PC Engine RGB jailbars, let us find a working solution

[viletim]

Only extra thing it needs a good quality multi gang (3+) potentiometer to adjust the video level (every PCB is a bit different). I bough a bag of 4 gang pots some time ago for this purpose, but the tolerance wasn't good enough. I'll see if I can get some samples from different suppliers to find something suitable.

viletim, did you manage to find any gang potentiometers with good enough tolerance ? I need one to step down some arcade RGB levels.

I found a supplier that stocks large, six gang pots that should do the task. I'll buy some samples soon to check the tolerance. It shouldn't be hard to build a test jig that can indicate which three gangs of the six are best matched.

[Fudoh]

You mean tap on top ?

yes, sorry. Tap with the tip of your finger - a few times in a row....

[rtw]

I found a supplier that stocks large, six gang pots that should do the task. I'll buy some samples soon to check the tolerance. It shouldn't be hard to build a test jig that can indicate which three gangs of the six are best matched.

Thanks for the info, maybe you will sell them in your shop as well when you have verified the quality ?

[rtw]

yes, sorry. Tap with the tip of your finger - a few times in a row....

Tapping did not make things any better, but I got the video.

https://mega.co.nz/#!IUdzHZrS!sFrTZuKO0 ... YF4KIkJnbo

You are right Fudoh, the top of the screen starts breaking up.

I also noticed that when the CD-ROM drive machinery starts you get a lot more "noise" in the picture.

[speedlolita]

Took a quick pic of Pac-Land running on my Duo R with Broken amplifier and RGB SCART lead.

http://i.imgur.com/o3KjuFS.jpg

Can't say I see any banding still, got this same amplifier in my N64 and will be installing one I assemble myself with the same values in my SNES Mini. Great amp.

[kamiboy]

You're referring to my AV-DRIVER board.

It's a general purpose AV driver amplifier. 4 channels video, 2 channels audio, 1 channel sync. It works well in the PC Engine and an in other applications too. It will be available to buy soon, after I've finished the documentation.

So, is this thing available for sale yet?

[viletim]

So, is this thing available for sale yet?

Not yet. I haven't finished the docs...

Looking at the date - these have been sitting here a while now! I'll try to get everything ready by the end of the month.

[CkRtech]

Not yet. I haven't finished the docs...

Looking at the date - these have been sitting here a while now! I'll try to get everything ready by the end of the month.

Nice! We're excited. Thanks, Tim.

[Fudoh]

not 100% related, but anyway:

I just talked to somebody who used the H/V sync ouputs directly on the Huc6270, since they provided him with much better compatiblity (and quality) compared to the composite video or composite sync output from the extension port.

I've never tried this, but I'm wondering if anybody ever used these two sync signals, ran them through a combiner circuit and compared to the results ?? Would be interested to see if this fixes the compability issues on certain processors (XRGB-3 included).

[RGB32E]

not 100% related, but anyway:

I just talked to somebody who used the H/V sync ouputs directly on the Huc6270, since they provided him with much better compatiblity (and quality) compared to the composite video or composite sync output from the extension port.

I've never tried this, but I'm wondering if anybody ever used these two sync signals, ran them through a combiner circuit and compared to the results ?? Would be interested to see if this fixes the compability issues on certain processors (XRGB-3 included).

Sounds interesting. Was there any mention of a circuit they used? I'm also wondering if something along the lines of a CLPD/FPGA solution (partial Hu6260 replacement for RGB output) could be devised using the data lines going to the Hu6260.

Looks like pins 71 & 72 are the two sync pins.

[Fudoh]

He was using Pins 25 and 26 on a HuC6270 (which PCEs have the 6270 and which have the 6260 you pictured?) without any additional circuit. RGBHV input on a 15khz-capable beamer.

[RGB32E]

He was using Pins 25 and 26 on a HuC6270 (which PCEs have the 6270 and which have the 6260 you pictured?) without any additional circuit. RGBHV input on a 15khz-capable beamer.

The Hu6270 is the CPU and the Hu6260 is the GPU/PPU, so those two are likely connected to each other. I'd be curious to find out if those two signals are routed elsewhere.

http://console5.com/wiki/TurboGrafx_16

EDIT: Perhaps improved audio output might be possible with Tim's AV-DRIVER by connecting it directly to the Hu6280 audio output pins (17, 18, and possibly 20).

[kamiboy]

The audio quality from the PC Engine is perfectly fine as is though.

[ApolloBoy]

The audio quality from the PC Engine is perfectly fine as is though.

The problem though is that if you tap audio from the expansion port, it's too quiet, which is an issue if you're modding a white PCE or a TG-16.

[kamiboy]

I see, in that case it makes sense.

[rtw]

The problem though is that if you tap audio from the expansion port, it's too quiet, which is an issue if you're modding a white PCE or a TG-16.

Audio on the expansion bus is taken directly from pin 17 and 18 of the HuC6280.

[CkRtech]

The problem though is that if you tap audio from the expansion port, it's too quiet, which is an issue if you're modding a white PCE or a TG-16.

Audio on the expansion bus is taken directly from pin 17 and 18 of the HuC6280.

According to the TG16 service manual, the audio signal from the 6280 goes through an amp prior to the expansion bus and RF modulator.

[rtw]

According to the TG16 service manual, the audio signal from the 6280 goes through an amp prior to the expansion bus and RF modulator.

The audio is tapped, converted to MONO. fed into an amp and then fed into the RF circuitry. However the AUDIO-L(1A) and AUDIO-R(1C) go straight from the HuC6280 to the EXT connector.

[CkRtech]

Ahh

OK. So the block diagram is rather generic (and "wrong-ish") as it -
1: Says that "audio" goes to IC106
2: Runs "audio" from the amp to expansion bus and RF modulator

The Parts list -
1: Refers to IC106 as the uPC358 (an op-amp)

The Schematic -
1: Takes Audio Left/Right and outputs mono via IC108 - labelled uPC358.
2: Shows that audio is also taken from the HuCard and mixed together with the mono output.

Did any HuCards actually output audio? Was that ever used?

I think they got their IC106 and IC108 mixed across these sheets. Looks like the service manual needs a revision (or at least the copy I saw online does). Fortunately, it is either one or the other as there is never both an IC106 and IC108.

[leonk]

FYI. Tim was super nice to sell me one of his AV drivers and it's a fine piece of equipment. Very versitile. Love the audio amp for TG16.

Unfortunetly I must report that in my TG16 the exact same faint jail bars I see with my Broken amp are there with Tims. In addition, Tims sync amp only works with composite sync, it doesn't work / amplify / pass thru composite video sync. Broken's amp is RGB only and sync is passed directly unmodified.

[kamiboy]

Well, that is a dissapointment. I had my hopes up for Tim's amp finally ridding me of these vertical bars.

[RGB32E]

Well, that is a dissapointment. I had my hopes up for Tim's amp finally ridding me of these vertical bars.

How bad are they on your setup? What circuit are you currently using?

[kamiboy]

They are not bad, but when they do show up they trigger the old OCD a bit. I can live with it, but I'd like to fix it just for fun as I enjoy modding systems.

Currently I am using the IC amp circuit which is mentioned in that other PC Engine jailbar thread that we had. I have tried the transistor based ones too once, in the past. They were even worse if memory serves me right.

[leonk]

I had more time to play with the AV-driver tonight. Consider this my own personal mini review.

Overall it is the most versitile video amp on the market. It includes:
- 4 channel amp
- sync amp
- audio amp

Video can be amplified or attenuated! It starts at 1.0 and in 0.1 increments, gain can go up to 4.1! Very complex device and I don't blame Tim for taking the time to document it. Here are my observations:

- Tim suggests 1.6 gain for PC Engine but on TG16 I find this too dark. A gain of 2.0 more closely mimics composite video brightness and color saturation.
- the sync amp only works with composite sync. It will not work on composite video
- jail bars are still there. The only way I could significantly reduce them to the point where they are not a distraction is by adding a 22uF 16V cap to pin 41 of the 6260. Adding cap to pin 43 has no effect and 220uF cap yields same results as 22uF
- the audio amp is amazing! It is the main reason I left this amp in my TG16 over the "broken" amp. I punched it to the max and took it down a 1/4 notch. Nice and loud and clean.


Overall a great amp that should be brought out to market sooner than later! Great job as always Tim.

[CkRtech]

Hey leonk. Thanks for sharing this info.

Where did you pull your ground from for the board? I saw on PCEngineFX that using like..pin 53 (can't remember the number) for ground is better for jailbar reduction? That sounds a little placebo, but <shrug>.

[leonk]

I pulled ground from the EXP port.. forget which pin.

[jamesv833]

Hello does anybody happen to know the value of c909 I fried it doing otakus mod

[holaplaneta]

The 7805 is a voltage regulator: http://potentiallabs.com/cart/image/cac ... 00x416.jpg

That image shows how it looks like and the pins for 5v and ground

Hey Artemio, would you mind reuploading the picture? The link is broken and I want to mod my IFU 30 with Tim´s AV Driver and I would like to use this photo for reference.

¡Gracias wey!

[rtw]

The 7805 is a voltage regulator: http://potentiallabs.com/cart/image/cac ... 00x416.jpg

That image shows how it looks like and the pins for 5v and ground

You could google for the device and the pins to use are in the picture I posted but here is the pinout:



Now remember this is from the front of the device so it is the reverse when looking at the soldered points on the PCB

[leonk]

these old threads are like a good friend you haven't seen in a long time.

How far we have progressed in this hobby in the last couple of years.