Yet another 124 build

[erwin_ve]

Grounding with the PS filter board can be done both ways. I made the PI seperate so you can decide.

[GAStan]

As I work on the BOM and parts lists I find myself needing to make decisions on various parts of this build. One big decision that will have a big affect on the normal use is the type of power cord. The chassis has allowances for both a hardwired or IEC type removable cord. Charlie Wilson made a post that made this an easy decision.

https://ampgarage.com/forum/viewtopic.p ... 10#p455110

As a lifelong electronics technician, computer user (learned BASIC on a TRS-80) and overall geeky nerd I can relate to the cons Charlie mentions, most by personal experience. A hardwired power cord simply makes more sense. A guitar player already has a multitude of items to take with them, one less thing to remember only makes life easier.

The challenge to this is what to do with the IEC cutout. I have searched extensively for a power outlet that fits and can only find the IEC type. Once I receive the chassis and take actual measurements I will look more closely at other options I am considering.

As always I welcome any comments, opinions and advice offered.

Glenn

[GAStan]

An update...

After no updates for 2 weeks on shipment progress of the chassis/boards from the Netherlands Erwin contacted the shipping company. Long story short we finally got an update that it is at US Customs and is scheduled for delivery Monday. Big THANK YOU to Erwin!

With the encouraging news of the chassis I decided to order the iron for this project. I went with Heyboer from Mojotone:
MOJO763EX Power Transformet
MOJO775 Output Transformer
MOJO777 Choke
I also got an additional relay board in case I need it.

Money invested so far ($US):
$350 for 19 pounds of iron. Free shipping.
$270 for chassis and boards including shipping. This cost depended on the current exchange rate, actual cost was 241 Euros including shipping.
$12 NTE452 JFET from Amazon Prime.

I am still putting together orders for the remaining items. For some items I need the chassis/boards to take measurements from. An example is the lead spacing for the 47uF radial power filter caps.

This build is easily going to exceed $1,000.

I am providing my actual build cost for those that are curious. I have noticed a few inquiries about cost and they generally get good estimates from the extremely helpful members here. I want to give an actual example as I build.

Glenn

[Stephen1966]

As I work on the BOM and parts lists I find myself needing to make decisions on various parts of this build. One big decision that will have a big affect on the normal use is the type of power cord. The chassis has allowances for both a hardwired or IEC type removable cord. Charlie Wilson made a post that made this an easy decision.

https://ampgarage.com/forum/viewtopic.p ... 10#p455110

As a lifelong electronics technician, computer user (learned BASIC on a TRS-80) and overall geeky nerd I can relate to the cons Charlie mentions, most by personal experience. A hardwired power cord simply makes more sense. A guitar player already has a multitude of items to take with them, one less thing to remember only makes life easier.

The challenge to this is what to do with the IEC cutout. I have searched extensively for a power outlet that fits and can only find the IEC type. Once I receive the chassis and take actual measurements I will look more closely at other options I am considering.

As always I welcome any comments, opinions and advice offered.

Glenn

Why not do what MrD did? Only option really if you can't find a receptacle of some other kind to go in the hole... cover it with a plate.

[sluckey]

The challenge to this is what to do with the IEC cutout.

I would use a IEC connector. And also use a cable clamp to secure the power cord to the chassis.

[GAStan]

Why not do what MrD did? Only option really if you can't find a receptacle of some other kind to go in the hole... cover it with a plate.

This very well be what I do, thank you for the suggestion.

The challenge to this is what to do with the IEC cutout.

I would use a IEC connector. And also use a cable clamp to secure the power cord to the chassis.

I have thought about filling the hole with an IEC power outlet, but it may never get used. Depends on if I can find a ready made cover plate and decide I'm too, ummm, "busy" to fabricate one.

I do plan on using a cable clamp similar to what you posted a pic of to secure the hardwired power cable to the chassis.

Thanks to both of you for the suggestions

Glenn

[GAStan]

We have iron!

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This amp won't be lightweight, that's for sure. At least it's just a head and not a twin combo.

Glenn

[GAStan]

Chassis and boards were delivered today. All I can say is WOW!! Erwin provides a beautiful chassis and boards set. He has good photos posted in the sales forum so I'm not going to post any because they would be redundant.

Power transformer fits perfectly. Holes for OT and choke line up well. So far I like everything I have seen on these items. I'm excited to continue this build.

Glenn

[GAStan]

Using the BOM from here, then checking the parts and quantities against the schematic I made some orders. This process began the day I started this thread. After searching and searching it took orders from 5 different vendors to find everything.
Costs:
$640 for parts
$27 shipping
$20 taxes
3 vendors charged shipping, other 2 had free shipping because I went over the minimum.
2 vendors charged taxes, others didn't need to because out of state.

I stuck as close as I could to the original parts with a few exceptions. I went with CTS pots due to personal preference, even found a J-taper. Belton sockets (just wasn't sure what HAD used). Nichicon power caps, couldn't find Atoms. Carbon film and metal film as shown on layout available here as much as possible.

Hope I remembered everything. I got knobs, screws, washers, standoffs, power cord/strain relief, LEDs, wire, pots, resistors, caps, trim pots, terminal strips, ground lugs, diodes, 12v regulator & xfmr, 5 pin DIN connectors & jack, coax, multiconductor cable for footpedal, 2 switch footpedal, switches, impedance selector switch, fuses & holder. I have items such as heat shrink, grommets, wire ties, solder etc. and 12 gauge solid wire for a ground bus from a piece of Romex. I'll figure out what I forgot when I need it LOL.

Once these orders come in I should have everything needed to complete the amp except the cabinet and tubes I'll probably order the cabinet in a month or so. I don't really expect to need it for several months but it will take about a month for the builder to finish it and ship it to me.

The tubes I'll order when I'm about ready to test out the amp. I don't want to go past the warranty return period prior to testing them out. Also I haven't decided exactly what brand of tubes I want to use.

[GAStan]

As I was working on the BOM and making the orders for the parts I needed I did have to make some decisions. Rather than explain my thought process I'll just post what I'm planning as an end result with this amp.

Later (precision?) power supply with 330uF and 47uF caps using the board supplied by Erwin.

4x 6L6 100 watts, no 1/2 power switch. 1 ohm resistors with external test points for bias adjustments.

#124 preamp, post mod. Normal and FET inputs, no FET relay switching. This section I want to stay as original as I can with the parts I was able to source (all current production, no NOS). My son's favorite guitar is a Strat so this should be a good fit.

I drew up (edit: using the great schematics already posted as reference i RE-drew...) some schematics separating the sections of the amp. The act of drawing these helps me to better understand and retain circuits. It will also be a good place to record actual component values as well as various voltages and currents as I build and test the amp. Here are a few of them. If there is interest I can scan these to PDF and post them. I have a hardcover journal I use for notes that for me is easier than anything electronic-just personal preference.

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[martin manning]

I agree that drawing up schematics yourself is a good way to get familiar with the circuit, but there is already a gold standard 124 schematic, the Skyliner version drawn by icracer.

[GAStan]

I agree that drawing up schematics yourself is a good way to get familiar with the circuit, but there is already a gold standard 124 schematic, the Skyliner version drawn by icracer.

I agree there are already great schematics on TAG. I edited my post to reflect that I used these as my reference to re-draw the schematics. I'm sorry that I came across wrong, it was not my intention.

[GAStan]

Adding to my previous post:

Thank you to the admin who run this site and all of the contributors that have made it what it is. This is something I can't say often enough and should have included in the opening post of this thread.

I particularly want to give a shout-out to ic-racer for the work he did to document #124 in his thread as well as all who contributed to it, simply too many to name. Much of this build is based on information from that thread and would be much tougher if not impossible without it.

Forgive my ignorance but I'm afraid I do not know who photographed #124 and made it available-I am grateful to that individual as well.

[ayan]

Adding to my previous post:

Thank you to the admin who run this site and all of the contributors that have made it what it is. This is something I can't say often enough and should have included in the opening post of this thread.

I particularly want to give a shout-out to ic-racer for the work he did to document #124 in his thread as well as all who contributed to it, simply too many to name. Much of this build is based on information from that thread and would be much tougher if not impossible without it.

Forgive my ignorance but I'm afraid I do not know who photographed #124 and made it available-I am grateful to that individual as well.

Well, that would be me, along with Billy Yates -- who had the amp in his shop for servicing before it was put in the market.

Gil

[GAStan]

Adding to my previous post:

Thank you to the admin who run this site and all of the contributors that have made it what it is. This is something I can't say often enough and should have included in the opening post of this thread.

I particularly want to give a shout-out to ic-racer for the work he did to document #124 in his thread as well as all who contributed to it, simply too many to name. Much of this build is based on information from that thread and would be much tougher if not impossible without it.

Forgive my ignorance but I'm afraid I do not know who photographed #124 and made it available-I am grateful to that individual as well.

Well, that would be me, along with Billy Yates -- who had the amp in his shop for servicing before it was put in the market.

Gil

Thank you Sir! And thanks to Mr. Yates as well.