CurtPalme.com Home Theater Forum

[gjaky]

With some luck and with a good intuition I was able to find out where is the scan frequency limitation of the NEC PG 6 family is applied. As a foreword I want to pin down that my intention with this is not operate the PGs at crazy high scanrates, but in some cases the extra scanrate may come handy, for example the Runco DTV-930 owners could expand their machines capability to lock signals past 50kHz, or PG10 upgraders who only had 6PG+, etc.

There are two boards affected in the scanrate limitation:

-On the DEF board IC5001 is altered on the two types: all PG6x00 uses the same 'FVA' type IC, while the PG9x00 have the 'FVB' type on the same place. The limitation of this IC doesn't seem very strict, I only know that the 'FVA' IC puts out an error signal at 90kHz scanrate, but as I've said this same IC was used in all 6PGs, yet this IC allowed the 6PG xtra to operate at 69kHz. So with a scanrate modification of 50 -> 69kHz probably don't require the swap of this IC.

The BIOS EPROM chip IC8209 on all SYSTEM PWB is the other one that limits the scanrate. I haven't seen enough of these to tell is there any sign for identification.
(I have one '2E2 2-2' signed from a PWC-4045 6PG xtra sys board, and a '2E1 2-2' from a PWC-3964 9PG xtra sys board, both said V:3.1 from itself)
So the trick is to swap this IC from 9PG system board to the 6PG system borad. This swap don't affect the saved presets, and this chip can be pulled out of system boards that are known for not syncing (party or at all) as that is a totally different problem from this IC's function.
BUT while the type of the IC is the same for all PG, attention must be payed because I strongly believe these ICs could be only swapped amongst the same class (9PG plain only with another PG plain, PG + only with PG+, and so on).
Hardcore modders could try to erase and rewrite the BIOS chip with a programmer or buy a blank EPROM (that is still available) and write the content in them.

WARNING: The deflection board design of the PGs doesn't allow to safely utilize really high scan frequencies, but with a well done raster setup (leave enough blank space at the edges!) AND WITH added fans to the deflection board they can go as high as 75kHz, BUT NOT MORE THAN THAT, yet this gives much more playroom for the users, it is even enough for 720P-96Hz for those who want to do 3D with a PG.

Achievements: I transformed a 6PG xtra deflection board to a 9PG xtra capable one (borrowed the 'FVB' IC from an old PG plain DEF board) and ran ~3500hrs since then without a hitch. Have erased a 6PG xtra BIOS EPROM and reprogrammed with the content of the 9PG xtra's and it works fine too! I have the content for BIOS V:3.1 for both 6PG xtra and 9PG xtra.
And as a final word: funny enough, but looked inside the content of these BIOSes and the Ver:3.1 BIOS was released at 27/09/1995, so happy birthday Version 3.1!

[CIR Engineering]

Cool work

craigr

[Tinman]

Congratulations!

This was inside knowledge anyway, but we never bothered to discuss it because it wasn't necessary at the time.

There is more, but I won't discuss that either.

[hansilili]

Great Job, thanks for posting this.

Does this mean, I can simply swap the BIOS EPROM chip IC8209 on the systemboard of my 6pg+ modded 10pg with the eprom of the other 10PG and increase scanrate?

rumpeli

[CasetheCorvetteman]

No, you need the file from a 9PG PLUS, and you need to swap out the other item on the DEF board.