Search found 450 matches

by gozzo
Wed May 05, 2021 4:12 pm
Forum: Hardware
Topic: ULA revision
Replies: 6
Views: 886

Re: ULA revision

dont think so, theres ways of telling what rom you have or if you have the rom fix board, but not ula, as far as i know, generally issue 1 boards will have 2c158 or 2c184 ulas, issue 3s 2c210 , but not necessarily always! you can tell board issue by looking in the expansion slot, if theres a transis...
by gozzo
Sat Feb 13, 2021 1:28 am
Forum: Hardware
Topic: Spectrum 48K Upper Ram Fault
Replies: 22
Views: 2143

Re: Spectrum 48K Upper Ram Fault

easiest replacement for the upper rams is a 4164 or equivalent, noting that it 'may' have to be a 128 cyle refresh type, not 256 as some are.? dunno if 256 cycles types work ok or not?? anyone??? may depend on the ram type link settings ..
by gozzo
Sat Mar 10, 2018 4:23 pm
Forum: Development
Topic: ZX81 ULA-in-a-CPLD
Replies: 236
Views: 82024

Re: ZX81 ULA-in-a-CPLD

whoah!!!!😊😊😊😊😊😊😊
by gozzo
Sat Feb 03, 2018 3:50 pm
Forum: Hardware
Topic: UK700 PSU running at 18.1 volts
Replies: 14
Views: 4791

Re: UK700 PSU running at 18.1 volts

or double up on the bridge diodes, use 2 in series for each quarter?...
by gozzo
Sat Feb 03, 2018 3:49 pm
Forum: Hardware
Topic: UK700 PSU running at 18.1 volts
Replies: 14
Views: 4791

Re: UK700 PSU running at 18.1 volts

you could fit a couple of 1n5401s between the output of the bridge rectifier arrangement and the cap..? that'd drop the output a bit...
by gozzo
Sat Feb 03, 2018 3:40 pm
Forum: Hardware
Topic: zx spectrum in zx81 case
Replies: 63
Views: 26977

Re: zx spectrum in zx81 case

can anyone supply preprogrammed cplds for this zxmax, as i have bought an empty board, can find the other parts easily,.. i do have 3 'used' cplds but as to whether they can be erased and reused i dont know, plus i dont know what software or programmer device would be needed to program them...
by gozzo
Mon Oct 23, 2017 7:26 pm
Forum: Hardware
Topic: UK700 PSU running at 18.1 volts
Replies: 14
Views: 4791

Re: UK700 PSU running at 18.1 volts

and ..what mains voltage is it rated for and what is it running on. if its designed for 220v (but that would normally be a EU700? or something like that?) and being run on 240v , it will be high....maybe has a 220v transformer fitted in a uk/240v case???
by gozzo
Mon Oct 23, 2017 7:24 pm
Forum: Hardware
Topic: UK700 PSU running at 18.1 volts
Replies: 14
Views: 4791

Re: UK700 PSU running at 18.1 volts

hmm, may have shorted turns on the primary winding, does it get warm/hot after a while when on no load? if so it could have. also test voltage with a reasonable load...
by gozzo
Fri Oct 13, 2017 4:09 am
Forum: Hardware
Topic: ZX81 rebuild
Replies: 175
Views: 42784

Re: ZX81 rebuild

these will almost certainly be genuine, very good supplier.. http://www.ebay.co.uk/itm/MPS2369A-MOTO ... 0653829622 the type number 'print' is totally different, seems to be 'etched' ...
by gozzo
Fri Oct 13, 2017 4:04 am
Forum: Hardware
Topic: ZX81 rebuild
Replies: 175
Views: 42784

Re: ZX81 rebuild

and i think that supplier above is where i got some mps2369s from..havent tried them yet..something about the type number printing doesnt look quite right, though..... maybe something else relabelled?!!