Search found 88 matches
- Fri Jan 20, 2023 10:04 pm
- Forum: Hardware
- Topic: Spectrum 128 +2 grey RAM fault
- Replies: 8
- Views: 2331
Re: Spectrum 128 +2 grey RAM fault
Data line 0 is IC32 on the +2 board ...
- Fri Jul 15, 2022 10:22 pm
- Forum: Hardware
- Topic: spectrum 48 iss. 2 screen image not sharp/focused
- Replies: 19
- Views: 3517
Re: spectrum 48 iss. 2 screen image not sharp/focused
The dark screen of the ill speccy looks like a poor signal output. Have you swapped the ULA's ? Any other result with the ULA from the good speccy? I suspect one of the components in the IC 14 area if the ULA swap has no effect.
- Fri Jul 15, 2022 9:19 pm
- Forum: Hardware
- Topic: spectrum 48 iss. 2 screen image not sharp/focused
- Replies: 19
- Views: 3517
Re: spectrum 48 iss. 2 screen image not sharp/focused
IC 3 an IC 4 are 74LS157 (and not 74HC157) types? Is it possible, that X2 is out of range (moving TC2 could sharpen the pic)? But if you touch TC2 it is better to follow the Service-Manual chapter 3.1.4. Look also for the different values for R47, R49 if you use a 5C112 or a 6C001 ULA.
- Tue Jul 12, 2022 10:01 pm
- Forum: Hardware
- Topic: Issue 4B upper ram PCB tracks
- Replies: 17
- Views: 3977
Re: Issue 4B upper ram PCB tracks
First of all, there is no -5V on the UPPER RAMS. Pin 8 is connected to +5V (some schematics available in the WWW are really bad to read or faulty)! I think someone has cut the lines to isolate a chip one by one to find a faulty one or added an expansion board with extension RAM and "switched off" th...
- Sun Jun 12, 2022 2:17 am
- Forum: Hardware
- Topic: spectrum 48 iss. 2 screen image not sharp/focused
- Replies: 19
- Views: 3517
Re: spectrum 48 iss. 2 screen image not sharp/focused
I think it would be good to compare the signal values of the two Iss 2 around the LM1889 to find the cause...
- Sat Jun 11, 2022 2:10 pm
- Forum: Hardware
- Topic: spectrum 48 iss. 2 screen image not sharp/focused
- Replies: 19
- Views: 3517
Re: spectrum 48 iss. 2 screen image not sharp/focused
Only a thought 'cause I had seen some faulty recapped issue 2's: is C65 (the one directly under the modulator) placed in the right direction? Plus must be to pin13 IC14 and negative to TR2. If you look on your pcb and the modulator is on top, plus is to the right and minus to the left. On the other ...
- Fri Mar 18, 2022 11:04 am
- Forum: Hardware
- Topic: Building a ZX Spectrum 3B, Looking for Parts
- Replies: 6
- Views: 3826
Re: Building a ZX Spectrum 3B, Looking for Parts
Here is a link for your ROM question (you could find more with "ZX ROM to EPROM' search in www)
https://spectrumforeveryone.com/technic ... -spectrum/
https://spectrumforeveryone.com/technic ... -spectrum/
- Thu Mar 17, 2022 8:23 pm
- Forum: Hardware
- Topic: Building a ZX Spectrum 3B, Looking for Parts
- Replies: 6
- Views: 3826
- Thu Feb 24, 2022 7:38 pm
- Forum: Hardware
- Topic: Harlequin Rev G: just lines 🙏🏻
- Replies: 2
- Views: 1327
Re: Harlequin Rev G: just lines 🙏🏻
Check all your soldering points - ROM is possible, but the white border indicates that the system is "booting". Also possible is, that an IC isn't inserted correctly ...
- Sun Jan 02, 2022 2:58 pm
- Forum: Hardware
- Topic: Harlequin 48K Rev. G - First Time Power Up
- Replies: 19
- Views: 5342
Re: Harlequin 48K Rev. G - First Time Power Up
I made such a "wired" modification (as I described above) on an 128K Harlequin and all banks where accessible with dip-switches. In the case of an 48K Harlequin it must also be possible to switch with the jumper J12. It will not work with the solution from 1024MAK (only If you make modifications on ...