PCM Sound & Stability Fixes Multicarts - 120 in 1, 138 in 1, 161 in 1 and others.

GadgetUK

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Glad you sorted it all out =) I will get one of those PSUs at some point! I have no problems at all with my current PSU but it might not last due to only being a 2 amp (and very small). Thanks for the tip on the socket there - might swap mine out later! Let me know how you get on with the 138 in 1!
 

mjsaville

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Will do mate, I've had a monster session on it today 3hrs plus and the MVS is totally rock solid through out. Big thumbs up from me!
 

Westcb

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A buddy of mine just did this fix on his 161-1 and he said it fixed any sound issue he had before. I have a cart that came to me with sound messed up on every single game and just put it up to mess with later. I will do this fix on my working cart and report back when I get some caps from him and I will also see if this fixes the cart that has never had any correct sound. Thanks for posting this fix!
 

GadgetUK

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It depends on what the problem is - if the sound is messed up completely, perhaps playing the wrong sounds at the wrong time etc that's likely to be a bad connection, a short, a faulty chip etc. These fixes work for carts that are working but have flakey PCM where the samples start / stop suddenly or change in volume level and get crackly etc. It's not a 'fix all'. Let me know how you get on, I hope it works for you!
 

Westcb

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It depends on what the problem is - if the sound is messed up completely, perhaps playing the wrong sounds at the wrong time etc that's likely to be a bad connection, a short, a faulty chip etc. These fixes work for carts that are working but have flakey PCM where the samples start / stop suddenly or change in volume level and get crackly etc. It's not a 'fix all'. Let me know how you get on, I hope it works for you!


Yeah basically it's crackly on every single game. All 161 :-/ my buddy is sending me 8 of the caps needed so I will go through 4 multicarts and report back. The others I have not noticed any sound issues at all, but I'll specifically go check out strikers and pulstar. I'll try a reflow on that messed up cart after the cap trick just to eliminate bad solder joints too.
 

GadgetUK

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Just make sure you get the 2 x 47pF caps in the right spot. The 100nF caps in other bypass positions are also needed on other carts but the 150 in 1 and 161 in 1 normally have all the other caps, they just lack the required 47pF caps on the 2 PCM inputs. And for anyone wondering where to buy caps - look on EBAY, a pack of 50 x 47pF ceramic caps are a couple of pounds ($3).
 
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mjsaville

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@ MODS - Can this thread be made a sticky please?

These carts have been around for years (with issues) until GadgetUK brilliantly found a solution to the issues and I for one would not like to see this thread lost.

What does everything think? We need to generate some support here!! :-)

MJ
 

GadgetUK

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Thanks for the support! Hearing from a few people here and there to say it has fixed sound problems on their carts.
 

GadgetUK

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Just a quick update to this thread. I did a follow on video covering fitting a 3.3v regulator to the CHA board of the 161 in 1, and quickly showed where the 2 x 47pF caps go on the 161 in 1.

https://www.youtube.com/watch?v=5a-67DIteMk

It's important to note that one person testing with a 2 slot is finding he loses sound completely after adding the caps. I've suggest dropping the size to 22pF in that case to see if it brings the sound back. Not clear on whether there's a difference on 2 slots, or whether there's another issue with that cart / system at play. In theory it should work just the same, but I do remember when I tried with 100nF caps to start with I found the sound almost disappeared - clicks and squeaks etc, so that capacitance value is important or it can affect the timing to the point the PCM is hardly there at all. I've had positive results back on at least 8 carts now from 4 different people - I think they are all based on single slots thought, mostly MV-1FZ.
 

SmokeMonster

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Thank you GadgetUK for coming up with an easy fix for this big problem, and for posting the great writeups and videos. I have a 161-in-1 coming and this will be the first thing that I do to it. I saw in your youtube video that you've added some extra caps to provide the boards with more of a power reservoir. Have you written that up anywhere? Very interesting work!
 

GadgetUK

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Thank you GadgetUK for coming up with an easy fix for this big problem, and for posting the great writeups and videos. I have a 161-in-1 coming and this will be the first thing that I do to it. I saw in your youtube video that you've added some extra caps to provide the boards with more of a power reservoir. Have you written that up anywhere? Very interesting work!

Thanks!!! The pictures below can help you work out what things to fit on the different boards. 161 in 1 just needs those 2 x 47pF caps, although as posted above I have one person that has a 2 slot and it makes the sound cut out completely on his system - yet to work out if its the cart, the system or the cap size related to that 2 slot motherboard.

138 in 1 and 120 in 1 pics:-
https://www.dropbox.com/s/nx0fhk0eimacrpi/multicartfix.zip?dl=0

161 in 1 pics:-
https://www.dropbox.com/s/kdf1bd2fqow6xkv/161 in 1.jpg?dl=0
 

GadgetUK

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Wow, it's surprising that 2 simple capacitors, that should cost like a penny each, solve audio issues in these carts. I bet chinese makers know these fix the problems, but they don't bother putting them in because chinese bootleggers.

Thanks!!.
Yes, they do know - if you look at the 2 traces in the 161 in 1 they are wiggly - that is designed to deal with the problem, it almost does (for 95% of the games on the cart), but it doesn't fix it completely. On the 120 in 1, there are 2 pads for the capacitors, so they knew about it when they designed that board, yet they shipped the cart without them =/ On the 138 in 1 they just didn't give a **** lol.
 

GadgetUK

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Do you mind if I put these tutorials on my site?
Not at all! Spread the word! Add to them, improve them etc - do what you want to them!!! =D I just want to spread the knowledge so people can get a better experience on some of these carts.
 

mjsaville

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@Mods - thanks for stickying this article - superb!

@ Mr GadgetUK - to quote the film Armageddon "You the man !!!" and congratulations on your first sticky by the way. Keep your good idea's and fixes coming, this is what is keeping this scene alive...

Bravo.....

MJ
 

SmokeMonster

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Thanks!!! The pictures below can help you work out what things to fit on the different boards. 161 in 1 just needs those 2 x 47pF caps, although as posted above I have one person that has a 2 slot and it makes the sound cut out completely on his system - yet to work out if its the cart, the system or the cap size related to that 2 slot motherboard.
I was referring to the extra electrolytic capacitors that it looks like you've installed in your own 161.

Also, is a ld1086v33 voltage regulator the only one that is suitable for adding to the 161? That part is a little expensive and hard to come by in the US.

It would be great if you could summarize all of the mods/improvements that you've made to your multicarts in one thread.
 
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GadgetUK

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I started that video thinking I needed to add a LD1086V33 (Low Drop Out 1.5 amp) but worked out quickly that it wasn't an over current problem with the Z80 error I had last time I tried an AMS1117 regulator. The Z80 error I originally got because I removed both diodes - the 1st one needs to be left in place in order to feed 4.3v to the CPLD related to the Z80 M1 ROM. So you can use a AMS1117 3.3v regulator which are dirt cheap!

I haven't added any additional electrolytics to my 161 in 1 - just the 2 x 47pF on the 161 in 1. If I get time at weekend I will try and summarize it all in text!
 

SmokeMonster

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I started that video thinking I needed to add a LD1086V33 (Low Drop Out 1.5 amp) but worked out quickly that it wasn't an over current problem with the Z80 error I had last time I tried an AMS1117 regulator. The Z80 error I originally got because I removed both diodes - the 1st one needs to be left in place in order to feed 4.3v to the CPLD related to the Z80 M1 ROM. So you can use a AMS1117 3.3v regulator which are dirt cheap!

I haven't added any additional electrolytics to my 161 in 1 - just the 2 x 47pF on the 161 in 1. If I get time at weekend I will try and summarize it all in text!
Exactly what I needed to know, thank you. My 47pFs and AMS1117 are on the way, all for $2 including shipping. Nice!
 

mjsaville

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@ GadgetUk

I've just done the mod's to my 138 in 1 cart - took ages to come from AliExpress and the quality is not as good as the 161 in 1 either.

That aside, I set about applying your cap fixes, etc. Then decided to house the dipswitch on the top front of the case - minimising trailing wires and keeping my OCD under control. :smirk:

Couple of things which may be of interest to people:

(1) Used 180uf caps at the JP2 connection and just below the C1 chip.

(2) I don't have a hot glue gun so used a clear plumbing silicon leak sealer (LS-X in the UK) to stick the PCB to the underside of the top half of the case, and surprised as to how secure it is.

(3) Dremelling the hole in the top of the case to allow the Dipswitch to come through - you also need to trim up the plastic to create a recess for the pcb to sit as the vent plastic is quite thick. If you don't - only half the height of the Dipswitch will come through fowling the switches from operating. Note:- There is loads of space/clearance under the case.

Here is some pics below, Enjoy -

IMG_0293_zpsszr9bqle.jpg

IMG_0294_zps9dtco2aa.jpg

IMG_0295_zps735ptcuj.jpg

IMG_0297_zpsrrzrjq0d.jpg

IMG_0299_zpsewb0qhvn.jpg

IMG_0302_zpskx1f0vif.jpg



Finally, I filled the hole in the side of the case where the cable came through also with LS-X.

Very pleased with the mod.
 
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GadgetUK

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Brilliant job there! Did you test before doing the mods (just out of interest)?
 

mjsaville

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Apologies, didn't test - my system is consolized I had it in my head that I needed to do the dipswitch mod just to get the cart to work. Then got carried away, I tested the dipswitch mod to make sure to was working before I decided to hack the case. My cart had exactly the same as yours though, same cable colours, including the surface mount resistor which I had to remove.

I also had to Stanley knife the case to get the 2nd board out, wedged solid - I used a fair bit of force and it wouldn't move - If I hadn't trimmed the case I would have damaged the board, cleaned out some of the flux from the boards. They were in a right straight. Even the outside of the case had scratches on it before I started molesting it. Overall - disappointed in the case quality with some signs of cracking, etc but not too expensive if it dies at a later date.

I would love to see the reaction of the ALIEXPRESS Vendor if I returned the cart to them, now modified and better than it left the factory. It would be priceless for sure.
 
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