It's doing something, and the main ICs are in sockets. Of course it can be fixed! That board uses a linear regulator. Recap it because it is most likely power supply problems. Keep in mind that little board is probably pushing that 5v 1A regulator to its limits. It also has a switching regulator right next to it with 40 year old capacitors. Did you check the power traces with a scope? I don't recall if you have one. Anyway, you can measure the mV AC on the power supply with a meter...
I didn't check it with a scope. But yes I think the next thing I will do is recap and then see what happens, if this works i'll be putting a Traco Power TSR 1-2450 switch mode regulator in, i've read many are replacing the 7805 with this one as it's cooler and more efficient.
Way old video now but heres my 2 cents on this: If you had a blown 7805, then it's highly likely the onboard power converter circuit which produces +12 and -5V from the external 9V power supply is also damaged. This in turn quite likely means the "lower RAM" chips (the chips on the bottom left with 4116 printed on them) are damaged. I wonder if you ever went any further with this!
I havent touched this spectrum since, it's still waiting to be fixed, as I had quite a few other projects I was (and am) doing. thanks for pointing me to the right direction! I will take note and once I get back to repairing this...I do want to own a working spectrum eventually..., I have both this 48k and 128k which both show a corrupted screen at startup.
Probably a touch late now, but power issues are really bad on the 48k. It generates a lot of different power rails inside the machine from the 9v input and the vintage ram is really vulnerable to being damaged if the power rails are supplied or removed in the wrong order (by a failing power rail, for example) It's likely in this case that's exactly what happened. Power was lost, RAM became damaged.
Hi this Spectrum looks to me like its stuck in the initialization ram test so i would be checking the lower 16k ram ic voltages , as youve been told there should be -5v 5v and 12v , there is definitely a ram fault, the spectrum should switch on , turn the border white and paper to black you should see those red dots flash an the screen as the computer does the ram test then it should settle at the Sinclair prompt
+1 to this looking like a lower RAM fault. The 4116 chips are hard to source, but you can get a replacement board at retroleum.co.uk or zx.zigg.net/LRR . Retroleum also sells 4116 if you want to keep it as close to original as possible. However the replacement boards only use the +5V and are more resistant to faulty voltage regulation.
Hi MsMad Lemon. If recap does not work, try replacing the low RAM memory (the 4116 chips). I had a ZX-Spectrum with this problem and after changing the memory chips, everything worked OK. Another thing that might be a problem is the ULA. Try remove it, clean the socket and chip legs with Isopropyl Alcohol and put in place again. This chip is harder to find than the 4116 chips of low memory. Good luck!
Membranes are being manufactured, the connectors are still in production. The membranes come brittle with age. Worth replacing the electrolytic capacitors, when the die, the 4116 memories can eat themselves if the lose the 12v supply.
Hi I just got a +3 spectrum and keyboard is not working. The strange thing is its making the noise when you hold a key down for a while and keep it pressed down. So I think either a good clean check to see if anything is jamming a key down. It doesn't look like there is but yet to open it up.
Great work, this is so interesting... I'm electronics trained but wouldn't have known where to begin with this project. Your retro HiFi videos are brilliant... I've assembled some stuff and had a crack at the subject as well. Thanks for posting.
Haha to be honest I had no idea where to begin once I saw the blocks haha, I knew the regulator was goofed from way back, but that was about it. Thank you Peter! :o)
On the 4116 memory chips, pin 1 should be -5V, pin 8 should be 12V and pin 9 should be 5V (I have just seen on the schematic, can really only remember the commodore schematics :))
Hi Maddie, I don't have anything to contribute, troubleshooting-wise, but I am following along and know that with all the tech support you're getting, you'll have this up and running in no time. :-) Regards, Tom
Upper or Lower RAM Failure, you can easily diagnose which chip is at fault by piggybacking a good chip over the faulty chip, it's just a process of elimination.
U need 240v straight to cpu and ram chip's. Then u get cod , salt and vinigar. Power on leave for 10 minutes ur dinner is served. It maybe a little crunchy to start with and may break your Teath but we'll worth it. It's good to wire 240v to ur tong afterwards.
This is a lower memory problem, the left hand memory chips. They are 4116’s, these chips need -12 volt, +5 volt and -5 volt to function. As they are quite old and hard to find, I’d remove them and replace them with 4164’s. They are pin compatible, only you need to bend pin 1 and snip it off, then bend pin 8 and solder it to pin 9 and snip off the remaining bit of pin 8. That’s all, you could do this on the sockets and keep the chips intact. Should make this Speccy rise like a Phoenix from the ashes 😀. I would also change the regulator with a Traco TSR-1-2450, reduces the energy consumption and produces less heat. As this is an issue 3 or issue 4 Spectrum I would definitely put a heatsink on that ULA chip, as this will prolong the life of that chip.
MsMadLemon no this has nothing to do with keyboard being disconnected, looks like ram chip failure. Check after having speccy running for few minutes if any tam chip is wormer that another... if u find one then it is more likely the one to replace. B careful with motherboard tracks lifting up when you attempt to remove the chip. Use low temp setting and be careful.
Oh my, you even have a spectrum! You definitely need to get an AY chip and there is a sound tracker that is moded to use tape for loading/saving tunes/samples. A lot of really good trackers came from Russia but you will need Beta drive emulator (correct me if I'm wrong about Beta) but a lot of new interfaces that use SD card for storage have this Beta option, most of them also have kempston build in. You can even get a tracker version with Kempstom mouse mod! But make sure that your kempston interface is mouse compatible(some of them allow to use PC mouse or regular Amiga din9 mouse). You can purchase the AY(stereo out with pass through for additional interfaces) and kempston joy/mouse interfaces at: Lotharek.com or combo (both in one interface) at sellmyretro.com (lots of stuff for amiga too there) But having your knowledge about analog tape decks you shouldn't have any problems using just tape deck! Good luck and thanks for great videos!
It's doing something, and the main ICs are in sockets. Of course it can be fixed!
That board uses a linear regulator. Recap it because it is most likely power supply problems. Keep in mind that little board is probably pushing that 5v 1A regulator to its limits. It also has a switching regulator right next to it with 40 year old capacitors.
Did you check the power traces with a scope? I don't recall if you have one. Anyway, you can measure the mV AC on the power supply with a meter...
I didn't check it with a scope. But yes I think the next thing I will do is recap and then see what happens, if this works i'll be putting a Traco Power TSR 1-2450 switch mode regulator in, i've read many are replacing the 7805 with this one as it's cooler and more efficient.
Way old video now but heres my 2 cents on this:
If you had a blown 7805, then it's highly likely the onboard power converter circuit which produces +12 and -5V from the external 9V power supply is also damaged. This in turn quite likely means the "lower RAM" chips (the chips on the bottom left with 4116 printed on them) are damaged.
I wonder if you ever went any further with this!
I havent touched this spectrum since, it's still waiting to be fixed, as I had quite a few other projects I was (and am) doing. thanks for pointing me to the right direction! I will take note and once I get back to repairing this...I do want to own a working spectrum eventually..., I have both this 48k and 128k which both show a corrupted screen at startup.
@@MsMadLemon Transistor TR4 could be blown, that's what happened to one of mine. It took out the 7805, 4116 (RAM) and of course the transistor itself.
Probably a touch late now, but power issues are really bad on the 48k. It generates a lot of different power rails inside the machine from the 9v input and the vintage ram is really vulnerable to being damaged if the power rails are supplied or removed in the wrong order (by a failing power rail, for example)
It's likely in this case that's exactly what happened. Power was lost, RAM became damaged.
Ah, the perils of trying to repair something that someone else has already had a go at...
Hi this Spectrum looks to me like its stuck in the initialization ram test
so i would be checking the lower 16k ram ic voltages , as youve been told there should be -5v 5v and 12v ,
there is definitely a ram fault, the spectrum should switch on , turn the border white and paper to black you should see those red dots flash an the screen as the computer does the ram test then it should settle at the Sinclair prompt
Thanks for the advice and info on this, I will check the voltages when I get back to repairing again!
+1 to this looking like a lower RAM fault. The 4116 chips are hard to source, but you can get a replacement board at retroleum.co.uk or zx.zigg.net/LRR . Retroleum also sells 4116 if you want to keep it as close to original as possible. However the replacement boards only use the +5V and are more resistant to faulty voltage regulation.
Awesome! Why I don't see more of these videos instead of celebrity feeds?
Hi MsMad Lemon. If recap does not work, try replacing the low RAM memory (the 4116 chips). I had a ZX-Spectrum with this problem and after changing the memory chips, everything worked OK. Another thing that might be a problem is the ULA. Try remove it, clean the socket and chip legs with Isopropyl Alcohol and put in place again. This chip is harder to find than the 4116 chips of low memory. Good luck!
Thanks for the guidance Douglas! I appreciate as I'm not sure fully what i'm doing if I get into it...At least now I have a few things to try. :o)
Membranes are being manufactured, the connectors are still in production. The membranes come brittle with age. Worth replacing the electrolytic capacitors, when the die, the 4116 memories can eat themselves if the lose the 12v supply.
Hi I just got a +3 spectrum and keyboard is not working. The strange thing is its making the noise when you hold a key down for a while and keep it pressed down. So I think either a good clean check to see if anything is jamming a key down. It doesn't look like there is but yet to open it up.
Great work, this is so interesting... I'm electronics trained but wouldn't have known where to begin with this project. Your retro HiFi videos are brilliant... I've assembled some stuff and had a crack at the subject as well. Thanks for posting.
Haha to be honest I had no idea where to begin once I saw the blocks haha, I knew the regulator was goofed from way back, but that was about it. Thank you Peter! :o)
Hi. Check the supply rails, there should be a 12V and also a -5V
On the 4116 memory chips, pin 1 should be -5V, pin 8 should be 12V and pin 9 should be 5V (I have just seen on the schematic, can really only remember the commodore schematics :))
Hi Dennis, thank you for the guidance! I appreciate your help, I will test these :o)
Hi Maddie,
I don't have anything to contribute, troubleshooting-wise, but I am following along and know that with all the tech support you're getting, you'll have this up and running in no time. :-)
Regards, Tom
Hi Tom, yes indeed I hope I can get this thing running, thank you for your support! :o)
Upper or Lower RAM Failure, you can easily diagnose which chip is at fault by piggybacking a good chip over the faulty chip, it's just a process of elimination.
Hi! I have one of these 😄 it’s still in its box!
U need 240v straight to cpu and ram chip's. Then u get cod , salt and vinigar. Power on leave for 10 minutes ur dinner is served. It maybe a little crunchy to start with and may break your Teath but we'll worth it. It's good to wire 240v to ur tong afterwards.
Thanks for the advice.... You do it first and show me, then i'll think about it.
@@MsMadLemon I have that's why I recommended it as it works
@@anthonyleedickinson3491 Need proof, show a video of you doing it or it didnt happen :op
@@MsMadLemon it's all ready on
@@anthonyleedickinson3491 link?
Polish solder from Cynel 👍
This is a lower memory problem, the left hand memory chips. They are 4116’s, these chips need -12 volt, +5 volt and -5 volt to function. As they are quite old and hard to find, I’d remove them and replace them with 4164’s. They are pin compatible, only you need to bend pin 1 and snip it off, then bend pin 8 and solder it to pin 9 and snip off the remaining bit of pin 8. That’s all, you could do this on the sockets and keep the chips intact. Should make this Speccy rise like a Phoenix from the ashes 😀. I would also change the regulator with a Traco TSR-1-2450, reduces the energy consumption and produces less heat. As this is an issue 3 or issue 4 Spectrum I would definitely put a heatsink on that ULA chip, as this will prolong the life of that chip.
Buen trabajo👍
Well done on getting it up and running your nearly there.I think one you recap it should solve the problem i hope :)
Yes, I think recapping will surely be the next step!...let's hope! hahah Thanks for the support dude! :o)
The apple 2 does a similar test screen without the keyboard
hmm interesting! Then it could possibly be due to the keyboard not connected/not working
MsMadLemon no this has nothing to do with keyboard being disconnected, looks like ram chip failure. Check after having speccy running for few minutes if any tam chip is wormer that another... if u find one then it is more likely the one to replace. B careful with motherboard tracks lifting up when you attempt to remove the chip. Use low temp setting and be careful.
don't worry for membrane. these are same all of them, worn and weak.
Oh my, you even have a spectrum! You definitely need to get an AY chip and there is a sound tracker that is moded to use tape for loading/saving tunes/samples. A lot of really good trackers came from Russia but you will need Beta drive emulator (correct me if I'm wrong about Beta) but a lot of new interfaces that use SD card for storage have this Beta option, most of them also have kempston build in. You can even get a tracker version with Kempstom mouse mod! But make sure that your kempston interface is mouse compatible(some of them allow to use PC mouse or regular Amiga din9 mouse). You can purchase the AY(stereo out with pass through for additional interfaces) and kempston joy/mouse interfaces at: Lotharek.com or combo (both in one interface) at sellmyretro.com (lots of stuff for amiga too there) But having your knowledge about analog tape decks you shouldn't have any problems using just tape deck! Good luck and thanks for great videos!
The lack of the colour denotes the 12V rail is missing.
Your vids are awesome. Love 'em. Keep it up good woman!
Thank you! :o)