Project to install LC575 Analogboard on Color Classic

[KeroXiee74]

Hi folks,

It was last week. An idiotic shipping company has destroyed my LC575.

I bought this at an auction in Japan, but I abandoned it because the main body will be collected if it is guaranteed by the shipping company.

I made a project to change my mind and help the Color Classic owner who is having trouble with analog failure :lol:
And I wanted to enjoy this experiment...The final goal of this project is to display 640X480 VGA.


By the way, I verified the difference between the LC575 and Color Classic analogs:

1, Difference in size. The depth is the same and the slots and back panel are exactly the same.

*The image below is after cutting.



2, ZP1 transformer wiring. The LC575 is close to wiring to run VGA mode if it is Mystic.

3, Stereo Audio output.This is not implemented in color classic only, the pattern is on the board. Two power ICs are mounted and it has a stereo output.

Did not discover any other differences...

The actual works

Cut the extra part. On the left side when viewed from the back, there are some surface mount resistors centered on the POT, and the cut line crosses them.

Just shift the two resistors that are on the cut line upwards, and attach a total of 6 jumper wires after cutting the others so that there is no problem in terms of functionality.

The chassis is cut according to the top on which the board slides. The size of the image fits perfectly in the case. Left and right 1.53 inches (38 mm) are cut.





Power-on and startup

I picked up a jumper miss with a carefully cut pattern. I imagined a failure or destruction, but I connected a 10 inch Color Classic CRT and turned on the power.

It started successfully, but the display area became smaller. It’s about 60%...lol 8-o



After that, I also confirmed that it was connected to a 13-inch CRT of LC575 and output at 100%. This is of course a natural result, but I wanted to see the difference between the ribbon cable that connects analog and logic. There is also a display license line.



I have a book of DoopingMac written By Tak Imai, Who created Mystic and Takky. There is a "10 inch Trinitron CRT designed as an Apple genuine 12 inch CRT compatible single resolution monitor. The horizontal sync frequency is 24.45 kHz and the vertical sync frequency is 60.15 Hz. The horizontal sync frequency is 35.0 in 13 inch mode. kHz, the vertical sync frequency will be 66.67 Hz."
I decided to think a little until I had a perfect idea...Please help if anyone understands the perfect concept of this analog board. And I hope this project can save as many Color Classics as possible from this world ;D

 

[superjer2000]

I got a bit lost at the end as to whether you are wanting us to guess how you solved the issue of using the CC CRT with the LC575 analog board but besides that...

AWESOME PROJECT!!  Cutting down the board like that was a brave and creative move!  

I think you are saying you got everything working at the end?  

 

[KeroXiee74]

superjer2000,

Hi thx for add ur comment, And Yes, It works perfectly for board separation and jumper wiring !
Since the function of LC575 is as it is, the display result was not good due to the difference between 11 inch CRT and 13 inch CRT as described above.

The work went well. The separation and wiring of the board are perfect 
I'm not frustrated or anxious about the 11-inch support, but I'm not in trouble. Since it is a part made by playing with spare parts, I think it's ok to proceed slowly.

Well, it's not for everyone... but you know? lol

BTW, These pix are the back pattern of the ZP1 transformer. In Mystic, we will modify the horizontal parallel voltage from 60V to 84V by disconnecting 8 pin and bridging to 10 pin. I don't know if this area will be the key this time, but the LC575 has a different pattern from CC so that it can be written in VGA as genuine. The board from which some of the capacitors are removed is CC, and the one with a stronger green color is LC575.

 

[KeroXiee74]

Finaly, All areas are displayed!

I replaced the two blue boost circuits in the image.View attachment lcvscc.jpg

Since it is a little wider, I used the open slot to attach it at a slight angle and jumpered the legs.



And exchange of FBT (flyback transformer).

CC is 157-0146, And LC575 is 157-0149. 

The 157-0146 is not in perfect condition, it makes a low frequency sound when I turn on the power, and it may be disturbed at the moment of switching screens (when the software fullscreen mode).


This FBT is CORONA OK...



The LC575 analog now has 100% display area. However, the deviation of the horizontal axis of RGB is large, and it probably exceeds the adjustment range of the yoke plate.



It will continue!

 

[KeroXiee74]

Just finished it so I will report it...

The PCB behind the CRT was also ported for convenience reasons. But if you want to do the same thing as mine, it's not necessary.
The ground wire is fixed at two places for the LC575 and one place for the CC, but this can be done by cutting one line.



Since the CRT red convergence did not match, I adjusted the yoke plate ring located at the base of the CRT, but it came to output perfectly
The sound output line hasn't been wired yet, but the LC575 is nicely stereo.

 

[KeroXiee74]

I posted the test result and the modification method on my blog.The data maybe incomplete, but if you are interested please check it out.

 

[cheesestraws]

This thread has been really interesting.  Thankyou!

 

[KeroXiee74]

This thread has been really interesting.  Thankyou!

Hi cheesestraws, Thank you for having interest! 
I recently noticed that the LC575 and CC have slightly different capacitors, resistors, and rectification.

Since I am only posting what I tried, I would like to try if there is a difference in interpretation...

 

[techknight]

the convergence could have been brought back into alignment much easier by adjusting the H-STAT control on the CRT Neck PCB. 

 

[KeroXiee74]

the convergence could have been brought back into alignment much easier by adjusting the H-STAT control on the CRT Neck PCB. 

I delayed to reply, I was not able to see this site for about 2 days because it was not displayed due to a server error and I could not log out also.
I forgot about this modification for a while, but I will try to adjust it. I'll let you know if I can adjust it well. Thank you as always, You really know and have high skills.

 

[KeroXiee74]

I delayed to reply, I was not able to see this site for about 2 days because it was not displayed due to a server error and I could not log out also.
I forgot about this modification for a while, but I will try to adjust it. I'll let you know if I can adjust it well. Thank you as always, You really know and have high skills.

I replied without reading it carefully, but what you are talking about is adjustment in York.
And in the case of my CRT, the convergence went awry, so I couldn't adjust the yoke unless I turned it about 180 degrees.

You can see that the convergence is out of order in the previous images...Convergence is now adjusted.
I was mistaken for the variable width range. But thx for advice!

 

[techknight]

I replied without reading it carefully, but what you are talking about is adjustment in York.
 

I dont know what a York is, but the adjustment I was speaking about is physically on the PCB that plugs into the back of the CRT, known as the CRT neck board. this control is called H-STAT, or otherwise known as Horizontal Static Convergence. it adjusts the potential to ground one of the grids in the CRT which affects horizontal convergence alignment. When I saw one of your pictures after you put the new board in, I knew right away that adjustment needed tweaked. 

 

[KeroXiee74]

That's right, I didn't do much fine adjusting at this post images. Although it does not fit a little in the lower left, I think it's better now.



The part surrounded by red is the yoke plate.

 

[techknight]

Yea those are the convergence and centering rings. Anyways, here:

 

[KeroXiee74]

Yea those are the convergence and centering rings. Anyways, here:

View attachment 35366

Thanks for the details. When I uploaded last images, it went high and I uploaded it without worrying about the details. 

However, this made the yoke adjustment once again, and the N/S and E/W adjustments made it even better. The E/W amplifier with the rightmost cylindrical coil wound has little effect, so I haven't played around with it so far. thanks for tell me.

BTW,  If you have time, please read my blog is a link above. I have been back in this world for the first time in 20 years. After all it is a fun world...