Tascam 246 PGM/Monitor L/R VU Meter not working and Track 3 Playback issue

[skindiva]

Hi all,

I'm in the process of refurbishing a Tascam 246 at the moment. So far I've manged to fix all the issues except these 2:

1. Track 3 will record to tape however it only plays back when the "monitor" switch is engaged. When I press the PGM switch in the volume drops dramatically to a barely audible level. Audio recorded to track 3 of the tape works as when the "monitor" switch is engaged I get full signal leading me to believe there is a fault somewhere in the PGM playback board but I open to hear if any of you guys here have any opinions?

2. The PGM/Monitor L/R VU Meters light up but do not move or register signal when playing back audio from tape. Not sure what could be causing this issue.

If anyone has any pointers as to where to start looking I'd be extremely grateful. thank you!

 

[sweetbeats]

1. If I had to make a guess, I’d bet you need to replace U102 on the Monitor A PCB. This is a 4000 series quad bilateral switching IC, a 4066. Anytime I’ve encountered weird signal flow issues like yours over the past 10 years or so in this era of Tascam gear, I look first to see if there is a switching IC involved, and if there is like maybe 85-90% of the time it’s a failed IC. This is increasingly common in the 388 and M-300 series consoles. The 4066 is still readily available and very cheap from places like Mouser and Digikey. The other thing to do/check is to see if exercising any connections to/from the Monitor PCBs helps, or if you can make signal intermittently work while gently manipulating any connections. The BUSS PCBs in these things, the board that spans across the bottom of all the mixer PCBs, are pretty notorious for being a problem too…failed solder joints. So you can check that too…not sure how the 246 is all put together…maybe that PCB is the only thing handling connections to/from the Monitor A PCB.

2. Do the meters jump when you power up?