Search found 15 matches
- Fri Sep 25, 2020 5:52 pm
- Forum: Hardware
- Topic: Searching for PCF1306P
- Replies: 19
- Views: 19524
Re: Searching for PCF1306P
Hello Popopo In the simulator, this charge pump circuit does work well and should have no problem supplying +12V for the colour encoding chip. I think the reason that Sinclair used a DC-DC converter based on an inductor (the ‘coil’) is because the 4116 (or equivalent) ‘lower’ DRAM chips use quite a...
- Fri Sep 25, 2020 5:11 pm
- Forum: Hardware
- Topic: Searching for PCF1306P
- Replies: 19
- Views: 19524
Re: Searching for PCF1306P
Thanks for posting the NE555 based charge-pump circuit for generating the +12V supply. I have a question, I can’t make sense of the circuit around Q1. The circuitry for the base makes sense, it’s monitoring the voltage on the +12V supply. So I presume it’s intended function is to control the NE555 ...
- Thu Sep 24, 2020 10:56 pm
- Forum: Hardware
- Topic: Searching for PCF1306P
- Replies: 19
- Views: 19524
Re: Searching for PCF1306P
Thanks for your reply bola_dor Don’t worry, I’ll work it out eventually... but not today :mrgreen: Mark 20200923_202643.jpg Ok Tr is conected to +5v . I marked in red points in continuity with 5v rail. Cian are GND And yellow and violet the other leads from Tr Tr is marked as 238B 20200923_203614.j...
- Thu Sep 24, 2020 10:53 pm
- Forum: Hardware
- Topic: Searching for PCF1306P
- Replies: 19
- Views: 19524
Re: Searching for PCF1306P
20200920_232124.jpg Just to show how it looks.. This is a CZ Spectrum (argentinian clone) the board is a slightly modified ISSUE 6A, low ram is +5v only.. many of them had the PCF1306P but many others had this ZX8401 board. Perhaps because of lacking of stock... the first argentinian Spectrum CZ200...
- Wed Sep 23, 2020 1:30 am
- Forum: Hardware
- Topic: Searching for PCF1306P
- Replies: 19
- Views: 19524
Re: Searching for PCF1306P
20200920_232124.jpg Just to show how it looks.. This is a CZ Spectrum (argentinian clone) the board is a slightly modified ISSUE 6A, low ram is +5v only.. many of them had the PCF1306P but many others had this ZX8401 board. Perhaps because of lacking of stock... the first argentinian Spectrum CZ200...
- Fri Sep 11, 2020 1:26 am
- Forum: WANTED
- Topic: ZX81 ULA or ULA Replacement
- Replies: 12
- Views: 14655
Re: ZX81 ULA or ULA Replacement
Hello again, Sorry but I couldn't get all information about it. Please to check : http://blog.retroleum.co.uk/electronics-articles/nebula-spectrum-ula-chip-replacement-module/ May it helps you? write to Phill, he will answer you properly. The price is pretty low compared with other solutions. Cheer...
- Sun Aug 30, 2020 11:34 pm
- Forum: WANTED
- Topic: ZX81 ULA or ULA Replacement
- Replies: 12
- Views: 14655
Re: ZX81 ULA or ULA Replacement
Hello again,
Sorry but I couldn't get all information about it.
Please to check : http://blog.retroleum.co.uk/electronics ... nt-module/
May it helps you? write to Phill, he will answer you properly.
The price is pretty low compared with other solutions.
Cheers
Sorry but I couldn't get all information about it.
Please to check : http://blog.retroleum.co.uk/electronics ... nt-module/
May it helps you? write to Phill, he will answer you properly.
The price is pretty low compared with other solutions.
Cheers
- Sun Aug 30, 2020 2:25 pm
- Forum: Hardware
- Topic: Searching for PCF1306P
- Replies: 19
- Views: 19524
Re: Searching for PCF1306P
For the record, the PCF1306P is the upper RAM multiplexor. It is also known under the ZX8401 name and the Amstrad part number 40058. It was introduced in the issue 5 board 48K Spectrum, and also used on the 6A board Spectrum, the 128K Toastrack, and the +2 (grey). See also this topic . Mark That's ...
- Sun Aug 30, 2020 1:52 pm
- Forum: Hardware
- Topic: lost in modifications 4A
- Replies: 11
- Views: 12755
Re: lost in modifications 4A
understood !! , i was referring to the capacity of the original caps which has changed after 36 years. but the condition of this spectrum shows is has been neglected for many years ,so a recap with fresh components will give me a more solid base for measuring the voltages . i hope the components wi...
- Sun Aug 30, 2020 1:44 pm
- Forum: Hardware
- Topic: Searching for PCF1306P
- Replies: 19
- Views: 19524
Re: Searching for PCF1306P
Hi, Few members have contacted to me about the PFC replacement that I have. It was developed based on the work of J.L. we did it on SMD format. I have few board left (9) from the last stock that we produced (about 60+). The few 9 left, I published to sell by ebay site. Here is the link: PCF1306P rep...