EHX - Frequency Analyzer EH5000

vhollund · Post by **vhollund** » 25 Nov 2008, 22:45

I love this effect but the use of just does not make any sence at all:

The bigger the better?

madbean · Post by **madbean** » 26 Nov 2008, 00:31

Yep, EH is a blend of awesome effects and retarded execution.

bumblebee · Post by **bumblebee** » 26 Nov 2008, 02:51

I love the EH trapezoidal enclosures. BTW you could TB that pedal easy enough, you already have the switch.

chromedoutgrillz · Post by **chromedoutgrillz** » 28 Nov 2008, 05:19

Why a 40v adapter for this ??
Going off the schematic (Can't really post it here,as it resides in a state of bannination,as far as I'm aware,but it's the one from the zip stash using the more available AD633))..
The circuit itself requires 15v to run,so something like a bipolar supply using 7815/7915 (like the ones in synth modules etc),would make more sense,unless I've missed something...

unbeliever · Post by **unbeliever** » 28 Nov 2008, 19:44

chromedoutgrillz wrote:Why a 40v adapter for this ??

Looks like the zener-based circuit is 'good enough' in terms of voltage regulation, and also this has a lower parts count than a proper voltage-doubler / double-regulator arrangement.

Offsetting the cost of the power supply into the adapter makes the pedal cheaper, and 'hides' this extra cost to a degree. The downside is the inconvenience of an unusual-voltage external supply. Where can you get a 40VDC adapter other than from EH?

chromedoutgrillz · Post by **chromedoutgrillz** » 28 Nov 2008, 23:07

Where can you get a 40VDC adapter other than from EH?

My thoughts exactly

:)
I'll kludge the bipolar supply in there and see how it goes (this would easily fit into one of those small B sized hammond boxes in it's current state,but looking at the data sheet for the 8038,there's a fair bit of scope for extending on this)

Cheers

vhollund · Post by **vhollund** » 30 Nov 2008, 20:09

Well it doesnt really need TB because its not sucking tone when its off.
But I migth consider a rehousing at some point.

beavis · Post by **beavis** » 02 Dec 2008, 14:02

Rehouse it, not too hard a job. It is one of my favorite pedals of all time.

Professor SourTone · Post by **Professor SourTone** » 16 May 2016, 16:15

I am having a problem with this one. It won't pass signal switched on or off other than a very faint hum, and I am getting some minor increase in that hum when turning the blend knob. I thought it might be the switch, but not so. Does the above schematic apply to this version as well?

Scruffie · Post by **Scruffie** » 16 May 2016, 21:23

The schematic in the first post should indeed match up to that unit.

Post some voltages up but if I had to guess the 741 is shot.

Professor SourTone · Post by **Professor SourTone** » 20 May 2016, 09:43

Ta very much, I will investigate that.

Professor SourTone · Post by **Professor SourTone** » 06 Nov 2016, 12:48

Finally got round to it, socketed and replaced the 741 (tried two new chips) with no joy, and wonder of wonders it turns out there are no volts anywhere in the circuit!

I'm in the UK, and its possible that somebody attempted to run it on 220v, in which case all manner of things might be shot. I'll try with a 15v supply, if I can find one, and see if anything's alive in there...

Professor SourTone · Post by **Professor SourTone** » 06 Nov 2016, 13:36

Will an 18v supply be OK, do you think - I read here that some EH pedals take in 18v and drop it to 15v.

Professor SourTone · Post by **Professor SourTone** » 06 Nov 2016, 16:31

Ordered a 15v supply - if the pedal's still alive, I may convert the current mains arrangement to a blank plate with a standard 5.5mm socket. But I am not optimistic...

Scruffie · Post by **Scruffie** » 29 Dec 2016, 13:19

Sorry I missed these posts, it's a bipolar supply so a 15V DC adapter isn't going to cut it, you need to replace the transformer if it's indeed shot.

Alot of the time the voltage regulators in these go bad from overheating, have you tested for AC on the outputs (the 2 outer wires) of the transformer to confirm if there's any life? You should also get a DC reading on pins 7 & 8 of the SG4501 regulator chip.

I'm in the UK too and have a lot of experience with EHX repairs if you'd like me to take a look at it.

Professor SourTone · Post by **Professor SourTone** » 29 Dec 2016, 14:13

Scruffie wrote:Sorry I missed these posts, it's a bipolar supply so a 15V DC adapter isn't going to cut it, you need to replace the transformer if it's indeed shot.

Alot of the time the voltage regulators in these go bad from overheating, have you tested for AC on the outputs (the 2 outer wires) of the transformer to confirm if there's any life? You should also get a DC reading on pins 7 & 8 of the SG4501 regulator chip.

I'm in the UK too and have a lot of experience with EHX repairs if you'd like me to take a look at it.

Hi there - thanks for your supply - yup, no joy with 15v DC - I attached it where the current would have been DC, being careful to get the polarity right. I then assumed something was wrong further down the line.

Bipolar supply is beyond my meagre knowledge!

I will def ask you to have a look at it - but I am away for some time in the NY and prob it would be best when I come back.

Could you PM me your details?

Many thanks - h

Professor SourTone · Post by **Professor SourTone** » 29 Dec 2016, 14:15

The transformer was not producing any volts at all - dead as a doornail...

EHX - Frequency Analyzer EH5000 [schematic]