Garbage screen on first build

[oO-cozy-Oo]

Hi Anarsoul, Just built the first one of ten and I`m getting a garbage screen, Ive checked that the CPLD is flashed and verified and no shorts on any pins, also cheched res and caps ? also the 24mhz crystal the dot is in the top left corner, what is the minimum parts to build to get it working as i will try and build the other 9 to see whats wrong.

cheers Rich

Also there is a lots of cpld which on is it? have i got the right one? Ive got ending in C5N

[anarsoul]

Does your computer power on when you turn switch 1 to another position? SW1 disables ROM mapping, so if everything is soldered correctly (i.e. good contact, no shorts), it should power on normally and allow you to program EEPROM in-system. Just load ESXMMC.TAP e.g. by using your phone

what is the minimum parts to build to get it working

It will work without shift register (U6) and WiFi module. Pretty much everything else is absolutely necessary.

Also there is a lots of cpld which on is it?

I am using EPM240T100C5N

[oO-cozy-Oo]

Progress when I flick the switch 2 the spectrum boots as normal, then I load the ESXMMC.tap and run the programme the flashing boarder flashes all colours when finished It says OK then I hit enter the esxdos briefly appears not all the items load then returns back to the zx basic screen, and nothing? If I then switch back switch 2 the garbage screen is back, sorry to be a pain. I did flash the eprom with a T48 progammer before soldering and all was flashed ok when verified.

cheers Rich

[anarsoul]

Switch 2 (bottom one) disables kempston joystick. Do you happen to have kempston interface on your spectrum that is active? Harlequin has one, it needs to be disabled

But anyway, if it works with switch 2 toggled, try running divramka (attached). It's divmmc RAM test

divramka.zip

[anarsoul]

BTW, you can hold "space" during reset, it will re-initialize ESXDOS and will stop at the end so you can check the status

[oO-cozy-Oo]

Holding space while turning on the spectrum on the esxdos says ESXDOS.SYS [error]
Ive tried two micro sd cards which are from my ZX Sizif and my Byte Delight Divmmc so I think its the micro sd card reader?
Ill test the divramka now to see if its a RAM issue. Thank you so much for replying as Im a noobie to making SMD soldering :)

cheers Rich

[anarsoul]

Do you have an oscilloscope to check if there is generation on clock generator? It has to be an active one. There are passive crystal oscillators in this form factor.

I'd suggest to double-check CPLD and SD card slot soldering

[oO-cozy-Oo]

Do you have an oscilloscope to check if there is generation on clock generator? It has to be an active one. There are passive crystal oscillators in this form factor.

I'd suggest to double-check CPLD and SD card slot soldering
I did buy passive at first then had to buy active ones.

Ive got a Tomlov micro scope so did double check the pins on the cpld to make sure they are correctly soldered so my next set is to check the sd card slot, Ill do that tomorrow as its late now and thanks for all the replys, Ill poat again with my results!!

cheer Rich

[anarsoul]

So your RAM (and likely ROM) seem to be working which is good. If it stops booting with bottom switch on, it means that it conflicts with Kempston (or anything on port 31) in your computer. You can just keep it disabled for now on divtiesus side and figure it out later.

If ESXDOS.sys fails to load, it's either missing clock (which you can confirm with an oscilloscope) or bad contact on SD card slot. Could also be a short somewhere.

[anarsoul]

Can you make a high-res picture of SD card slot contacts?

[oO-cozy-Oo]

I`ll have to get a new oscilloscope (my one is only 10mhz) I made a new one today and Im getting the same issue :(
Here are some pictures of the sd slot.

Is pin 3 from the left Ground?

Thanks again
Rich

[anarsoul]

I`ll have to get a new oscilloscope (my one is only 10mhz) I made a new one today and Im getting the same issue :(

If you are having the same issue, you definitely need to check the clock. If you are using an original Spectrum, it also might be a faulty M1 line in Z80

Is pin 3 from the left Ground?

Yes, it is

[anarsoul]

BTW, the faulty M1 you can confirm even with slower oscilloscope

[oO-cozy-Oo]

I`ll order a better oscilloscope :( Ive got 3 specrtums and my other divmmc work also used my ZX MAX 128, yes pin 24 M1.

[oO-cozy-Oo]

The active 24mhz smd crystal, with the dot facing top left when soldered,bottom left is earth top two are on the 3v.

[anarsoul]

with the dot facing top left

Pin 1 on the crystal is indicated by a different shape of the pad (it is the only one that has one corner cut, i.e. it's a pentagon, the rest 3 are rectangles). You cannot rely on the markings on the crystal itself, especially if you sourced it off AliExpress

Are you 100% sure that pin 1 is aligned with the dot on the PCB?