Shin-ei/Jax - 8Tr Fuzz Wah  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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fuzzbuzzfuzz
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Post by fuzzbuzzfuzz »

Slight thread resurrection. I'm currently repairing an ELK Fuzz Wah. Big silver case. I have a MICA branded version too. The latter is a six transistor circuit (and seems common in this OEM Shin Ei derived fuzz under many brands). However to my surprise the ELK has a Maxon PCB with only 5 transistors, two of which are power on the wah half of the board.

So what is it? A three transistor Superfuzz? It has the octave thing but as its broken I don't have a reference really.

Here's pics of mine:

Cheers.
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signedDC
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Post by signedDC »

I have same pedal except its the companion version. Will certain capacitors bring a certain sound to the pedal if I replace the old ones?

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Dirk_Hendrik
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Post by Dirk_Hendrik »

No.
Also consider these were budget pedals and most likely little to no attention was given to the concept that components may (or not) influence the sonic character.
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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kizzer
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Post by kizzer »

Hi guys

I've been building pedal's on stripboard for a couple of years now and decided it would be nice to learn to trace a circuit and make my own stripboard and pcb layout. I decided to start with my Fathers old Shin ei 8 transistor fuzz wah.

The tracing is going well apart from interpreting the values of the green capacitors, they have weird designations. I have been able to work out a couple, but was wondering if you guys could help me understand the others or point me in the direction of a resource for this.

These are the designations, I may have a couple wrong, they're hard to read!

1H102K
.1K 50
50V .2
60V .05
50V .05
50V .033

Thanks for any help you can give.

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marcao_cfh
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Post by marcao_cfh »

1H102K: 102 is basically the same as you read a resistor. 10 with two zeros = 1000. The unit is pF, so you have 1000pF = 1nF (or 0.001uF)
.1K 50: not sure on this one. Probably 0.1uF 50V
50V .2: 0.2uF = 200nF. You'll probably find for sale a 220nF rather than a 200nF cap.
60V .05: 0.05uF = 50nF. You can use a 47nF cap.
50V .05: same as above. The difference is the maximum voltage rating, which doesn't really matter on stompboxes as long as it's more than the voltage at that part of the circuit.
50V .033: 0.033uF = 33nF

Btw, if you google for shin ei fuzz wah schematic, you'll find one. I suggest you to do that after you trace your unit, to compare schematics and check if you did it correctly.

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kizzer
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Post by kizzer »

Thanks for the info.

Yes there is a schematic inside the lid that I am cross referencing as I go to check. That's where it gets weird as this is what is on the schematic:

0.001UF /1NF 2
0.01UF /10NF 1
0.03UF /30NF 1
0.1UF /100NF 2
0.2UF /200NF 2

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kizzer
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Post by kizzer »

Here's some close up pictures of the cap's.

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marcao_cfh
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Post by marcao_cfh »

Nice thing the schematic is inside the lid! That's exactly the same one that's around the internet. Just keep in mind they're not always correct. But anyway.

When you read a schematic and/or parts value, keep in mind there are some values that are "standard" for some brands/types of parts and doesn't exist on other brands/types of parts. Also, some "standard" values were changed somewhere across the years. And also some values are more common on some countries but rare on other countries. Just go for the closest value and you're fine.

A few examples: you can find some schematics that calls for a 25K pot, but all you can find locally are 20K pots. Close enough. The same can be said for a 220K pot and a 250K pot. Also, you can find right at the beginning of the schematic a 1.9K resistor, while the commercial value is 1.8K.

For your caps:

1H102K: this is your 1nF cap, marked as 0.001uF on the schematic
.1K 50: this is the 100nF cap, marked as 0.1uF on the schematic
50V .2: this one is a 0.2uF (as marked on the schematic), and while there are .02uF/200nF caps, it's easier to find a 0.22uF/220nF cap
60V .05: see below
50V .05: see below
50V .033: the schematic calls for a 0.03uF cap. This one is a 0.033uF cap, a more common value

For the .05 caps: to my eyes, all of them are marked 50V .05, which is a 0.05uF/50nF cap rated for 50V, and the commercial value you'll find at the stores is 47nF. The thing is... I can't find them anywhere on the schematic.

Aside from the list of caps you made, there are 12 10uF electrolytic caps. Maybe some of those electrolytics were replaced for the 47nF caps, which gives the fuzz a different voicing. Count how many electrolytic caps you can find. Or instead, don't totally trust the schematic and instead trace the unit, and you'll probably find out some caps were replaced by those 47nF caps.

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kizzer
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Post by kizzer »

Thanks for all the help. Finished up with the components part of the trace. You were right about the missing electrolytic's.

There are 2 missing 10uf's replaced by a 50V.05 and a 60V.05.
10nf replaced by a 50V.05
1.9k replaced with 22k
2k replaced with 1.5k

Now to trace the connections and attempt a schematic.

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marcao_cfh
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Post by marcao_cfh »

Ok, so you have two caps with values 200x smaller and one cap 5x bigger than what's expected to be, according to the schematic. This doesn't really mean the schematic is wrong, they may have used what they had on hand at the time (check the big muff versions story), or they just copy-pasted together the schematics from the fuzz and the wah, changed a few values so they could work better together but forgot to change those values on the schematic.

Without knowing which exact cap had been replaced, you can basically assumes a bigger cap replaced by a smaller (10uF>47nF) means less bass in that place of the signal chain, while the opposite means more bass. 10uF is a very big value, often used for fat fuzzes. Distortion usually uses something like 10nF/100nF for the caps.

For the resistors, 1.9K isn't a commercial value, it's 1.8K. But 22K is close enough (and more common on pedals). 2K is a commercial value (but not so common on pedals), and 1.5K is close enough (and also more common on pedals). They probably had a good amount of those and just used them. Fuzzes have a kinda big tolerance for resistors values. Again, the big muff versions were created this way: "we are out of 10K resistors... ah just use a 12K or 15K and call it a day".

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kizzer
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Post by kizzer »

Forgot to update this, but I traced it, drew up a Stripboard Layout and built it.

This is the first Stripboard Layout I have made, so with revisions I could no doubt make it smaller and neater, but it works and compares very well to the original unit.

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