| View previous topic :: View next topic |
| Author |
Message |
leonk
Joined: 05 Mar 2005
Posts: 64
|
 Posted: Mon Sep 26, 2005 7:26 pm Post subject: top loader - getting rid of bad video, lets figure this out! |
 |
|
I have an extra top loader that I don't mind experimenting with to try and figure out how to get perfect video out of it.
Here's what I know so far:
- the top loader / front loader have the same CPU and exact same PPU
- the video quality does not improve with the AV mod
The only thing I did notice between the top loader and front loader is the actual traces on the board. The top loader uses very thin traces! Thinner than ones on carts.
Has anyone had any luck with fixing video on this system? |
|
| Back to top |
|
 |
Quietust
Joined: 19 Sep 2004
Posts: 1028
|
| Posted: Mon Sep 26, 2005 7:59 pm Post subject: Re: top loader - getting rid of bad video, lets figure this |
|
|
| leonk wrote: | | - the top loader / front loader have the same CPU and exact same PPU |
Actually, this is not true - from numerous reports, frontloaders use an RP2C02G PPU while toploaders use an RP2C02H, and this is reported to be part of the problem. |
|
| Back to top |
|
|
leonk
Joined: 05 Mar 2005
Posts: 64
|
| Posted: Mon Sep 26, 2005 8:31 pm Post subject: Re: top loader - getting rid of bad video, lets figure this |
|
|
| Quietust wrote: | | leonk wrote: | | - the top loader / front loader have the same CPU and exact same PPU |
Actually, this is not true - from numerous reports, frontloaders use an RP2C02G PPU while toploaders use an RP2C02H, and this is reported to be part of the problem. |
I will confirm tomorrow.. but when I did compare the 2 this past weekend, they were identical. |
|
| Back to top |
|
|
Great Hierophant
Joined: 23 Nov 2004
Posts: 260
|
| Posted: Mon Sep 26, 2005 9:59 pm Post subject: |
|
|
My Famicom AV doesn't have the problem and is extremely similar to the Top Loader in design. It uses a RP2C02G and the traces are likely equally thin to the Front Loader. It could be the chip, PCB layout, a circuit board mistake or poor quality parts being used.
Has anyone ever used a SNES power supply? Maybe the NES-001 power supply just isn't well-suited to the Top Loader. You may get a better picture if you can use a power supply with the same specs. My Famicom AV does.
What should be done is to take the video signal directly from the PPU pin and feed it through the video amplifier shown on the NES 001. If the problem still exists, then you can likely eliminate the PCB as a suspect and concentrate on the chip itself. |
|
| Back to top |
|
|
leonk
Joined: 05 Mar 2005
Posts: 64
|
| Posted: Wed Sep 28, 2005 3:06 pm Post subject: |
|
|
Well folks.. here's what I found out.
My NES-101 (top loader) has the following:
PPU - RP2C02G-0 (3CM 37)
CPU - RP2A03G (3CM 10)
My NES-001 (front loader) has the following:
PPU - RP2C02G-0 (9G2 13)
CPU - RP2A03G (9G1 24)
I can take pictures of the PCB's for those of you that don't trust me, but the problem is NOT with the PPU as previously suspected! My top loader has a front loader PPU from the factory, yet still has the "jail bars" on the RF output.
It's something else.
Anyone care to share PCB pictures of the AV famicom? |
|
| Back to top |
|
|
loopy
Joined: 19 Sep 2004
Posts: 193
Location: UT
|
| Posted: Wed Sep 28, 2005 3:40 pm Post subject: |
|
|
Last edited by loopy on Wed Aug 20, 2008 10:57 am; edited 2 times in total |
|
| Back to top |
|
|
Guest
|
| Posted: Wed Sep 28, 2005 3:49 pm Post subject: |
|
|
Is that AV famicom???
It seems to have the 'H' PPU which makes me believe it's actually a US top loader. |
|
| Back to top |
|
|
loopy
Joined: 19 Sep 2004
Posts: 193
Location: UT
|
| Posted: Wed Sep 28, 2005 4:07 pm Post subject: |
|
|
Last edited by loopy on Wed Aug 20, 2008 10:57 am; edited 1 time in total |
|
| Back to top |
|
|
Great Hierophant
Joined: 23 Nov 2004
Posts: 260
|
| Posted: Wed Sep 28, 2005 7:52 pm Post subject: |
|
|
| While we have a picture of the AV Famicom's guts, can anyone tell me what the Nintendo branded chip does? Also, why do the PCB traces seem to be masked? Is one side of the board used more often than the other side? |
|
| Back to top |
|
|
teaguecl
Joined: 21 Oct 2004
Posts: 162
Location: San Diego
|
| Posted: Wed Sep 28, 2005 10:07 pm Post subject: |
|
|
| Great Hierophant wrote: | | While we have a picture of the AV Famicom's guts, can anyone tell me what the Nintendo branded chip does? Also, why do the PCB traces seem to be masked? Is one side of the board used more often than the other side? |
I'm not sure, but I would guess the Nintendo chip is the CIC. As far as the traces, they are definatley not "masked". This board is much smaller than the original. Notice that there is not much surface space on the board left, since it's almost entirely covered with parts. All the interconnecting traces are done on internal layers of the board. |
|
| Back to top |
|
|
loopy
Joined: 19 Sep 2004
Posts: 193
Location: UT
|
| Posted: Wed Sep 28, 2005 10:19 pm Post subject: |
|
|
Last edited by loopy on Wed Aug 20, 2008 10:57 am; edited 1 time in total |
|
| Back to top |
|
|
Quietust
Joined: 19 Sep 2004
Posts: 1028
|
| Posted: Wed Sep 28, 2005 10:21 pm Post subject: |
|
|
| teaguecl wrote: | | Great Hierophant wrote: | | While we have a picture of the AV Famicom's guts, can anyone tell me what the Nintendo branded chip does? Also, why do the PCB traces seem to be masked? Is one side of the board used more often than the other side? |
I'm not sure, but I would guess the Nintendo chip is the CIC. |
It can't be, for 2 reasons:
1. It's 32 pins! The CIC is only 16 pins.
2. The Famicom never had a lockout chip in the first place.
My guess is that it contains the logic of the two 74368s (for the controllers) and the 74139 (for address decoding). |
|
| Back to top |
|
|
tepples
Joined: 19 Sep 2004
Posts: 4887
Location: USA
|
| Posted: Wed Sep 28, 2005 10:48 pm Post subject: |
|
|
I'm inclined to agree. Here's why:
Above the 2A03 is "U6 CPU". Above the 2C02 is "U5 PPU". Above the mystery chip is "U3JIO" which I took to mean "joystick I/O". |
|
| Back to top |
|
|
Memblers
Site Admin
Joined: 20 Sep 2004
Posts: 1836
Location: Indianapolis
|
|
| Back to top |
|
|
leonk
Joined: 05 Mar 2005
Posts: 64
|
| Posted: Thu Sep 29, 2005 5:48 am Post subject: |
|
|
hmm...
it's difficult to compare the top loader USA to the famicom AV.. the layout is completly different and some of the IC's are also different.
Maybe what we should do is trace pin 22 (video out) all the way to the RF out and compare that to the front loader?
Also, I've noticed that the famicom top loader has a few more electrolitic caps (which the US one does not). The vertical bars I notice on the output reminds me of the "jail bars" one sees when their arcade monitor needs a new cap kit!
Has anyone tried adding the "missing" caps? and if so.. what did you do? |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
