Search found 23 matches

by zx-heinz
Mon May 22, 2017 9:35 pm
Forum: Hardware
Topic: Resurrecting a ZX81 - Step by step help appreciated.
Replies: 26
Views: 6813

Re: Resurrecting a ZX81 - Step by step help appreciated.

Check R6 for the right value with a meter. It should have 2.2kOhm and it is located between the ULA and the CPU for Iss3 boards.
by zx-heinz
Fri Apr 28, 2017 4:19 pm
Forum: Hardware
Topic: Opinion poll - AY channel mixing.
Replies: 24
Views: 5272

Re: Opinion poll - AY channel mixing.

This is the AY-board ("Mr. X") made by Sascha: channel C is fed into channel A and B. AFAIK the 470 Ohm resistors are now 1K: http://forum.tlienhard.com/phpBB3/viewtopic.php?f=2&t=464&p=29208#p29133 Siggi The shown scheme is not due to Sascha but it is a modification of a scheme done by Wilf Rigter...
by zx-heinz
Thu Apr 27, 2017 9:00 pm
Forum: Hardware
Topic: Opinion poll - AY channel mixing.
Replies: 24
Views: 5272

Re: Opinion poll - AY channel mixing.

.