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Posted By

marcin
on 2018-10-05
02:45:45

Plus4 another black screen but not always

Hello,
im new user C= Plus4, many years ago I was the owner Atari 800xl so now i miss the 8-bit world and go back this year

I bought occasionally Plus4 with power supply, tape recorder, joystick and some cassette. Expect black screen after reading many post this forum.

Turn on with RF out on Panasonic Viera I see atrefacts and many screen noises on channel 36. Next power off and on = black screen. Next ~100 On and Off with warm up 1-5 min only black screen and one time artefacts. Next day again many times On and Off computer with sometimes turned On more than 5min(warm up capacitors?), and before that I see Commodore Basic screen with many screen noises - snow, vertical lines and all deformed. Off and black screens again. Im remove softly all MOS and put it again. After every On in few minutes all MOSes and RAM is warm, only 8501R1 is hot. My electronical skill are poor. What i can check first, what i can do come back to life my Plus4? Is chance to not dead CPU or TED? Please Help.

Posted By

MIK
on 2018-10-06
05:18:48

Re: Plus4 another black screen but not always

Hard to pin point what the issue might be, however the first thing that comes to mind is your TV and the fact your using RF. In the UK a TV channel known as Channel 5 stared to transmit on the same frequency as old computers and game consoles that used RF. Some of the later TV's refuse to show anything other than the TV channel via RF so what a lot of people do these days is opt for an AV / Composite Video lead as an alternative.

Here is an example: https://www.ebay.co.uk/itm/Commodore-C64-C128-VIC-20-Video-Lead-TV-RCA-A-V-Cable-High-Quality-OFC-Cable/250811214485?

The C64, C128, Vic20, C16 & Plus/4 all use the same Composite lead, they are all wired the same way inside the machines. I would try an AV lead first just in case it's your TV, or try a different screen.

S-Video will give you the best picture for C16/Plus4 but you really need and old school CRT and one that supports S-video, (many don't even though they have the socket) to see it properly! Modern screens are not very good at showing such low resolutions in the way they should be seen, why an old TV is recommended.

Posted By

marcin
on 2018-10-06
08:34:35

Re: Plus4 another black screen but not always

Thanks for Your reply.

I will try with this type AV/Composite Video lead when I get it

If no effect buy an old TV CRT.
Is good idea to get old monitor LCD with TV tuner and composite/AV/S-video input for some future 8-bit machines ?CRT is used a lot of space

I check the voltages on power supply - original Commodore(plug is the same like c64 - round, not square)
5,38V DC and 10,4 AC - are these vaules good?

Posted By

MIK
on 2018-10-07
09:11:11

Re: Plus4 another black screen but not always

Sorry I can't help with the power supply voltage of the Plus/4, UK ones are the cheese block with the square connection. Low volts that are listed on one of my Plus/4 PSU's are 9V~1A & 5V-1.5A.
The only thing I know for sure is that the C16 uses 9V DC, (ZX Spectrum PSU's also work on C16).

Maybe some one else here can help or ask on Lemon64.com forum under the "Other 8-bit Commodore computers" as a good number of people there mess about with both.

As for CRT's from my point of view... If you don't mind sitting in front of the screen like you would a desk top PC then your find 14" CRT's are the "optimum" size for picture quality. Anything above Playstation 1 is best suited to 20" or bigger but anything from Atrai 2600 to Playstation 1 your find 14" is best. The bigger the screen the bigger the scan lines...
While time is running out fast for CRT's as they are becoming fewer and fewer and prices are going up, thankfully 14" CRT's are the most common to find. The last era of CRT's to be made are mostly silver in colour being very late 1990's to early 2000's. Even cheap brands such as Mikomi to Goodmans, Sharp ect will give an excellent picture from this time as they all shared the same tube which I believe was a Phillips tube. If you find a nice one and love it then it's best to grab a spare for a rainy day.

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