Color Classic VGA Woes

JDW

JDW

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Oh, wow! And only $2.79 too... That's really amazing. Thank you for convincing Console5 to add that kit!

I'm still filming my video on the CC Analog Board parts swap. Having to deal with some lifted pads right now. Not torn-off pads, just lifted. Not too surprising in light of how hot those areas got through the years. I'm also pondering the implications that raising the parts off the PCB will have. That better cools them, but it also puts more stress on the pads.

I tried the original gray-colored JB-Weld under one pad today. Takes 24 hours to cure. I'll then see what happens when I solder the component leg to it. If it holds, I'll probably add UV solder mast atop that to further keep it down.

I originally thought about heat-shrink tubing on the legs, especially to prevent shorting, because I am lifting the new components up and off the PCB. I soldered in my DL21 diode replacement that way. And I think that's fine because that part isn't too big and heavy. But the resistors are pretty massive. I then remembered that I have some transparent silicone tubing that I bought to repair the rollers on my Macintosh Portable's trackball. Silicone is pretty heat resistant and thicker than heat-shrink tubing, so I will try to add some of that tonight after work to see if it better supports those big replacement resistors. Ceramic stand-offs would work too, but I can't find those on Amazon and prices on Mouser are pretty crazy. So my Silicone tubing idea is probably best in the end. Again, my thinking here is to prevent a heavy component that sits on its legs from pushing out the pads on the solder side of the PCB over time.
 
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JDW

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jibsaramnim said:
This might be a good place to mention that Luke from Console5 has graciously answered my request of turning your list of diodes/resistors into a ready to buy kit. His kits have been a life saver for folk like me who don't really have easy access to Mouser or the like. Here's the link, in case it is of use to anyone else following along:
https://console5.com/store/macintos...575-630-0349-630-0355-resistor-diode-kit.html

I have received the kit a few weeks ago but have not yet gotten around to opening up my CC again, I'm eagerly awaiting a moment when I can though.
Click to expand...

Could you please measure resistance on the light green resistor shown in the Console5 kit below?

1754372946632.png


I only just now noticed it is 5-band, and unless my eyes are deceiving me, that means it is the wrong value...

BRN-BLK-BRN-GLD-BLU = 10.1Ω, 0.25% tolerance

The correct resistor for RL22 is 100Ω, not 10.1Ω. And it needs to be 5W. In fact, all 3 resistors really need to be 5W. They probably are, but if you find the green resistor is wrong, when you speak to Luke about it, you should re-confirm the wattage. I would also recommend he put the resistance values and the wattage values on his web page for that kit.
 
jibsaramnim

jibsaramnim

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JDW said:
Could you please measure resistance on the light green resistor shown in the Console5 kit below?

View attachment 22642

I only just now noticed it is 5-band, and unless my eyes are deceiving me, that means it is the wrong value...

BRN-BLK-BRN-GLD-BLU = 10.1Ω, 0.25% tolerance

The correct resistor for RL22 is 100Ω, not 10.1Ω. And it needs to be 5W. In fact, all 3 resistors really need to be 5W. They probably are, but if you find the green resistor is wrong, when you speak to Luke about it, you should re-confirm the wattage. I would also recommend he put the resistance values and the wattage values on his web page for that kit.
Click to expand...

Apologies for the belated response. I was able to measure the resistance of the resistor yesterday, and can happily report that it does measure correctly at ~100Ω. I was working on the analog board of my CC I too was scratching my head, as as I couldn't make sense of its value based on its color bands. I even asked my wife if I was perhaps seeing the wrong colors, but she confirmed seeing the same colors.

I do agree it would be helpful for Luke to add a bit more description to the listing, and update their wiki page to list these too. I was referencing your (very helpful, thank you!) images/gifs when working on my board, as I like to have a visual companion when doing these types of things.


I can also happily report that my second Color Classic seems to be working very nicely so far after recapping its analog board and replacing these resistors and diodes with Console5's kit(s). I must admit that the included 1N5344B diode has legs that feel way too thick, so it's not actually possible to install it without increasing the hole sizes a bit. That's a bit of a scary undertaking especially as these components that run super hot already seem to increase the odds of lifted/loose pads.

Still, the CC has been running like a champ for 3-4 hours yesterday and about the same today so far, which I'm very happy about.
 
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JDW

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I'm both pleased and shocked that resistor measures 100Ω. Great you don't need a replacement, but that Blue or Violet 5th band at the end is unusual. It's not unheard of for high precision resistors like 0.1% tolerance ones, but those are expensive and your kit was cheap, so it can't be that. Again, this is why having more detail specs on each part is helpful. Anyone with a good eye for resistor color bands may be misled into thinking that 100Ω resistor is only 10Ω. But again, thanks for confirming it's correct.

It was interesting to hear you couldn't get that one diode installed through the holes in the PCB. Does that mean you drilled them out?

Thick wires are actually a good thing because the heat will flow from the super hot body into the legs and eventually into the pad and copper PCB traces too. All will dissipate that heat on some level. The thinner the legs, the less surface area and less heat dissipation they would offer. Current flow is another benefit of having thicker legs. But obviously, if they are too thick, you have problems with some PCB pads (holes too narrow).
 
jibsaramnim

jibsaramnim

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JDW said:
I'm both pleased and shocked that resistor measures 100Ω. Great you don't need a replacement, but that Blue or Violet 5th band at the end is unusual. It's not unheard of for high precision resistors like 0.1% tolerance ones, but those are expensive and your kit was cheap, so it can't be that. Again, this is why having more detail specs on each part is helpful. Anyone with a good eye for resistor color bands may be misled into thinking that 100Ω resistor is only 10Ω. But again, thanks for confirming it's correct.
Click to expand...

Same here, I'm glad it measured correctly. I've reached out to Luke to ask about this (and to ask if he's able to put detailed specs in his product listing as-well as update the Console5 wiki), I'll follow up with any updates I might get pertaining this!

JDW said:
It was interesting to hear you couldn't get that one diode installed through the holes in the PCB. Does that mean you drilled them out?
Click to expand...

Indeed I did yes. I understand that thicker wires (or, legs) can be helpful, but as they were they just couldn't fit through the board. Some hole expansion did the trick though, but I do feel like this helps push the whole process of replacing these diodes to a slightly higher difficulty level. Not impossible though, as even amateur-hour I was able to get it done I suppose :).
 
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jibsaramnim said:
... the whole process of replacing these diodes to a slightly higher difficulty level.
Click to expand...
We should perhaps say, "with the Console5 diode." Because the parts I purchased from Mouser did not require any drilling, and the legs on that particular diode were pretty meaty too. I guess yours was just meatier still.

I agree though that drilling isn't something most people would want to do, especially when most people probably wouldn't even have the right sized drill bit. On top of that, you run the risk of loosening the pad from the solder side of the board. Glad to hear that didn't happen to you though. I lifted some pads simply by using my FR-301 desoldering gun while removing the stock components! All that heat through the years makes some pads quite weak and there's little that keeps them clinging to the board other than the green UV solder mask on them.
 
jibsaramnim

jibsaramnim

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JDW said:
I only just now noticed it is 5-band, and unless my eyes are deceiving me, that means it is the wrong value...

BRN-BLK-BRN-GLD-BLU = 10.1Ω, 0.25% tolerance

The correct resistor for RL22 is 100Ω, not 10.1Ω. And it needs to be 5W. In fact, all 3 resistors really need to be 5W. They probably are, but if you find the green resistor is wrong, when you speak to Luke about it, you should re-confirm the wattage. I would also recommend he put the resistance values and the wattage values on his web page for that kit.
Click to expand...

Slightly belated response from me on this, apologies. I had heard back from Luke from Console5 but didn't get around to wading through my inbox until today. Luke from Console5 shared this with me:

The 5th band on that resistor is a Yageo series indicator. A little confusing and certainly of limited use outside of the OEM and board assembly house.

1758087852642.png
Click to expand...

The product listing and Wiki page have also been updated to include the relevant information.

This should hopefully help anyone else who down the road might be looking at picking up a set from Console5 for their CC :)
 
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JDW

JDW

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jibsaramnim said:
The product listing and Wiki page have also been updated to include the relevant information.
Click to expand...
You might want to check with Luke to see if either his listing or his choice of DF2 diodes is in error because right now it's the same as the stock diode:

1758262082975.png


In other words... Because the stock DF2 diode normally doesn't burn, replacing it with the same exact low-wattage 0.5W part gets you nothing beneficial in terms of heat dissipation. You would need to use the 5W part mentioned above to gain a benefit.

DF2​

Beefier part: 8.2V Zener 5W (Izt=150mA): 1N5344B-TP

Stock part: 8.2V 0.5W Izt=20mA 1N5237B
 
jibsaramnim

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Follow-up; It was indeed an oopsie in the description, the part being sold is a 1N5344B / 5W diode. Luke has updated the product description already, with the wiki update being imminent too I believe.

Thanks again for catching this! It could have been rather confusing for potential buyers otherwise.
 
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Marconelly

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Recently my Color Classic has started misbehaving again :( Same thing as before - works for some time, then I can hear a high pitched electrical hiss and a few seconds later it shuts down. Lately this has started happening only a few minutes after powering it on, and I've noticed that the hissing sound is coming right from the spot where the power plug is located. This got me thinking that I should try a different power cord to ensure it makes a good contact. Turns out the new cord didn't make a difference, but it got me to tinker around this area, and I discovered something very encouraging: When I apply some pressure onto power switch (push it inwards towards the computer) I could modulate the hissing sound, and with enough pressure make it disappear completely, which made the computer work fine for as long as I was applying the pressure onto the switch. After letting go of the switch, the hiss would return and the computer would shut down.
I'm fairly sure I've already reflowed all the switch and power plug contacts on the board, but I'll double check that tomorrow. Right now my suspicion is that the switch internals need cleaning. Either that, or there's a problem with the connection between the AB and the case - because when applying the pressure onto the switch, I'm also pushing in the AB towards the case. I'll have to experiment some more with this to try and see where it's losing the connection, but it seems the problem is simply something of mechanical nature. If I need to replace this switch, is there a modern drop-in replacement for it?
 
JDW

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Those are large solder pads under the power switch, and to better reflow mine, I used a soldering iron just after heating the area with a hot air station. I used flux to better ensure good solder flow. Very well could be that even if you've desoldered before.

Also note there is one extremely hot component in close proximity to the power switch that stays at about 100°C all the time (while the power switch is set to ON). Not sure if that is making the sound, but it's worth listening too...

1759377613094.png
 
M

Marconelly

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JDW said:
Those are large solder pads under the power switch, and to better reflow mine, I used a soldering iron just after heating the area with a hot air station. I used flux to better ensure good solder flow. Very well could be that even if you've desoldered before.

Also note there is one extremely hot component in close proximity to the power switch that stays at about 100°C all the time (while the power switch is set to ON). Not sure if that is making the sound, but it's worth listening too...
Click to expand...
Right - that component was my prime suspect for a while, since I also noticed how hot it gets, and it sounded like the hiss was coming from around that area. I even found out what the component is, and there is a replacement sold for it (I think it's a PTH451C thermistor). But the thing is, computer would sometimes shut down after even less than a minute of working from a completely cold boot, not enough time for that component to heat up a lot. Also, I don't think my pushing the switch could impact that component. I'll see if I can desolder, disassemble and clean the switch tomorrow. If I can't, I do have an LC575 analog board, so maybe it's time to start poaching components like this switch from it. I believe it also has the black square thermistor component you pointed out.
 
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Marconelly

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I pulled all those black rectangular components around the power plug from LC575 board, and transplanted them onto the CC board that I'm troubleshooting - it changed nothing :( I did however notice that pushing and slightly twisting the analog board does change or eliminate the electrical hiss that precedes the computer shutting itself down.
I have eventually noticed that it seems to be that specifically pushing/poking the flyback onto one side is what causes this to happen. Pushing it from the other side tends to shut the computer off instantly. This is only the case once the hissing starts however. If it happens to be working normally, I can push the flyback all I want and nothing happens. Still this suggests that something inside the flyback is losing contact or otherwise failing intermittently. As a last ditch effort, I'll try desoldering the flyback and soldering it back into place firmly placing it onto the board. But its solder points have already been touched up, so I'm not at all confident this will accomplish anything. I guess that's the end of the road for this board, I'll keep it for parts, convert my other board into VGA and use that.
 
JDW

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Yes. Desolder the flyback. Remove it. Examine it. Put it back. Resolver it. Test. If the flyback is bad, you're dead in the water without a replacement because the LC575 A.B. Flyback cannot be used. @Kay K.M.Mods confirmed that in the past.

Now if pushing on the analog board creates something to happen, it means one of two things:

1. Hairline cracked trace or solder joint somewhere, or.
2. The Motherboard's GROUNDING LOOPS may not be making good contact with the metal shield. That's big. Other people have reported it. Normally pushing on the Analog Board won't also push on the motherboard, but who knows. Motherboard grounding is important. Very important. And the way it achieves that is by the grounding loops on the bottom of the motherboard. The pieces of metal that protrude downward and look like half loops.
 
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Marconelly

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JDW said:
1. Hairline cracked trace or solder joint somewhere, or.
2. The Motherboard's GROUNDING LOOPS may not be making good contact with the metal shield. That's big. Other people have reported it. Normally pushing on the Analog Board won't also push on the motherboard, but who knows. Motherboard grounding is important. Very important. And the way it achieves that is by the grounding loops on the bottom of the motherboard. The pieces of metal that protrude downward and look like half loops.
Click to expand...
I've made very sure that grounding loops on both the AB and main board have good contact with the shielding.
I was thinking about the cracked trace, but the thing is, once the hissing starts, even the light push onto flyback modulates it. I guess it could still be a trace on the board somewhere (although, I've looked it over under magnification many times over now), but it seems more likely that something inside the flyback itself has come loose and pushing it slightly changes it. I could prove it conclusively by transplanting the flyback from the working board, but I'm not sure if I want to start dismantling the working board just to prove this.
 
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