Search found 6 matches

by bverstee
Thu Jun 21, 2018 3:03 pm
Forum: SALES
Topic: ZX81CCP
Replies: 104
Views: 79212

Re: ZX81CCP

Yeah, it's so strange. I'm certain I couldn't get anything out of the ZX8-CCB without the transistor mod first.
I have no idea what the difference is causing this.
by bverstee
Thu Jun 21, 2018 11:21 am
Forum: SALES
Topic: ZX81CCP
Replies: 104
Views: 79212

Re: ZX81CCP

Alright. Well. So far for ZX8-CCB -alone-. I added this circuit: https://www.classic-computers.org.nz/blog/2016-01-03-composite-video-for-zx81.htm That boosts voltage levels and inverts picture. Now look at the result - left is output of this very simple transistor circuit, right is with the ZX8-CCB...
by bverstee
Thu Jun 21, 2018 9:39 am
Forum: SALES
Topic: ZX81CCP
Replies: 104
Views: 79212

Re: ZX81CCP

Ok, more studying brought me to the conclusion the supply voltage created by D1 (which outputs about 3.7V) is too high for the LVC1G08 to switch with the video input of the ZX80. I've replaced D1 by some 1N4001's to get to a supply voltage as low as 2.5V, which finally gave me some output. Most prob...
by bverstee
Thu Jun 21, 2018 8:58 am
Forum: SALES
Topic: ZX81CCP
Replies: 104
Views: 79212

Re: ZX81CCP

While measuring I found some strange things. Video input voltage level (average by multimeter) is about 0.9V, so ok I guess. This signal is fed through R1 into IC3, an AND gate. But this AND gate does not output any signal on pin 4. Yes, there is a voltage input on IC3, about 3.7V, the output of D1 ...
by bverstee
Thu Jun 21, 2018 8:12 am
Forum: SALES
Topic: ZX81CCP
Replies: 104
Views: 79212

Re: ZX81CCP

Ok, just tried a ZX80 EU version, get no output as well. What am I doing wrong here? So I connect 5V (legs of 7805 for testing) and the yellow wire to the input of the modulator. I solder an RCA female plug to the ZX8-CCB output, connect it to an LCD TV and measure the voltage as well: 0.0V, no pict...
by bverstee
Wed Jun 20, 2018 11:20 pm
Forum: SALES
Topic: ZX81CCP
Replies: 104
Views: 79212

Re: ZX81CCP

Hey guys,

I have 2 USA versions of the ZX80 here, one from myself and another one from a customer.

I am trying to use the ZX8-CCP module on it, but get no output at all.
Is this module compatible with the USA version of the ZX80?


Ben