Tascam DX-2D DX-4D Calibration

The DX-8 or DX-4 are a different animal and they are full of problems from Tantalums and those cockeyed relays- I can remember using up 8 hours to fix some of them which then Tascam made an exchange program for a fixed cost. Those days are gone now. The double sided boards of the DX-8 are also notorious for cracks besides the other problems.
 
I totally agree with Skywave regarding the transistor. And anyway the ‘A’ parts are a higher spec part than the ‘B’ grade so usually you can always sub in an ‘A’ part for a ‘B’ or ‘C’.

I too was wondering what IC he is talking about. It helps to be as specific as possible when asking for help.

And, yes, again, I would never touch any trimmers or adjustments inside the processing chains of something like a dbx noise reduction unit unless I had the definitive calibration instructions and equipment to execute them. “Calibrating” a dynamics or noise reduction unit is not like simple level set calibration…yes there is that to do too at the input and output stages of the unit, but calibrating the dynamics processors, as mentioned earlier by Skywave, typically requires a pulse generator and a good oscilloscope among other bits of test gear…and the knowledge and expertise to use them.
 
My two DX-4D's don't need calibration the way my DBX 150'S and DBX 150X's Do.
I just plug them in and hit record. Wished I would have had the DX-4D'S back in 1985
for my Tascam 48ob which still works great today.

Jack
 
Okay, I don't touch the calibrations.
I understand the two versions of the IC and then I mount the SC2878A version.
The IC damaged was Q109.
Other damaged components I don't see.
The electrolitic capacitors seems to be good but I don't have a capacitor to check them.
Some welds are not stable and I will have to redo them.
 
The designation for a Transistor is Q while and IC is U. The 2SA are lower power than the 2SB parts and the 2SC are lower power than 2SD normally 2SA, B are PNP while the 2SC and 2SD are NPN A KSC1845 would have worked in this place. All datasheets gives a lot of subs.
 
Okay, I don't touch the calibrations.
I understand the two versions of the IC and then I mount the SC2878A version.
The IC damaged was Q109.
Other damaged components I don't see.
The electrolitic capacitors seems to be good but I don't have a capacitor to check them.
Some welds are not stable and I will have to redo them.
Okay. So in case it wasn’t clear in Skywave’s last post, transistors are not ICs. “IC” is short for integrated circuit, like a chip which includes multiple types of component functions on a single die. A transistor is a discreet (individual) solid-state component.
 
The designation for a Transistor is Q while and IC is U. The 2SA are lower power than the 2SB parts and the 2SC are lower power than 2SD normally 2SA, B are PNP while the 2SC and 2SD are NPN A KSC1845 would have worked in this place. All datasheets gives a lot of subs.
And I want to be clear when I was talking about ‘A’, ‘B’ or ‘C’ I was talking about the suffix…you won’t always find a part available in these different grades but sometimes you do.
 
Sorry,
I was wrong to writing.
Yes, it is a 2sc2878B NPN transistor, I will buy it as soon as possible.
 
IF you are going to play around with the encode and decode trimmers this would be the time to get the Bourns Cermet Trimmer so that the levels stay where they are set. I would be very careful not to mess around with the other trimmers as it takes equipment that I don't even have to work on these. A perfect stair step generator could be made but then why waste all that time doing it when these adjustments only go out by people tampering with them.
 
I found a hi-fi technician in my place who have the equipment to check the Tascam and gave me his help.
 
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