Need help with DIY N64 RGB mod.

[the_crayon_king]

Hello all,

I haven't posted on a forum for maybe a decade or so.
At any rate I have done 30-40 ish N64/SNES mini RGB mods.

I have always used this as a guide: http://retrorgb.com/n64rgb.html

What I can't figure out is why I am getting a black screen on my XRGB-mini but get a perfect picture on my Panlong converter.
I am using luma as sync. On the framemeister I am using a sync stripper that should convert to C-sync.

Anyway I am not getting picture with my new mods on the XRGB but I am getting picture with my old mods.
They literally look identical. Same .1uf cap same 75ohm resistors everything. I am on my 5th one and am getting desperate for a solution.
The chip THS7314DR is getting pretty hot (not sure if that is normal). I tried a c-sync enabled console and get the same thing.
Also note I am getting a black screen not a blank screen. The same thing for the snes-minis
Any troubleshooting tips would be much appreciated.

I can tell you that the problem has to be in the chip area itself or maybe with my cord also that it isn't bridged connection/short. On the last one I made I left all the connections unsealed (in shrink tubing) so I can tell pretty clearly it is not a short.

Links to what I am using:
http://www.ebay.com/itm/201418796668?_t ... EBIDX%3AIT
http://www.ebay.com/myb/PurchaseHistory ... 2749.l4670
http://www.ebay.com/itm/10pcs-THS7314DR ... xy2YtRrASJ
http://www.ebay.com/itm/151870250806

EDIT: I think I may have found something relevant. The chips (THS7314DR) have different numbers near the TI logo.
The old ones I used to use say 53K, the one on the site (retro RGB) says 2AK, The new lot I have say 01k it may even say 0.1k or something TBH I can't read it too well. I am almost certain this is where the problem is but I don't know what those numbers are referencing any idea ?

[Fudoh]

I am using luma as sync. On the framemeister I am using a sync stripper that should convert to C-sync.

and what do you get without the sync stripper ? What sync level setting on the FM are you using ?

[the_crayon_king]

My sync level is at 9. I have no idea what this represents. I'll just tried everything in-between same result. I am under the impression that the chips are to blame this is a different batch of THS7314DR all the other parts are identical. I am about to build another amp with an old chip to see if that is what is to blame. Fingers crossed.

[mickcris]

i read somewhere about some batches of 7314 from china being silk screened upside down. I wont buy those from ebay anymore, just from a legit supplier like Mouser or Digikey. Possibly you got some bootleg ones that are silk screened incorrectly.

[the_crayon_king]

i read somewhere about some batches of 7314 from china being silk screened upside down. I wont buy those from ebay anymore, just from a legit supplier like Mouser or Digikey. Possibly you got some bootleg ones that are silk screened incorrectly.

I tried the old chips out and can confirm they work fine. Funny thing is the non working batch I bought from a US seller and the working (old ones) I bought from china. Both on ebay however. I will just buy from a legit distributor now thanks. I still wonder if these chips maybe have different specs or something as they both work on the panlong just fine.

[mickcris]

i read somewhere about some batches of 7314 from china being silk screened upside down. I wont buy those from ebay anymore, just from a legit supplier like Mouser or Digikey. Possibly you got some bootleg ones that are silk screened incorrectly.

I tried the old chips out and can confirm they work fine. Funny thing is the non working batch I bought from a US seller and the working (old ones) I bought from china. Both on ebay however. I will just buy from a legit distributor now thanks. I still wonder if these chips maybe have different specs or something as they both work on the panlong just fine.

Think they are just bad bootlegs or possibly ones that were ment to be scraped but someone stole them and sold them. Probably the eBay seller from the USA bought them cheap from China to resell.

[Voultar]

i read somewhere about some batches of 7314 from china being silk screened upside down. I wont buy those from ebay anymore, just from a legit supplier like Mouser or Digikey. Possibly you got some bootleg ones that are silk screened incorrectly.

That was me.

http://www.retromods.net/viewtopic.php?t=556

A "hot" THS7314 is a sharp indication that you have power and ground gooned up on the package. Own a meter? Set it to diode and check the resistance across the pins to find power/ground. Once you do, see if it's aligned to the silk-screen.

[the_crayon_king]

A "hot" THS7314 is a sharp indication that you have power and ground gooned up on the package. Own a meter? Set it to diode and check the resistance across the pins to find power/ground. Once you do, see if it's aligned to the silk-screen.

I do have a multimeter not sure what readout I should expect from power/ground. I have only ever used my multimeter to check for shorts and continuity. Since the chip only has two possible orientations on the SOIC board I will just install it upside down and see how that goes. More out of curiosity really since I already ordered 50 'legit' ones to replace these. Even if these knockoff's work I don't know if I would be comfortable using them. Unless maybe they were legit but rejected due to the flaw of being printed upside down.

I will edit with an update in a day or so. Also thanks so much for the info I would have never have guessed it was printed upside down.

Will test the pins in a few but I am now under the impression that they ARE knockoffs or at least after hours prints.

Legit one is on top. Notice the differences on the chips. Like the legs are a different type of metal (its more chrome on the legit ones).
The font is slightly yellower on the knockoffs (can't tell in the picture) also it looks like the lettering is spaced out differently in places.
There is also differences on the back it has different indents. Sorry for the potato quality my phone can only zoom so much.

[Voultar]

These aren't Knock-Off chips. They're factory defected chips that were more than likely sold to some shitty 2nd market Asian resellers at cost to flip.


THS7314
1[]----O8
2O----O7
3O----O6
4O----O5



^ Set your meter to Diode or resistance mode.

Probe legs 1 and 8, record resistance.
Probe legs 2 and 7, record resistance.
Probe Legs 3 and 6, record resistance.
Probe legs 4 and 5, record resistance.

The values should be pretty much the same between your driver inputs and outputs. When you see a stark change in the value, you know you've found the power and ground pins. Look for the big number change.

[the_crayon_king]

These aren't Knock-Off chips. They're factory defected chips that were more than likely sold to some shitty 2nd market Asian resellers at cost to flip.


THS7314
1[]----O8
2O----O7
3O----O6
4O----O5



^ Set your meter to Diode or resistance mode.

Probe legs 1 and 8, record resistance.
Probe legs 2 and 7, record resistance.
Probe Legs 3 and 6, record resistance.
Probe legs 4 and 5, record resistance.

The values should be pretty much the same between your driver inputs and outputs. When you see a stark change in the value, you know you've found the power and ground pins. Look for the big number change.

For the life of me I couldn't get a good read on the pins as the chip kept moving around and I don't have one of those holder things.
I did install one upside down to see if maybe the chips really were printed upside down.
I had pretty poor luck with this. The screen got a very faint image that was severely distorted.

So IDK. I don't think these other chips work at all at least not with the XRGB. I will do some troubleshooting later to make sure I didn't install the upside down chip wrong (besides being upside down) but I doubt there will be anything I did wrong.

So I would say the chips aren't printed upside down. They are just non-functional.