TASCAM 48 Needs Repair

  • Thread starter Thread starter steveneudaly
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steveneudaly

steveneudaly

New member
Greetings, everyone. I'm new to the message board and look forward to picking your brains or offering advice where I can.

I've just recently purchased my first multi-track tape deck, a Tascam 48. I found a seller near my home town getting rid of the deck, two Tascam DX-4Ds, and a box full of Ampex 456 and 3M 996 and the original manual for the 48. The only catch was the deck is non-operational. But, given that, I was able to pick up the lot for $100. Not bad, in my opinion.

The deck powers up, and the motor spins up smooth and quietly, but the green LED display remains unlit, and none of the playback buttons trigger any response from the deck. Play, rewind, record... no buttons cause any tape transport.

I'd love to have this machine working, but understand that could be quite the process. Does anyone have any insight on what exactly is wrong with the machine, or a suggestion of who I could start talking to about repairing the unit?

I appreciate any advice available. Thanks for listening.
 
Awesome find...you could get your money back on selling the DX-4D's alone, so at the very least you're not out anything.

The very first thing I would do is make sure the power supply is putting out all the right voltages. All you need is a cheapy multimeter to do this. In the manual there are good instructions for how to access the power supply PCB as well as others. You just need to take off the upper rear panel. The wiring diagram in the schematic section will show you which connector(s) carry what voltages and you can turn it on and start checking. Let me know if you need more specifics...I just don't have my 48 manual handy right now.
 
OH! And actually, check all the fuses first, with the multimeter set on continuity. Don't rely on a visual check with the fuses.
 
Sweetbeats-

Thanks for the quick reply. When I get some free time this weekend, I'll pull the back off, sit down with a multimeter, and let you know what I find.

-Steve
 
Have you checked things out yet? Can you post any picks of the process?
 
Things have been quite busy, so I've yet to get my hands inside the deck.

As soon as I do, I'll update with stories and pictures.

Thanks for the interest, everyone.
 
So I checked all the fuses with a multimeter, and they all came up OK.

Where exactly do I measure the output from the power supply? Is this done at the fuses? What do I use as negative?

Thanks advising a dedicated newbie.

Oh, and attached are the pictures you asked for. Enjoy!
 

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Well, I realize now that Sweetbeats gave me pretty good directions on how to check the voltages. I need to look at my manual more closely.
 
I hate to ask this but did you have tape on the machine when you tried it?
Or if not did you lift the tension arm up when you hit the buttons?
Sorry but I am not sure how much you know about a reel to reel from your first post and you didnt mention if you had tape on it.
Incase you dont know the right tension arm needs to be up when you hit the buttons for the machine to do anything.
And if you already know that sorry for this post.
 
Good point Herm...

stevenuedaly please calrify if you were raising the right tension arm when you tried testing the transport functions...

Also, do you have a manual?
 
Hahaha, sorry about the lack of info. Though, I wish the problem was that simple.

I have tried it with tape loaded onto the machine. This isn't my first deck. I grew up playing with my dad's Teac X-1000, and have an Akai GX series deck now that I live elsewhere (which currently has a horrible hum in the left channel, but that's another thread). Anyhow, my fascination for these machines is what lead me to pick up the 48.

I did note in my first post that the LED counter display does not light up when the deck is powered on. The green LED above the STOP button, also remains unlit. I feel this has a great deal to do with whatever the problem is, but again, I'm just talking out of my "you-know-what."

And, yes, I do have the full manual with wiring diagrams and all that good stuff.

Thanks for the replies!
 
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Do the record-ready lights flash and sync lights come on when you press those buttons down on the arming panel? How about the monitor source (input, sync, repro) LED's? Does the LED above the REC button light or...or anything at all in the transport control section (with the counter)?

I really think its time to start checking the voltages off the power supply.

Disconnect the 48 from the mains power, and then switch it on for 15 minutes to dissipate the power supply.

Look at page 8-52 of the manual. That's the schematic for the power supply. You can see on the left of the schematic are all the inputs from the main transformer to the PCB on P2, P4 and P5. You want to leave those connected. Disconnect all the other connectors. Those are the outputs and they are labeled on the schematic as far as where they go and the plug number. I cannot recall but I think they are all different sizes to they can only go back onto the connector they came off of, but as a failsafe you can get a fine-point permanent marker and label the plug connectors.

So unplug the connectors at P1, P6, P7, P8, P9, P10 and P11.

Now the power supply is isolated from the guts of the 48.

Now you can turn it on and get your favorite AC/DC volt meter and confirm that the voltages are close to what is listed on the schematic for each pin of each connector.

Go slow. Take your time and savor the sleuthing.

If you study the schematic you can see the connections that are duplicated. You don't have to check all the connectors. You're having a logic problem so if you did nothing else but checked P10 you'd have a lot of info right there...set your voltmeter to DC mode and measure across pins 5 and 6 (should have about +24VDC), across pins 1 and 3 (should see about +15VDC), and across pins 2 and 3 (should see about +5VDC)

Let us know!
 
The yellow Sync LEDs illuminate when pushed in.

The red REC LEDs come on when depressed, but do NOT flash.

The output source (input, sync, repro) LEDs all light up when their respective switch is selected.

No lights in the transport control section ever illuminate.

Thank you for the detailed instructions, sweetbeats. Between you and my manual, checking those voltages shouldn't be much of an issue. I'll let you know my results once I've completed the tests.
 
So, I've yet to find the time to check the PSU voltages.

Although, I have strongly considered opting out of all my classes for the rest of the semester and dedicating the time to this deck. :D
 
heeheehee...careful...

Just be prepared that if the PSU shows voltages at all points, that does not mean it is clean/healthy voltage. You would need an oscilloscope to check that. I'm a newbie at much of that but learning quickly.

And because of what you are describing with your transport control section and record ready lights I'm guessing there is some blown logic circuitry which repairing would be a very advanced task, far beyond my advisement.

Not trying to rain on your parade, but the 48 is not well.

Worst-case-scenario if you are dedicated to the 48, you got a SCREAMIN' deal on a clean parts deck and a set of DX-4D's...really. $100 is great. You could look for a healthy 48 and you'd be set for parts which, IMHO, is getting smarter and smarter to do.

If you decide you are over your head you'd be able to get your investment back in selling the DX-4D's alone on eBay. They go for at least $50 each +S&H. They'd go pretty quick if you listed them BIN at that price.

Keep us posted. Like I said, I'm not trying to discourage you, just think its good to have a relative stance before going in further. And remember, go slow, think about what you are doing before you do it. A single voltmeter probe accidentally laid across 2 of those small pins (shorting) can cause bad things to happen. "Don't cross the streams."

BUT...have fun, learn, and who knows? Maybe something is hosed in the PSU (and I know somebody that has a spare 48 PSU). :D
 
Saying goodbye...

Well, due to my lack of knowledge and inability to repair the deck, I'm putting it and the two DX-4Ds up on eBay. This deck is a project I'd love to get into, but currently lack the extra funding to fuel my interest.

Thanks for all the advice earlier in the thread. I feel very welcome on these message boards.

Tascam 48

DX-4D #1

DX-4D #2
 
Man I'm really sorry to hear that your selling them. It's too bad you didn't list them here before you put them on junkbay. At Least you know they would have gone to a good home. The best of luck. I'm looking at the auctions now.
 
Your problems are 100% IDENTICAL to the problems that I am having with my 42B. I, also, haven't had the time to chase electrons around in the unit. I am at a distinct disadvantage in not owning a manual for mine. If I could figure out the problem with mine I'd be very intererested in your deck and DBX so that I could remix some of my old tapes from my 80-8 days. :(
 
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