Fryette Effects - SAS EF86 Overdrive  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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drbob1
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Post by drbob1 »

SAS1.JPG
sas2.JPG
sas3.JPG
sas4.JPG
sas5.JPG
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Fryette left VHT, kept his circuits and started Fryette where he primarily builds amps. He has done a small line of tube based distortions and I guess they haven't sold well, this was on sale at GC when I stopped in and for an EF86 based pedal running at full voltage, I had to take a look! There are a couple of reasons I believe his contention that this is a high voltage tube: one is that it doesn't pass signal at all till it has time to warm up (unlike most "tube" overdrives which use the tube for color in some kind of parallel arrangement with diodes or op amps). Secondly, it uses a 12v AC power supply and there's that chunky transformer in there to bump it up to whatever he felt was needed... There's also a fairly stout looking set of power supply caps there. Anyway, the middle knob is bias rather than tone. It seems to pass the most volume and bass in the middle setting, so I'm guessing for this particular tube it's underbiased (cold) to the left and overbiased to the right. It gets thinner and more distorted at the very left. The other knobs are Gain and Volume. Gain goes from crunchy trails on the ends of notes to really heavy distortion. Volume goes from normal with the distortion up above midway and the volume at maybe 9, to REALLY, REALLY loud and punchy with the volume above that. This is a ridiculously loud pedal! The distortion is harsher than I really like, maybe due to being a pentode? or maybe because it's a Sovtek EF86, which doesn't have a great rep. I think I've got a Mullard around here somewhere I might try... Oh yeah, why do folks who use the square, cutout 9v jacks put them opposite the footswitch so you've got to bend the PCB to get the footswitch out and disengage the 9v from the cutout?

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Post by Bernardduur »

Ah, could it be a clone of the Vox EF preamp or another overdrive engine based upon the EF? Seen em both :). Only really downside are those LED's....... guess one of em is for fake tube lightning?
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Post by okgb »

Online not a particularly good deal , otherwise it'd be interesting to hear
thanks for posting , was it cheaper locally ?

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Post by bancika »

wow, those caps look the same as fake caps I had. I gutted the black one to find blue one inside, which had brown one inside of it. These black and brown caps in SAS look exactly like the ones I had.

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Post by drbob1 »

Yup, the LEDs are for tube lighting. There's a mild reddish glow all the time that brightens up when you engage the effect. Since an EF86 has the plate surrounding the tube, you can't see much of a glow inside it when it's on, so I guess I can see the reason for the fake lighting... also, it appears to be some kind of relay bypass. With no power the pedal passes signal unchanged no matter what you do with the footswitch. When powered up, it bypasses signal with the switch off, and takes about 15 seconds to pass signal with the switch on while the tube warms up.

Interesing about those caps, not only are they different colors and apparent manufacturers but the labels suggest different values?

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Post by diagrammatiks »

the brown ones are nippon chemicon. They make a ton of caps. It wouldn't be surprising that they are sometimes faked. I'm sure Fryette gets them from a good supplier though or the factory.

What's the IC there? I couldn't read the top from your pictures.

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Post by drbob1 »

TL072 I believe....

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Post by bancika »

drbob1 wrote: Interesing about those caps, not only are they different colors and apparent manufacturers but the labels suggest different values?
yeah, I bought them as 20uF 500V caps and inside it's a 22uF 400V cap (in between it's 100uF 160V which doesn't make any sense)
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Post by bancika »

btw, the brown one is probably not fake but it's obviously a pull from old equipment. They extended the leads to make it look like axial cap.
You can tell by looking at the joint between lead and cap. If it's just a black plastic hole then it's likely a fake. Real caps have some sort of solder joint, not a hole.
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Post by ppluis0 »

Hi there,

I think that the power supply section of this unit has almost the same principle that the upper part of this diagram that found in the web:

Image

From the AC jack there is a bridge (B1 in the diagram) formed by the diodes D5, D6, D7, and D8 in the photographs, and the 2200/25v electrolytic is in the same position that the 4700/16 in the drawing.

From the positive pin of this condenser Mr. Fryette implement an LM317 (U3) to obtain 6,3 Vdc to feed the heater of the EF86 that drain 200 mA. So the regulator does not need to use heatsink if it´s loaded at this current.

Also, from the same positive pin of this condenser I see connected another regulator, U2 (78 L 12 maybe ?), to feed the dual opamp, leds and relay.

The transformer is connected to raise 12 to 240 Vac; B2 in the diagram correspond to D1 to D4 in the photographs, and the three black electrolytics do the same RC cells that filter the high voltage needed by the tube, due are placed a pair of resistors between these caps if we seen the solder side picture.

Personally I think that this unit deserve to be traced. Remember that the tube pins are numbered seen from below and increase the counting clockwise.

Also hope this diagram helps to determine the components surrounding this tube:

Image

Cheers,
Jose

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Post by borislavgajic »

just to compare
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Post by ppluis0 »

Hi drbob,

Still have you this unit disassembled?

Please post a picture of the board that has the tube socket as it seems that there are some more components in that place.

Also I find it curious that with only five wires the tube can be connected to the main board.

Cheers,
Jose

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Post by drbob1 »

I put it back together, but I can take it apart again. Dang builders that use that square cutout for adapters...

Do you guys think you're going to be able to trace it from the pics if I get some more, or is someone going to need to go further?

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Post by ppluis0 »

drbob1 wrote:I put it back together, but I can take it apart again. Dang builders that use that square cutout for adapters...

Do you guys think you're going to be able to trace it from the pics if I get some more, or is someone going to need to go further?
Hi drbob1,

Thank you for your disposition to open again this unit. :applause:

It's necessary remove the tube (carefully), and unmount the tiny board that has the tube socket since has some more components there.

Please take a picture of each side and of the position of each of the wires that ends in the 5 way connector.

From the images you posted I think that I´ve already done a rough drawing of this unit. To complete this schematic need to know the value of some components that I can´t read based in the photographs.

Please tell me:

1) Value of each potentiometer

2) Values of all capacitors

3) Model of a couple of zener diodes mounted near the IC (I guess 1 N 47xx)

4) Please tell me also the designation of U2

I think that the opamp must be an TL071 and U3 be a LM317, so please confirm it

Perhaps be need to measure what is the AC voltage at the secondary of the transformer mounted in the main board, or measure the DC value at the terminals of the first filter condenser.

Any of these two measurements be risky due my guess is that can be at least 200 Vac or 250 Vdc respectively.

If you feel safe to take any of these measurements, and have an DMM fitted with alligator clips that you can count, go ahead.

But if we clone this unit using any transformer of 12 to 240 volts of similar size we´re enough close, I think, and is better not to expose to an accident or damage the unit.

Cheers,
Jose

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Post by ppluis0 »

Bump this thread !!!!!!! [smilie=bump.gif]

I already completed the preliminary drawing of this overdrive, based in the images previously posted.

Let me say that this unit is very simple in its conception, and can be easily cloned.

drbob1, when you have time, please open this unit again and tell me about the values ​​of the missing components mentioned in my previous post.

May also be useful to measure the value of the voltage appearing at the transformer secondary winding.

Cheers,
Jose

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Post by drbob1 »

Sorry this took so long. I'm going to upload more detailed pics in a little while. I'll get the values for the caps, but I have to confess, I'm not going to spend the time that it would take me to winkle out the resistor values, I may be slightly color blind but I can't tell the difference between blue and black on those damn blue resistors...

Also, since I took it apart the gain control no longer works, it's stuck on "wide open". I'll touch up the solder and check the pot, anything else I should look at?

1 47n
2 10m
3 22j???? (orange chiclet)
4 ???
5 10m
6 22n
7 10m
8 ??? wima
9 ??? wima
10 1m
11, 12, 13 22m @ 450v
14 10m
15 10m
16 2200m @ 25v
Tube Socket 47m

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Post by drbob1 »

sas10.JPG
sas9.JPG
sas8.JPG
sas7.JPG
sas6.JPG
sas5.JPG
sas4.JPG
sas3.JPG
sas2.JPG
sas1.JPG

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Post by ppluis0 »

Hi drbob, and thank you for the data you posted.

I think that there is enough information to draw a preliminary schematic of this unit. I try to read the resistor values from the images (previous and recent ones) you posted, but I think that all the values will be readables.

Only wish to know what is the value of each potentiometer. If you have trouble with the gain pot of your unit the only solution is to replace it, I think.

In a couple of days will post a drawing. Stay tuned...

Cheers,
Jose

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Post by drbob1 »

Thinking about this last night, the power supply can be simpler than what was proposed since the heater can work off of 12v AC, direct from the wall wart?

I'm sorry about the pots, since it wasn't working correctly I contacted Fryette and I'm returning it to GC, it's boxed up and ready to go... I'd rather not disassemble it again.

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Post by ppluis0 »

drbob1 wrote:Thinking about this last night, the power supply can be simpler than what was proposed since the heater can work off of 12v AC, direct from the wall wart?
Bear in mind that the EF86 heater work with 6.3 Volts @ 200 mA. You can place in series with the heater a resistor of 27 to 33 ohms (rated at 2 watts) instead the LM317 and feed that string directly with 12Vac.

Also the relay can be replaced by the usual 3pdt stomp switch. But it´s still necessary a supply for the op amp.
drbob1 wrote:I'm sorry about the pots, since it wasn't working correctly I contacted Fryette and I'm returning it to GC, it's boxed up and ready to go... I'd rather not disassemble it again.
OK. Don't worry about that.

In a few days I will post the diagram and think that someone in the forum can estimate these potentiometer values and talk about this design.

Hope you have your unit working back soon, and enjoy that. 8)

Cheers,
Jose

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