Color Classic Speaker Issue

[MrFrog]

Hello, I recently got a stock color classic, it was in working condition, I recapped the analog board and logic board and everything still worked. I followed this forum to replace some resistors that get hot. I replaced RL62, DL22/DL22, RL22, and RF11. When I replaced DF2 with a 5W (Izt=150mA): 1N5344B-TP LINK I ran into an issue with the screen and it was displaying in the bottom and the top of the image in the middle of the CRT on top of each other, removing that resistor and putting the old one back fixed the screen issue.
This is what it looked like with the replaced resistor in shown below:

At some point during the replacing the resistors, the CC’s speaker started to act up, they start up normal, you hear the boot up sound but during the start up like 30 seconds or so in, the speaker starts playing this weird static noise but normal sounds work like turning the volume up and down those come out clear through the static noise. And to add to this, when I go through the top menu the static noises react to it, so I’m assuming maybe something is leaking voltages to the speakers? I replaced the old resistors and checked my solders with a multimeter but the issue still stands.
if anyone is able to point me in the right direction of what this could be?
Here is the video of the issue.

Demo of the noise when I go through the top menu:

 

[MrFrog]

Picture of the analog board.

 

[lfletche]

Keen to watch this one and see if anyone knows what causes this as I have seen it as well on a recapped CC in the past. Although in my case the noise wasn't quite as pronounced as what you are seeing there.

 

[Kai Robinson]

Ah - remember, the ground shield on these models also acts as a ground between different points on the logic board - IIRC Adrians Digital Basement also encountered the same issue as this, make sure the contact between the board and the ground shield is good.

 

[68Krescue]

Double check the repairs on back of the AB near RF16, and TP39. From the pic, it looks like there are bridged traces.

 

[JDW]

@YMK
I'm rather embarrassed to say that even though I bought all the components for the swap, I've actually still not made time to do it yet! That's something I plan to do a video on, but it's not done yet. However, since you have done the component swap, did you experience any noise increase through the speaker like show in the OP's video?

He also is saying the component swap impacted the display too.

@MrFrog
In your OP, you started talking about a diode but then spoke about it like it was a resistor. You said this:

When I replaced DF2 with a 5W (Izt=150mA): 1N5344B-TP I ran into an issue with the screen and it was displaying in the bottom and the top of the image in the middle of the CRT on top of each other, removing that resistor and putting the old one back fixed the screen issue.

 

[MrFrog]

@YMK
I'm rather embarrassed to say that even though I bought all the components for the swap, I've actually still not made time to do it yet! That's something I plan to do a video on, but it's not done yet. However, since you have done the component swap, did you experience any noise increase through the speaker like show in the OP's video?

He also is saying the component swap impacted the display too.

@MrFrog
In your OP, you started talking about a diode but then spoke about it like it was a resistor. You said this:

Yea sorry, I meant to say diode.

 

[MrFrog]

Ah - remember, the ground shield on these models also acts as a ground between different points on the logic board - IIRC Adrians Digital Basement also encountered the same issue as this, make sure the contact between the board and the ground shield is good.

I will look into this

 

[MrFrog]

Double check the repairs on back of the AB near RF16, and TP39. From the pic, it looks like there are bridged traces.

I’ll double check but it looks weird in the photo but I did make sure their was no bridging.

 

[MrFrog]

Update: So messed with some of the metal shielding and the noise is definitely lower now, gonna mess with it some more to hopefully fix it

 

[MrFrog]

Double check the repairs on back of the AB near RF16, and TP39. From the pic, it looks like there are bridged traces.

I checked them over with the multimeter and everything is checking out without any bridges

 

[MrFrog]

Update: So messed with some of the metal shielding and the noise is definitely lower now, gonna mess with it some more to hopefully fix it

I was unfortunately unable to fix it, I do believe the noise isn’t as loud anymore but the ground is there, I can check it with the multi-meter

 

[YMK]

I'm rather embarrassed to say that even though I bought all the components for the swap, I've actually still not made time to do it yet! That's something I plan to do a video on, but it's not done yet. However, since you have done the component swap, did you experience any noise increase through the speaker like show in the OP's video?

I haven't noticed a problem.

 

[JDW]

Update: So messed with some of the metal shielding and the noise is definitely lower now

"Messed with the metal shielding" how, specifically?
The fact that "messing" changed something is a bit concerning.

 

[MrFrog]

I just looked at where the shielding was touching the grounds and just made sure they were touching the shield. I don’t believe this is the issue as I never messed with shield prior, I was just bending some of the tabs under the were analog board bottom metal sheet touches. Most were touching some were not touching so I was making them touch the shield.

 

[MrFrog]

New update:
I replaced DF2 but this time with the 1.3W (Izt=25mA): BZV85-C8V2,113 diode and the noise seems to have gotten a lot better, it just has a very faint noise now.

I did also go ahead and add a second 1N5355B 5W 18V Zener for DL21/22 which was not needed per the mentioned forums but put it in since I ordered for troubleshooting

I think the issues might have been me soldering on legs from extra cut off when I recapped the capacitors to the old DF2 to make it stand more off the board. From inspecting it, one the legs didn’t have the best solder connection. Photos below:

 

[MrFrog]

I wanna thank yall for the replies! Im still fairly new to the vintage computer hobby but loving every bit of it!

 

[JDW]

New update:
I replaced DF2 but this time with the 1.3W (Izt=25mA): BZV85-C8V2,113 diode and the noise seems to have gotten a lot better, it just has a very faint noise now.

I think the issues might have been me soldering on legs from extra cut off when I recapped the capacitors to the old DF2 to make it stand more off the board. From inspecting it, one the legs didn’t have the best solder connection. Photos below:

@YMK said he didn't experience noise, and he did the component swap. However, it does not seem that the legs on his replacement components were very long...

https://tinkerdifferent.com/threads/color-classic-analog-board-trouble.2367/#post-21638

So I am wondering if the raising up of larger components by an extra centimeter off the Analog board would really induce that much noise into the onboard Speaker circuit?

And because I've not done the component swap myself yet (I will eventually), I cannot say how much difference diodes make when using different parts. I believe we did discuss that in YMK's thread, but I'd need to read through every post to find it, and I lack time for that right now.

 

[MrFrog]

@YMK said he didn't experience noise, and he did the component swap. However, it does not seem that the legs on his replacement components were very long...

https://tinkerdifferent.com/threads/color-classic-analog-board-trouble.2367/#post-21638

So I am wondering if the raising up of larger components by an extra centimeter off the Analog board would really induce that much noise into the onboard Speaker circuit?

And because I've not done the component swap myself yet (I will eventually), I cannot say how much difference diodes make when using different parts. I believe we did discuss that in YMK's thread, but I'd need to read through every post to find it, and I lack time for that right now.

All is good, thank you for the response. I will mess with making short the larger components and see what that does.