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In this thread we build the projects that others have shared - TD-IO (JVS to JAMMA)

I am getting close. I have a board finished but need to add the firmware and do you think I can find the right cable? I am sure I have one somewhere around.

I have an interesting problem though. I am getting 5v, 12v and 2v out of the Naomi power plug on the initial test. I am assuming that I have miscalculated something related to driving the SIC437 anyone prepared to share their values?
 

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Big_P Big_p said:
I am getting close. I have a board finished but need to add the firmware and do you think I can find the right cable? I am sure I have one somewhere around.

I have an interesting problem though. I am getting 5v, 12v and 2v out of the Naomi power plug on the initial test. I am assuming that I have miscalculated something related to driving the SIC437 anyone prepared to share their values?
Click to expand...

I’m getting a bouncing voltage between 3.2v and 4v on the 3.3v line
 
Sp33dFr34k said:
What did it set you back for 1 @Big_P Big_p?
Click to expand...

@xodaraP is pretty much spot on.

xodaraP said:
I’m getting a bouncing voltage between 3.2v and 4v on the 3.3v line
Click to expand...

Bugger.

From what I can tell it's just a resistor divider over a reference pin, the reason I think it's a maths problem at my end (or a problem understanding exactly what the ref pin is looking for) is that the resistor divider should tell it how many increments of a voltage to output and i seem to be consistently outputting 2v.

What value is your R32 and R33?

If it's bouncing it sounds like it may be connected to something.

Sp33dFr34k said:
Missed this one, seems like an interesting alternative to the Sega IO's :)
@Big_P Big_p?
Click to expand...

Oh way better than sega I/Os. the reason I am so determined to get this power working is that it can supply 8A over the 3.3v line so you can run your netdimm setup from it and it has no lag. Basically a Capcom I/O plus plus.
 
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My maths seems to be correct but it's definitely a problem before U5 and U5 is working as it should. I seem to have 2v on the reference pin? Going to have to check a few things.
 
Somewhat comforting.

It appears R32 (4530 ohms) and R33 (2000 ohms) are set up as a resistance/voltage divider from the 5v line. They supply pin Vfb with a reference voltage. When I checked the voltage after the resistors but before Vfb it matched perfectly what I was seeing on the output. Before I do anything I want to know why the maths is not adding up. My problem is that I don't have a schematic because the project was built in an old version of Kicad and while every other schematic seems to work this one does not. As a last resort we can probably change the values at R32 and R33 but I want to understand it a bit more before I go that route.

On a good note, it looks like the SIC437a was used to ensure that the unit could supply the required amps to a netdimm setup.
 
Like the best engineers I did the maths in detail after what i thought would work didn't work. While a 2k ohm resistor in R33 is ok for an ideal circuit with the sic437a attached a 1k ohm resistor in R33 gives you a perfect 3.3v output. Problem solved, I think.
 
Ok, I’ll get some 1k resistors ordered with the last few parts I need

Out of interest, what switches are you using? I ordered the same switch they use on the GitHub images but they don’t fit. Have ordered a couple more styles to try and find one that does

Also need to find the correct audio RCA sockets
 
Switches - I used the part number referenced in kicad JS202011JCQN. Be really careful because there are 2 part numbers very similar one is the J leg and the other is through hole JCQN and CQN I think. They are a pain to hand solder that close.
 
Ahhh I got it with SMD legs instead of J leads. Ok easy I’ll grab these with the resistors and the handful of other bits

Is there a Digikey part number for the RCA jacks?
 
Yep PJRAN2X1U01AUX I didn't go that route, I mean it looks like a nice rca but at $10 for 1 it would want to be. I looks like you can use any RCA-105a standard connectors, be careful if going this route because RCA-105 and RCA-105a are different pinouts. I had some 105a connectors lying around but building valve amps is another one of my vices. One day I'll put a single ended class A valve amp in a cabinet.
 
Thank you for confirming the correct type, will track down some of those now

Time to get a Digikey order together for everything else - with the change in the resistor hopefully it will be good to go
 
invzim said:
Great project! Playing with this board on my desk right now, but was lazy and bought it assembled :)
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What have you learnt about it?

When I decided it was finally time to get a Naomi out of a box and running again, I thought that putting one of these together would help me get over my fear of setting up the Naomi. It also looked like the best way to go, given my current cab situation with Capcom IOs getting harder to find and more expensive. It could power a netdimm setup and had a set of features that combined were not available on other IOs, including no lag.

I needed 2 and built 4 because I was terrified of hand soldering the tiny U5 no leg package that provides the 3.3v with enough amps to power the netdimm setup. As of tonight I have 3 that are all delivering 3.3v, have the uf2 uploaded to the pico pi and appear to be working with the last one being the first attempt at soldering U5 and likely only needing a reflow of it. I have not yet fully tested one on a Naomi and I don't know if that is because after all the work building one by hand I am afraid of it not working or just afraid of it leaving my work bench after all the time we have spent together.

It was really great to have @xodaraP building one at the same time and I look forward to others putting one together. The build was challenging but not too difficult for someone with a base level of SMD soldering skills and equipment and really built my confidence with quad flat no lead (QFN package) soldering.

Anyone else wanting to give it a go I still have boards available and once I have tested the ones I put together I may also have a complete board or 2 which will likely be a good deal given the current prices of the TD-IO.

But given I haven't yet tested one I am really interested in your impressions.
 
xodaraP said:
With the change in the resistor hopefully it will be good to go
Click to expand...
If you are getting a stable 1.9v to 2v changing R33 from 2k to 1k will almost certainly work. I am not sure where 2k came from. It is what you would use in an ideal voltage/resistor divider to get 3.3v but reading the datasheet for the SIC the example circuit they give for the package is pretty clear.

If you are getting between 1.5v and 1.6v however I not sure of what the problem is. The one board of mine that is not working is delivering about 1.6v, which was close enough to 2v for me to be hopeful that swapping the resistor would fix it but it dosen't appear to have. I am hopeful a reflow will solve the problem. I had one board not delivering any voltage to the 3.3v line and as I had yet to put any of the plastic components on reflowed it tonight with total success. As I am out of kapton tape the jst power header and volume know are a little close for comfort on the other one so it will have to wait until uncle Ali or digi delivers some more Kapton.

I have a few bits and pieces left that I am unlikely to use in other projects and i am sure i can spare a 1k resistor or 10. If you PM me a list I may be able to reduce your digikey order a bit. I am unlikely to have everything but I may have a few things, I may not too, depending on what you still need.

And anyone reading this far who has a 3d printer, print one of these. It works amazingly well, the cheap ones uncle Ali delivers are rubbish and I have a problem spending $80 for something my fingers ate perfectly capable of doing. Thats my Christmas present to everyone.
 

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I’m getting just over 1.9v so it sounds like the resistor is the go. I needed some other stuff from Digikey to finish up some other projects so I had enough to fill an order, it’s due early next week. Will be good to get this one completed

I would prefer to test it with something cheaper than my NAOMI but I don’t have any other JVS boards so as long as the voltages are good at some point I just need to trust it
 
xodaraP said:
I would prefer to test it with something cheaper than my NAOMI
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The NAOMI is not really a concern, I have a number of boards with c29 trace damage sitting around, so plenty of spares if anything does go wrong. The netdimm is another thing altogether, that would be a pain.

If you have just over 1.9v the resistor change will fix it.
 
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