Whoa. I was literally desoldering capacitors from my CT3600 and noticed those guys on my card just before I sat down and hit vogons. I chuckled a bit as I figured it was a bit of whoopsie daisy last minute cap addition after the PCB was completed - or was something required for this variant vs whatever other models used this PCB.

My card also has that green jumper wire along with a little bit of hot glue to hold it in place.

I can't find the odd components on the top side (edit: found the green wire, was actually more obvious on the thumbnails 😁), but you're probably right about the ones at the edge connector. The brown SMT components looks like caps (rectangular, unmarked, brownish ones usually are), coupled as bypasses between signal leads and ground plane, to shunt away high frequency noise.

Through my career as a marine engineer, I've seen a few examples of mods like this done at the factory, extra components hand soldered after an automated assembly process, to remedy problems with the original design. It's been on very specific stuff manufactured in much smaller series than I imagine those cards were though, so I wouldn't bet my right hand that's the case with your card. Might just as well be a user mod.

Gotta say you have a keen eye by the way, would never had noticed that myself 😀

CkRtech wrote:

Whoa. I was literally desoldering capacitors from my CT3600 and noticed those guys on my card just before I sat down and hit vogons. I chuckled a bit as I figured it was a bit of whoopsie daisy last minute cap addition after the PCB was completed - or was something required for this variant vs whatever other models used this PCB.

My card also has that green jumper wire along with a little bit of hot glue to hold it in place.

How crazy. I only saw 2 cards on ebay with the same mod and figured it was a somewhat common mod, as in google there are no cards with the mod.

I really wonder what its for.

kaputnik wrote:

I can't find the odd components on the top side, but you're probably right about the ones at the edge connector. The brown SMT components looks like caps (rectangular, unmarked, brownish ones usually are), coupled as bypasses between signal leads and ground plane, to shunt away high frequency noise.

Through my career as a marine engineer, I've seen a few examples of mods like this done at the factory, extra components hand soldered after an automated assembly process, to remedy problems with the original design. It's been on very specific stuff manufactured in much smaller series than I imagine those cards were though, so I wouldn't bet my right hand that's the case with your card. Might just as well be a user mod.

Gotta say you have a keen eye by the way, would never had noticed that myself 😀

I see two on ebay with the same mods done so I have to assume youre right. Its got to be a fix that just did not get applied to most of the production run of this card.

I come from doing a lot of repairs and mods on game consoles so I've just got the habit is closely inspecting everything. Has helped me fix a lot of these cards ive been salvaging!

goodtofufriday wrote:

kaputnik wrote:

I can't find the odd components on the top side, but you're probably right about the ones at the edge connector. The brown SMT components looks like caps (rectangular, unmarked, brownish ones usually are), coupled as bypasses between signal leads and ground plane, to shunt away high frequency noise.

Through my career as a marine engineer, I've seen a few examples of mods like this done at the factory, extra components hand soldered after an automated assembly process, to remedy problems with the original design. It's been on very specific stuff manufactured in much smaller series than I imagine those cards were though, so I wouldn't bet my right hand that's the case with your card. Might just as well be a user mod.

Gotta say you have a keen eye by the way, would never had noticed that myself 😀

I see two on ebay with the same mods done so I have to assume youre right. Its got to be a fix that just did not get applied to most of the production run of this card.

I come from doing a lot of repairs and mods on game consoles so I've just got the habit is closely inspecting everything. Has helped me fix a lot of these cards ive been salvaging!

Ah, well, then it almost has to be something like that, yes.

So you were actually studying the card, that explains it. Thought you just noticed it at a quick glance 😀

The CT3900 also comes with a green wire job. Right of the CT1745 mixer: http://hw.fagear.ru/wp-content/uploads/20150117_844476.jpg

I also have that green wire mod. So i think it is a factory mod.

My SB16 CT2230 has a 1/4W resistor on the back.
One wrong push and the card is dead... 😐

My CT4380 AWE64 has a green wire as well. Don't have a pic of mine, but googling and looking on Ebay, mine definitely isn't the only one. Example: http://mail.lipsia.de/~enigma/neu/pics/awe64.jpg

kaputnik wrote:

The brown SMT components looks like caps (rectangular, unmarked, brownish ones usually are), coupled as bypasses between signal leads and ground plane, to shunt away high frequency noise.

It appears the caps on the back side are on DACK7 and DACK5, and the front cap with green wire is DACK6. Most likely to slow down signal edges to prevent ringing (kind of HF noise yes) so only one transition/edge of the signal is seen instead of many.

Later designs have them on board (http://www.amoretro.de/wp-content/uploads/cre … _pnp_ct3600.jpg, see white caps C166, C167, C168.

Sometimes there will be an error in the PCB layout or board construction process, passives that don't get installed, traces that do not make it to the PCB. When the boards are already assembled it was often cheaper to apply a patch wire or resistor or capacitor rather than retooling the design. IBM's PC boards frequently show some patching.

Jepael wrote:

kaputnik wrote:

The brown SMT components looks like caps (rectangular, unmarked, brownish ones usually are), coupled as bypasses between signal leads and ground plane, to shunt away high frequency noise.

It appears the caps on the back side are on DACK7 and DACK5, and the front cap with green wire is DACK6. Most likely to slow down signal edges to prevent ringing (kind of HF noise yes) so only one transition/edge of the signal is seen instead of many.

Later designs have them on board (http://www.amoretro.de/wp-content/uploads/cre … _pnp_ct3600.jpg, see white caps C166, C167, C168.

Well there it is. I find that to be pretty awesome, though I was a little hopeful it was a mod lost to time.
Sega genesis consoles have a lot of factory jumps like that, the first run japanese ones even had an entire daughter board just for a patch.

There's an early CT3600 on eBay that's missing the fix entirely. I guess those are the ones you really want to avoid if you can: http://i.ebayimg.com/images/g/WKgAAOSwCQNWfdCw/s-l1600.jpg