Electra 500D | parts orientation and sanity check

[jessenator]

So I'm looking at this board of the Electra Distortion 500D / Mysto Dysto /  Boston / Nadine's etc. Not sure of these diodes, but they are of Japanese make I'm guessing (based on the origin of the board used in those pedals). I know old soviet germaniums are reversed, but don't know about 1980s JDM fare. Is it safe to say the blue band is the cathode?

https://rvb-img.reverb.com/image/upload/s--rRQGl2K7--/a_0/f_auto,t_supersize/v1692070464/qvskslkl74w2but2qdfx.jpg

I'm planning on following the advice of the FSB post breaking down the Mysto Dysto, and putting in some 4148s, unless anyone has a better suggestion

Thanks

[mauman]

I always measure to be sure.  Here are three quick ways to verify diode anodes:

If you have a diode test setting on your multimeter, it will read voltage (Vf) when the red (+) lead is on the anode, and no voltage when the red + lead is on the cathode.

If you don't, use the ohms setting on your multimeter, it will read a resistance (1k to 100k) when the red + lead is on the anode, and a much higher resistance (megohms) when the red + lead is on the cathode. 

Connect a battery to an LED thru the diode.  In one direction (anode to +V) the LED will light up, in the other direction (cathode to V+) it won't.

[jessenator]

I always measure to be sure.  Here are three quick ways to verify diode anodes:

If you have a diode test setting on your multimeter, it will read voltage (Vf) when the red (+) lead is on the anode, and no voltage when the red + lead is on the cathode.

If you don't, use the ohms setting on your multimeter, it will read a resistance (1k to 100k) when the red + lead is on the anode, and a much higher resistance (megohms) when the red + lead is on the cathode. 

Connect a battery to an LED thru the diode.  In one direction (anode to +V) the LED will light up, in the other direction (cathode to V+) it won't.

Sadly I don't have the board on my possession to actually check it :/

[mauman]

Oops, sorry.

[jessenator]

no worries

[jessenator]

perhaps?
https://www.retroamplis.com/epages/62070367.sf/en_GB/?ObjectPath=/Shops/62070367/Products/DI-1S1588

[jessenator]

I'm going to go with that as the use and assume it follows the JP-NA pattern of the band being the cathode mark, and orient the footprints to match that.

[derevaun]

As an additional data point, I got these from Retroamplis:

[jessenator]

As an additional data point, I got these from Retroamplis:

Super! Thanks for that.

[jimilee]

As long as they're facing opposite directions, it won't matter how you put them in.


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[jessenator]

As long as they're facing opposite directions, it won't matter how you put them in.


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Totally sure for the clipping pair. Those two other ones were doing something else that I didn't quite grasp. Maybe in the buffer? ¯\_(ツ)_/¯

I'm just a little persnickety atm heh

Not final yet, but I'm just redoing the board as a single -sided homage/replica.

[jimilee]

Maybe so, do you happen to have a schematic?


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[jessenator]

Maybe so, do you happen to have a schematic?

https://forum.pedalpcb.com/threads/electra-distortion-500d-600d-schematic.20134/
someone traced it on FSB, and another traced from a vero by mirosol on tagboardeffects. I tried both on the breadboard multiple times (granted, without the buffer, so I might've mucked that up), and I'm so bloddy sick of it not working I'm going to just mimic the danged board from the original hahah. if that doesn't work, well, I'll cross that bridge eventually.

I might've messed up on the removal of the buffer, but I also couldn't get the reverse-vero schematic (sans buffer) to work, either. But that could still be my fault.

Traced from the board c/o FSB:


My edit in Eagle (PDF attached):


Now I'm thinking about it, are those NPNs even necessary anymore, since the drive from the circuit comes from the 4558? Do I need to remove the NPNs completely; i.e. were they part of the buffer, too? Hooray for swiss cheese knowledge


side note it's wild to me there were so many localizations of the 500D. Same board! Thank goodness Reverb listings occasionally have some gut shots, like the one in the OP.

[jimilee]

Ah perfect, thank you. Looking at the second schematic, the diodes are clipping, so as long as the are facing opposite directions, it doesn't matter which way they are oriented. The NPNs are a buffer, so you can go without them, if you want.


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[jessenator]

Ah perfect, thank you. Looking at the second schematic, the diodes are clipping, so as long as the are facing opposite directions, it doesn't matter which way they are oriented. The NPNs are a buffer, so you can go without them, if you want.


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Awesome, thanks, Jimmy!

So would a more better modified schematic look like this? I.e. if I wanted to prep this for true bypass?

I chopped it based on what I see on the the OD250.