Сборка Пентагон 128к

[andy150677]

zorel, нашел фотки, которые при сборке делал. Там мало что изменилось - только кондеры, которые навесным напаяны, по-человечески припаял, и для второй линейки ОЗУ блокировочных поставил на обратной стороне. В любом случае - не стало ни лучше, ни хуже.
http://i54.fastpic.ru/big/2013/0211/...30da421e2f.jpg
http://i54.fastpic.ru/big/2013/0211/...2ed41250a3.jpg
http://i54.fastpic.ru/big/2013/0211/...6ea8a3f0b8.jpg

[zorel]

zorel, нашел фотки, которые при сборке делал. Там мало что изменилось - только кондеры, которые навесным напаяны, по-человечески припаял, и для второй линейки ОЗУ блокировочных поставил на обратной стороне. В любом случае - не стало ни лучше, ни хуже.
http://i54.fastpic.ru/big/2013/0211/...30da421e2f.jpg
http://i54.fastpic.ru/big/2013/0211/...2ed41250a3.jpg
http://i54.fastpic.ru/big/2013/0211/...6ea8a3f0b8.jpg

сигнал на +5 посажен через кондер.

[andy150677]

сигнал на +5 посажен через кондер.

Оптическая иллюзия
На самом деле это блокировочный кондер, он впаян в шины питания, переходное отверстие посередине не затронуто.

[Shockwav3]

Turned out I had C7 connected to an incorrect via (PCB print is slightly confusing there), which seems to have fixed the random RAM garbage appearing on screen (yay). Sadly the machine still seems to be slightly unstable (crashes in TRDOS after 5-10 seconds and after roughly a minute in 48k basic) and the SYNC still isn't working correctly, but we're getting there

[zorel]

SYNC still isn't working correctly

Need to check the meter DD11, DD12, frequency counter or oscilloscope. And check out the Pentagon on a second TV.

[Shockwav3]

Just as a little follow up: I've built my second Pentagon and it has exactly the same issue
I have pretty much tripple checked everything by now and used the Pentagon with another tv (even tho the tube TV I first used works fine with my Pentagon1024SL) ... I'm starting to get a little frustrated since I don't have access to an oscilloscope/frequency counter.

Could my failing RGB signal come due to me using a 74ls37 (555ЛА12) instead of a "real ttl" 7437 155ЛА12 for D72 ... wikipedia said they "should" be compatible?

[Advertiser]

[solegstar]

Same goes for the quarz Q1, depending on which scheme I use I get values 14Mhz (which I used) or 14.3Mhz

try quartz on 14.3 MHz, with it the vertical sync has to be 50 Hz. if you use quartz on 14 MHz, vertical sync is 48.9 Hz. Probably in it a problem.

[Shockwav3]

Okay, I got my RGB issue sorted out
Silly me used a Scart Female plug to connect a 1:1 scart cable which meant I had to connect RGB_Sync to Pin 19 instead of 20

[Shockwav3]

And another one ...
I've started soldering my second Pentagon, sadly it won't even start. For the ease of debugging I'm not using a ROM. Various decoupling capacitors have been placed on the board already. I'm roughly seeing the bands I should get, but they're randomly changing color between red and blue character wise.
ICs 37, 39, 38, 40, 41, 42 & 46 have been checked already. RAM has been verified as good and the problem remains consistent between 2 different sets I'm using.

A video of the problem can be found here:
http://youtu.be/mipe27poaZY

[Shockwav3]

Good news everyone

The Pentagon is working - it loads programs and plays music
I'm still having 2 minor issues with the video (minor "ghosting" on my LCD TV) and for some reason I can only access drive a: in TRDOS, but for now I'm happy it is working nicely.

short note about decoupling: apart from the RAM chips, I didn't have to decouple any additional chips.


---
EDIT: For some reason I can't find out what's wrong with the "ghosting" which seems to apply to both TVs I'm using. It always looks like some attributes/characters are embosed.
Here's a picture of how it looks like with the "bugs" being highlighted ... sadly the picture isn't every good since my camera sucks.
http://img40.imageshack_.us/img40/63...buteembose.jpg
Scart is connected at a minimal approach: R, G, B & Sync on their corresponding pins + ground and 3V on Pin16, no 75Ohm resistors or transistors (tried that which only seems to make it worse)