Langevin AM-16 DIY?

[CJ]

actually, the board is big enough to scan it without removing the components.
i can copy mine if you like.
i hate to desolder vintage stuff, puts ideas in myy head that it won't sound the same when i put everything back.
carbon comps in the original. you guys gonna change to metal?
cj

 

[NewYorkDave]

Now CJ, be careful: that's the kind of talk that drives people to pay $300 for rolls of "vintage solder" on eBay :wink:

 

[CJ]

i know, i am supersticious.
notice that any of my images go from 12.jpg to 14.jpg!
i never use 13.jpg.

 

[alk509]

[quote author="NewYorkDave"]I didn't mean to sound facetious.[/quote]

I didn't think you did either! I'm serious!

[quote author="cjenrick"]actually, the board is big enough to scan it without removing the components. i can copy mine if you like.[/quote]

PLEASE DO! Save us all from my horrible, horrible PCB's!

Thanks CJ!

Al.

 

[PRR]

alk509> making a PCB for this

Those TO5 output transistors dissipate nearly a Watt each, too much for 20-year reliability in a TO5 package. Be sure you have plenty of room for a heatsink. That layout looks a little tight around that area.

OTOH, the wires around the input stage bases seem to run all over the place, which is usually a poor plan.

 

[Flatpicker]

[quote author="PRR"]...OTOH, the wires around the input stage bases seem to run all over the place, which is usually a poor plan.[/quote]I was going to say - use jumpers! It might not look as pretty, but I'm sure the sound (or lack of hum) will thank you for it. :wink:

 

[CJ]

OK, here are some AM 16 pics:

I used "Big Bertha" to solder the endplates to the rack chassis:
(this iron works great for surface mount too!):razz:

I just tacked down the ends and added some more welds inbetween:

OK, some pcb pics.
Hopefully you genius's out ther can do a board from this:

 

[CJ]

Does anyone know what kind of transistor this is?
I tried 2N4032 but that turned out to be a PNP, and this guy, out of the Langevin AM-16, one of the output transistors, is definately a NPN.
I tried a 2N403, but thats a really old transistor that I would not think would be paired up with the other transistors, which are Motorola 2N5210's.

Thanks.
cj

 

[CJ]

I compared the parts list from a Langevin AM 16 document that is floating around the web and found out that it does not come close to matching the actual parts in the amplifier, at least my AM-16.
So, i made up a correct parts list.
All resistors 1/4 watt unless noted.
There is no R12.

here is a link for the schematic that the parts list matches:

http://vacuumbrain.com/The_Lab/TA/Langevin/am_16_sch_large.jpg

here are some more high res shots of the board with
the resistors removed. The board measures 1.5 inches by 5.125 inches. I am going to use
metal film instead of carbon comp:

http://vacuumbrain.com/The_Lab/TA/Langevin/am_pc_1.jpg
http://vacuumbrain.com/The_Lab/TA/Langevin/am_pc_2.jpg
http://vacuumbrain.com/The_Lab/TA/Langevin/am_pc_3.jpg
http://vacuumbrain.com/The_Lab/TA/Langevin/am_pc_4.jpg
http://vacuumbrain.com/The_Lab/TA/Langevin/am_pc_5.jpg

 

[PRR]

> Does anyone know what kind of transistor this is?

40321, like it says. This number scheme was used a LOT by RCA.

> this guy, out of the Langevin AM-16,

Those big output devices are not super critical. They are locked-in by transformer ratios, the exact part hardly matters. This was a Good Idea in days when transistors varied a LOT, but good transformers could be wound with high precision. Other main spec here is a big enough die and case to dump the rather high heat. Those fingers around the transistors are heat-couplers. In this case they seem to throw heat into the PCB, which works better than you might think, though I never like that idea.

What is this, a 24V power supply? And the windings will kick above the rail, but there is a large voltage drop in emitter resistor. So the transistors need more than a 40V rating, and 60V is probably safer.

Check Langevin's original suggested parts: http://www.sowter.co.uk/schematics/langevinam16.pdf

2N3053 seems like the most-likely generic bet. We used that puppy everywhere, though often under mystery part numbers; there's profit in spare-parts.

All these cross to NTE154: 40321 BF259 MM3009

Description:
The NTE154 is a silicon NPN transistor in a TO39 type package designed for use as a video output
to drive a color CRT.
Features:
High Voltage: VCEO = 300V Min @ IC = 5mA
Low Capacitance: Cob = 3pF Max @ VCB = 20V
High Frequency: ft = 50MHz Min @ IC = 15mA
High Power Dissipation: PD = 7W @ TC = +25°C

So the 40321 may be a high-voltage high-Ft 2N3053. There were a few years before RCA fell apart when they were very good at pushing the envelope. RCA needed video drivers for TV sets, and a LOT of them, so when Langevin was shopping they maybe found 40321 as cheap as 2N3053. (It sounds awful familiar: maybe I've shopped for 2N3053 and come home with 40321.) The AM16 does not need anywhere near 300V rating, 60V is plenty, but the 300V rating doesn't hurt if the tranny is fast and cheap.

If you don't mind a board revision, TIP42(?) will probably work great, and plastic is a lot cheaper today than any metal can.

 

[Rob Flinn]

CJ [/quote]I compared the parts list from a Langevin AM 16 document that is floating around the web and found out that it does not come close to matching the actual parts in the amplifier, at least my AM-16. [/quote]



Looking at both my AM 16, I 100% agree with the parts list that Chris has supplied. As stated in my previous post all the small signal transisitors are 2N5210

 

[CJ]

While re-stuffing my AM-16 board, I noticed that I had R3 and R4 on the parts list as 130K.
They s/b 150K. The parts list has been edited.
Sorry for the screwup.
cj

 

[rafafredd]

Do you mean R4 and R5...???

 

[CJ]

yes, thanks Raf!

 

[CJ]

Well, I am trying to get the hang of this pc board software and here's what I have so far for the Langevin Am-16 board. The stock board sounds fabulous, so I did not think it was a good idea to start moving traces around.
Have to do the back next.
cj

 

[fazeka]

Cool!

However...

TOO MANY PROJECTS! :shock: Augh!

Solution? Sleep less! :green:

:guinness:

 

[ytrehalf]

This could be a good parts pig if the price is right.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=23790&item=3762044320&rd=1&ssPageName=WDVW

 

[dukasound]

Hi
Here are my redrawn both sides of pcb. I cant find tracing for red labeled path.
Excuse me for bigger pics.
I made it in Corel but I can send like pdf.

 

[Gus]

Duka

Nice

 

[jrmintz]

Very cool, Chris and Duka! Do we know what the physical dimensions of the board are?

:guinness: :sam: