ADA Depot - A Forum To Support Users of ADA Amplification Gear
ADA Preamps => MP-2 => Topic started by: lesag002 on July 15, 2014, 01:51:32 PM
-
Ever since I bought my MP2 (early 90's?), it has always remained in standby mode (with the "tubes warming up..." message) when first turned on. In order to get out of standby, I've always had to turn the power switch off and on again. It's as if a sensor is not detecting that the tubes are warmed up, so it never switches the unit out of standby. But when it's turned off and on again, the sensor apparently detects heat and bypasses standby and the unit is then ready to play. This is the only problem I've ever had with it. Still kicking myself for not returning it for another unit. Any fix for this?
-
There's no heat sensor or anything like that.It actually works with a sort of timer.Usually the problem is U104,that's a 74ls08 ic.Normally when you replace it ,it will sove the problem.It's also cheap around 0.5 to 1 $.If that doesn't help try to replace C104 (33µF/50V).
-
Awesome! Thanks very much!
So, is this IC clearly marked on the pcb? Is it in a socket so I can easily swap it out?
-
Normally yes,try to locate it in the schematics pcb.
It's not in a socket so be carefull.
http://tuukan.fliput.net/pcbfix_en.html
Best way if you don't a desoldering gun is to cut the legs and get them out one by one,see link.
-
Thanks again! I just noticed the eprom is version 1.23. Any chance upgrading that would fix the issue. At least that's in a socket ;)
What does ver. 1.41 do?
-
No that doesn't fix this problem.
Fixed some small bugs but most importent faster switching.