Search found 1912 matches

by 1024MAK
Mon Apr 23, 2018 8:51 am
Forum: Hardware
Topic: Streaky video
Replies: 4
Views: 63

Re: Streaky video

Can you solder?
Does your TV have a composite video input on a phono / RCA connector?

Mark
by 1024MAK
Mon Apr 23, 2018 12:25 am
Forum: Hardware
Topic: Streaky video
Replies: 4
Views: 63

Re: Streaky video

Does your TV have a fine tuning control? The modulators used in 1980s computers are analogue with a simple oscillator, so they do not produce an output at the exact TV channel frequency that modern LCD TVs expect. So see if using the fine tuning control helps. Also note that because the inside of th...
by 1024MAK
Wed Apr 18, 2018 2:07 pm
Forum: Hardware
Topic: ZX80 3K Ram Pack memory
Replies: 37
Views: 1065

Re: ZX80 3K Ram Pack memory

If you want to compare the board to a schematic, I have found these two different versions: This version is by Phill (Prime) on this forum, ( link to post). This version I found in a link from a post by Markus on forum.tlienhard.com ( link to forum page ) link to zip file . Neither shows any connect...
by 1024MAK
Tue Apr 17, 2018 8:11 pm
Forum: Hardware
Topic: ZX80 3K Ram Pack memory
Replies: 37
Views: 1065

Re: ZX80 3K Ram Pack memory

by 1024MAK
Tue Apr 17, 2018 7:39 pm
Forum: Hardware
Topic: ZX80 3K Ram Pack memory
Replies: 37
Views: 1065

Re: ZX80 3K Ram Pack memory

So looking at that page that Moggy helpfully provided, comparing it to a picture of a 3k RAM pack, and comparing it to the edge-connector details for both the ZX80 and the ZX81... It looks like the 3k RAM pack is linking edge-connector terminal 23B to 0V/GND. This does not matter on a ZX80, as this ...
by 1024MAK
Tue Apr 17, 2018 6:34 pm
Forum: Hardware
Topic: ZX80 3K Ram Pack memory
Replies: 37
Views: 1065

Re: ZX80 3K Ram Pack memory

Ahh, thank you Moggy :D

Mark
by 1024MAK
Tue Apr 17, 2018 2:35 am
Forum: Hardware
Topic: Sinclair 128k ZX Spectrum +2 Grey UK no video after inverted polarity
Replies: 10
Views: 260

Re: Sinclair 128k ZX Spectrum +2 Grey UK no video after inverted polarity

Note, the +12V and -5V are also on the edge-connector. If you have a regulated 12V supply, you could always feed it in via either the edge-connector, or via D20 cathode connection. Of course, check, test and double check the polarity ;) You still need a nominal +9V on the power jack input for the 78...
by 1024MAK
Tue Apr 17, 2018 12:32 am
Forum: Hardware
Topic: ZX80 3K Ram Pack memory
Replies: 37
Views: 1065

Re: ZX80 3K Ram Pack memory

Mark, I ran your code on my 2k TS1000 with the ram pack attached and got the exact same result as you :( , so I am assuming that something in it needs to be changed to work on the TS. Like I've said, I'm dumber'n a box of rocks when it comes to this stuff. Hmm. I have a TS1000 around he somewhere. ...
by 1024MAK
Tue Apr 17, 2018 12:26 am
Forum: Hardware
Topic: Sinclair 128k ZX Spectrum +2 Grey UK no video after inverted polarity
Replies: 10
Views: 260

Re: Sinclair 128k ZX Spectrum +2 Grey UK no video after inverted polarity

TR9 has to be a fast switching power transistor. I'm not sure a BC548 will work (the BC548 and similar transistors are for audio frequency low power amplifier applications). Certainly a BC548 will not last long in the 16k and 48k models (although in these there is a higher load on the +12V supply). ...
by 1024MAK
Mon Apr 16, 2018 7:49 pm
Forum: Hardware
Topic: Sinclair 128k ZX Spectrum +2 Grey UK no video after inverted polarity
Replies: 10
Views: 260

Re: Sinclair 128k ZX Spectrum +2 Grey UK no video after inverted polarity

It's likely that TR8 (ZTX213) and TR9 (ZTX650, or ZTX651 or ZTX653) have been damaged. I suggest replacing TR9 first. If you test across C41 connections (or between D20 cathode (K) and 0V/GND) when the internal DC/DC circuit is working correctly, your meter should show about +12V even if the input s...