Echoplex ep3. Anyone knows it well ?

[Xplorer]

i removed the 47 k resistor, and well, there's no much change. still some buzz on the sos head, but anyway, i can't use it at max . still some hiss too noticeable when the echo played back is stronger than the original signal, when the volume is increased. and this occur even when there's no tape running.
this machine is really alive, the sound changes quite often.

[demonufo]

With regards to the hiss, it may well be exaggerated by worn heads, or heads that need relapping. If you do some google searching on lapping/relapping tape heads you can find some useful information and may get some ideas from measuring/examining what sort of state they are in. Any visible wear marks from tape usually spell bad news though.

BTW, relapping is not the sort of thing that can be done DIY style, but there are still a few decent tape deck service centres out there who can.

[Xplorer]

yes, sure . i know a guy in england who can refurbish heads, but here my problem is really electronical. as i said previously, even when there's no tape running , this is the same hiss. so these heads seem to be very good, as they don't add noise to this electronical hiss and sos buzz.
thanks anyway.

[SnorkelMonkey]

Hey X, are you still having this issue?

[Xplorer]

hi,

well, yes. i'm gonna follow some advices i received , and change the switch ,to see if it goes better, and if not, i'll replace the sos head with a 120 ohms resistor, to see if the rumbling hum disapear, then it's a head problem, if not, it's a filter problem.
do you have any new advice ?

regards
Adrien

[Xplorer]

so,

with some help, i found that the shield of the sos head was broken. i'll replace it, but as a test, i've put a 100 ohms resistor instead of this head, on the switch. then, the rumbling noise disapeared. there was juste a bassy noise , but not the same, quite useable. but i think that the transistors produce some bad noise, they don't amplify the thing very well at some point. over 2 or 3, it comes to the mind that : why put a pot from 1 to 10, if over 3, the sound isn't useable ? it doesn't make sens, it can't be normal. here it is how it sounds ( in the beginning, volume from 3 to 10, with a 100 ohms resistor instead of the sos head . then, going back to 3. then, switch to the echo channel, then volume from 3 to 10, and 10 to 3 again. )

https://rcpt.yousendit.com/974122191/87 ... 2516146fd9" onclick="window.open(this.href);return false;


here are my values :


e, b, c maybe inverted . all transistors MPS8098, except the fet transistor , Q5 , TIs98

Q1 e: 3,94 b : 1,17 c : 0,58
Q2 e : 9,69 b : 3,94 c : 3,33
Q(?) down left on the second board : e : 12,10 b : 0,98 c : 0,39
Q(?) down right on the second board : e : 15,46 b : 1,35 c : 1,21
Q5 : e : 15,02 b : 0 c : 0,93

for the fun, a cool mod i've found :

http://forum.metroamp.com/viewtopic.php?f=12&t=33323" onclick="window.open(this.href);return false;

[rgorke]

so,

with some help, i found that the shield of the sos head was broken. i'll replace it, but as a test, i've put a 100 ohms resistor instead of this head, on the switch. then, the rumbling noise disapeared. there was juste a bassy noise , but not the same, quite useable. but i think that the transistors produce some bad noise, they don't amplify the thing very well at some point. over 2 or 3, it comes to the mind that : why put a pot from 1 to 10, if over 3, the sound isn't useable ? it doesn't make sens, it can't be normal. here it is how it sounds ( in the beginning, volume from 3 to 10, with a 100 ohms resistor instead of the sos head . then, going back to 3. then, switch to the echo channel, then volume from 3 to 10, and 10 to 3 again. )

https://rcpt.yousendit.com/974122191/87 ... 2516146fd9" onclick="window.open(this.href);return false;


here are my values :


e, b, c maybe inverted . all transistors MPS8098, except the fet transistor , Q5 , TIs98

Q1 e: 3,94 b : 1,17 c : 0,58
Q2 e : 9,69 b : 3,94 c : 3,33
Q(?) down left on the second board : e : 12,10 b : 0,98 c : 0,39
Q(?) down right on the second board : e : 15,46 b : 1,35 c : 1,21
Q5 : e : 15,02 b : 0 c : 0,93

for the fun, a cool mod i've found :

http://forum.metroamp.com/viewtopic.php?f=12&t=33323" onclick="window.open(this.href);return false;

Whatever your setting was from :20 - :40, it sounded great!

[Xplorer]

well , loool, from 0:30 to 1:20 , it's a virtual echo in cubase !!! producing an echo on the dry signal first, played back over and over by the real echoplex, with the sos....
but i prefer a lot the real echoplex echo, from 2:32 to 2:50 for example, this is the echo tone i like , produced by the echoplex.

[Tone seaker]

On my EP3 I had hum issues using it with my old marshall plexi. I lifted the earth ground and that helped a lot but not completely. Then i plugged it in backwards (reversing the polarity) and that eliminated the hum completely. It is still grounded threw my guitar cable to my marshall that is earth grounded so all is safe and quite.

[Xplorer]

thank you.
well, this echoplex isn't grounded, and if i plug it in the other side, turning the plug, it doesn't work.

but i'm doing a big preparation work, previous to any work on it. i'm gonna change the transistors, the electrolytic caps, the resistors, to schematic specs. i'm analysing each board right now.when it's done, i think i'll share it here.

[SnorkelMonkey]

There's some good information over at the Echoplex group also.

http://launch.groups.yahoo.com/group/el ... hochamber/

[Xplorer]

i know ! ; )
yes, metroamp peoples, go there it's gonna be a cool board for the echoplex.
thanks to snorkelmonkey

[rgorke]

Resurrecting an old thread.

I have an ' new' echoplex that has a bad noise problem when I push the volume past 2 or so. Once the noise starts, is stays the same regardless of how far I turn the volume knob.

And yes, I have done all the regular cleaning, demagnetizing, etc. The issue happens if there is a tape in the machine or not, so I know it isn't tape related. Almost sounds like a grounding issue. I have been through everything and can't locate. ANy help is welcome.

Thanks

Here's what it sounds like.

http://soundclick.com/share.cfm?id=12046391" onclick="window.open(this.href);return false;

[Xplorer]

with or without the echo, there's definitely a problem. did you already change all the electrolytic caps ? compared your ep3 with the schematic ?

[rgorke]

with or without the echo, there's definitely a problem. did you already change all the electrolytic caps ? compared your ep3 with the schematic ?

The noise comes when the echo is engaged, even without a tape in. I changed the electrolytics on the middle board. Next move is changing the big orange Sprague 500uf caps near the motor.

Yes, I've looked a the schematic and also compared side to side with my other EP3 that doesn't have the problem.