Low speaker volume on a repaired issue two speccy
I repaired an issue two speccy which was totally wrecked and missing many parts.
I installed the missing parts (resistors, transistors) and replaced some others according to the modification for issue two pcb (for better cirquit performance) explained in the lil old spectrum guide.
The speaker was missing so i replaced it with another that i removed from an issue 3b board that i have for spare parts. Is the speaker on early issues of spectrum the same with those on later ones (ohms and such)?
On another working issue two that i have, the speaker is bigger in size compared to the ones that you find on later issues.
The thing is that the sound volume is much lower compared to a normal spectrum.
Is the speaker supposed to be different compared to the one i installed OR could there be a larger value resistor somewhere than it should be?
I installed the missing parts (resistors, transistors) and replaced some others according to the modification for issue two pcb (for better cirquit performance) explained in the lil old spectrum guide.
The speaker was missing so i replaced it with another that i removed from an issue 3b board that i have for spare parts. Is the speaker on early issues of spectrum the same with those on later ones (ohms and such)?
On another working issue two that i have, the speaker is bigger in size compared to the ones that you find on later issues.
The thing is that the sound volume is much lower compared to a normal spectrum.
Is the speaker supposed to be different compared to the one i installed OR could there be a larger value resistor somewhere than it should be?
Post edited by gtsamour on
Comments
As far as I recall, the speakers used on later board issues were slightly more powerful, but that may be wrong. The main difference is that the issue 3 and above routed +5V to the loudspeaker instead of the feeble signal that the ULA alone provides. Issue 3+ has a ZTX450 to amplify the ULA output to the +5V (it basically just switches +5V to the speaker whenever it gets a signal from the ULA).
Mr G, I know you know what you're doing, since you've repaired that issue 2 - but for the benifit of those that don't: You can, if you know what you're doing, amplify the sound by using a ZTX450 amp - for details, take a look at the circuit diagram of an issue 3+. My normal disclaimer applies, and to be blunt but honest, if you can't understand the circuit diagram well enough to make the mod, you shouldn't meddle. Which, is a great Pink Floyd album, but I digress :)
So if i get this straight, the speakers used are the same to both early and later issues (although on the early ones, issue 2 and below they are smaller in size), and it is normal for an issue two to make faint sounds, right?
That said, you could always build a little beep booster amp based on an LM386 or similar if you fancy louder sounds.