ZX Max 128 issues...

[kilauea]

Any help appreciated here, I just bought of these off ebay and it's got issues I think.

1. Keyboard faceplate isn't secure properly so keys are sticking down. I assume this will be a gluedown job? it's in a white repro case but I don't want to open it up to confirm or damage it by doing it.

2. It won't boot with my DivIDE future plugged in. This also fouls the reset switch which is way too close to expansion port imo. I assumed this would be compatible but is anyone else using them together? The divide is fine with my other speccies.

3. It won't load from bluetooth at all. Not even a flicker of the border. I've tried a little firely BT adapter into the ear socket to make sure there is a signal coming from the PC and that loads (Not very reliably but you can see data loading via the borders). Not a flicker doing the same thing via the built-in bluetooth. Are they known to be problematic?

Thinking I need to send this back but be interested in anyone elses experiences.

Cheers.

[oO cozy Oo]

I had mine from ebay from richuk99-8 he replys very quickly(I did see that listing),Mine was the motherboard only and I did remove the reset switch as I was fitting it in a + case and used the reset cable instead, as when I used my Divmmc from Zaxon It pressed the reset and would not work( It now works).It never came with bluetooth as I was going to use the divmmc anyway.If you can desolder try that remove the switch but if its faulty the seller might not have it back.
See this viewtopic.php?t=9408

[kilauea]

So yes mine was off same seller. Still waiting for a reply though.

I can sort the keyboard with a dab of glue - easy fix.
I have removed the reset switch which was causing issues - it now boots with the DivMMC connected, but goes straight to 48k mode and can't get into esxdos. You can see the esxdos screen briefly on startup but clearly isn't loading properly. It does work as a kempston interface still. I've sent a message to tfw8b to see if they have any ideas, I guess it might just not be compatible.
I've removed the bluetooth module, tbh I doubt I'd use it. I have a zxduino and hopefully can get the divmmc working.

So no returning it now as I've butchered it If I can get the divmmc working great but otherwise it works fine via tap loading and puts out a great picture.

[oO cozy Oo]

I would format a new SD card with new files from the http://www.esxdos.org/ and try that, In the past when I did bobs fossils file system I had to reformat as It did`nt load, seen the black screen with the files but nothing when I pressed the button, worked after I did a fresh Install. As for the keyboard try a warm(NOT HOT) hair dryer to make the double side sticky tape warm and press it down again.

[kilauea]

Ah cheers, good tip on the keyboard. I might have to take it off and redo it though as its basically not attached from keys 3 to 8 right down to the bottom row. It's pot luck if a key press registers over most of the keyboard.

I think the divmmc is good - I did format and rebuild the sdcard last week when I upgraded to esxdos 89. it works fine on my 48k+.

Noticed another issue with this now - video wobbling like mad after a power cycle, stays there until randomly sorting itself out or sometimes not doing and just getting worse. Left it for a while just and it blinked out a few times and then came back, still wobbling.

I've been had over here. You live and learn.

[kilauea]

So I've noticed mine has a non-standard regulator at U7 also, which also has a green LED hanging off it. Which I don't particularly like as it serves no useful purpose how its been done just flopping about inside the case. So I'll replace that with the recommended recom parts also. I might re-case it in my 48k+ case too as though it fits in the rubberkey, it is very tight. Particularly around the video output where components have been soldered to the surface with no leg showing - so there is no bend in them. I've found the video singal issues don't seem to be occuring when the case is left open.

The other thing that occured to me is the divmmc behaviour is exactly like those with the missing M1 line off the cpu. I'll grab a spare z80 and see if that cures it. It maybe it came with a duff z80 or was that reset switch enough to misalign the pins and fry m1 with 12v? I'm pretty careful but maybe.

[oO cozy Oo]

The one I had also had a cheap 5v buck Regulator, I replaced it with this one Recom 80000046 R-78E5.0-0.5 DC/DC Converter 7-28V In 5V Out
ebay link https://www.ebay.co.uk/itm/125433478871



and a new RGB Scart Lead for Sega MegaDrive 2 Games Console (quality screened cable) ebay link https://www.ebay.co.uk/itm/202661136166



As I was getting wobbles and noise, but its all working fine now and I`m happy.

Look at this ebay listing on a cheap buck Regulator link https://www.ebay.co.uk/itm/203547304365

Read the description...


"While these buck converters allow for more current through them and produce a lot less heat than the LM7805 they may produce more electrical noise and may not be suitable for Audio or Video applications." ********************************* need I say anymore audio and video lol **********************

[kilauea]

Yup - that's the regulator mine has and has an led wired alongside it too. I can't see that being ideal! I've ordered that recom part and a spare z80, I'll grab a better quality scart lead while I'm at it. I think I'll make a decent machine out of this yet, just isn't the finished article I'd hoped for. Had no response from the seller, seems he only does if you get ebay involved (it was delivered late too and I had to report a non-delivery before he responded then). I can't be bothered, I'll just fix it myself. Could have saved some money but never mind.

Thanks for your help.

[oO cozy Oo]

Let us know how you get on mine turned out nice in the end aswell

[kilauea]

Just to close this out - The Z80 was as I expected faulty. On taking it out the socket the pins were not in very good condition. Looking at the expansion slot its unlikely it was the reset switch that caused this so the seller is likely just using any old z80 he can get his hands on without testing them.

I also changed the voltage converter to the recommended part and now have no video issues.

So I have a nice working 128k Max at last, it just cost me a lot more time and money than I expected. I still need to clean all the flux he left on the board and reflow a few dodgy looking points and then put it in the 48k+ case so it fits properly.

Lesson learned - watch who you buy off!

[oO cozy Oo]

I did put a bad review on ebay I was one of the 5 lol, The zx 128 max is a great board just be carefull who you buy from!!! If you have the skills to make one do so !! Enjoy