things like this that can turn a really good amp into a great amp.