New Build: JTM45 VSoZo ABCC LarMar IEC LarrysGnd Turret Fuse

[ldanmartin]

I am in the process of a new JTM45 build:

Contents/Modifications:
JTM45 Metro Kit
Vintage Sozo Capacitors
Allen Bradley NOS Carbon Composition Resistors
Lar/Mar PPIMV
IEC Power Receptacle
Larry's Grounding
Kurts Equipment / Brian Haberman Turret Board & Fuse Holder

I have never built an Amp before. Please feel free to comment and point out any mistakes as I go along.

Questions:
1) The original kit instructions on Step#8 says to use 20 gauge bus wire to the ground lug on the Internal Filter Cap... but I used the black 22 gauge kit wire as I needed to go farther away to Larry's Grounding point#3. Is the 22 gauge wire going to be ok for that?

2) Larry's Grounding point#5 indicates five items should be connected there... but I only see four connections on most peoples pictures. Items to connect: Screen Filter, Main Filter, HV CT (via fuse), V4 & V5 Cathodes (1R bias resistors).
I believe the Main Filter is the F&T dual 32uf can cap mentioned in Step#3. Where is the "Screen Filter" and what step is that mentioned in the instructions?

Thank you MetroAmp and the forum members for all the insight (I have read for days before I bought a kit, and before/during this build process). This is a fun kit to build!

Dan Martin

[Flames1950]

The 22awg wire will be fine.

I'm guessing most guys connect the two power tube cathodes together before making a single run to the grounding point; that's how I've implemented this before anyway. I think I used some buss wire and sleeving between the tubes, then the black 22awg wire from V5 to the ground lug, but I'd have to walk twenty feet away from my computer and turn an amp over to be sure, and it is getting late.............

OK, talked me into it, and that is what I did.

[ldanmartin]

I started by drilling some holes for the Lar/Mar PPIMV & IEC Power Receptacle:
http://img824.imageshack.us/i/dsc0002vu.jpg/" onclick="window.open(this.href);return false;
http://img808.imageshack.us/i/dsc0020p.jpg/" onclick="window.open(this.href);return false;
http://img828.imageshack.us/i/dsc0032e.jpg/" onclick="window.open(this.href);return false;
http://img713.imageshack.us/i/dsc0033ei.jpg/" onclick="window.open(this.href);return false;
http://img69.imageshack.us/i/dsc0034w.jpg/" onclick="window.open(this.href);return false;
http://img245.imageshack.us/i/dsc0036vw.jpg/" onclick="window.open(this.href);return false;
http://img543.imageshack.us/i/dsc0037so.jpg/" onclick="window.open(this.href);return false;
http://img827.imageshack.us/i/dsc0040wk.jpg/" onclick="window.open(this.href);return false;

I ran 22AWG from V4 to Ground#5, and 22AWG from V5 to Ground#5... not bus wire... (I originally went from V4 to V5, then V5 to ground#5)?

DSC_0002.jpg (36.04 KiB) Viewed 3124 times

DSC_0010.jpg (45.71 KiB) Viewed 3124 times

DSC_0012.jpg (54.06 KiB) Viewed 3124 times

Thanks,
Dan

[Flames1950]

Sure, that's fine too!

[ldanmartin]

Is there a "Screen Filter" on a JTM45?
Where is it on this image connected to ground#5?

Ground connection #5 has 5 connections:
5) Screen Filter, Main Filter, HV CT (via fuse), V4 & V5 Cathodes (1R bias resistors)

http://img820.imageshack.us/i/grounding20scheme1.jpg/" onclick="window.open(this.href);return false;

Just checking.

Dan

[ldanmartin]

I want to remove this extra ground lug I have in my build that incorporates Larry's Grounding point#5 (if there is no additional Screen Filter or additional Main Filter ground wire to run).

I want to remove the extra ground lug in the upper left of this picture if I have nothing else to solder there:

http://img827.imageshack.us/i/dsc0040wk.jpg/" onclick="window.open(this.href);return false;

Dan

[ldanmartin]

dsc0033ei.jpg (64.71 KiB) Viewed 3240 times

dsc0040wk.jpg (73.34 KiB) Viewed 3240 times

[arledgsc]

Larry's Grounding point#5 indicates five items should be connected there... but I only see four connections on most peoples pictures. Items to connect: Screen Filter, Main Filter, HV CT (via fuse), V4 & V5 Cathodes (1R bias resistors).

The confusion is the large Main and Screen filter capacitor connected at Larry GND #5 share the same grounding wire to the solder lug. So a single ground connect covers both since the capacitor package connects the ground for each capacitor side internally. Think of it as Main/Screen filter,....

You are doing a great job BTW. Keep those questions coming and we'll be happy to answer them (if we can!) Scott

[ldanmartin]

Thanks for the info Flames1950 and Scott, and for the encouragement!

I have removed the extra ground lug from point#5.

Pot's installed, input jacks installed and wired.

[ldanmartin]

Working on the PTP board now...

[ldanmartin]

Since I am working in the garage, this is taking a while, as it's still hot in the Phoenix Arizona Metro area. It was 100 degrees in the garage tonight at 8PM when I started (90 at 2AM). Making progress. Here are some more pics:

(Large images):
http://img412.imageshack.us/i/dsc0052hq.jpg/" onclick="window.open(this.href);return false;
http://img189.imageshack.us/i/dsc0054yn.jpg/" onclick="window.open(this.href);return false;
http://img704.imageshack.us/i/dsc0057nw.jpg/" onclick="window.open(this.href);return false;
http://img684.imageshack.us/i/dsc0058cfz.jpg/" onclick="window.open(this.href);return false;
http://img641.imageshack.us/i/dsc0059oo.jpg/" onclick="window.open(this.href);return false;
http://img641.imageshack.us/i/dsc0060gu.jpg/" onclick="window.open(this.href);return false;
http://img534.imageshack.us/i/dsc0061lzs.jpg/" onclick="window.open(this.href);return false;
http://img831.imageshack.us/i/dsc0062d.jpg/" onclick="window.open(this.href);return false;
http://img411.imageshack.us/i/dsc0063gs.jpg/" onclick="window.open(this.href);return false;
http://img62.imageshack.us/i/dsc0064ym.jpg/" onclick="window.open(this.href);return false;

Here are some in a smaller format:

DSC_0054.jpg (47.78 KiB) Viewed 3125 times

DSC_0057.jpg (72.45 KiB) Viewed 3125 times

DSC_0058.jpg (61.6 KiB) Viewed 3125 times

[ldanmartin]

Here's some more:

DSC_0060.jpg (52.47 KiB) Viewed 3125 times

DSC_0063.jpg (73.18 KiB) Viewed 3125 times

DSC_0064.jpg (65.33 KiB) Viewed 3125 times

[ldanmartin]

How do you clean the inside of the chassis, parts and solder joints?

1) Can of air?
2) Deoxit? (What do you do, spray the whole inside and let it dry? Where do you get it from?)
3) Isopropyl Alcohol?
4) Other ideas?

Thanks in advance,
Dan

[ledzep443]

How do you clean the inside of the chassis, parts and solder joints?

1) Can of air?
2) Deoxit? (What do you do, spray the whole inside and let it dry? Where do you get it from?)
3) Isopropyl Alcohol?
4) Other ideas?

Thanks in advance,
Dan

Isopropyl Alcohol and an acid brush.

[ldanmartin]

Thanks LEDZEP443!

I went and got the Isopropyl Alcohol and an acid brush (I'll use them at the end, after populating the PTP board).

More pics, pots wired:

DSC_0074.jpg (66.58 KiB) Viewed 3059 times

DSC_0066.jpg (48.12 KiB) Viewed 3059 times

DSC_0065.jpg (59.75 KiB) Viewed 3059 times