| Posted By
billdeg
on 2003-09-25
|  I have 4 Plus/4's and they all have the same monitor problem
What kind of luck is that? All 4 of the Plus/4's I own have the same problem. when attached to any of three working monitors I have, or a t.v. set the display looks like a "diagonal snow field" if that makes sense to you. I can make out that the start screen is being attempted but the rolling diagonal pattern is impossible to use. I plan on taking each computer apart and swapping chips until I get one complete and working unit (have done before to make 3 broken c128's into 2 working ones). Just wondering if anyone has had the same problem and found a fix. I have found schematics and will do it the hard way, but maybe you all have some advice to speed up the process....thanks...billdeg@aol.com
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Posted By
Bionic
on 2003-09-26
| Re: I have 4 Plus/4's and they all have the same monitor problem
Most probably your monitor cable is wired the wrong way. Do you see fine diagonal stripes? This
is the color carrier. Maybe you tried to connect composite out to a b/w monitor or some other
weird combination. Please refrain from trail and error repair, it will most probably just destroy something.
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Posted By
Bionic
on 2003-09-26
| Re: I have 4 Plus/4's and they all have the same monitor problem
Btw. are your Plus/4s and monitors NTSC or PAL? Did you check the power supply?
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Posted By
JamesC
on 2003-09-26
| Re: I have 4 Plus/4's and they all have the same monitor problem
I have sent the following message to this person:
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You wrote in the forum at plus4.emucamp.com that you were having trouble with several Plus/4 units.
With your email being aol.com without a country extension, I am presuming that you are in the US or Canada. In this case, I expect that you are using NTSC standard monitors and televisions.
My question is, where did you obtain these Plus/4s? If they were not purchased at retail, but instead from mail-order or Ebay, you may have received PAL units.
A quick test to see if these are the wrong video frequency is to enter POKE 65287,72. This will switch the Plus/4 to NTSC output. To go to PAL output, enter POKE 65287,8. (Both POKEs are entered without a period at the end.)
Downloading programs from the Internet, or using prepackaged software not for your correct video standard, may also muck up your video settings. Once we establish 100% where you are and what version video output your machines have, then we can advise what software can be used.
The whole Plus/4 group is eagerly anticipating your reply on the forum at plus4.emucamp.com, or if you prefer you may email me directly at the address shown in the 'reply to' line.
James
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Hopefully he will reply here, but if he does contact me personally I will attempt to assist.
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Posted By
billdeg
on 2003-09-27
| Re: I have TWO Plus/4's and they both have the same monitor problem...
here is an update.
After re-testing I found that I was inaccurate with my original post. TWO of my Plus/4's have the problem described in the original post to this forum, not 4. The third completely does not work. I do not have a forth plus/4 (I have a C16 instead). sorry about that. I was working from memory and I was mistaken.
regarding two of my plus/4's...
I power on the unit and attach to a 1702 monitor. on the two units I see diagonal lines "snow" that is green and orange. I take it this is the text color of the basic ready prompt screen, but I can't read the text itself as it's tumbling all over the screen in a diagonal pattern.
I am using a 1702 monitor. I am familar with commodore hardware and I am a computer professional so I am being very careful when I plug into the monitor. I use the monitor with c128, c64 (with newer video jack) just fine so I know the monitor is OK.
I have tried the POKE 65287,72 and this had no effect. I do not believe that I have a PAL unit.
The serial number of the first computer is CA1060929
The serial number of the second computer is CA1065388
Both computers read "Plus/4" on them (not +4C).
I have not tried to run any programs yet, I am only in the testing phase. I am willing to sacrifice the third plus/4 to fix the other two, or two to get one working.
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Posted By
JamesC
on 2003-09-27
| Re: I have 4 Plus/4's and they all have the same monitor problem
Bill, a Commodore Plus/4 will come up with a white screen, black letters, and a purple-to-blue screen border, just like the C16. It looks like you have a problem with the video output circuit.
If your C16 works, pull the 7360 or 8360 from its little cage on the motherboard, and put it in one of the Plus/4s (replacing a 7360 or 8360 on the Plus/4 motherboard).
If this doesn't help, try adjusting the potentiometer inside the video cage. There is a blue box with a yellow arrow adjustment; adjust slowly with a jeweler's screwdriver to see if the picture improves.
You might also try hooking the unit up through the RF port on the left side of the machine. A single RCA plug to your video input on the 1702 is sufficient for testing, but be sure the monitor's volume is turned down.  If this works but the video port on the back doesn't, then you're looking at component-level repairs or a bad solder joint.
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Posted By
Crown
on 2003-09-27
| Re: I have 4 Plus/4's and they all have the same monitor problem
The 1702 has both composite and Y/C inputs, did you tried both?
It is enough if you connect just to the Luminance input, as it contains all sync sygnals, both the composite and Luminance output on the cabel can be connected here, you should at least see a back and white screen if this works....
If you have an FCC permission on the label where the serial is then your Plus4s are NTSC, otherwise it is most likely PAL. In that case the POKE is not enough, you'd need to change the clock crystal / (and the ROM) as well to be able to get proper NTSC video sygnal...
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Posted By
JamesC
on 2003-09-27
| Re: I have 4 Plus/4's and they all have the same monitor problem
Crown, I tested my POKE before I submitted it. When an NTSC machine is plugged into an NTSC monitor, performing the PAL poke does indeed allow a PAL program to be seen. Timing is off, yes, but the TED itself can be switched with this simple trick.
I learned this from an Australian fellow who had to modify some US programs for his PAL system down under. 
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Posted By
billdeg
on 2003-09-27
| Re: I have 4 Plus/4's and they all have the same monitor problem
James, I will try what you suggested using the c16 parts, etc. thanks. I will let you know.
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Posted By
billdeg
on 2003-09-28
| Re: I have 4 Plus/4's and they all have the same monitor problem
I decided not to swap the C16 chip into the two bad plus/4's, because the 16's working fine and I don't want to take risks with a working unit. I think that I'll probably sell/trade/shelve the 3 plus/4's I have as "parts units" and buy another that I can confirm works correctly.
If anyone is interested, and they want to trade for something of equal value...One of the three has the original box, books, power chord and is in good shape, the other is in pretty good shape with just a power supply. the third does not work, but it's (apparently) a 1984 olympics "+4C" plus/4 with a special cover (see recent post on this board). I will gladly trade the three for a "junky but working" plus/4, but Ebay seems to have them in the 10-20 dollar range in quantity. It's frustrating because I want to try the games and software for the plus/4, that's the whole reason I got involved with this project to begin with!
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Posted By
SVS
on 2003-09-29
 | Re: I have 4 Plus/4's and they all have the same monitor problem
Billdeg: To avoid risks, try to put the supposed wrong/bad into the working C16, and NOT the contrary. In this way the good-working ICs of your C16 are not risked. And you can know what are the parts of the bad machine, still good.
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