does anyone have an original fender phaser?

[pinkjimiphoton]

the ac one, with the internal transformer...
i got one off evilbay yesterday, with the original transformer, which appears to be smoked..
does anyone know what kind of transformer i would need for this, or have a schematic they can point me at?
search function is no help.
thanks!!

[armdnrdy]

Judging from gut shots that show the transformer it appears to be a center tapped transformer.

Most effects from that time period incorporated +9/0/-9, +12/0/-12, or +15/0/-15

If you have a variable bipolar power supply, try +9/0/-9 first. Or you can use a few 9 volt batteries to produce the bipolar voltage.

[pinkjimiphoton]

yep, definitely a bipolar supply... someone cut the leads off short, but not short enough i can't strip 'em and see if the transformer is good.. i'm assuming as long as i get continuity from center tap to each tap on the secondary (and from secondary to secondary) and both sides of the primary without continuity between them, the transformer may be ok. i'm hoping
the transformer is ok, i'm betting the ac cord broke on it and nobody knew how to repair it.

i called fender's tech support, and they were very nice, offering to try and dig me up a schematic for it.

i'll try messing with it after my step daughter leaves tonite... thanks for the advice!!

[pinkjimiphoton]

well, i checked the transformer...it's good!

primary reads about 1.7k, secondary reads about 120r end to end, and 60r at the center tap. no continuity up to 20 megs on my meter between primary and secondary, so it SHOULD be good i hope.

it looks like the ac cord went bad, somebody took it apart and couldn't figure out how to fix it. with a little luck...

i will ask my girlfriend to use her camera (my phone sucks) and will post gut shots soon... it's an ota phaser, main chip is a 4136 so i bet it sounds good...
the info i've found so far says it's a nice sounding phaser, so hopefully some kind soul can help me reverse engineer it into a DIY project for the community!!



if i can get it working, i'll be psyched... i've got 45 into it, and if i can get it fixed and running, AND be able to give a "missing" vintage effect back to the community, i'll be happy

[armdnrdy]

Good news!

Which OTA IC does it use? 3080, 13600, 13700?

[pinkjimiphoton]

it's a 1458 for the opamp, and a rcn 4136 for the the transconductance amp.

i think it's a 4 stage phaser, as there's 4 identical transistors/resistors/capacitors near the rcn.

i got it wired up, didn't have any 1/4 amp fuses, so i jumpered it with some roach clips. 

not reccomended. but, i AM insane. it worked... i pulled the board out to check voltages, and they were close enough for rock and roll, and no spirits or poltergeists flew across the house.
so i powered down and put the board back, and fired it up.

it passes signal.. BIG volume drop...but no phasing.

i took a preliminary voltage reading, and everything seems to be in the ballpark, and i think it's modulating cuz the voltage keeps moving around on some of the pins. it's 2 am here, so i don't wanna get that deep into it now...

next step, i'll write out the parts, and voltages...and see if we can't make this puppy phase again.

guts:

[armdnrdy]

Cool!

It's a JFET Phaser. Those four transistors are JFETs and the 4136 is a quad op amp. The 1458 will be for the LFO. The lone transistor is most likely a NPN for the input.

Trace it! Let's add it to the collection. I'll help you work on it.


You got the signal to pass....did you try to adjust the bias trimmer?

[pinkjimiphoton]

yah, i tried adjusting the trimmer, all it seemed to do was bring the volume up just slightly.

getting a SEVERE volume drop...so somewhere i bet it's a bad cap or something.

i don't really know how to trace anything, but i'll give it a shot and see what we can do. these are supposed to sound great, so maybe we can fix it, and improve it,
so it's at least at close to unity gain (or an RCH above).

thanks larry!

[armdnrdy]

Hey Jimi,

I super imposed the flipped trace side onto the component side to work out the circuit. If you can supply the component values I'll work up a schematic.

[pinkjimiphoton]

i will get on it right now, larry... let's crack this nut!!!

i'm gonna go smoke a bol so my eyes won't crap out on me... glaucoma sucks for trying to look at stuff close up.

can you send me the superimposed image? then i can print it, write right on it and scan it when i'm done!!

thanks bro!!
peace
jimi

[armdnrdy]

i will get on it right now, larry... let's crack this nut!!!

i'm gonna go smoke a bol so my eyes won't crap out on me... glaucoma sucks for trying to look at stuff close up.

can you send me the superimposed image? then i can print it, write right on it and scan it when i'm done!!

thanks bro!!
peace
jimi

Yeah.....my 50 year old eyes have seen much better days! I think the warranty has expired too!

Superimposed image sent.

[mth5044]

That is a beautiful PCB. Spaghetti traces and all the colors on the top look fantastic.

[armdnrdy]

That is a beautiful PCB. Spaghetti traces and all the colors on the top look fantastic.

I like how all the "little men" are laying down! 

[pinkjimiphoton]

BEAR WITH ME, ALL THE CHIPS CAPS AND TRANSISTORS ARE LABELED, WORKING ON THE RESISTORS AND DIODES NOW!!

[pinkjimiphoton]

ok, here we go... first, a couple more gut shots with the board removed









and finally, the board, with all the parts labled. the 470k resistors may be 480, i couldn't tell if it was purple or gray on them.




i played with the trimmer, but i can't get the volume up, and can't get it to phase. it SEEMS like it's phasing, or at least modulating, but i'm not hearing it.

here's my notes, including voltage readings:

470K MAY BE 480, HARD TO TELL PURPLE/GRAY

TRANSFORMER:
PRIMARY 1.7K, 120V 60HZ, 5 WATTS .25 AMP
SECONDARY 120R RED TAPS, YELLOW 60 R
10-0-10 VAC

SWITCH SPDT, RED WIRE RIGHT SIDE TO INPUT JACK TIP

AND CONNECTOR 2 (LEFT TO RIGHT)

SWITCH TOP LEFT, PURPLE TO OUTPUT TIP
BOTTOM LEFT BLACK TO CONNECTOR 1

CONNECTOR:
PIN 1 BLACK WIRE TO SWITCH (CCT OUT)
PIN 2 RED WIRE TO INPUT TIP, SWITCH IN
PIN 3 220U@16V+
PIN 4 GREEN WIRE TO GROUND, INPUT JACK, BOTH NEG

PINS OF 220U'S
PIN 5 BLACK WIRE PIN 1 RATE POT
PIN 6 BLUE WIRE PIN 2 RATE POT
PIN 7 220U@16V+
PIN 8 10V TAP ON TRANSFORMER SECONDARY
PIN 9 10V TAP ON SECONDARY

CENTER TAP OF SECONDARY (YELLOW) TO INPUT JACK

RING

+ SIDE OF AC TO .25 AMP FUSE, OUTPUT OF FUSE TO

INPUT PRIMARY OF TRANSFORMER

OUTPUT PRIMARY OF TRANSFORMER

SPEED POT 2.5M

LM1458
1  4.90
2  4.90
3  4.67
4  0
5  4.50-5.25
6  4.89-5.34
7  3.60-6.60
8  10.29

RC4136
1  3.58
2  4.91
3  2.25
4  4.94
5  4.91
6  4.92
7  0
8  4.92
9  4.91
10  7.56
11  10.29
12  2.25
13  4.90
14  4.91

T1
C  4.85
B  4.31
E  4.92

J1
G  2.26-2.31
S  4.92
D  4.91

J2
G  2.26-2.31
S  4.92
D  4.91

J3
G  2.26-2.31
S  4.92
D  4.91

J4
G  2.26-2.31
S  4.92
D  4.91

http://www.datasheetdir.com/2N5952+N-Channel-JFET

http://www.datasheetdir.com/2N4126+PNP-Transistors

any ideas where to begin to look?

[armdnrdy]

Thanks Jimi,

I have to step out for a while, I'll hop on this when I get back.

Upon first glance at the voltages that you supplied, it seems as if the circuits being fed with a single supply. 10 volts and ground.

It doesn't make sense that they would use a center tapped transformer to create a single supply.

Also, the two 1N4001s should be a half wave rectifier to be used for a bipolar voltage. If this were a single supply they could have used a full bridge rectifier for a "cleaner" DC.

I'll take a closer look when I get back.

[pinkjimiphoton]

beats me, it's definitely the original transformer/hookup. seems weird to me too.

i'm assuming it's a 10-0-10 secondary, one tap reads 9.19 (pin 8 of the connector) some vac, the other 8.94 ish. i figured that would be 10v, close enough. its a bit higher with the board out.

on the anode sides of the 4001's i get the same voltage,  on the cathodes no ac, but i get a 10.53vdc.

the trimmer changes the gate voltage on the jfets, from 1.64-1.67 min to 3.11-3.15 maxed. drain and source don't change.

i don't know squat about phasers bro.

[artifus]

i don't know squat about phasers bro.

imagine each fet as ldr to ground. each fet a section. you've seen this before. wobbletron/magnavibe... x4

*edit* ps - i bet you know what they sound like!

[pinkjimiphoton]

lol... i know what they sound like, but i'm thinking this thing may have been a wee bit molested.

audio probing now, signal is seeming to be where i expect it, tho some of the stages are "muddy" and some "brighter"...

shoot me now!!   

[pinkjimiphoton]

i made a couple mistakes... the 350k resistors (and the 35k) i misread, all are 150k.

so (not that i figured this out by myself) i'm the proud owner of a fender script phase 90!

thanks to larry for all the help...

went thru, changed the electros and the tants, removed the 4136, added socket, plugged in new chip, turned trimmer, and WANGO!

we have achieved phaser!!

thanks armdnready!!

awesome... nice sounding phaser. a little "chewier" than the mxr i used to have i think. seems to depend on where the trimmer is set.

but anyways, one more vintage effect cracked, by jiminy... nothing as cool as the ludwig, but still cool (to me, at least)

larry is working up a schematic etc... i believe he'll post it when he gets a chance.