Journey Cassette Audio Issue

[flynn54321]

So I just finished restoring my Journey - however there is a slight problem with the cassette player audio.

There seems to be a loud grumbling noise in the line somehow. You can hear it when the tape player kicks in... even in the tape player test mode. If you turn down the volume pot for the cassette player speaker inside the coin door you can hear it as well... its still there even with that volume pot turned down.

I hooked the earphone jack plug up to my portable minidisc and there was perfectly clear audio - however when I plugged in the power cord to the mini disc the sound came right back.
So somehow there is a problem with grumbling noisy audio in the line when the power cord is hooked up to the cassette player...

Anyone have any thoughts?

 

[flynn54321]

anyone have any thoughts on this?

 

[Jedidentist]

My only comment is that I've got the same thing. I didn't mess around as much as you did trying to diagnose it, but I get the same issue. Maybe some sort of power feedback when the signal goes out to start the player? Hopefully someone more knowledgeable about this can chime in...although most people don't even have one to be that knowledgeble about it.

 

[natey_boy]

if the cassette player uses its own power cord use a drop ground plug and that should cure it

 

[don1400]

I've tried a few things back around the holidays to try and solve problem for Brad to no avail and was talking to him last night and suggested what I thought would be a bypass of the problem, use a relay to start cassette. My idea was to power the cassette with a wall wart, since with it's own power everything works beautiful, and have the game fire a relay. So he got a 5v relay from radio shack and I wired it up this morning and naturally it didn't solve the problem, as soon as I put the power to the relay coil problem started again. I did discover that anything hooked up to the power supplied by the game for the cassette causes the problem, for example I hooked up a 12v coin door light bulb and the problem continued. We tried another linear supply, no change. So basically any load put on the voltage that runs the cassette causes the problem, I did try natey_boy's suggestion and that didn't fix it.
Considering the new info in this post anyone have any other thoughts?
Thanks,
Rich

 

[natey_boy]

Well thats all the advice I could offer lol.

 

[flynn54321]

Here are a few things we tried to eliminate the problem...

Different power supply board
Different Cassette interface board
Different suitcase

the noise is still there.

Right now I have a wall wart plugged into the suitcase - that powers the cassette (at all times when the machine is turned on) but the audio will only kick in when its called for. This does solve the problem with the noise - but I dont like that loop tape to be running constantly (even if its not heard all the time)

 

[crowbarz]

I was having this same problem yesterday. Now, I cant get any power at all to the cassette player. Ive tried 2 new MCR Power Supply Adapters too. Im thinking the problem is in the cassette interface board. Anyone else have an idea?

 

[crowbarz]

Bump!

Can someone please give some advise for these issues. I even email electronforge and still have not received a return email for over 3 weeks now. Is that place still open?

 

[WindDrake]

If you had a scope, I'd say probe your cassette power lines. My guess is that it looks like garbage and is coupling noise onto your audio circuit.

If the wart is handling the noise issue, then you're definitely looking at inductive coupling. Using an isolated power source may be better for it in the long run.

Without Schematics, it's going to be hard to help you on this one. I don't really know the MCR hardware very well.

I'm assuming the Cassette Interface Board powers up the cassette only when it's needed?

Your friend was right in trying the relay idea. Have the interface board wired to an appropriately rated relay, so that when it trips, it fires the relay, and connects power to your cassette via the wart. Though, if you are still having noise coupling issues, try switching GND instead of whatever your supply voltage is. You could always try building a pass filter to suck out some of the noise, too. Though.. If you're coupling noise through a relay.. You may want to look into a Switcher to replace your aging linear PSU.

Like I said, however. Without Schematics, it's hard to help.

 

[flynn54321]

This has been one of those "gremlin in the machine" problems. Don1400 and I went over it and over it and cannot figure it out.
We tried a new suitcase, a new interface board, different boardset, rewired the power and audio cable to cassette player.. as well as a different player.

 

[don1400]

Like I said, however. Without Schematics, it's hard to help. [/QUOTE]

If you have the time there's a PDF of the manual here:

http://www.crazykong.com/manuals/Journey.man.pdf

maybe you could take a look and throw out a few ideas. All boards were swapped out with another KLOV'rs and the boards from Flynn's game worked fine in the other members game but with his boards in Flynn's game the problem persisted. The only thing that wasn't swapped out was the harness. All ground straps are connected including the AC plug, I tried to filter out the noise with some high value filter caps, nothing has worked. Don't have a scope available so I can't take a look at the voltage. Very frustrating.
Rich

 

[WindDrake]

Aha! In my Googling, I didn't come across that one. I'll take a whack at it over lunchbreak today and see where I get with it.

Obvious question time: You don't have your harness near your marquee flouro power lines do you? Dumb question, but 60hz makes a neat growl sound.

More Edits: With your DMM on the power line for the Cassette Player, what's it read? Schematic says 6VDC (J3 on Power Amp Board, Red and Black Wires). Check this.

Yet Another Edit: Co-Worker pointed this one out to me, because I forgot. Whoops!

One way to listen for noise is to wire up a sound version of the Video Probe. Use (preferrably) a crystal earpeice or one side of a pair of old junk headphones (may be too quiet..). Wire Return/Ground to your PSU's Power Amp Return Path (Black Wire on J3), then put a 10K-Ohm Resistor and really any value capacitor (For a Positive Supply: Cathode to Signal Wire, probe with Anode. Use an extension wire off of anode if you won't want to be holding stuff ) in SERIES (to Strip DC Signals out. You only want to let riding AC into the earpeice) with the earpeice's signal wire. Use this to probe your power circuit and listen for hum. Hum means NOISE. More hum = more crap and noise. Be warned, I have no idea where the volume will be, doing this.

Holy Crap, More Edits!: Not lunchbreak yet, but this one has me interested. Via J1, there's +12V Supply to the Audio Amp Board. And you said via the +6V Cassette Supply, the thing hums, if any load is put on it. This makes sense. You've likely got a dying/dead cap in the 6V Supply Rail. Do you have access to an ESR Meter? That'd get you sorted out right quick. If not.. Check C501 (1uF (They use the MF Designation for Microfarad) Tantalum Cap per Schematic) , C500 (.1uF Ceramic), C402 (100uF Electrolytic), C401 (4.7uF Tantalum), C400 (.1uF Ceramic), CP1 (220uF Electrolytic), and CP2-7 (.1uF Ceramic). Check out PDF Page 32 of the Manual for parts reference. You might be best off just replacing the large value Electrolytics (CP1, C402) first, as they're Vintage 83, and probably shot now.

More Thinking: The LM317T Adjustable Regulator is getting +12v in, and outputs +9.2v. Make sure it's putting out +9.2v (+/-2%) Otherwise your 6V line off the 7805/Transistor Pair will be way off. This is set by Resistor R400, R401, and Capacitor C401.

Post-Lunch Edit: Yeah, I think I've about covered it. With this info, you should have what you need to walk the circuit back and figure out what's making the noise.