EH Soul Preacher Schems DO have errors

[markm]

Hello DIYers,
If any of you have been following the continuing "saga" of the EH Soul Preacher, be rest assured that IMO opinion ALL schems that are circulating around the net are incorrect. At least they are not schems of the same board that I received from infinitemonkey.
A VERY Special thank you to him for kindly supplying an original EH board for me to look at for this project! 
Let me just say, not being an authority on anything EH, I can guess that this unit was built somewhere in early 1978 as the pot codes on it are from the 49th week of 1977. The IC Date Code is the 44th week of 1977....I don't know when production started on these pedals from EH, nor do I really care (!) but, it is safe to assume that this unit was from circa '78.
Maybe the schem on the net are from a different era unit, I assume that they are as there are some difference.
First, the board I have contains only 21 resistors where as the schem call for 22. Which is extra, I'm not sure yet.
The electro cap count is correct....8 total including tants.
Between the ceramics and film caps there are 6.
The Diodes are in fact 1N3666.
The input DOES in fact enter through a .1uF cap with a 680K resistor to ground, into the 220K resistor, through another .1uF cap.
The trannys;
3 BC239 (2 in the powersupply and one as the input buffer.
1 BC309 which is the PNP in the "compressor engine"
The JFET is a B2818 and for the life of me I cannot find info or a data sheet on it as of yet.
I'm not much on drawing schematics but, I think some sections of the schems are conected wrong as the power supply circuit I built from the handwritten schem does not match the correct voltages specified, the schems have the voltages reversed.
There's much more and I am trying to make heads or tails as to what I have in front of me but for now....stay tuned!

[R.G.]

Welcome to the next level of understanding of EH effects.

EH is (in)famous for putting out effects which varied in the particular values of components. There are rumors that they'd buy whatever was cheap at the then-operational New York electronics surplus outlets and build effects out of that.

The fact is, having one EH board with one set of values does not mean schematics taken from some other board or from an EH schematic are incorrect. The EH schematics were not much more than laudable goals, bent to suit what was economical to build.

[aron]

markm,

Thanks for the update. Good luck on your quest!

[markm]

Thank you Aron.
This has turned into a much bigger project than I had expected.
Just when I feel like giving up on it, I figure something else out and I'm on it again. 

[StephenGiles]

I had it on good authority that at least around 1980, all new EH pedals were built to full specification during the design stage. The question would then be asked - "what can we take away but still leave it working - just?" However, I don't think that there was much difference between the prototype Space Drum and the final version, which by the way does need some intelligent thought to extract the more than half decent peak follower and put it to good use.........even if it is in just another fuzz

[R.G.]

I had it on good authority that at least around 1980, all new EH pedals were built to full specification during the design stage. The question would then be asked - "what can we take away but still leave it working - just?"

Ah! Muntzing - the procedure of clipping out part until it doesn't work any more, then pasting that one back in.

The procedure is (in)famous among EEs and Manufacturing Es, named for a gentleman who ran a TV manufacturing facility back in the 1940s and 1950s. He noted (correctly) that 90% of the market for TVs was people who lived in major population areas, within 10 miles of a TV tower, but the EEs put in all the parts needed to pick up TV well from 50 miles or more. See Bob Pease' excellent article on Earl (Madman) Muntz - http://www.national.com/rap/Story/0,1562,17,00.html.

[Mark Hammer]

As I often do in such instances, I remind you to take a peek at the 1981 pricelist here: http://hammer.ampage.org/files/1981_E-H_pricelist.gif

The "sale" prices shown are actually pretty close to decent street prices at the time.  Consequently, it is reasonable to categorize E-H as aiming for a budget-conscious market, just as they did when they first emerged a decade or so earlier.  The "Muntzing" of their designs was a big part of what allowed them to turn something approximating a profit, given the exceptionally large catalog of products they had.  I counted 57 products in that ad, and there are likely things missing from that ad that came and went.  As a company, they likely marketed more products to musicians at that time than probably any other pedal maker.  Certainly the catalog outstrips MXR, Maestro, Musitronics, Boss, and DOD.

[markm]

 
My layout has plenty of errors in it too......
I'll be revising it this evening and from looking at the EH board, I have some revisions to make.

[markm]

For those following this project, (is anyone following this  ) I am revising a layout for this project......stay tuned!

[PKV]

thanks mark for doing the research and sharing your findings. the SP was the first circuit that caught my eye as I stumbled upon the webs vast store of schematics; I'll certainly be following along, as the Preacher is top on my list of 'eventual' builds (baby steps first)...good work!

- PKV