Search found 47 matches

by acsi
Tue Oct 17, 2023 7:59 am
Forum: Hardware
Topic: ZX81+38 Build Help
Replies: 24
Views: 2721

Re: ZX81+38 Build Help

My eyesight isn't what it used to be but it looks like one pin on the 74HCT541 (I think that's the one (It's the chip in the middle next to the resister network) isn't soldered? I'm probably wrong though.
by acsi
Thu Oct 12, 2023 7:50 am
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

Update I tried replacing the transistor Q301 on the tape PCB which was a C1815 with a 2N2222a (its what I had that was equivalent) but that didn't change anything and loading still fails more often than not. I then build an amplifier circuit as described here ( https://www.youtube.com/watch?v=qUIv-A...
by acsi
Fri Oct 06, 2023 7:40 am
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

So one more bridge for the keyboard and one for the edge connector and the machine appears to be up and running again. Bad news is that the tape loading still fails... Good news is that it no longer seems to be doing the same with the Divide+ Changes made so far Z80 replaced, ULA replaced with ULA12...
by acsi
Fri Oct 06, 2023 5:02 am
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

Progress after almost putting it aside for a rainy day. After checking everything again I decided to try replacing TR7 as it's connected to A0 and I now get the correct boot screen. I cannot however get my diag cart to work so will now bell out the edge connector. Yet to also test keyboard input and...
by acsi
Wed Oct 04, 2023 6:56 am
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

So I thought I had it there for a while. Found a faulty IC socket for one of the Ram chips. Desoldered and managed to break another track :oops: Either its due to the age of the PCB or it's my eyes and hands. Soldered in another IC along with the other 7 I had to remove to track it down (Murphy's La...
by acsi
Tue Oct 03, 2023 8:08 am
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

Progress. It seems I did indeed lift or break a track or two. Even with the magnifying glass I couldn't make out the break but it's there somewhere. So I've patched what I have found so far either by testing the connections from the chips I removed and now it seems to want to boot into 48k basic or ...
by acsi
Sun Oct 01, 2023 6:14 am
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

Hi Mark, I've been over my soldering both by eye and with a meter also testing the sockets are good. As my eyesight isn't the best even with my glasses and a magnifying glass I will redo this and try and test the connections between components from the 40058 as well to ensure my soldering is ok and ...
by acsi
Wed Sep 27, 2023 10:00 am
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

So a few more hiccups with me dropping the glass tube from my desoldering iron and smashing it (replacement took a few weeks to arrive) and then accidentally destroying the regulator (Now replaced with a Traco one). I've desoldered the 40058 chip and put in a socket as well as socketing the ram. How...
by acsi
Tue Aug 29, 2023 9:03 pm
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

Well this is turning into a mission and in normal fashion for me it'll be the last chip or thing I change that gets it working. I've ordered a ZXMUX to replace the 40058 chip which I suspect is the culprit and have removed the old one and soldered a socket in place for the ZXMUX however putting the ...
by acsi
Thu Aug 24, 2023 10:08 am
Forum: Hardware
Topic: Spectrum 128 +2 grey loading issue
Replies: 27
Views: 8010

Re: Spectrum 128 +2 grey loading issue

It's an Z70500 issue 3.