Audio all static...

[co13ghoul]

I just got my heavy sixer and hooked it up. All the switches work beautifully, the video is good, but the audio is all static. How can I go about trying to figure out what is wrong? Any help would be greatly appreciated.

 

 

<edit: Because I can't spell>

Edited July 10, 2007 by co13ghoul

[A.J. Franzman]

There are several possibilities involving the audio mixer circuit, but these are the most common:

 

The adjustable choke, which is a colored translucent plastic tube (usually pink, but sometimes orange or another color) standing up from the board with a few turns of heavy copper wire around its bottom end on most motherboards, is out of adjustment or the ferrite tuning core inside it is broken.

 

or

 

The polystyrene film capacitors near the above mentioned adjustable choke are bad.

 

or

 

The audio carrier frequency oscillator transistor (also near the adjustable choke) is bad.

 

 

Start by visual examination for damage to components and circuit tracks in the vicinity of the adjustable choke, both sides of the board, and including the ferrite slug core inside the tube of the choke. If you find nothing, then with a game running, try pressing a finger on the two clear and silver capacitors, and rocking it back and forth a bit. If you notice the sound changing at all when you do this, then at least one of those capacitors is bad and both should be replaced. If you still haven't found anything, you can try adjusting the ferrite core. If at all possible, you should use the proper plastic or fiberglass adjustment tool. If you don't have one, then my next recommendation would be to try to carve one from wood, or a bamboo kabob skewer, etc. Only use a metal hex key or Allen wrench (0.075 inch) as a last resort, with great care; the ferrite material is brittle and easily broken, and the presence of metal will affect the tuning of the circuit (when you think you have it tuned right, removing the metal tool will change it again -- this doesn't have too much effect on the sound circuit, but it may be a problem if you try to adjust the choke in the RF modulator with a metal tool).

Edited July 10, 2007 by A.J. Franzman

[co13ghoul]

Thanks for the info, Ill see if I can pull it apart later today and take a look at the things mentioned above.

 

Also, I gave a bad description earlier, the audio isn't really all static unless i turn the volume up, its more like no audio at regular volume. Sorry to have give a bad description of the problem originally.

[co13ghoul]

Well I pulled it apart today to look at the traces etc. None of the traces look broken, but on the back there are some areas on the traces where the insulating layer appears to have 'bubbled' up a bit. Is this normal / damaging? Sorry for the blurry photos.

 

I have not messed with the sound adjustment yet as I dont want to damage it. Could a proper tool be purchased at radio shack, or do I need to order one from a 'real' electronic supplier?

 

As a side note... Does everyone's Heavy Sixer come with the beautiful 'calculator tape' taped to the sheilding / board? Again, sorry for the blurry pics.

[A.J. Franzman]

Well I pulled it apart today to look at the traces etc. None of the traces look broken, but on the back there are some areas on the traces where the insulating layer appears to have 'bubbled' up a bit. Is this normal / damaging?

It's very common for the green solder mask to blister or peel, and nothing to worry about.

 

 

I have not messed with the sound adjustment yet as I dont want to damage it. Could a proper tool be purchased at radio shack, or do I need to order one from a 'real' electronic supplier?

Radio shack may or may not be stocking them anymore, but if they aren't, chances are some stores still have them. Look near the soldering irons, pliers kits, etc. for something like this: Universal Color TV Alignment Tool Kit. My set has a blue and a green driver instead of the orange one and the second red one like in the picture. The red tube on the left in the image is an extension handle for working on high voltage or highly sensitive circuits; you won't need to use it when working on a video game console.

 

This is the closest thing I can find on Radio Shack's website, but I don't know if it has a driver the right size: 3-Piece Anti-Static Set. As an anti-static set, these tools are conductive so should probably not be used around high voltage (you might have noticed that they don't say "TV" on them).

 

 

As a side note... Does everyone's Heavy Sixer come with the beautiful 'calculator tape' taped to the sheilding / board?

They all came with that from the factory but if the console has ever been opened it's fairly common for it to be missing. Later consoles only had one piece of this paper, on the shielding, but heavy sixers may have as many as four. Edited July 11, 2007 by A.J. Franzman

[co13ghoul]

Thanks for the info. Now that you mention it I remember seeing TV color adjustment tools sets, similar the those in the picture at one of the radio shacks around here. Ill see if I can track down a set at one of the half dozen stores around. Hopefully this will fix my problem. I'll keep ya updated.

[co13ghoul]

Ok, I found a set of TV alignment tools at the Shack today. But, turning the ferrite core didn't seem to have any effect on the sound. Any idea of what to check next? Could it be the TIA? I have a fully working vader system, would it be worth it to try and swap the TIA's? Thanks for all the help thus far.

[A.J. Franzman]

I gave a bad description earlier, the audio isn't really all static unless i turn the volume up, its more like no audio at regular volume.

Now I'm not sure how to interpret your description of the problem. You say you have no audio at regular volume, and static when turning it up. Do you get any game sounds when the sound is turned up, or only static?

 

 

I found a set of TV alignment tools at the Shack today. But, turning the ferrite core didn't seem to have any effect on the sound. Any idea of what to check next? Could it be the TIA? I have a fully working vader system, would it be worth it to try and swap the TIA's?

If both of the TIAs are socketed, swapping them might be able to rule it out as the cause. However, I believe most Vader motherboards have all their chips soldered directly to the board.

 

If you have no game sounds at all, the TIA could be at fault, but I believe the transistor is most likely. It could still be the polystyrene capacitors too -- the "finger test" I described before only sometimes confirms that they are bad; it can not confirm that they are good. Another possibility is the coupling capacitor, but this is rather unlikely without any visible damage.

Edited July 12, 2007 by A.J. Franzman

[co13ghoul]

Now I'm not sure how to interpret your description of the problem. You say you have no audio at regular volume, and static when turning it up. Do you get any game sounds when the sound is turned up, or only static?

 

There are no game sounds at all. When at normal volume there is only slight static, when turning volume up there is a lot of static.

 

If you have no game sounds at all, the TIA could be at fault, but I believe the transistor is most likely. It could still be the polystyrene capacitors too -- the "finger test" I described before only sometimes confirms that they are bad; it can not confirm that they are good. Another possibility is the coupling capacitor, but this is rather unlikely without any visible damage.

 

Is the transistor you are referring to the one right next to the Sound adjustment coil? Is there a way to test this (maybe checking voltages)? And could you tell me where the coupling cap is?

 

Sorry for some many questions, but thank you so much for the help.

[A.J. Franzman]

If you have no game sounds at all, the TIA could be at fault, but I believe the transistor is most likely. It could still be the polystyrene capacitors too -- the "finger test" I described before only sometimes confirms that they are bad; it can not confirm that they are good. Another possibility is the coupling capacitor, but this is rather unlikely without any visible damage.

Is the transistor you are referring to the one right next to the Sound adjustment coil? Is there a way to test this (maybe checking voltages)? And could you tell me where the coupling cap is?

Yes, that's the transistor -- type PN3563 or equivalent. I don't know if it's practical to test it in-circuit; I usually just swap it out if it's suspect.

 

The audio output coupling capacitor from the mixer is a 47 pF, in series with a 1k resistor, according to this schematic (this resistor is shown as 1.8k in the Field Service Manual). I believe this is C211; it's directly to the right of the adjustable choke if you're looking at the board as it would be oriented when the console is facing you. There's also an audio input coupling capacitor to the mixer, C210 0.1 uF, third component along the edge of the board below the 16-pin buffer IC.

[co13ghoul]

Thanks for the info, I'll see what kind of spare parts I have lying around.

 

P.S. - Sent ya a PM

[chadtower]

BTW, I have an audio problem on a heavy sixer I'm working on right now, so this is hugely helpful.

 

I tried the wiggle test on those two caps, no change in the audio. I need to find a tv adjustment toolkit now, I think, but I suspect I'll end up shotgunning most of this circuit to see when it comes back into operation.

 

I can't find those caps on the schematic for some reason... what are their values? Thanks!

Edited July 29, 2007 by chadtower

[Prodos8]

I can't find those caps on the schematic for some reason... what are their values? Thanks!

 

They're obsolete polystyrene 820pf caps.

[A.J. Franzman]

Here's a detail from a 6-switcher schematic, showing the audio mixer section:

 

Note that "pF" is written as a single combined character (known in the typesetting trade as a "ligature") which looks like a "p" with a hook on top. The 820 pF caps are drawn to the left of and below the transistor.

Edited July 30, 2007 by A.J. Franzman

[chadtower]

I see what you mean. If these are obsolete, what do I replace them with? Electrolytics?

[Prodos8]

I see what you mean. If these are obsolete, what do I replace them with? Electrolytics?

 

You can still obtain them online, but I can't find them anywhere around here locally. In a pinch I suspect you could use a 0.001 uF (1000pF) mylar cap, though I've never tried. I scavanged some (the 820pF polystyrene) from a dead board last time I needed them.

[A.J. Franzman]

I see what you mean. If these are obsolete, what do I replace them with? Electrolytics?

You can still obtain them online, but I can't find them anywhere around here locally. In a pinch I suspect you could use a 0.001 uF (1000pF) mylar cap, though I've never tried. I scavanged some (the 820pF polystyrene) from a dead board last time I needed them.

There's a small chance that electrolytics would work, if they were made in such small values. Dielectric materials and capacitor construction types each have their own unique characteristics as far as frequency, inductance, series resistance, leakage and losses go, and I'm sure polystyrene film was chosen for a reason. Also, as a film type capacitor, these would have a fairly high self-inductance value, so replacing them with a 1 nF (102) ceramic disc type would probably not work. But another film type of similar value may do the trick.

 

The few 820 pF polystyrene caps I have were all scavenged from 2600 boards.

Edited August 3, 2007 by A.J. Franzman

[chadtower]

The few 820 pF polystyrene caps I have were all scavenged from 2600 boards.

 

 

Finally got back to this 6 switcher... check this out.

 

Edited March 4, 2010 by chadtower

[A.J. Franzman]

The few 820 pF polystyrene caps I have were all scavenged from 2600 boards.

Finally got back to this 6 switcher... check this out.

 

Nice find, and nice prices!

 

One thing to be very careful about when replacing the polystyrene capacitors, is that polystyrene has a very low melting point -- you MUST use a heatsink on the lead being soldered, and you should try to work as quickly as possible. A bit of practice beforehand may be a good idea if you don't do much electronics soldering.

Edited March 5, 2010 by A.J. Franzman

[chadtower]

Nice find, and nice prices!

 

One thing to be very careful about when replacing the polystyrene capacitors, is that polystyrene has a very low melting point -- you MUST use a heatsink on the lead being soldered, and you should try to work as quickly as possible. A bit of practice beforehand may be a good idea if you don't do much electronics soldering.

 

 

I'm good with the soldering, thanks, but I do appreciate the warning. I ordered a few PN3563 as well - may as well get them both while I'm in there vs going back in.

[chadtower]

Final report: replacing the two caps and the transistor gave me some nice clear audio. This particular 2600 is now repaired.

[tetrode kink]

Ahh, one precious VCS saved from the landfill. Huzzah!!!

 

-tet

 

[edit]I guess it won't give you the smiley if you spell it, "thunbsup..." [/edit]

Edited March 13, 2010 by tetrode kink

[A.J. Franzman]

Ahh, one precious VCS saved from the landfill. Huzzah!!!

... and it took less than 3 years to fix it!

[chadtower]

... and it took less than 3 years to fix it!

 

[cOLeCoHiTMan]

thanks.. this thread saved my boxed heavy sixer i got on craigslist!