Echoplex EP-3 EP-4 serial numbers

Myopic Void · Post by **Myopic Void** » Tue Dec 11, 2007 8:57 am

Tazin wrote:For a rough date of manufacture you could read the date codes on the pots, and the serial number on the motor.

Tazin---> Thanks for the heads up

...I should have thought about that

Let's first three digits are the make 134 etc, the next two date and last two month. Is that about right?

Cheers,

Eric

Myopic Void · Post by **Myopic Void** » Tue Dec 11, 2007 9:18 am

Tazin------------------------->GOOD NEWS! I have dated them. My #1 is a 1971 and my #2 is a 1974. They are both Chicago Telphone Co. (CTS) pots.
Their code is 137. It goes like this 137 (CTS), 71 year, 30 week. 1377130

Hat's off to you Tazin

I always wanted to know exactly what years and now I know. #2 is older than I thought 1974 and #1 1971 is right at the very beggining!

Cheers,

Eric

AtomicChunk · Post by **AtomicChunk** » Tue Dec 11, 2007 9:22 am

Myopic Void wrote:Tazin------------------------->GOOD NEWS! I have dated them. My #1 is a 1971 and my #2 is a 1974. They are both Chicago Telphone Co. (CTS) pots.
Their code is 137. It goes like this 137 (CTS), 71 year, 30 week. 1377130

Hat's off to you Tazin I always wanted to know exactly what years and now I know. #2 is older than I thought 1974 and #1 1971 is right at the very beggining!

Cheers,

Eric

Congrads great info to know!

btw is that a Royer R-121 on your cab!?

Myopic Void · Post by **Myopic Void** » Tue Dec 11, 2007 9:37 am

AtomicChunk wrote:
Myopic Void wrote:Tazin------------------------->GOOD NEWS! I have dated them. My #1 is a 1971 and my #2 is a 1974. They are both Chicago Telphone Co. (CTS) pots.
Their code is 137. It goes like this 137 (CTS), 71 year, 30 week. 1377130

Hat's off to you Tazin I always wanted to know exactly what years and now I know. #2 is older than I thought 1974 and #1 1971 is right at the very beggining!

Cheers,

Eric
Congrads great info to know!

btw is that a Royer R-121 on your cab!?

Atomic----Thanks, it's great finally put the mystery to rest! I feel stupid for not thinking of this

Mic's...yes it's a Royer 121 and a June 1970 Nuemann U87.

Cheers,

Eric

AtomicChunk · Post by **AtomicChunk** » Tue Dec 11, 2007 9:40 am

Myopic Void wrote:
AtomicChunk wrote:
Myopic Void wrote:Tazin------------------------->GOOD NEWS! I have dated them. My #1 is a 1971 and my #2 is a 1974. They are both Chicago Telphone Co. (CTS) pots.
Their code is 137. It goes like this 137 (CTS), 71 year, 30 week. 1377130

Hat's off to you Tazin I always wanted to know exactly what years and now I know. #2 is older than I thought 1974 and #1 1971 is right at the very beggining!

Cheers,

Eric

Congrads great info to know!

btw is that a Royer R-121 on your cab!?
Atomic----Thanks, it's great finally put the mystery to rest! I feel stupid for not thinking of this

Mic's...yes it's a Royer 121 and a June 1970 Nuemann U87.

Cheers,

Eric

(((Fabtastic rig)))!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Myopic Void · Post by **Myopic Void** » Tue Dec 11, 2007 9:41 am

Thanks my friend!!

Cheers,

Eric

T.J.Fuller · Post by **T.J.Fuller** » Tue Dec 11, 2007 10:51 am

Tazin wrote:For a rough date of manufacture you could read the date codes on the pots, and the serial number on the motor.

Great info. Thanks!

couldn't find a serial no. on the motor but, the pot ID ...hell yeah!

my Ep-3 dates at 1976- serial #28255

Eric,
you mentioned you have 2 Ep-3's with one being brighter than the other.

Is the later model the brighter of the 2 ?? and does it have greater gain?

There is a resistor that is 250K on earlier models vs. 100k on later models, going to the echo mixer section.

This would have an impact as far as output.

there are capacitor differences on earlier models versus later models.

The which unit is brighter info. - would be greatly appreciated, if you happen to read this post.

Myopic Void · Post by **Myopic Void** » Tue Dec 11, 2007 11:25 am

T.J.Fuller wrote:
Tazin wrote:For a rough date of manufacture you could read the date codes on the pots, and the serial number on the motor.
Great info. Thanks!

couldn't find a serial no. on the motor but, the pot ID ...hell yeah!

my Ep-3 dates at 1976- serial #28255

Eric,
you mentioned you have 2 Ep-3's with one being brighter than the other.

Is the later model the brighter of the 2 ?? and does it have greater gain?

There is a resistor that is 250K on earlier models vs. 100k on later models, going to the echo mixer section.

This would have an impact as far as output.

there are capacitor differences on earlier models versus later models.

The which unit is brighter info. - would be greatly appreciated, if you happen to read this post.

Hey TJ,

Ok the 71 is brighter the 74 is a lot darker and a bit less output. I would like for them to match. Can this resistor change make difference in the way of brightness? As far as the Schems go I could only find one difference in the 71 and 74 and I think this had to do with the motor cap.

I hope we can figure this out.

Eric

T.J.Fuller · Post by **T.J.Fuller** » Tue Dec 11, 2007 11:47 am

I'll post the differences in schematics later when I get home.

The resistor shouldn't effect the brightness, however it's a unique circuit.

but, from the schematics I have , the cap before 1st. transistor would and I think there is a bypass cap. difference in the circuit as well, other than the motor.

I have had mine apart recently and I'll be experimenting shortly.

...might be best to let me swap some stuff first, I'll share the results.

I'll still list what is different later.

but, I have the FULL Echoplex manual w/ all the schematic variations on all models and years , even the sireiko echoplex version on PDF.

PM me if you would like it.

Myopic Void · Post by **Myopic Void** » Tue Dec 11, 2007 12:33 pm

T.J.Fuller wrote:I'll post the differences in schematics later when I get home.

The resistor shouldn't effect the brightness, however it's a unique circuit.

but, from the schematics I have , the cap before 1st. transistor would and I think there is a bypass cap. difference in the circuit as well, other than the motor.

I have had mine apart recently and I'll be experimenting shortly.

...might be best to let me swap some stuff first, I'll share the results.

I'll still list what is different later.

but, I have the FULL Echoplex manual w/ all the schematic variations on all models and years , even the sireiko echoplex version on PDF.

PM me if you would like it.

TJ---> if you can do some test that would REALLY help. I can't wait to see what you find out regarding resistors and brightness. I want to get these two EP3's on the same page.

I just picked up my number #1 1971 EP3 3-4 months ago. A client who came in to record at the studio saw my rig and said I have one of those "tape things" but it does not work. I said I want it. When he brought it over he had the original manual, papers, original footswitch, record level metal cap in what looked to be a unit NEVER used.

I bought it for $100.00 untested and later found out it just needed a solenoid adjust

.

My #2 has been with me since I was kid (my first and only effect). Now having two rigs side by side I can A&B easily and the differences are stark. The #2 has been re-capped, new motor belt, pinch roller biased and serviced and still sounds really dark.

Cheers,

Eric

Tazin · Post by **Tazin** » Tue Dec 11, 2007 8:28 pm

Glad I could help....

I've got a copy of an original Market Electronics Co. schematic for the revision 2 model EP3 [Serial numbers 9451 to 12960] which is dated January 12, 1971. There's a good chance that revision 2 started around that time frame.

Kinda surprised there was no serial number on the motor?.......The one I have carries this: 8GA 77275.

Myopic Void · Post by **Myopic Void** » Tue Dec 11, 2007 8:37 pm

Tazin wrote:Glad I could help....

I've got a copy of an original Market Electronics Co. schematic for the revision 2 model EP3 [Serial numbers 9451 to 12960] which is dated January 12, 1971. There's a good chance that revision 2 started around that time frame.

Kinda surprised there was no serial number on the motor?.......The one I have carries this: 8GA 77275.

Motor has this # Tazin...11FA 75981 Universal. How can you read this code?
My serial # falls into the early era of revision two. I am only a hundred or so off from the first series which amounted to only a few hundred I think.

Cheers,

Eric

Keep us posted TJ

Tazin · Post by **Tazin** » Wed Dec 12, 2007 8:48 pm

Eric.

I was hoping there was some kinda date code within the motor serial numbers.....If there is; it's well hiddin.

Maybe you can help me out on something here. Any chance you can tell me the orientation of the TIS58 J-FET transitor in your EP3? The TIS58 transitor is mounted in the upper left hand corner of the middle (number 2) pcb. I think the one in my EP3 might have been installed backwards. Anyhow, mine is installed with the "flat" section of the transitor facing towards pcb#1 or left.

T.J.Fuller · Post by **T.J.Fuller** » Wed Dec 12, 2007 9:08 pm

TIS58 because it is a JFET the drain and source can be interchanged
it is the gate or base that if hooked up wrong that would be an issue.

There are some obsolete electronic suppliers still sitting on stock of these transistors even though they are no longer being made.

**EDIT- I just checked mine, all 3 on that board are flat side facing left

Eric, from what you posted, you prefer the brighter sound EP3..correct??

Myopic Void · Post by **Myopic Void** » Thu Dec 13, 2007 9:10 am

T.J.Fuller wrote:TIS58 because it is a JFET the drain and source can be interchanged
it is the gate or base that if hooked up wrong that would be an issue.

There are some obsolete electronic suppliers still sitting on stock of these transistors even though they are no longer being made.

**EDIT- I just checked mine, all 3 on that board are flat side facing left

Eric, from what you posted, you prefer the brighter sound EP3..correct??

TJ I prefer the brighter 1971. The 74 is a lot darker. It would great to understand why and possibly brighten it up a tad.

Cheers,

Eric