New Amp Build. This time, an Express

SG John

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Last year, I started sourcing some parts for another amp build. I got some stuff for either an 18 Watt Watkins Dominator or Marshall. At the same time, I was also looking for transformers for a Trainwreck Express. Eventually, I found someone through the Ampgarage forum who could hook me up with everything except the cabinet. We struck up a deal, and I eventually had a big box of parts in my possession.




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As I was making sure that I had everything, including enough spare time, I started plotting my course. Serial number??? Trainwrecks did not have serial numbers, but women's names instead. What to do? My choices eventually were narrowed down to Freyja and Lorelei. Both are tied to music, and were fitting of the build to me. Eventually, I went with Lorelei because I loved the story of her luring sailors to their deaths with her enchanted singing.




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I made a jig to hold the pots out of a paint stirrer. It made soldering the pots real easy, and very neat. This is how I'll always do this in the future. No chassis lip to deal with.


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I made good use of my Little Joe Circuit Board Holder.






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Got the turret board done and mounted, and it's starting to look like an amp. As I finish all the socket wiring, I'll get the bias board and all the filter caps put in. I need to take a break, as my left arm is bugging me from being vertical too much the past few days. I'll add some more in a couple of days.


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I managed to pick up a bad bug before heading to England, but am finally shaking things off. Before I got sick, my wife had my best friend fly out from Minneapolis for Thanksgiving. Since he’s a PhD electrical engineer retired from NASA, he critiqued my soldering and other connections. Naturally, I did a bunch of resoldering.

This week, I got the lower level of filter caps soldered together, and glued to the chassis. Also got the last of the connections done to V1 - V3. Hopefully tomorrow I’ll have some more free time to prep for the bias board.

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I managed to pick up a bad bug before heading to England, but am finally shaking things off. Before I got sick, my wife had my best friend fly out from Minneapolis for Thanksgiving. Since he’s a PhD electrical engineer retired from NASA, he critiqued my soldering and other connections. Naturally, I did a bunch of resoldering.

This week, I got the lower level of filter caps soldered together, and glued to the chassis. Also got the last of the connections done to V1 - V3. Hopefully tomorrow I’ll have some more free time to prep for the bias board.

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Are those the only guts outside of transformers? Nothing in it.
 
Did some more soldering tonight. There are a couple of little issues developing, but not unsurpassable. I also can't find my cable strain reliefs. I'm sure there will be a couple of other things I need to grab when I drive by You-Do-It Electronics in Needham on Thursday. I'm trying to get this done before the end of the year. It will probably be the quickest I've done any of my projects.


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Exciting!!
Trainwreck Christmas!!

I would like some soldering tips from a guy like that!

Glad you are feeling better, and doing this stuff I guess your hands / arms are better as well. (I think it was you mentioned some hand pain unless I have mistaken that for someone else)

On the bias board, the BIG 25w ceramic resistor - does that get hot / is it ok for the wires to be close to it?

EDIT: I see @67plexi board the wires run close beside it.
 
Exciting!!
Trainwreck Christmas!!

I would like some soldering tips from a guy like that!

Glad you are feeling better, and doing this stuff I guess your hands / arms are better as well. (I think it was you mentioned some hand pain unless I have mistaken that for someone else)

On the bias board, the BIG 25w ceramic resistor - does that get hot / is it ok for the wires to be close to it?

EDIT: I see @67plexi board the wires run close beside it.
Well that was my first amp build and the 25 watt resistor is a false choke and is elevated off the board pre soldering station
but I did make all the boards I tried to order a Express amp from Ken but he was sick after many hours on the phone Ken
faxed me a schematic and a parts list then told me it couldn't be done we both went through the electronics training in the US Navy
Ken's best friend Jim and I were friends Ken put up with me then Ken have me service all the Marshall amps he modified on the west coast
that ended after 911 Alaska Airlines closed my shipping account then Jim called me and asked what's going on with Kenny
he faxed is life's work to Jim it took three days then Jim called me and said Kenny passed on I was in shock
I'm thankful for the training and knowledge passed on to me I built 4 Express amps and two Rocket amps
it did open doors for me when I started the Dumble amp quest I'm still learning but my lead dress has improved.

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Exciting!!
Trainwreck Christmas!!

I would like some soldering tips from a guy like that!

Glad you are feeling better, and doing this stuff I guess your hands / arms are better as well. (I think it was you mentioned some hand pain unless I have mistaken that for someone else)

On the bias board, the BIG 25w ceramic resistor - does that get hot / is it ok for the wires to be close to it?

EDIT: I see @67plexi board the wires run close beside it.
That particular board is totally pissing me off. I had very little room to fit that resistor, and did not know it needed to be elevated. There are some issues with that board, it's placement, and the power transformer's placement that is giving me some trouble. Otherwise, RJ did put together a good kit. I wish some of what he did, and what Ron W. put together at the AmpGarage matched a bit better. I'll deal with it, and get this working. I've also learned what I would change if I source this whole thing myself next time.

As for that 25 watt ceramic resistor, it is close to the board. I did dress the red and white wires so that the white wire has about a 3/16" gap and the red wire has a 3/8" gap. When the chassis is inverted, they will be well below the resistor, and heat rises. The board on the other hand...

Once I'm done with the filter caps, I will try to change the dress of the yellow wire between the first filter cap and bottom of the 25 watt resistor. I will give it a bit more breathing room.

What I got, what I paid, and what I expected to learn were all well within my expectations. This was the best way for me to take a plunge into this type of project, and an Express is what I really wanted my next project to be. Hopefully now that I'm this closer to being finished, there won't be too many steps backwards.


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Got some more photos from Mike at Faith Amps today. He said it should ship the end of next week. I hope I finish the amps soon, and can mate them up. He's sending two face plates in case one gets damaged when drilling the holes for the controls.

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The cabinet did arrive a little over a week ago. I'm slammed with other stuff, so haven't really been able to finish. As far as the amp itself is concerned, I just need to get the power cable and fuse holder installed and wired, and also remember to get the ground wires from the filter caps to the lugs finished. Then I have to drill and counterbore the bottom plate for the chassis, and drill and fit the chassis in the cabinet. Hopefully, this week I'll get it wrapped up.

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Nice job, John!

The high-power dropping resistor in front of the screens is often pretty close to the board. Have a look at vintage Traynors (470R 10W) or even the Egnater seminar amps. You could probably replace it with a 10-15W resistor (25W is overkill) if you want more space between ceramic body and turrets (e.g., to elevate it a bit). I like to use chassis-mounted resistors to help with heat dissipation, but that would take you away from the original look.
 
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