VERAULT
Veteran Member
I bought this 48K spectrum at auction a few years ago with the intent of fixing it up for my wife. She grew up with one in Europe so I thought it would be a nice surprise. This is a photo of the board AFTER the modifications I mention below.
ITs an issue 2 board. Using this website as a guide: http://www.breakintoprogram.co.uk/computers/zx-spectrum/hardware I have recapped all the electrolytic caps and replaced all the transistors with the idea that the previous American owner may not have known it was center negative.
I have replaced TR1, TR2,TR3 (which has 4 possible posts on the board although I re-used the same 3), and TR6 which I guess is a ZTX313 and is connected to pins 11 and 30 of IC2 (the Z80) and pin 33 of IC1 (the ULA). I used MPS2369's instead as I read they are compatible for the ZTX313's.
I replaced TR4 which was a ZTX651 with a new ZTX651. I replaced TR5 which was a ZTX213 with a ZTX751 which is supposed to be compatible.
I replaced the 7805 regulator with a new 7805 regulator. Using an ac adapter I modded for center negative the 7805 is getting 10.41V in and 4.98 V out.
I replaced the RF modulator with the Project Speccy composite mod as seen in this photo.
Other than the power, do I need to do anything additional to get video? Does this thing beep when booting properly? I only get distortion on my screen. I am using the same monochrome green Zenith composite bench monitor I use on everything else. I am getting no life on screen I can see anyway. I could really use some help on this.
Mick
ITs an issue 2 board. Using this website as a guide: http://www.breakintoprogram.co.uk/computers/zx-spectrum/hardware I have recapped all the electrolytic caps and replaced all the transistors with the idea that the previous American owner may not have known it was center negative.
I have replaced TR1, TR2,TR3 (which has 4 possible posts on the board although I re-used the same 3), and TR6 which I guess is a ZTX313 and is connected to pins 11 and 30 of IC2 (the Z80) and pin 33 of IC1 (the ULA). I used MPS2369's instead as I read they are compatible for the ZTX313's.
I replaced TR4 which was a ZTX651 with a new ZTX651. I replaced TR5 which was a ZTX213 with a ZTX751 which is supposed to be compatible.
I replaced the 7805 regulator with a new 7805 regulator. Using an ac adapter I modded for center negative the 7805 is getting 10.41V in and 4.98 V out.
I replaced the RF modulator with the Project Speccy composite mod as seen in this photo.
Other than the power, do I need to do anything additional to get video? Does this thing beep when booting properly? I only get distortion on my screen. I am using the same monochrome green Zenith composite bench monitor I use on everything else. I am getting no life on screen I can see anyway. I could really use some help on this.
Mick