Hello, I'm a newbie to posting here and 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 after fixing several problems. As far as I can tell all the transport now functions, and it passes audio on all channels, meters work etc. Though I have not yet tested every single audio routing.
Anyway... my current problem is a large thermal resistor on the control pcb (2w 47k) R405 which is getting super hot right away when turning the machine on. I know somethings not right there and is drawing too much current?
When I first got the machine there were burned flux/heated marks from this resistor around the area and on the inside casing of the machine it's self, the old resistor seemed fine when I tested it, but replaced it anyway. There is a cap close to it that looks to of had some heat now also... 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 high readings on two of the feeds on both AC and DC. The other one is correct and what I would expect.
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?
I could be testing it wrong but have double check a few times now? it's strange as everything seems to be working fine regarding the transport etc?
Has anyone had a similar problem and how did they resolved it? or If anyone has any ideas of what I should look at/check next regarding this it would be a great help.
I maybe missing something really simple but thought I would ask here first before I start taking it apart again.
Thanks in advance
Robin
I have recently been fixing up a Tascam 388, the machine now seems to be all working after fixing several problems. As far as I can tell all the transport now functions, and it passes audio on all channels, meters work etc. Though I have not yet tested every single audio routing.
Anyway... my current problem is a large thermal resistor on the control pcb (2w 47k) R405 which is getting super hot right away when turning the machine on. I know somethings not right there and is drawing too much current?
When I first got the machine there were burned flux/heated marks from this resistor around the area and on the inside casing of the machine it's self, the old resistor seemed fine when I tested it, but replaced it anyway. There is a cap close to it that looks to of had some heat now also... 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 high readings on two of the feeds on both AC and DC. The other one is correct and what I would expect.
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?
I could be testing it wrong but have double check a few times now? it's strange as everything seems to be working fine regarding the transport etc?
Has anyone had a similar problem and how did they resolved it? or If anyone has any ideas of what I should look at/check next regarding this it would be a great help.
I maybe missing something really simple but thought I would ask here first before I start taking it apart again.
Thanks in advance
Robin
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