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Hardware articles index > The Jupiter Ace 4000

PLEASE NOTE: There have been a number of Jupiter Aces sold on the auction site eBay as an Ace4000. If you can NOT see the monitor output socket and also a small slide switch under the machine then this is not a North American Ace4000. It could be standard 3K Jupiter Ace in an Ace4000 case or a European Ace4000. Why not send us some images of the pcb so we can authenticate it?
email: postmasterATjupiter-ace.co.uk [replace the AT with @]
A very rare machine indeed! With only 800 reportedly ever made. The reported number of Ace’s sold before Jupiter Cantab closed for business was around 8,000.

The Ace4000 has a different pcb designs, issue 3, similar to the issue 1 and 2 with some extra modification add to the pcb. The specification is the same as issue 1 and 2 Ace's. An extra output socket for the monitor signal. On the bottom of the case there is a small slide switch to select the VHF TV channel 3 or 4. A ROM-Deselect feature signal is available on the edge connector, which means that the standard Aces ROM could be switch out and external ROM's added.

The case is also different, being stronger, injection moulded instead of the yoghurt pot type of case the issue 1 has. The speaker / buzzer can also be seen though the grill, as it’s mounted on the bottom of the pcb. The Ace4000 was destined for the USA market, probably because of the positive review FORTH received in the USA magazine BYTE in 1980's.

European Ace4000? It seems that some European Ace4000's were made how many we do not know. They do not appear to have the channel slider switch on the bottom of the case like the USA version. There seem to be mystery around the Ace4000 was there a European Ace4000 with the features of the USA version, or was the European Ace4000 just a standard 3K Ace in a better case? - If you have any images of a European Ace4000 please send them in!


Front Cover    Spine, and yes thats the correct way its on the manual!    Back Cover
Jupiter Ace4000 Manual Covers, also available as a pdf

Ace4000 pcb.
[Its the only real one we have seen!]

Hover your mouse over the yellow letters for a brief description of the modification.



Some changes to Ace4000 pcb [solder side].

  • A: Different year on pcb 1983.

  • B: Diodes and resistors that make up the ROM-Deselect signal. Also note, that the ROM solder holes on the pcb on the left looks like it can take a 28 pin chip as holes are not used by the ROM, but are part of the ROM-Deselect circuit. In the close-up image you can see the where the pcb tracks have been cut.



  • C: VHF TV Channel 3 & 4 selector slide switch.

  • D: Feed wire from the 47pF Capacitor on the MIC socket to the speaker. The wire goes thought the board. This allows the Ace4000's MIC socket to be connected up to an external amp, and when you save a program to tape you can hear the tape output from the speaker. You can also use a .001uf capacitor which the archive team have done to reproduce this mod on a standard JA 3K.

  • E: Hard to see here, but there is a blue wire that's part of the 60Hz modification for the USA version only. The wire starts here and passes thought the pcb to the 74LS193 [Z9] chip.

  • F: The previously unused edge connector pad the left of the recess is used for the ROM-deselect signal.

  • G: Extra Capacitor added across the 5V line to stabilise the supply.

  • H: The pcb has been drilled out a bit more, looks like someone did not check if the pcb would fit the case!

  • I: Speaker mounted on the bottom of the pcb. The sound from it is louder due to the grill in the case. Also it allowed Jupiter Cantab to increase the size of the heat sink to help stop overheating.
Ace4000 pcb [Component side].

Hover your mouse over the red letters for a brief description of the modification.

Some changes to Ace4000 pcb [Component side].

  • A: Bigger heat sink, by moving the speaker to the solder side of the pcb allows for a slightly bigger heat sink

  • B: The 6.5hz crystal has been moved to make room for the monitor output socket.

  • C: Extra Capacitors to help stabilize the power lines, 5v and 9v.

  • D: RI noise reducing coil.

  • E: The small capacitor soldered to the MIC socket, with the wire passing out to the bottom of the pcb. This allows the Ace4000's MIC socket to be connected up to an external amp, and when you save a program to tape you can hear the tape output from the speaker. You can also use a .001uf capacitor which the archive team have done to reproduce this mod on a standard JA 3K.

  • F: Unclear? But this is part of the 60Hz mod the blue wire pass from the bottom of the pcb to these two diodes which are soldered to the 74LS193 [Z11] chip.

  • G: Unclear? This is part of the video out mod, there seems to be added a transistor, resistors and diodes to the monitor socket.

  • H: Monitor socket mounted into the case, on a standard 3K Ace this is where the crystal can be seen.

  • I: This small black wire is the GND wire soldered to the shielding card, to reduce RI noise, see close up..
    Close up of the GND wire soldered to the shielding card, to reduce RI noise.



  • J: Spot the drilled out bit on the pcb to make the board fit the case.

  • K: Note the rubber keyboard mat has been cut to make it fit the case.

  • Other Notes!
    • The 2114 RAM chips have been solder in to the pcb on all the Aces I have seen they are in IC Sockets.

    • The modulator is also different than the UK version.

    • There is a card/ foil screening to help shield the RI noise to comply with the FCC conditions.

    • ROM version: We cannot confirm if the Ace4000's is different but its now looking as it is the same ROM as the standard 3K Ace. Once we get a Ace4000 ROM image we will confirm it.

    • The speaker volume may be louder, if the transistor mod is included as seen drawn on the schematic below. The transistor amplifies the sound signal a little this modification was first documented in Ace User No 4.


Jupiter Ace4000 3K Schematics



Jupiter Ace4000 3K Schematics


You can download the schematics image here, its a 16 meg bmp zip file.