After doing a lot of Duo repairs lately. My own personal experience and preferences are....
Duo:Pro'sHeadphone jack
SMT caps <- I prefer this style - replace with ceramics is a breeze, but costs more
cd-rom pin holders seem more sturdy (less prone to breakage)
power input jack
Con'sLeaky caps - If fixed in time no further worries
Side output A/V
Difficult to fit larger supercap for battery backup
7805's are right next to audio caps <- possible heat issue
6260 <- On bottom of board, running wires for RGB is a bit more difficult.
Duo-RPro'sBetter caps <- They still get old and worn out, 25-30yrs prolly should replace them anyways just like regular Duo.
Only a couple caps by 7805 <- Less of a heat issue
Easy RGB modding 6260 is on top of board
Tons of room to add a larger supercap like a 1.5F
ConsAll thru-hole radial caps and micro caps. <- If you don't have a desolder gun this board can be very tedious to work on.
A/V port <- Prone to solder cracking
Game pad port <- Prone to solder cracking
power input port <- Prone to solder cracking
The above 3 I have read and noticed on the two Duo-R's I have sitting here. By wiggling the A/V cable and having the video and sound flicker was the diagnosis of bad or cracked solder joints.
BothPro'sThey both use the same laser's HOP-M3
They both have the exact some pots for adjustment
They both can be region modded at about the same speed. <- Special note for the US-Tech video. He has his own special region mods that he makes. He made one that goes right on the pins. The metal shields in the Duo-r's pose some rethinking like how he showed in the vid on how to do it. Using the Obey region mod the protective metal shield is a non-issue as you are connecting wires to the cut pins instead.
ConsOn both you need to solder wires directly to the 6260 for RGB. This can be difficult to people that are not used to soldering such small wires to such small pins that are extremely close to each other. You can mess stuff up here if you don't know what you are doing.
Region mods require you to permanently alter the internals of the HuCard slot and outer casing for a switch.
These systems are old. <- If you use them, pamper them. Get the caps replaced, if they have not been already. I would think doing it in the Duo-R's is a smart idea as well. Think of it as preventative maintenance. It'll last another 25yrs as long as the laser holds out.
Lasers, replace when needed, they seem to be readily available, just depends on the price.
Both version's of the Duo use the Arcade Duo Card instead of the Arcade card pro.
So for me, it all comes down to color. Do I want Black and grey or Black and purple or white and purple.
I have a few of each in front of me right now that I am getting ready to sell, or try and sell. The Duo-R is region and RGB modded. Just waiting on my cables and ends so I can put a scart with it along with the regular A/V cable.
The Pc Engine Duo is recapped and fully working, just waiting on my cables for the scart ends.
And, the one US Duo I have that I repaired someone was using as a parts machine. It's in bad shape but with a fresh recap and some minor fixes it works. Just the shell has been abused, although it is a US shell. I have not region or RGB this one yet.
So I have some experience working on these now and imo they look really good. Ceramic caps for SMT/SMD locations and all Nichicon for thru-hole. Except for one Duo-R where I used a cap kit from console5.
