Manual : Presto 6N Lathe and 1D Cutterhead

[blacknwhite]

A forum member was kind enough to send me these for free when I first joined. Whoever that was - thanks.

Decided to pass them along now, via my web server, for free, to anyone interested, as long as disk space permits.

Presto 6N lathe manual: (10 meg PDF)
www.xxxxx.xxxxxxxx/Presto_6N_Manual.pdf

Presto 1D cutterhead manual, and technical article: (6 meg PDF)
www.xxxxx.xxxxxxxx/Presto_1D_manual_n_article.pdf

- Bob

[Steve E.]

awesome! Thank you.

That's what this section is for!!

[Steve E.]

The 6N manual can be found elsewhere on our site, but the Presto 1-D is lost. does anyone have this file?

[Steve E.]

presto_1d_manual_n_article.pdf

[EmAtChapterV]

Hi, I'm a long-time lurker, first-time poster.

I have a Presto 1D wound for 500 ohms, and reading this manual plus slowly teaching myself electrical theory has helped answer quite a few questions I've had, especially regarding the large bump in response at 4.2 kHz I could never get rid of. It looks like the capacitor and resistor will help tame it, but I'd like to do a sanity check: they mean 4 MICROfarads, not 4 millifarads, don't they? As near as I can tell, a 4 mF film capacitor would be larger than a gallon jug of milk, and would cost upwards of $1500. Somehow that seems a bit off.

I have a few more questions:

In another thread, a poster talks about unwinding another 500 ohm 1D to find it contained 120 feet of AWG #37 wire. And other people are mentioning putting fuses between their amps and heads that seem to be rated roughly double the maximum current for the estimated corresponding wire gauge as per this reference - http://amasci.com/tesla/wire1.html . This would mean if my 500 ohm head has the same #37 wire, I should be looking for a 250 volt, 125 mA fast-blow fuse. Does this sound about right?

Also, the DC resistance of my head is 92 ohms. I understand with inductance the reactance changes with frequency, but I'm still worried that through the impedence-matching transformer and lacking the recommended capacitor/resistor circuit, the setup I thought was presenting a 4 ohm load to the amplifier could instead be as low as 0.6 ohms. That would explain the problems I've been having with clipping. I'll try using a different tap on the transformer and put a variable resistor in the circuit as an experiment, and see where that gets me. I wonder how many watts any permanent resistor ought to be rated for?

Finally, does anyone have the original factory specifications, or their own measured specs, for a 500 ohm 1D head, in terms of nominal DC resistance, capacitance and inductance? Once I can get my hands on an LCR meter, I can measure mine and plan how best to flatten the response curve, but in the meantime some ballpark figures would be helpful, plus they'd show how far mine may have drifted over the decades.

[markrob]

Hi,

As far as the capacitor is concerned, you are correct its 4uf. Back in the day, they used to use mf to inducate this.

Have a look at this chart. Much more reasonable numbers.

http://en.wikipedia.org/wiki/American_wire_gauge

The chart you referenced was complied for Tesla coil builders. These are run at very high frequencies, so skin effect reduces the allowable current drastically.

The series resistor sets the 500 hz RIAA turnover and does not affect the 4Khz resonance. In the case of the 500 ohm coil, I believe the capacitor is present to compensate for the distributed capacitance of the windings. It adds a bit of high frequency boost.

I don't think the DC resistance has anything to do with this. If you are not getting good levels cut to disk, check the voltage at the head with a 1Khz sine wave and make sure the drive is correct for 500 ohms. If not, you have the transformer connected wrong or some other error. You should only need 1 watt drive at 1Khz to achieve a good level. If the head voltage reads correct and you still have level issues, check the head to make sure the damping is not dried out or some other mechnaical issue such as dirt. Also, make sure you are using the long shank stylus.

Mark

[bruisedtongue]

Does anyone have the 6N Manual?

[Steve E.]

Try the second posting in this link (by me). If it doesn't work, let me know.

http://lathetrolls.com/viewtopic.php?f=9&t=335

[Stevie342000]

Try the second posting in this link (by me). If it doesn't work, let me know.

http://lathetrolls.com/viewtopic.php?f=9&t=335

It did not work when I tried the link.

[Steve E.]

This one? Be patient.

Presto_6N_Manual_Color.pdf

[Stevie342000]

This one? Be patient.

Presto_6N_Manual_Color.pdf

Yep that one worked for me.

[bruisedtongue]

This one? Be patient.

Presto_6N_Manual_Color.pdf

Yep that one worked for me.

Thanks!

[Steve E.]

In the interest of having the important stuff living directly on the site (as opposed to in links elsewhere), here is the Presto 6N manual and 1-D document again.

[groovin']

https://steampoweredradio.com/pdf/presto/catalogs/Presto%20Instantaneous%20Sound%20Recording%20Equipment%20and%20Discs%20Catalog%201948.pdf

[Steve E.]

Wow ! Great!