Tascam Portastudio 414 MkII - No playback on track 2

[AaronC]

Hello I have recently acquired a Tascam 414 MkII

The unit is in really good condition both inside and out, the only thing that looked worn out were the rubber belts which I have since replaced.

Everything works perfectly tho track two does not seem to record to tape, or rather, play back what has been recorded.

When monitoring live track 2 the VU meter lights up and I can monitor my input perfectly. When I go to record through track 2 nothing is recorded.

I have traced continuity on all the wires leading to the record and play head, all are fine.

I also did the trick where I recorded on all four tracks and then flipped the tape over and played in reverse. It seems track 2 is able to record after all because I had what was recorded on track 2 playing on track 3, but what was recorded on track 3 was not able to be played back on track 2, the VU meter would not work at all and no output was heard.

So I guess the short has something to do with playback from the playhead?

Do you have any advice on how to continue diagnosing this? The board looks basically spotless and no caps look busted, no leaks, no solder messed.

I feel like i'm so close and just need someone with more experience than me, hence why I am reaching out here.

Does anyone know where I can find a schematic? Could it be a bad IC? or broken op amp or something?


Thanks for you time,

Can post pictures and answer more questions, Thank you!

Aaron

 

[RKY6]

Hey man, Im having the same type of problem with my 488.. sorry I dont have an answer but Ive been asking anyone I can think of that might know as well. Please keep me posted if you get this figured out and Ill do the same. Good luck

 

[AaronC]

Hello @RKY6 I have seemed to fix the problem.

I opened up the tascam and sprayed deoxit on every connector plug, both sides. I'm not sure if thats what fixed it, I also visually inspected track 2 pcb layout as its clearly arranged in a line.

On the board I noted two points of interest, some solder that looked slightly discolored.

I reflowed the solder over one of the op amps 'u201' on the board, I also turned my attention to the other point of discoloration, a single 1uf 50v capacitor, it did not look bad in any way or bloated or leaking but there was a slight discoloration on the solder points so I thought best to replace it.


While trying to replace it I actually popped the pcb pad clear off the circuit board! and had to repair it very carefully with copper tape to create a new pad.

I then successfully replaced the capacitor, put it back together, and prayed.... and! it worked!

So in order I did this
Sprayed Deoxit on EVERY connector plug
visually inspected all solder point on channel 2 section of pcb
Reflowed solder over op amp on channel 2 section of pcb
Made sure the suspect solder points were not touching (shorting each other)
Replaced Capacitor 1uf 50v that looked suspect


Unfortunately because I did more than one thing at once I cannot say what it was that fixed it.
The biggest take away is that I kept diagnosing and troubleshooting the problem to pinpoint it.

At the time of making the post I ruled out it being the problem of the connection to the play and record head, I proved it could record it was just a playback problem, that narrowed my search significantly

Dont give up and god speed! You can fix it, I pray in good faith, you will!

Aaron

 

[RKY6]

Nice! That’s awesome, glad you got it fixed. Thanks for the reply/info I’ll have to try the same. Thanks again man I really appreciate it!