Sinclair ZX80 / ZX81 / Z88 Forums

Good news, see picture

It's working without that I had to replace one part...

I do not exactly understand why but it's working. Ram test is running in a loop since about 2 hours now.. No more graphics corruption or crash... ALl good.

What I did, I refresh all solder point from all memories but it still didn't work. It did'nt help.

I decided to remove all ram from the board and I soldered 16 sockets.

Then, I simply put the ram in socket but I reverted the top set ram with bottom set one. I mean I reverted the 2 lines auf ram.

Strangely, it's working perfectly. I can imagine that one or more ram are not 100% in the specification and when they are on a more sensibel position, they are creating troubles....

All together I put IC5, 15,16 on socket. Replace Socket from Rom and CPU. Put the ram on Socket and replace the PAL by the new GAL. And also reverted the 3X 2N3094s.

Now the spectrum deserve a full recap Is there any other hack/fix interesting to do on the 2+ grey ?

Thanks a lot for the help and all the very good explainations.

Another problem...

The Audio quality is realy poor... I have to set the TV volume almsot at the max to hear little bit of music. And I think due to the fact that the volume is at it max, there is lot of noise.
In R-typ for exemple, when shooting and so, sound are OK but also with lot of noise....
When playing intro music from a game or background music, I have to put the volume at max if I want to hear something. Anfd here also very noisy....

I am using a RGB cable whith a jack for the Audio.

EDIT : I just tried connecting the 2+ through RF cable to the TV... Of course quality picture is very poor but the sound seems to be normal.
EDIT 2 : Found one solution in forum for the strange noise... Disconnect the tape recorder... I found the thread with all related fix for the 2+ Grey. I have to check and understand what to do to solve this and the volume difference between the beep and music.... Also, improve RGB by removing a caps....
Still some things to fix on the baby

Well done on the repair

There is a whole thread on the correction of the hardware errors over on WoS forums. Is that the thread you are referring to?

Mark

Yes it is.

Very interesting thread.

The capacitor that has to be removed for better RGB was not present. This was already done... I understand now why I had from the start a good clear image on my LCD TV

Just waiting for some resistors to correct the sounds level and parts to recap.

After that, I will see if I need to add the relay to the tape recorder or not....

Are there disadvantages to use a traco instread the 7805 ?

Thanks

gseb wrote: ↑Fri Jun 12, 2020 10:46 pm Are there disadvantages to use a traco instread the 7805 ?

Yeah, it will no longer keep your hands warm during colder weather

Your power company will make less money from you

The only technical potential downside, is because less power is being used from the mains PSU, the output voltage of the mains PSU will be a bit higher. Not a problem for the Traco Power / Recom or other DC-DC converter that you fit. But if using an interface, if it has a 7805, it will run a little bit warmer.

Mark

Some news on my +2 grey.....

I replaced all the capacitors included the one from the tape recorder.
Replace some resistors with other one with other value to have better sound cohesion.
Replace the old regulator with a traco.

Also put a wire to join 2 GND surface on the tape recorder PCB, I 've seen this somewhere on internet and it solved the noise I had when the tape recorder was connected to the spectrum board. Maybe the caps replacment helped also, I did both at the same time.

All working perfectly ! Happy

Just when loading a tape, the mecanism is noisy... Not by rewind or forwarding the tape, just by playing.... But it loaded almost all tapes I gave it....

Thanks very much for the help... Now working on the ZX81 extension....

I have a +2a that has a noisy tape player when playing. Its pretty quiet when fast forwarding and rewinding. I wonder if they are just a bit noisy?