🇧🇾 Астра (Astra) ZX Spectrum Clone: Part 2 (Power On - NOK) [TCE #0618]
8I was able to create an RGB cable for the РГ1Н-1 type port ... the plug was labelled «РШ2Н-1-17» (I think). Unfortunately the machine doesn't seem to work as powering on gives a garbled screen with some sync issues. It's been a while since I've had to troubleshoot a Speccy. I vaguely think that maybe it's a RAM issue, although an initial check of each DRAM chip seems to be okay.
Manual & schematic can be found here (Russian):
https://zxbyte.ru/astra.htm
Trying with a diagnostics ROM ... or no ROM chips at all ... makes no difference.
00:00 ... Intro
01:50 ... Video cable
08:20 ... Video pinout
09:10 ... Power on - NOK
11:35 ... Motherboard closeup
13:25 ... Channel thanks & outro
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From Part 1:
Let's have a quick look at this Soviet-era Sinclair ZX Spectrum clone from Minsk in the Byelorussian SSR ... it's called Универсальная Телеигровая Приставка Астра, or Universal Television Game Console Astra.
It's an interesting machine as it looks to have less chips than a genuine Speccy but doesn't use a БМК (Basic Matrix Crystal, the Soviet version of a ULA or gate array). It does use some "mini ROMs" (similar to the Сантака 002) ... a pair of КР556РТ4А (KR556RT4A), labelled "К" and "С", which are 1024 bit (256x4) and one socketed К155РЕ3 (K155RE3), labelled "М" which is 256 bit (32x8).
It uses a genuine Zilog Z80 but otherwise has Soviet parts ... notable are the aforementioned "mini-ROMs" and a pair of КС573РФ4Б (KS573RF4B) 64kbit EPROMs (i.e. 2764) that would have the 16KByte Speccy ROM (or some cloned variant).
It also has it's "good" capacitors (the ones with palladium & silver) still intact!
It has an interesting mix of exterior ports as well.
We have the usual 5-pin DINs for cassette (МАГ) and +5VDC power (БП) but we also have some 2x4 РГ1Н-1 (RG1N-1) ports which use a 2.5mm pitch. The Western equivalent is probably the D-sub interfaces like DE9 and DB25.
One is used for the "remote control" (ДУ = дистанционное управление) which is probably a joystick ... this is unusual as usually there would be a 5-pin DIN (they didn't use DE9 in the USSR).
The other is for the RGB video output (ТВ). At first this seems weird as they could've used a 5-pin DIN like most other machines, but this machine doesn't have an internal speaker and thus includes audio with the RGB signal. Fair enough ... other machines of the era used a 7-pin DIN then.
Perhaps these were not available, hence the use of the РГ1Н-1.
Not sure what I'll do - not worried about the joystick port, but the video output ... ? I could replace it with a 6-pin DIN as there looks to be space, or I could try to source the equivalent plug from Ukraine ... let's see.
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