Starting to populate the chassis....
Moderators: pompeiisneaks, Colossal
Re: Starting to populate the chassis....
124 low plate classic, version 2 preamp board, with boards from AN.
Re: Starting to populate the chassis....
New pics, almost done, transformers are mounted, PT and choke are wired, couple three four days yet.....
Glued a LED into the pilot light housing, need to trim off the light buld socket part.
Replaced all the required resistors with the correct 2, 3, 5 watt ones.
Brian, feel free to comment
Glued a LED into the pilot light housing, need to trim off the light buld socket part.
Replaced all the required resistors with the correct 2, 3, 5 watt ones.
Brian, feel free to comment
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Re: Starting to populate the chassis....
The shielded cable to V1A and V2B should only have the shield tied to ground at one end. If both ends of shield are tied to ground it can cause a ground loop. I can only see the tube end of these so don't know if other end is tied to ground but thought I'd mention it.
Glenn
I solder better than I play.
I solder better than I play.
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Starting to populate the chassis....
I would try and stick closer to what HAD used in #0124 regarding part selection. I mentioned previously that he used 6PS and not 716 orange drops. I would strongly suggest you swap them out and use 6PS. I would also change out those 2watt metal oxide power tube grids for 1/2watt carbon film resistors. While you are at it change out the grids on V1 and V2 from metal film to carbon film and the silver mica snubbers on V1b and V2 to ceramic.
Are you sure the screens are 3 watt? They look like 2 watt to me...
Are you sure the screens are 3 watt? They look like 2 watt to me...
Ian
Re: Starting to populate the chassis....
Thanks, shielded coax "IS "grounded at one end only, (pot end when possible) all resistor wattage is per schematic now. Unless I missed one or two.
I can change the 716s, not a problem. That's why I post pics. Please tell me what I could do better or what I'm doing wrong.
Screens are 3 watt, that's what I bought....
I'm not an expert and this is actually fun for me. But like you guys I would like it to work when I'm thru with it.
Brian
I will change out to 6PS caps
I can change 2 watt metal oxides to 1/ watt carbon film.
V1,V2 grids to carbon film
silver mica snubbers on V1b, V2 to ceramic.
I can and will change anything you guys think will be better, you are the experts, I'm not, I just want a killer amp........
Questions:
How important is that tatalum cap on the preamp board, I have a 1uf, 25v cap as shown on the "low plate classic" picture? And what is the rating on the Tantalum cap.
Question: If the two wires from the 10K Bias pot go to the board in the 3rd picture what wire goes to the Bias point in picture #1?
I can change the 716s, not a problem. That's why I post pics. Please tell me what I could do better or what I'm doing wrong.
Screens are 3 watt, that's what I bought....
I'm not an expert and this is actually fun for me. But like you guys I would like it to work when I'm thru with it.
Brian
I will change out to 6PS caps
I can change 2 watt metal oxides to 1/ watt carbon film.
V1,V2 grids to carbon film
silver mica snubbers on V1b, V2 to ceramic.
I can and will change anything you guys think will be better, you are the experts, I'm not, I just want a killer amp........
Questions:
How important is that tatalum cap on the preamp board, I have a 1uf, 25v cap as shown on the "low plate classic" picture? And what is the rating on the Tantalum cap.
Question: If the two wires from the 10K Bias pot go to the board in the 3rd picture what wire goes to the Bias point in picture #1?
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- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
Re: Starting to populate the chassis....
25V is more than fine. I think it sees 0.7V
I you want to use that bias board, take a look at the layout for #0183.
Last edited by ijedouglas on Fri Mar 29, 2024 3:59 am, edited 1 time in total.
Ian
Re: Starting to populate the chassis....
Definitely this
- ijedouglas
- Posts: 718
- Joined: Fri Sep 22, 2017 9:07 pm
- Location: Southern California
1 others liked this
Re: Starting to populate the chassis....
For a first time build, your best chance of success:
- select an amp to build (you chose #0124.. great choice)
- Study the layout and schematic until you are pretty familiar with it
- Try and find pictures of the amp you are building ( http://www.amparchives.com/folder/2493/)
- stay as close as possible to the parts used in the amp. 124 is pretty much 1/2watt carbon film with Dale RN65 100K plates and metal film cathodes. 3 watt power tubes screens. 1watt PS dropping string. 1/4watt 10M on the LNFB. 1 watt piher carbon film GNFB resistor. Ceramics on V1 and V2
- lead dress is extremely important with these amps. Study gut shots and try to follow what HAD was doing
- search the forum if you get stuck, chances are someone else got stuck in the same place and asked this same question.
- ask questions
- select an amp to build (you chose #0124.. great choice)
- Study the layout and schematic until you are pretty familiar with it
- Try and find pictures of the amp you are building ( http://www.amparchives.com/folder/2493/)
- stay as close as possible to the parts used in the amp. 124 is pretty much 1/2watt carbon film with Dale RN65 100K plates and metal film cathodes. 3 watt power tubes screens. 1watt PS dropping string. 1/4watt 10M on the LNFB. 1 watt piher carbon film GNFB resistor. Ceramics on V1 and V2
- lead dress is extremely important with these amps. Study gut shots and try to follow what HAD was doing
- search the forum if you get stuck, chances are someone else got stuck in the same place and asked this same question.
- ask questions
Ian
Re: Starting to populate the chassis....
Good info, sometimes I forget to look at drawings and schematics and post a question instead.
I promise to be better!
Thank you all, new parts are ordered, couple days to ship, I should finish it next week, "HOW EXCITING!!!!"
Brian
Thanks on the info on the #183 schematic, I checked it out, no problem makes perfect sense.
I promise to be better!
Thank you all, new parts are ordered, couple days to ship, I should finish it next week, "HOW EXCITING!!!!"
Brian
Thanks on the info on the #183 schematic, I checked it out, no problem makes perfect sense.
- martin manning
- Posts: 13347
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Starting to populate the chassis....
I see you have installed the filter and dropping resistor in the left rear corner of the chassis (as seen from the front) shown in the 124 layout. The main filter board you are using includes that filter. See the 183 layout for the B+4 and 5 connections that go with the board you are using.
Re: Starting to populate the chassis....
Another thing you might want to consider is capacitor orientation when you get the 6PS caps.
Capacitor outside foil placement
Cap tester
Capacitor outside foil placement
Cap tester
Glenn
I solder better than I play.
I solder better than I play.
Re: Starting to populate the chassis....
I will check the #183 drawing again....
So I can just take the filter and dropping resistor off and run the wire right to the B+ connection?
Thanks to both of you, that's exactly how I check the caps for neg.
Brian
So I can just take the filter and dropping resistor off and run the wire right to the B+ connection?
Thanks to both of you, that's exactly how I check the caps for neg.
Brian
Re: Starting to populate the chassis....
I can take out that dual 10uf 450volt cap too...
Brian
Brian
- martin manning
- Posts: 13347
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Starting to populate the chassis....
Question:
What are these abbreviations ???
LNFB
GNFB
Thanks Brian
What are these abbreviations ???
LNFB
GNFB
Thanks Brian