22-2: Level discrepancies in L and R channel

[Saudade]

Hi,

I use the tape deck to bounce mixes from my DAW and record it back. Recently I noticed a huge difference in levels between the L and R channels.

When I input to both channels at equal and constant levels (a sine wave loop at 1 khz), the deck meters (set to source) reflected L ch at -1 and R ch at -6 (dbv? dbu? whatever ) and my A/D inputs (roundtrip) reflected L -19.5 and R -19.3 (dbfs?).

When I engaged the monitor to "tape", the A/D shows L -16.7, R -22.6 (at 7.5 ips) and L -17.3, R-22.2 (at 15 ips).

I hope I am making sense here, I know this is a very unscientific way of testing, but I was trying to apply the naive and logical (to me) thinking that deck meters and my A/D should roughly show the same thing (which apparently doesn't) and that with the tape engaged in the signal path, the discrepancy is even larger.

So what is wrong here? Which part(s) of my deck is breaking down?

For the moment I can compensate by turning up the right (softer) channel, but I am worried if these are symptoms that some critical component is failing. Is there anything I can fix myself here? (a tape deck is non-existent here )

I have already tested all other components in the chain, all cables are new, my soundcard inputs and outputs are alright. The tape used are new unused rolls. The heads and tape path are all cleaned.

 

[The Ghost of FM]

Your 22-2 needs an internal calibration and a head wear and alignment check up.

If you have the full manual with servicing instructions, it would step you through the calibration process but it's probably best to seek out an experienced service center in your area and have them do it. For a two track deck, it shouldn't take them longer then an hour to do a full mechanical and electrical calibration and then the deck should be stable for several hundred hours of use.

If the heads are worn out, then that could add to the repair cost.

Where did you get this deck from? Do you know the full history of the deck, as in how much use it saw and if the previous owners messed around with the internal settings?

Cheers!

 

[Saudade]

okok...6 mths later....now I have found the local Tascam authorised dealer/servicing centre is willing to have a go at it. But I am worried about them making it worse cos the older generation of technicians (those who worked on tape decks before) have retired

So my question is, assuming they have nothing but those electronics testing equipment, what do I need to provide them with to align/calibrate the deck? Do I need to give them a MRL tape (what brand?). Do I need to tell them to align it to some brand of formulation of tape and provide them a sample of the tape? I have a reel each of LPR35, SM468 and "NOS" Scotch 207 (bought it sealed in origina packaging off ebay).

Is there any specific instructions I should give them on what to check on (i have the full instruction/servicing manual on pdf)? And are there any sites that run through the calibration/alignment on this model so I can read up before I send it down?

Thanks for any insight

 

[cjacek]

Is there any specific instructions I should give them on what to check on (i have the full instruction/servicing manual on pdf)?

All you really need to give a competent tech (one who ideally has all the necessary test gear) is the operations / service manual, which goes into great detail, outlining exactly what needs to be done and also bring the tape that you want them to bias the machine for. The LPR35 is a good choice. They also need to have an alignment / calibration test tape and set the parameters precisely as per the manual.

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