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Atari 5200 2 port No sound


mtarallo
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Hi Guys - was wondering is this jump on the bottom of the 5200 2 port MB is normal? it is located on what I believe is the Pokey audio chip - bottom left of 4 big chips in center.

 

I would like to get this thing working again and was told it may be the Pokey chip or some cheap caps - but before I go through all that - I was not sure if this white wire jumper is normal.

 

t9fxmw.jpg

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I would take a look at all the solder joints around the circuit. Could possibly be a bad transistor such as Q4 or Q5. Maybe a bad ceramic cap in the circuit somewhere.

 

I have a question too for anyone that may know this. I'm trying to figure out if this is an error in the schematic or if it is supposed to be like this, but my question is in regards to two diodes I was also going to ask him to take a look at CR8 and CR7(edited I accidentally typed 9 first) both appear to be in series with each other with nothing and no other connections in between. I'm not sure what the deal is there and why two are necessary. Did they leave out a dot where the two lines intersect to show a connection or do they overlap each other and not connect?

Edited by SignGuy81
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Update:

 

I just found a high resolution pic found here https://upload.wikimedia.org/wikipedia/commons/9/9a/Atari-5200-4-Port-Motherboard-Flat.jpg

 

and was able to zoom in on the two diodes(CR7 and CR8) I had the question about and found that between the two it does split off and go to C10 so that answers my question so yes the dot was left off on the schematic or it didn't show up during copying.

 

EDIT:

I searched 2 port just realized it the pic I found was 4 port but that part is probably the same though I'm sure.

Edited by SignGuy81
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OK so I took my 4 port apart and swapped pokey chips (A7) same results - no sound - so it could be something else. I'm wondering if i hook up to the pokey chip leg to an RCA Audio jack like my modded 4 port is - and see if I get sound. Since the sound comes from the RF signal, I'm wondering if there is an issue in the modulator. Thoughts?

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Hi SignGuy - thanks for your reply - yes- I did a visual inspection and they look really good, the board is super clean topside, but underneath - there are areas with a lot of crusty flux residue. I'm being upfront - I am new to testing components with a multimeter, so that would be my next step. If there any tips you can share - thank you. However, I don't expect you to give me a troubleshooting lesson :) - I understand - there is a certain level of knowledge I should have up front.. Next is to test the transistors in that area. I will update the post shortly. Thanks again.-- Looking at the PCB attached to the RF modulator - there is a green ceramic cap that has some white discoloration on it - wondering is that might be a clue, a short perhaps.

 

2s8sppl.jpg

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If it helps isolate the area to look, you can attach a wire from the north leg of R50 and wire in a 10uf 16v cap inline of that to an RCA jack temporarily just to see if you get audio out from that. I believe that is tapping the audio before it gets to the modulator this way so you can at least know audio is being generated.

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There are a couple of ways to do more thorough testing but I'm not sure if you have the tools to do the tests. I didn't mention trying to adjust L1 yet because it might be fine and you need to be able to read the frequency to adjust it properly. That is another possibility though or even L1 or L2 could be open. You can check to see if you have +5V on the collector of Q4 and that should rule out an open inductor(still may need to adjust L1 however). Does your multimeter happen to have a frequency setting? It could also be a couple caps but I would first test Q4 to rule it out.

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Thought I would share this with you.

 

https://www.ebay.com/itm/ER-MU-118-DIGITAL-6-FUNCTION-MULTIMETER-with-TEMP-FREQUENCY-COUNTER/272469204181?hash=item3f706e1cd5:g:pOsAAOSwnDZT8Vlo

 

With this meter with a frequency counter you would be able to go through the troubleshooting flow chart http://www.digitpress.com/library/techdocs/5200_field_service_manual_rev_3.pdf on page 87 of 194 of the PDF. Also has transistor and capacitance test.

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So first you all have been awesome and thank you - I just ordered a digital multimeter with all the testing capabilities as I plan on continuing my retro repair journeys. BUT - I came to update you all with my recent success - and as I came in here to update the post I see that Crosbow already suggested what I completed. You see, I have a modded 4 port so I took it apart and replicated the exact same setup with the audio as he suggested as well and IT DOES WORK! I plan on doing a UAV mod if I can find a way to order the chips from Bryan - - but yes I am a bit curious as to what failed as inquiring minds want to know. Thanks guys! Hope to contribute a bit more as I get time.

 

On another note - Just as an FYI I have been modifying NES controllers to work with the Atari 2600 (1 button) / 7800 (2 button) and even got a request for a custom order to make Button A replicate the push up to jump action - the guy wanted it specifically for C64 games (Contra). After I built it I tried it with Mountain King and SMURF for the Atari 2600 and would you believe it, it actually made the darn SMURF game playable?!? - LOL (if you know about jumping the fence obstacle on the 2nd screen then you know what I am talking about). You can see the post here - http://atariage.com/forums/topic/276397-nes-sega-master-system-control-pad-controllers-for-atari-2600-and-7800/- I am selling them on eBay - it started out as a quest to make a controller my Dad with rheumatoid arthritis could use easier than the 7800 controller and it just became a fun hobby. Thanks all!

 

Oh an BTW - I got this one: https://www.amazon.com/gp/product/B00EYYJRC0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1- thanks for the post as well!

 

2qwjwon.jpg

Edited by mtarallo
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You see, I have a modded 4 port so I took it apart and replicated the exact same setup with the audio as he suggested as well and IT DOES WORK! I plan on doing a UAV mod if I can find a way to order the chips from Bryan - - but yes I am a bit curious as to what failed as inquiring minds want to know. Thanks guys! Hope to contribute a bit more as I get time.

 

 

 

I figured Crosbows suggestion would work, you pretty much confirmed that when swapping the chips that the problem wasn't the chip. I didn't know you were going to be modding the console as well but yeah it would be nice to get it going stock first and come back with the results as to which component it was.

Edited by SignGuy81
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it would seem to point to an issue in the RF modulator at this point. That is my best guess. Not sure were to source a replacement, other than Best Electronics? You order the UAV by sending Bryan a PM directly to ask about it. For the 5200 I advise you get the kit you assemble yourself. Unless you don't plan on using the RF anymore. If that is the case, then you don't need the upper RF shield and you can use a preassembled UAV and just solder the socket it comes with to the top of the 4050 itself and go from there. You already have the audio taken care of so you wouldn't have to worry about that.

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it would seem to point to an issue in the RF modulator at this point.

I disagree.

 

More circuitry between the point he tapped and the RF modulator where all the signals are mixed before going in.

 

But if I'm wrong it won't be the first time.

Edited by SignGuy81
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That was why i suggested he pull the audio from R50 and not from the Pokey itself. As you said, the Pokey was likely good. I don't have the schems in front of me, but R50 is usually where I pull the audio when I mod. it is also where Bryan suggested pulling it when you provide it to his UAC board.

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That was why i suggested he pull the audio from R50 and not from the Pokey itself. As you said, the Pokey was likely good. I don't have the schems in front of me, but R50 is usually where I pull the audio when I mod. it is also where Bryan suggested pulling it when you provide it to his UAC board.

 

I agree and it was a good suggestion. I didn't know he would be doing the mod to the board as he hadn't said yet plus he already swapped chips to verify problem wasn't the chip. I was just saying it is more than likely before the RF modulator however where the problem lies, in the circuit on page 38 of the schematic linked above the circuit that goes before the modulator with the inductors L1 and L2, Q4, the diodes C7 & C8, and the caps in that circuit it is more than likely something there, before the signal gets mixed with the others that go into the modulator. But yes that was another good suggestion/method to verify the chip was outputting audio.

Edited by SignGuy81
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Thanks guys and BTW - if you are interested in how all this hubbub came to be, it stemmed from this post I started a few weeks back: http://atariage.com/forums/topic/275781-miner-2049er-not-working-4-port-atari-5200/- I loved Miner 2049er on my Atari 800 as a kid - but the cart would not work on my 4 port. I actually returned them back to the seller and got another one, and the 2nd one also did not work. At the time I was not sure if the mod had anything to do with it (likely not) - Crossbow you did reply in that thread - thank you. So I came across a thread somewhere on the internet (not sure if it was AA) where someone had the same issue. So I ordered a 2 port - and it works on the 2 port! So I honestly would like all my games to work on one machine - but it is a weird situation. Also I ordered a homebrew cart that was a dump from an Atari XL - Jumpman Junior - and that cart would boot - but it would then lock up and display a bunch if characters on the screen - that happened on both machines. The guy is sending me a new one. Thanks for everyone's communication and contribution. It means a lot.

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Thanks guys and BTW - if you are interested in how all this hubbub came to be, it stemmed from this post I started a few weeks back: http://atariage.com/forums/topic/275781-miner-2049er-not-working-4-port-atari-5200/- I loved Miner 2049er on my Atari 800 as a kid - but the cart would not work on my 4 port. I actually returned them back to the seller and got another one, and the 2nd one also did not work. At the time I was not sure if the mod had anything to do with it (likely not) - Crossbow you did reply in that thread - thank you. So I came across a thread somewhere on the internet (not sure if it was AA) where someone had the same issue. So I ordered a 2 port - and it works on the 2 port! So I honestly would like all my games to work on one machine - but it is a weird situation. Also I ordered a homebrew cart that was a dump from an Atari XL - Jumpman Junior - and that cart would boot - but it would then lock up and display a bunch if characters on the screen - that happened on both machines. The guy is sending me a new one. Thanks for everyone's communication and contribution. It means a lot.

 

Then you also need to swap out the bios on your 2-port 5200 for a 4-port bios if you want one machine that plays all the games. The 2-port can't play Moutain king, Pitfall, and Krazy Shootout without the bios change off the top of my head. You can get modified versions of those games onto cart that will work, but it is easier and cheaper to just swap out the bios chip.

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So just to update you all on this (issue with Miner 2049er working on my 2 port and not my 4 port) - I swapped every darn socket-ed IC chip there was - between the 2 5200s - and the 4 port (modded) still did not boot Miner 2049er. The 2 port (not modded - yet) - works just fine. I am wondering if it has something to do with the video mod - we'll find out once I mod my 2 port. The 2 port does have some ICs that are not socket-ed like the 4 port. (could be those are causing the issue) - and 1 other thing - on my 4 port there is a scoket-ed IC with a resistor soldered to one of the legs (not the pokey R50 IC) - looks like another mem IC but standalone - not sure if that was standard - but my 2 port does not have that (assume they made the improvements when making another rev). Who knows.

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OK so I took my 4 port apart and swapped pokey chips (A7) same results - no sound - so it could be something else. I'm wondering if i hook up to the pokey chip leg to an RCA Audio jack like my modded 4 port is - and see if I get sound. Since the sound comes from the RF signal, I'm wondering if there is an issue in the modulator. Thoughts?

 

Check those two silvery polystyrene caps in lower left of this pic. They handle sound in most Atari systems. Sometimes, just pushing downward on them will make them work a bit. Always replace them in pairs.

post-25215-0-00501100-1521075443_thumb.jpg

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Check those two silvery polystyrene caps in lower left of this pic. They handle sound in most Atari systems. Sometimes, just pushing downward on them will make them work a bit. Always replace them in pairs.

 

Yep, that is C13 and C14, two of the components that are mentioned to replace along with Q4 for no sound in one of the steps on page 87 of the PDF.

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