Re: Trying to fix my ZxSpectrum+
Posted: Sun Jun 09, 2019 4:48 pm
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Trying to fix my ZxSpectrum+
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Re: Trying to fix my ZxSpectrum+
Posted: Mon Jun 10, 2019 8:36 am
Ok, on the next weeks i'll buy some new equipment to repair this damage. I will keep you informed on how it is proceeding. For now thanks to all!
Re: Trying to fix my ZxSpectrum+
Posted: Mon Jun 17, 2019 11:24 pm
Hi guys, a little update. With a software I designed the lower ram pcb scheme to be sure not to make mistakes later when I try to restore the tracks. Did I do everything right? Thanks in advance for every reply.
Re: Trying to fix my ZxSpectrum+
Posted: Mon Jul 01, 2019 4:28 pm
Hey guys, it's been a bit that I didn't update my post. Here some news:
I put all the 7 sockets!!!!! And I'm very proud of me guys!!! Now I've a doubt, I dunno where to solder this pin:
it's near the blu capacitor..
I put all the 7 sockets!!!!! And I'm very proud of me guys!!! Now I've a doubt, I dunno where to solder this pin:
it's near the blu capacitor..Re: Trying to fix my ZxSpectrum+
Posted: Mon Jul 01, 2019 7:16 pm
Well while I'm sorry I can't help you much here, as the person that sent you here from another social media site (shhhh!), I'm impressed with the effort you are persisting with to get it fixed.
Re: Trying to fix my ZxSpectrum+
Posted: Mon Jul 01, 2019 8:12 pm
I think it should be connected to the pin 14 of IC7, but i'm waiting some confirm! 
Re: Trying to fix my ZxSpectrum+
Posted: Mon Jul 01, 2019 8:15 pm
I only have a picture of a populated Issue 6A board, but it’s fairly high resolution. The trace form that via goes up and is likely connected to the via next to Pin 3 under the socket. It’s best to use the schematic and a tester in continuity mode and determine the exact routing by process of elimination.
Still, I hope this picture will help you:
Still, I hope this picture will help you:
Re: Trying to fix my ZxSpectrum+
Posted: Mon Jul 01, 2019 10:11 pm
Re: Trying to fix my ZxSpectrum+
Posted: Mon Jul 01, 2019 10:42 pm
yes, now next step will be buying rams and ZTXs
Re: Trying to fix my ZxSpectrum+
Posted: Tue Jul 09, 2019 10:43 am
Time for some updates, 751 and 651 are in place!
Can i do some tests now? (I still don't have ram)
Can i do some tests now? (I still don't have ram)
Re: Trying to fix my ZxSpectrum+
Posted: Tue Jul 09, 2019 11:06 am
With multimeter in continuity mode i got:
ZTX 651 values:
670, 671, 1, 1
ZTX 751 values:
670, 668, 1497, 1
ZTX 651 values:
670, 671, 1, 1
ZTX 751 values:
670, 668, 1497, 1
Re: Trying to fix my ZxSpectrum+
Posted: Tue Jul 09, 2019 11:27 am
I power on without ram for some seconds and the screen is bit better then before. THERE IS STILL LIFE! 
Now with new ZTX 651 and 7651 (without new RAMS)
After some seconds I pressed the reset button and this is result:
https://imgur.com/a/Se0bVKu
this was before:
https://imgur.com/raae8HW
Now with new ZTX 651 and 7651 (without new RAMS)
After some seconds I pressed the reset button and this is result:
https://imgur.com/a/Se0bVKu
this was before:
https://imgur.com/raae8HW
Re: Trying to fix my ZxSpectrum+
Posted: Tue Jul 09, 2019 11:38 am
Looks like the CPU can fetch and execute the first few instructions, including a jump, from the ROM, which is great news.
Re: Trying to fix my ZxSpectrum+
Posted: Tue Jul 09, 2019 11:41 am
Wow! I'm really, really, really happy today! Next step will be RAM!Ast A. Moore wrote: ↑Tue Jul 09, 2019 11:38 am Looks like the CPU can fetch and execute the first few instructions, including a jump, from the ROM, which is great news.
Re: Trying to fix my ZxSpectrum+
Posted: Tue Jul 09, 2019 3:57 pm
Sure!
Test the voltages on pins 1,8 and 9 in the position where IC6 was (or any other of the 4116 or equivalent DRAM chip positions). With the negative probe to 0V/GND (e.g. the case of the modulator or the heatsink).
Expected voltages:
PIN 1: between -4V and -5.5V
PIN 8: between 10.8V and 13.2V
PIN 9: between 4.75V and 5.25V
If all these are good, then the next stage is to sort out the ‘lower’ DRAM chips.
Mark
Re: Trying to fix my ZxSpectrum+
Posted: Tue Jul 09, 2019 7:28 pm
pin 1: -5,21v1024MAK wrote: ↑Tue Jul 09, 2019 3:57 pmSure!
Test the voltages on pins 1,8 and 9 in the position where IC6 was (or any other of the 4116 or equivalent DRAM chip positions). With the negative probe to 0V/GND (e.g. the case of the modulator or the heatsink).
Expected voltages:
PIN 1: between -4V and -5.5V
PIN 8: between 10.8V and 13.2V
PIN 9: between 4.75V and 5.25V
If all these are good, then the next stage is to sort out the ‘lower’ DRAM chips.
Mark
pni 8: 12,38v
pin 9: 4,98v
yesssssssss!
Re: Trying to fix my ZxSpectrum+
Posted: Wed Jul 10, 2019 7:09 pm
Keep on walking! 
-If it’s not problem for you, please use Postimage to upload your photos. It is easier as Postimage button is pinned on “reply” mode, but also is way better and safer for you photos to stay online for long time.-
-If it’s not problem for you, please use Postimage to upload your photos. It is easier as Postimage button is pinned on “reply” mode, but also is way better and safer for you photos to stay online for long time.-
Re: Trying to fix my ZxSpectrum+
Posted: Thu Jul 18, 2019 10:14 am
I just noticed that retroleum website has lower ram module out of stock... damn!
Re: Trying to fix my ZxSpectrum+
Posted: Thu Jul 18, 2019 11:41 am
See here for another source of Lower RAM modules 
I have bought from here before and got good service
Mark
I have bought from here before and got good service
Mark
Re: Trying to fix my ZxSpectrum+
Posted: Sat Jul 20, 2019 9:44 am
I sent an email to the guy of retroleum and he re-stock the item! I just bought 1 lower ram! Let's wait for it!
Re: Trying to fix my ZxSpectrum+
Posted: Tue Aug 06, 2019 1:11 pm
Ram arrived! Check pictures. There is still issue. 
I uploaded also a video, I pressed reset button after a bit.
http://imgur.com/a/0UGyyEQ
As a test, i checked all voltage on upper Ram module on pin 8 and i have all 4.98V.
I uploaded also a video, I pressed reset button after a bit.
http://imgur.com/a/0UGyyEQ
As a test, i checked all voltage on upper Ram module on pin 8 and i have all 4.98V.
Re: Trying to fix my ZxSpectrum+
Posted: Wed Aug 07, 2019 7:26 pm
I double checked the wires I soldered for Lower ram traces and I discovered a wire not connected!
I download OTLA software and try to load some .tap:
I download OTLA software and try to load some .tap:
Re: Trying to fix my ZxSpectrum+
Posted: Wed Aug 07, 2019 7:35 pm
Hurrah! Really happy to see this mate, I applaud your perseverance.
Also big thanks to everyone who helped Hyuma, I knew I could rely on you when they first enquired about their problems on another (inferior) website, and I suggested a better place to ask!
*sheds small tear and salutes
Re: Trying to fix my ZxSpectrum+
Posted: Wed Aug 07, 2019 7:39 pm
I've noticed that with OTLA loading games some are working, some others not, dunno why... and not all keys are responding when i press... maybe the keyboard need some clearing or some other to check?
Re: Trying to fix my ZxSpectrum+
Posted: Wed Aug 07, 2019 7:48 pm
Thank you so much, friend!DouglasReynholm wrote: ↑Wed Aug 07, 2019 7:35 pmHurrah! Really happy to see this mate, I applaud your perseverance.
Also big thanks to everyone who helped Hyuma, I knew I could rely on you when they first enquired about their problems on another (inferior) website, and I suggested a better place to ask!
*sheds small tear and salutes
