tascam 246 portastudio help...

T

towser

New member
Hello,
I bought a 246 for $30, and have been cleaning it up. All new rubber is on the way. However, pgm buss 1 in & out does not pass a signal. Busses 2,3,4 in/out are fine. I have schematics, just don't know where to start looking. If anyone can help, I greatly appreciate it. Thank.
 
Thank you. Anyone else have an idea where I might start troubleshooting my 246? Greatly appreciated.
 
So what happens if you plug a source into the PGM BUSS 1 input jack, and then monitor off the PGM BUSS 1 output jack? Does audio pass?
 
Yah. Do that first. Look to see if there is oxidation or corrosion on any connectors when you do that. In the meantime, with the information you provided about the lack signal integrity from the BUSS 1 input to output jack, I'll take a look at the schematics.

Are you prepared to test stuff? I mean do you have a multimeter and such?
 
Sweetbeats,
Yes, I have x meter and schemos...I've really covered connections and deoxed...just don't know where to start...
 
Open it up. On the IN/OUT PCB ASSY (B) (that's the one with the BUSS in and out jacks) you should see a 7-pin connector P002. Set your meter to resistance and put one probe on the + conductor of the PGM BUSS IN 1 jack (stick it in the hole), and the other on pin 6 of P002. You should get around 22K ohms resistance showing on your meter.

Now touch one probe to the shield of the PGM BUSS IN 1 jack (the outer part of the jack), and the other to pin 7 of P002...you should get a dead short (i.e. no resistance).

What we are doing is, step-by-step, checking continuity of the BUSS IN to BUSS OUT path.

Do you have a signal generator of some sort? Something that can produce a 1kHz test tone? This could even be a CD with test tones on it, or a wav file of a 1kHz test tone played back from your computer.
 
OK. I'll test with my meter. I have the deck open. I do have a Teac tone generator that I've been using. Will let you know what readings I get....
 
Sweetbeats,
OK...got 22.2 on buss 1 / pin 6....0 reading on shield / pin 7...
 
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And when you say 0 reading pin 7 to shield is that "0" the same as what you get when you connect the probes directly to each other?
 
Sweetbeats,
Thanks for hanging in there with me....I checked the readings again this morning...22.2 buss 1/pin 6 in....buss1 shield to pin 7 I get 00.0...so yes. I also put in new belts, idler tires, and pinch roller assembly. Transport works great! Pgm 1 still no signal. The effects buss I/O works, both left and right...just the dang pgm buss 1. When I play a tape and monitor in pgm mode, vs cue mode, the 4 pgm/track meters work and smaller pgm/monitor right meter indicates a signal. In cue mode, just pgm/track 2 and pgm/monitor right meters indicate a signal....
 
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Yes. I've been pulling boards this afternoon...looking for broken solder joints, blown caps...cleaning the pots. Things " look" OK....I now have the monitor fader 1/2 section out.
 
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Well, I put all the boards back in, and I get the same result...no pgm left in or output. The cue fuction works fine as I get output from both left and right, with all the meters working. Not so in the pgm mode.
I'm thinking the problem could be the u101 logic chip on the monitor buss A board since it's first in line after the signal leaves the buss PCB and goes to the monitor buss A board. Still looking for help...
 
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I'll have to take your info and study the schematics when I can. I'll try and get to this soon. Have a busy week and am *this close* to having my motorcycle back up and running...finished. So you're playing second fiddle to a CX500. :D But I'll be back to you soon.

If you play back a tape tht you know has material on track 1, can you hear anything from that track?

I'm less suspicious of a logic issue and more suspicious of a bad pre fader buffer amp or post fade booster amp, or something associated with that path...bu, again, I gotta study it. Never owned or even seen the insides of a 246.
 
Yes, I can only hear tape playback on track 1 when using the cue/monitor setting. When I switch to the pgm/monitor setting, track 1 goes silent. Tracks 2,3,4 work in either setting.
Good luck with your motorcycle! And thanks again for you help.
 
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Okay. I'll do what I can, but those details will be helpful in narrowing down the issue...you may be right after all regarding a logic issue...have to see what is in place as far as the IC for that. Good news is it isn't intermittent. It just plain doesn't work which is easier to solve than some whacky intermittent issue.

"Rufus"...almost done...

IMG_3176.jpg


This is a sample of the "before" state...15 years dead in a barn he was...

IMG_3578.JPG
 
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