Schematic for a Electro Harmonix linear power booster pedal.

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BobbyRay
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Schematic for a Electro Harmonix linear power booster pedal.

Post by BobbyRay » Tue Jan 31, 2006 9:55 am

Where can I get a schematic for a Electro Harmonix linear power booster pedal? I emailed EH, they have no schematics for their older units. I used this pedal when I was A teen and loved it. Unfortunately the 9volt. battery clip thing feel apart so I thought I would solder on a new one. Well I did not take notes on the wiring cause I was a know it all teenager. So I could not remember witch wires go where. Recently I have tried a couple obvious points with no luck.

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trashy
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Re: Schematic for a Electro Harmonix linear power booster pe

Post by trashy » Tue Jan 31, 2006 10:44 am

BobbyRay wrote:I emailed EH, they have no schematics for their older units.
??? That seems ludicrous to me.

analoghacker
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Post by analoghacker » Tue Jan 31, 2006 12:40 pm

actually, and i'm sorry to rain on your parade, it is SO true. EH is not even slightly organized and it does not, nor has it ever, operated rationally or efficiently. we are way beyond such petty notions. if you know anything about NYC and its history, and you know what an orchard street schmatta shop is, and if you ever went to the hellfire club, then you'll know everything and more than you will ever have to know about EH. its shpilkas and sextoys. alot of our stuff is drawn on napkins, sandwich wrap and toilet paper and then mimeographed. lipstick, cigar slobber and eyeliner often appear in the margins of "official" documentation (there are too numerous cross dressing engineers and tech staff). design changes are so numerous and so quickly forgotten as to be the stuff of legend... or simply forgotten. who knows? the parts business, being what it is, is run way worse... you design something with one part only to have it go obsolete on you and therefore unobtainable 11 months later. we tend to replace things with leftovers anyway, so catch as catch can, right! it makes the pedals worth more anyway because someone somewhere will absolutely insist that those were the ones you really wanted. and others will believe the schmuck, too. the main thing is that when you plug the battery in, shit happens! we garauntee it. just remember that ludicrous to one is lugubrious to another. and godspeed!

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Post by joel hamilton » Tue Jan 31, 2006 2:56 pm

I love the above post.

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trashy
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Post by trashy » Tue Jan 31, 2006 7:22 pm

gross.

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pandatone
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Post by pandatone » Tue Jan 31, 2006 9:42 pm

they just sent me the schematics for an old mike mathews freedom amp. at their own cost!!

within like a week of me asking!

lovely

panda

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Post by Gonny » Wed Feb 01, 2006 8:11 am

BobbyRay - the red lead goes to the ground lug on the output jack (there should be a resistor attached there already), and the black lead goes to the on/off switch (not the footswitch, the slider). It should be obvious on the switch which lug it goes on, cuz it will not have anything connected to it now, but will have the telltale signs of solder suggesting something used to be.

I have an LPB2 that I got around 1980. It went up in a puff of smoke a few years ago (literally). When I saw your post yesterday I went home, opened it up, and found a little note to myself about how the battery leads should be connected. :lol:

It all came back to me. I had yanked the battery clip to use in a different device, and left a note to myself on how to rewire it when I got a new one. Well, I got a new battery clip at some point, soldered the red lead to the output jack, and then wondered which lug on the footswitch? I plugged in and started touching the lead to the various lugs on the footswitch and.....poof. Looking closer at my note I see that I had written on/off switch, not footswitch. :oops:

I replaced it with an MXR Micro Amp, which works quite well for my purposes (clean volume boost for solos).

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Post by r0ck1r0ck2 » Wed Feb 01, 2006 8:18 am

it [EH] does not, nor has it ever, operated rationally or efficiently. we are way beyond such petty notions.
hear hear...

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marc
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Post by marc » Wed Feb 01, 2006 11:56 am

I still don't understand if that post was a joke or not. If analoghacker's story is a joke, I'll be patiently awaiting your next novel; if it's not, I'mma go buy some more EHX gear on my way home from work.

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Post by analoghacker » Wed Feb 01, 2006 12:47 pm

i'm afraid, funny tho it is, that it is no joke. ask joel or anyone who has actually visited the factory... and especially the engineering dept.!
jc

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Post by Gonny » Wed Feb 01, 2006 1:06 pm

I've heard some interesting things about EH over the years as well.

Back in the early 80's I had a Deluxe Electric Mistress (flanger with slapback echo feature that produced a delighful chorus sound). The slapback part died, so I took it in for repair. It sat on the bench torn apart for a couple of years before the music store went belly up and I never saw it again (at least they loaned me an MXR flanger). I was told at the time that it was common practice for EH to buy bunches of obscure military surplus ICs and design circuits around them, which made getting replacement parts difficult at best. Last I heard they were still trying to find that elusive replacement IC. Don't know whether to believe it or not, but interesting....

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Post by rodabod » Wed Feb 01, 2006 3:12 pm

If you're still stuck, I made an LPB when I was about 16 and could have a look.

Incidentally, when I showed my local electronics shop keeper the schematic (he was ~ 50 - 60), he frowned and said "that's not great, change this bit like this..." The other shop keeper said "typical of Electro Harmonix" back in the day.

Anyway, I made the pedal as standard and thoughr it was ok, but then tried the shop keeper's suggestion. It was way, way better with the shop keeper's mod!

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Post by BobbyRay » Thu Feb 02, 2006 8:58 am

Gonny thanks a lot for the tip, I'll give it a try tonight. I figured this was a total shot in the dark, I am surprised that anyone else even knows of the pedal.

Unfortunately one of the resistors has lost it's solder joint as well on one end. Maybe it goes to the output jack like you suggested.

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Post by analoghacker » Thu Feb 02, 2006 9:05 am

just google electro harmonix LPB-1 schematic... thats what we do when we can't find a drawing.
its not very complicated and a really good simple diy gadget. you can approximately make one out of one or two transistors in linear feedback mode (go look it up). i find it fascinating that some old shop guy said "why'd they do it like that? change it like this..." if you are not buying one, thats what its all about.
jc

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