Component Out - How easy is it to accomplish?

Thanks for the suggestions Calpis, I will make the corrections suggested and take a recent pic tomorrow so you can see.
Also how do I decouple 5v with the cap? Can you tell me what points to connect?

I made a pic from an emu shot so you can see what kind of distortion I have (other than the bottom + lower parts that are apparent in the pics and are static)



Now the platform on the right moves up and down. If you see I have darkened horizontally the screen across - left and right of the platform -, as thick as the platform itself. Now imagine that darkened area moving with the platform up and down. Is this because of a ground loop? Sadly I don't have an oscilloscope or easy access to one...
So to recap: upper+bottom parts have this static distortion and moving parts on the screen that have big color differences (like the platform vs. solid background) have moving shadow at the screen.

Maybe you can guess a workaround based on the fact that the previous rgb amp that was discussed here worked with great quality? Maybe calculate how much it reduces/enhances the input? I don't really know since I lack the needed knowledge , maybe this suggestion is crap, just thinking...

 

@APE : this cap is connected where? on the 7374 amp? because I already have a 100nf cap connected between vcc+gnd on it...

 

ok here is a quick pic of how I connect the thing:



I have left the 2 NC pins floating, and GND+BYPASS+DISABLE are all connected to GND.

I have tried with 100nf caps for input and decoupling: you can see the mediocre results in the previous posts
I have tried with 150nf caps for input and a 100nf for decoupling: somewhat better results but I had some flashings and shadows
I have tried with 220nf caps for input and a 22mf for decoupling: the best results so far, there is little discoloration in the up+bottom parts of the screen and there is no moving shadows from the platform for example... BUT the colors look a little washed up and there is some faint shadow ripples in the background, gnd problem?

In all situations the pixels are VERY sharp and clear, even if they have the wrong colors but the overall result is nowhere near the old rgb amp, it might have less sharp pixels but the colors are more vibrant and there is no discoloration or shadow effects at all...
IMHO (and my limited knowledge on the matter) it must be a matter of finding the correct values that PCE outputs and adjust the input to the 7374 amp.

I am open to suggestions and corrections , I don't want to give up the 7374 yet for the PCE

edit: if you notice I am not using composite on pin1 but sync , just like the old amp... I just realized this since I did this some time ago to avoid the background lines effect on lcd...

 

The 5V decoupling should be 22-100 uF according to the datasheet, not mF. Each capacitor size + construction corresponds to a different useful frequency range, when it's too far out of range it's not effective at decoupling.

I didn't mean 100 nF OR 22 uF, I meant BOTH. The 22 uF isn't very important, it can be soldered to the adapter, but the 100 nF should be soldered directly to the chip and the leads should be shortened to 1 cm or so.

One thing that the old amplifier has is AC coupling on the output. This might be important to your TV depending on how it's designed. You can add this to the THS amp by putting 220 uF C in series with the RGB outputs (+ towards the amp), then putting the 75 R after. Other than that I don't see what can be "wrong", the old amplifier doesn't really do anything, so all I can think of is that the PCE's signals swing too wide and distort with the THS which tries to amplify them 2x. The way to fix this would be to measure the signal going into the amp, then attenuating it with resistors.

 

thanks for the info (again) I will make corrections/additions tomorrow and see what the result is
I have tried with both an LG lcd and a CRT tv, they both display the same flaws in the image... I hope I get better results tomorrow, the 7374 really produces a sharper image which I like
the amp looks quite horrible atm with all that experimentation, I just was bored making it look nice and having to replace the caps later... I hope it does not get burned or something LOL...

thanks again Calpis!

 

There's something about the threads on this site which never cease to make me feel stupid haha
I get sick of people spouting the "it wortks therefore it's fine" crap when it comes to other things "oh yes my hard disc makes a dreadful clicking noise and everytime my computer boots up it warns me that the drive is throwing out SMART errors like nobody's business but ya know, windows boots up so clearly everything is fine and dandy.
Yet I've been trotting along with the same naievety when it comes to console modifications :/ I wish I understood properly, ignorance isn't bliss, it's sad and boring

 

OK, today I built this little monstrosity :biggrin-new: according to the info given, it's ugly but remember it was for testing...



it works but with a mediocre result... I don't like it and there is still discoloration in the upper+bottom parts of the screen... it's less but it's there.
I am abandoning this project for now because obviously signal measurements are needed and I cannot provide them...

I will now try and install this in my N64 and replace the existing amp , should be way simpler according to mmmonkey's guides...

 

well, at least the N64 amp replacement was a smashing success, I get a less blurry picture now:








also we were discussing the PCE-7374 troubles with gtsamour and he found this schematic that uses different amps but works fine:



and this drawing:



do they give any kind of clue? maybe use electrolytic caps for input/output?

 

Usually a + by capacitor symbol indicates electrolyte caps. Most capacitors are non polarized (can be used either direction) while electrolytes are polarized.

 

The NJM amp does the same thing as the THS, except worse (well, it has sag correction which is nice).

10 uF on the input won't help here, the THS amps have very high input impedance which means they don't need very large input capacitors to get good low-frequency response.

I looked in the THS datasheet, it seems for AC coupled signals you need an external pullup resistor.... That's probably what the issue is. They say to use ~5.36 M resistors for 5 V midpoint biasing, not the easiest value to get... Anyways keep the 100 nF caps. Also since there will be a DC bias on the output, you should really keep the 220 uF output capacitors.

 

Very interesting read this thread. I recently made something similar to the mmmonkey guide. I did however switch the c-sync for composite video as I couldn't get an image at all on certain TVs in my house, although for the two screens it did work for there's not much difference.

Would definitely be interested in using a more effective solution, which would you recommend Calpis? You seem to know your shit.

 

I'd go with the THS, it won't be easy to find a better amp for the price, and with the PCE it's 3x better than necessary for a good picture. Discrete amps and older IC amps can't hold a candle to it really.

 

Just an update, I got a refund from the eBay HK seller I got the 7374 chips from, no questions asked... I just had to send him a pic of them destroyed.
He might be a good seller or not caring for 20$ or simply knows that they might be dodgy parts and not bother more with them...
Since then I got some 7314 from Bad_Ad84 and will give them a shot...

 

Another question, is composite video or composite sync best for sync?

 

I got some of these amps from a legit seller, rather than a dodgy chinese seller. Will test them out at some point and see if I get better results than keropi

 

Using c-sync can help in LCD tv sets, you avoid some jailbar effect... on crt sets it doesn't make a difference AFAIK

@Bad_Ad84 : yeah it will be interesting to see your results, the 7374 seems a VERY good chip , I hope you succeed!

 

Bad_Ad84, let me know how it goes. If you'd like a PC Engine to test it with then let me know too, perhaps.

I've had more success with composite video honestly, but it seems to have more motion blur.

Also on my Ferguson CRT the image switches to 16:9 as per RGB specification (5v being 16:9 on the 8th pin) - how would I bump this so that it sets to 4:3?

 

Let me finish up the stuff I have piled up here already, then we can sort something out.

 

I had exactly the same problem with my Mega Drive RGB cable. Because the Mega Drive only provides 5v I have used a SIM1-0512 to get 12v on SCART pin 8.

 

Awesome, thanks for the post!