Stumped - No right channel sound output with Simple stereo board

[Beeblebrox]

Well this one has got me stumped.?

 

My 800XL board came preinstalled with the Simple Stereo Board below. It's plugged into a small set of speakers and utilities like sys info and demos like Cyberpunk always report a stereo capability. However I realised that actually I am not getting any output from the Right audio channel at all.

 

So this is the board:

 

https://lotharek.pl/productdetail.php?id=57

 

I've checked  and it is wired up correctly according to these instructions: https://lotharek.pl/files/stereo/manual.pdf

 

Note: a slight variation is that the board I have has the header mounted for the LED, which isn't the case in the image above.

 

 

Also the switch that is used on my board is this simple 2 way:

 

 

I don't have the Uswitch PCB add on that allows U1MB (also currently installed), to control the stereo on/off in menu so there is no direct connection to the U1MB. Nevertheless I've also tried having Stereo enabled in tne U1MB menu just in case - makes no difference an I wasn't expecting it too.

 

As I mentioned Sys info software and demos like Cyberpunk show Stereo is detected and LED is on, indicating Stereo mode is enabled.

 

Yet I don't get any sound coming from the right audio channel (red).

 

I've swapped cables over, tried new cables. No difference.

I've double checked the pokey chips in other A8s to make sure they aren't bad and they work perfectly.

 

I also used my multimeter to check all continuity with the L R and ground contacts on both the phono jacks as they relate to the headers on the Simple stereo board:

 

  

My multimeter confirms continuity for the L G G R points on the PCB and the those on the phono jacks themselves.

 

I checked it wasn't my external speakers and tried another set.

 

I've read various AA topic posts, notably here: 800xl-stereo-install-detected-but-no-right-channel  and here u-switch-with-stereo-pokey-and-u1mb/

 

The first has a reply that advises grounding the manual stereo enable switch to a ground point. How do I go about this as I have a simple 2 way switch?

 

One of the things that I am confused about is the connection of the 2 way switch to the PCB here:

 

It came to me like this and understandably the documentation doesn't tell you which of these 2 pins of the six available are the ones to connect the two wires to for 2 way switches (because the switches supplied with the Stereo mod are DPDT 6 pin types - see the link to the documentation above).

 

However it appears to work connected this way as flicking the switch before powering up each time does disable and re-able the stereo in terms of it being picked up in checks at least, even if it makes no difference with the actually audio output:

 

 

 

One thing I did notice during my continuity of the stereo PCB board's connections itself was this: Of all the the 40 pins of the 2nd Pokey chip on the board, they all show a connection with the adjacent solder points on the PCB's lower socket pins that plug into the 800XL's Pokey socket, with the exception of 1 - which appears not to be connected to anything:

 

 

Of course this is likely by design as I can't imagine the tracers on the PCB have a fault (and there is no obvious damage) - but at this stage I am checking for anything that might possibly be tricking the setup into detecting the 2nd pokey and report a stereo capability, but not actually outputting to the right channel, thus providing a mono output via the left phono jack only.

 

Would anyone have any suggestions about the above and perhaps also elaborate on the grounding of the 2 way on off switch?

 

By the way this is the same 800XL with my AKI USB keyboard mod but this lack of stereo issue occurs as illustrated above when I've reverted back to plugging the 2nd Pokey directly back into the socket of the Simple stereo board, so has no bearing. It has no right phono jack output whatever I do, even whether the relocation mod is used or completely removed from the setup.

 

thanks in advance

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited August 20, 2021 by Beeblebrox
adding more info

[Paul Westphal]

Have to tried eliminating the on/off switch?

 

It does work without it - default is Stereo on if there is no switch. This MAY help..

 

I would also take a hard look at those janky RCA output jacks and possibly the wire connections might be bad.

Paul

Eightbitfix.com

[Beeblebrox]

57 minutes ago, Paul Westphal said:

Have to tried eliminating the on/off switch?

 

It does work without it - default is Stereo on if there is no switch. This MAY help..

 

I would also take a hard look at those janky RCA output jacks and possibly the wire connections might be bad.

Paul

Eightbitfix.com

@Paul Westphal many thanks. I'd checked out the RCA output jacks and their connections and they all show continuity. However I hadn't thought of eliminating the switch altogether. I'll look into how to do this as presumably I can't just disconnect the 2 pin connector from the header? I am not sure it'll make any difference as the switch is working given flipping it does initiate a mono and stereo capability indicator in sys info and cyberpunk demo (as per images).

Edited August 20, 2021 by Beeblebrox

[Paul Westphal]

I'm just throwing spahgetti at the wall here..

 

I have put many of these in and never experienced a problem; That's what caught my attention.

 

Have you tried switching out the pokey's? Maybe one is bad...

[Beeblebrox]

@Paul Westphal Throw away! ?  Yup both Pokey chips fine as tested both in another A8s I have.

[Beeblebrox]

@Paul Westphal Incidentally do you have this exact same model pcb and is it wired up as per these instructions (with the switch the mod typically comes with): https://lotharek.pl/files/stereo/manual.pdf  ?) Putting you on the spot I know heh heh!?

 

A4 – this signal can be found in many places on ATARI BOARD, but for now please solder wire between CPU - (https://en.wikipedia.org/wiki/MOS_Technology_6502) pin 13 and STEREO BOARD A4 pad

 

BELL – this signal can be found on GTIA CHIP pin 15. Please solder wire between pin 15 of GTIA ( code name CO -14889) and SSTEREO BELL PAD

[+mytek]

Unless I'm mistaken, you really need the full switch as shown (or possibly some jumpers) since I would imagine that the audio is being switched to achieve either the left channel Pokey's audio going out both RCA jacks (mono mode), or the right channel Pokey's audio out the right channel jack, and of course the left channel Pokey's audio out the left jack (stereo mode). With the present switch, you are only activating or deactivating the 2nd Pokey (right channel) addressing, and nothing else.

 

This what the U-Switch was for. It allowed for both analog audio switching and 2nd Pokey enable/disable to be done with a simple SPST switch (or a single I/O line from a U1MB). In my Stereo board design I built-in the U-Switch ability.

 

Edited August 21, 2021 by mytek

[Beeblebrox]

4 hours ago, mytek said:

Unless I'm mistaken, you really need the full switch as shown (or possibly some jumpers) since I would imagine that the audio is being switched to achieve either the left channel Pokey's audio going out both RCA jacks (mono mode), or the right channel Pokey's audio out the right channel jack, and of course the left channel Pokey's audio out the left jack (stereo mode). With the present switch, you are only activating or deactivating the 2nd Pokey (right channel) addressing, and nothing else.

 

This what the U-Switch was for. It allowed for both analog audio switching and 2nd Pokey enable/disable to be done with a simple SPST switch (or a single I/O line from a U1MB). In my Stereo board design I built-in the U-Switch ability.

 

@mytek ah that makes sense. I may try to source that switch. Many thanks 

[Beeblebrox]

5 hours ago, mytek said:

Unless I'm mistaken, you really need the full switch as shown (or possibly some jumpers) since I would imagine that the audio is being switched to achieve either the left channel Pokey's audio going out both RCA jacks (mono mode), or the right channel Pokey's audio out the right channel jack, and of course the left channel Pokey's audio out the left jack (stereo mode). With the present switch, you are only activating or deactivating the 2nd Pokey (right channel) addressing, and nothing else.

 

This what the U-Switch was for. It allowed for both analog audio switching and 2nd Pokey enable/disable to be done with a simple SPST switch (or a single I/O line from a U1MB). In my Stereo board design I built-in the U-Switch ability.

 

@mytek ah that makes sense. I may try to source that switch.

Edit. You mention jumpers. There is no indication what the 6 pins configuration are so I wouldn't know which config to place a jumper or jumpers. It's not something documented. Any ideas? Many thanks 

[Paul Westphal]

On my 256k stereo 800xl, I left the on / off switch out.

 

Works great ! take a look :

 

Yeah, I have the exact same board. No U-switch. I may have one if you need one. Looks like Lotharek canned the Simple Stereo board now that the new Pokey's are out, so he may not carry the U-switch anymore either.

[+mytek]

5 hours ago, Beeblebrox said:

You mention jumpers. There is no indication what the 6 pins configuration are so I wouldn't know which config to place a jumper or jumpers. It's not something documented. Any ideas? Many thanks 

Here's a schematic I marked up.

 

Here's how the switch works.

 

 

For Stereo operation there's no need to jumper the addressing side which defaults to STEREO. Only a single jumper is required on the audio side to route the output from the Right Channel Amplifier to the Right RCA jack. I don't know which side of the switch controls what on the actual PCB, but the simple way to find out is to connect a continuity meter on the center of your right RCA jack and probe the PCB switch pads (center ones). When you get an indication, that'll be the side of the switch you need to jumper. Checking for continuity from R7 will let you know what to jumper to.

 

Edited August 21, 2021 by mytek

[marauder666]

That switch looks like it has 6 contacts, maybe soldered together vertically?

[Beeblebrox]

Hi all

 

Just a quick update. I decided to order the DPDT 6 pin toggle switch and install it. Got this one from Amazon UK:

Yibuy Red 2-Way Design AC 125V 6A Double Pole DPDT On/On 2P Toggle Switch:

 

 

I had mulled over using jumpers but I wanted to still be able to toggle between mono and Stereo on the fly.

 

Switch arrived today and after a bit of solder work it instantly worked with outputs in both left and right speakers in Stereo for stereo enabled demos, etc.  

 

Stereo demos like Cyberpunk and Faraway sound great and indicate when the Stereo is present. Demos like Drunken chessboard (which aren't outputting a stereo soundtrack) play through the single channel when in stereo mode, or both channels when toggled to mono mode. (Where it just outputs mono through both channels/speakers). 

 

Install was relatively simple. I pulled the existing 2 pin header connector from the board and discarded the old 2 way switch it was attached to. With some salvaged IDE cable wire I soldered the 6 x legs of the new DPDT switch directly to the Simple stereo header pins as per Lotharek's diagram below from the installation instructions here:

 

 

I used some heat shrink for each of the 6 x header pins on the simple stereo pcb to prevent shorting as they are very close together.

 

The case had a pre-existing hole from another mode which the was in reach of the switch so it fitted perfectly.

 

So thanks everyone ( @mytek @marauder666 @Paul Westphal @tf_hh ) for your help and input on this one.

I naturally assumed because this 800XL came preinstalled with the Stereo that it was working with the existing switch.

 

Edited August 28, 2021 by Beeblebrox

[Beeblebrox]

@Paul Westphal Hey do you reckon you could upload the XEX of Euglena Zielona and any other cool stereo XEXs you might think sound great? (Thank's for posting that vid BTW). I had a quick look for it on AA but couldn't find it.

 

I only have a few Demos with Stereo output. I'll have a look around AA later this eve for some more stereo music.

 

I'd personally love to hear a A8 stereo Pokey version of the late great Origa from Ghost in the shell soundtrack fame. (I don't think it's been done on A8s)

 

If you go to .57 seconds in on the YouTube video of Origa's Rise below, and imagine her voice synthesized on stero Pokey chips (now there's a challenge someone):

 

 

[Beeblebrox]

Wow - just listened to PG's Skyride tune on Stereo with some powered speakers - blown away!

 

 

[Beeblebrox]

Another Ghost in the shell tune I'd love to see playing Stereo Pokey:

 

 

 

 

[Paul Westphal]

25 minutes ago, Beeblebrox said:

Wow - just listened to PG's Skyride tune on Stereo with some powered speakers - blown away!

 

 

I was going to do a video of Skyride, but the only .xex I can find uses the onscreen CPU usage, which is headache inducing. If I could find the .sap file, I can convert it to .xex with WASAP. I'll look again...

[Paul Westphal]

1 hour ago, Beeblebrox said:

@Paul Westphal Hey do you reckon you could upload the XEX of Euglena Zielona and any other cool stereo XEXs you might think sound great? (Thank's for posting that vid BTW). I had a quick look for it on AA but couldn't find it.

 

I only have a few Demos with Stereo output. I'll have a look around AA later this eve for some more stereo music.

 

I'd personally love to hear a A8 stereo Pokey version of the late great Origa from Ghost in the shell soundtrack fame. (I don't think it's been done on A8s)

 

If you go to .57 seconds in on the YouTube video of Origa's Rise below, and imagine her voice synthesized on stero Pokey chips (now there's a challenge someone?

 

 

PM sent. I have more!!