Technical Advisory A021095
Situation:
The earliest models of the Sony PCM digital audio recorder (3324 and 3324A versions) have a different head configuration and electronics than does the 3324S (the current version). On the older versions, high errors sometimes occur in the insert mode. This behavior is often attributed to tape, but we have often found that the tape is fine. Solution: In the normal position, the relays are connected to the advance record head. Thus, if a user has low errors in the advance record mode but much higher errors in the insert mode, it is highly recommended that the record switching relays be replaced. In the newer 3324S, there is only one record (write) head, a playback (read) and an optional confidence (read) head. On the 3324 and 3324A models, there are TWO record (write) heads and a single playback (read) head. The head configuration looks something like this:
All models of 3324 recorders have only one set of record amplifiers. In the newer 3324S version, the record amplifier is directly connected to the record (write) head. In the older versions, however, the record current must be switched between the two record heads depending on the recording mode (advanced or insert) desired.
One of the standard field modifications for the 3324 and 3324A is the replacement of the reed relays that direct the record current to the proper head. If the contact resistance on these tiny relays increases at all (and it sometimes does), the amount of record current to the record head is decreased, the PCM code recorded on the tape is lower in level and the signal will have improper equalization. This may result in high errors and an inability to correctly recover recorded data.
3M Audio and Video Products Division
3M Center, Building 223-5N-1 St. Paul, MN 55144-1000