MSXmakers support

Страница 1/10
| 2 | 3 | 4 | 5 | 6

By msxmakers

Champion (468)

Аватар пользователя msxmakers

09-01-2022, 11:48

Hello,
My name is Jordi Solís and I am in charge of some tasks at MSXmakers.
I manage the blog, lead almost all the projects, review the instructions, test the components, and prepare the kits.
I reply to the msxmakers email in gmail as well I usually give all the support, which I spend a lot of time on, and they are often repeated replies.
But MSXmakers is not just me, it is a club of friends and in the past several of its members have shown their commitment.
This thread is for anyone to ask questions here and report any issues. In the same way, anyone can respond and if I do, the answer is public.
If you have to request an order or send me personal information, use the email, but if you need support, please use this channel.
If everyone does it, I will get some extra time and the projects in progress can move forward.
Thanks for your understanding.

Для того, чтобы оставить комментарий, необходимо регистрация или !login

By steswart

Supporter (9)

Аватар пользователя steswart

09-01-2022, 20:49

I bought the linkfor 3rca hdmi device listed below from aliexpress(https://es.aliexpress.com/item/4000102209277.html?spm=a2g0s....), but it does not seem to work. If I connect it to my Omega MSX 2+ (just normally with s-video or rca cables) then i am getting a flashing and rolling screen changing colours all the time.
Do you know what this could be? I have tried different monitors and hdmi cables.

By msxmakers

Champion (468)

Аватар пользователя msxmakers

10-01-2022, 02:05

Hi,
I think your problem must be on the s-video wire. I have this converter, it has a wire for s-video and another for RCA composite, there's a button to change between s-video and composite (even audio is common) and there's another button to choose the resolution.
I had a similar problem with the s-video wire and a scart connector and it was the s-video all time.
Another thing to check is the PAL/NTSC Omega configuration, the BIOS I've sent you must be NTSC (if MSX2+) but if PAL/NTSC jumpers are wrong or the linkfor converter is not compatible with (I've tested NTSC).
If possible try connecting the OMEGA without this converter and tell us what's happen.

By msxmakers

Champion (468)

Аватар пользователя msxmakers

19-03-2022, 10:44

Ludovic Avot sent me this question by email:

Quote:

Hi,
I built the Omega and everything went right up to the smoking test 3 (I did the test with the halt-cbios, it was OK). I have the blue screen with the "memory not found" error but if I put the ICs for smoking test 4, I have a 'black' screen with signal and nothing happens. If I do a reset I still have the "memory not found" error...
I checked all the soldering and IC positions, all voltages are OK...
Any advice?

Unfortunately there are many things that can be but my first advice is not to rush to solve it, think about what you do and make sure you don't make things worse by trying crazy. This is your opportunity to learn electronics, that's why we built the Omega.
Something you should check is that no component burns, the hottest is always the VDP and although after a while it is really hot, it should not be so hot as to burn your finger.
It's hard to touch every capacitor and resistor in the circuit, but if nothing catches fire nothing will be damaged by testing.
The next thing I would try is to remove the inserted components one by one (from 0), review them and insert them again. Although it may not seem like it, it is possible that the problem comes from a component with a bent pin that has not been a problem until this step.
If that doesn't change the result, I would try to complete all the components on the board and try again.
The reason is I did not use a complete study to determine the parts to place in each step, simple trial and error, but sometimes using a component from a different manufacturer can ruin the result of my smoking tests.
Although perhaps the best thing you can do is keep track of the signs. Check the electrical schematic and check the signals that reach the RAM chip. Power on the computer as it is, with the chips in smoking test 4, press reset, and simply check that /CS of the RAM chip is "0". I think it should be 0 all the time, but you might have to look at it with an oscilloscope to see if it at least pulses low after a reset.
So check the /RAM0_CS signal, on pin 22 of U7, if there is no pulse, this signal comes from U32, then check its pins 1, 2 and 3 which should be (or pulse) 0 too, etc.
When you find one that does act as it should on the input, check the input and output on that same chip and check that it doesn't have a socket or cold solder problem.
Of course this supposes a reverse analysis of the circuit, knowing and understanding what function each chip fulfills.
If the /RAM0_CS signal pulses 0, the problem may be in the slot or sub-slot register.
Do you have any way to verify that the chips are working? What if the RAM chip is simply bad?
Tell me your progress and I'll have more ideas.
Regards.

By GFX

Supporter (7)

Аватар пользователя GFX

19-03-2022, 17:22

Thanks Jordi,
I did check all the IC legs and removed/placed them again... with no success.
Then I plugged the oscilloscope, here are the results:
U7 RAM : pin 22 stays HIGH even when the Omega is resetted.
I then follow to U2 (74AHCT138N) and 1,2,3 pins stay LOW and 4,5,6 stay HIGH even when reset. (7,9,10,11,12,13,14,15 remain HIGH and 8 LOW)
I then went to U13 and pin 5 goes from HIGH to LOW during reset but pin 15 stays HIGH...
I tried with different SRAM 512ko the chip is ok.
I have the blue screen with ERROR: MEMORY NOT FOUND everytime I switch on the omega now Sad

By msxmakers

Champion (468)

Аватар пользователя msxmakers

20-03-2022, 00:10

It looks like you have a problem with /RAM_SL because pins 5, 6 of U32 (not U2) should not stay high, so /RAM_SL is high for you (so U13 pin 15 should not be high).
check that GAL chip, I had several times problems with the three gals and their sockets.
check this: /RAMSL = SLTB * SLTA * /MREQ * RFSH * FFFF * SBSLTB * /SBSLTA
so, pin 15 should be 0 (active) when pins 8, 9, 4, 5 & 7 are H and pins 3 & 6 are L. This happens at any time?

By GFX

Supporter (7)

Аватар пользователя GFX

20-03-2022, 10:51

Hi Jordi,
after more than 2 hours yesterday night, tracing signals and swapping ICs I figured it out !!
It was these dam... U2 82C55. I had two of them and both were not fully functionnal, I had to stack them on top of each other to make the Omega works. I discovered next that one of my RTC chip was also crappy, but now everything work like a charm ! So glad to have it running now. Running Naked in a Field of Flowers
Thanks a lot Jordi for your support and help !

By msxmakers

Champion (468)

Аватар пользователя msxmakers

20-03-2022, 11:27

Nice!

By GFX

Supporter (7)

Аватар пользователя GFX

20-03-2022, 23:50

A last question, I have a little bit of noise in the image (kind of wavy pattern) I is because of the cheap 5V power supply I'm using?
Do you have any recommendations to remove this noise in the image?
Best

Ludo

By msxmakers

Champion (468)

Аватар пользователя msxmakers

22-03-2022, 12:31

GFX wrote:

I have a little bit of noise in the image & is because of the cheap 5V power supply I'm using?

humm,
I've heard this before, but I don't remember all the solutions posted.
What I did to solve this was to replace the cheap power supply with a higher wattage one (I actually use a PS 6A) and replaced the input capacitors (I mean 100uF on the motherboard) and the output video capacitors ( 220uF) for ones of type LowESR.
Generally speaking, noise comes from a bad power supply and ends up in the output signals, but with less load the noise usually decreases as well.

By msxmakers

Champion (468)

Аватар пользователя msxmakers

22-03-2022, 12:34

Note: 6A because I have connected the Omega's boards, FM and o4Mega extensions, internal floppy drive, amplifier and two speakers, HDMI converter...
For the base equipment I prefered a 3A PS even it should be enough with 1A ones.

Страница 1/10
| 2 | 3 | 4 | 5 | 6