Hello, I was just wondering if anyone can give some tech advice...
I have recently been fixing up a Tascam 388, the machine now seems to be all working as far as I can tell, all the transport functions, and it passes audio on all channels, Though I have not yet fully tested every single audio routing.
My problem is a thermal resistor on the control pcb (2w 47k) R405 which is running extremely hot and heats straight away after turning the machine on. Somethings not right there and is drawing too much current I guess?
When I first got the machine there were burned flux/heated marks from this resistor on PCB and the inside casing of the machine it's self, the old resistor seemed fine when I tested it, but I replaced it anyway. There is a cap close to it that looks to of had some heat now also, after having it on a short time to test. Visually everything else looks ok - I did recapped all the board and hoped this would get rid of the problem, but has not. I'm thinking it must be a short somewhere on the board? or a power supply problem?...
When testing voltages on the mother board (2) at power supply pcb pins, I'm getting two high readings: P6 pin 1 should be +25v (reading +40v) and P6 pin 3 should be +15v (reading +20v)
Would this be related to my control board resistor problem??
Is something drawing too much power? or not enough power to get the higher volt readings? or is this a different problem altogether?
Has anyone had this problem before? or If anyone has any ideas of what I should look at and check next regarding this it would be a great help and greatly appreciated.
Thank you in advance,
Robin
I have recently been fixing up a Tascam 388, the machine now seems to be all working as far as I can tell, all the transport functions, and it passes audio on all channels, Though I have not yet fully tested every single audio routing.
My problem is a thermal resistor on the control pcb (2w 47k) R405 which is running extremely hot and heats straight away after turning the machine on. Somethings not right there and is drawing too much current I guess?
When I first got the machine there were burned flux/heated marks from this resistor on PCB and the inside casing of the machine it's self, the old resistor seemed fine when I tested it, but I replaced it anyway. There is a cap close to it that looks to of had some heat now also, after having it on a short time to test. Visually everything else looks ok - I did recapped all the board and hoped this would get rid of the problem, but has not. I'm thinking it must be a short somewhere on the board? or a power supply problem?...
When testing voltages on the mother board (2) at power supply pcb pins, I'm getting two high readings: P6 pin 1 should be +25v (reading +40v) and P6 pin 3 should be +15v (reading +20v)
Would this be related to my control board resistor problem??
Is something drawing too much power? or not enough power to get the higher volt readings? or is this a different problem altogether?
Has anyone had this problem before? or If anyone has any ideas of what I should look at and check next regarding this it would be a great help and greatly appreciated.
Thank you in advance,
Robin