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TM3 calibration

Posted: Jul 3rd, '14, 18:26
by maurice
I followed the steps and never found anything about TM3 value.
TM4 is 130mV in the noise section
TM2 and TM1 set two periods in the cymball
TM3 just sits there ?

Did i miss something ? :?:



Also, handclap is muted (maracas is not) for the moment but I will try first what I found on other threads,

"Q28 or Q29 doesn't work properly . Try to replace first Q28 then Q29 "
I dont know how to test them so Ill change both.

Re: TM3 calibration

Posted: Jul 3rd, '14, 18:47
by ElSchtroumpf
TM3 is the calibration for the handclap offset, you can find this procedure on p.14 of the original 808 service manual.

Re: TM3 calibration

Posted: Jul 4th, '14, 11:30
by jeroenbvo
LOL, I was just wondering the exact same! Sorted, thanks ElSchtroumpf!

Re: TM3 calibration

Posted: Aug 5th, '14, 10:43
by maurice
Can someone explain the procedure here ? All I found was a intriguing drawing :oops:
http://imgur.com/hevr78Q
Image

Re: TM3 calibration

Posted: Aug 6th, '14, 15:43
by guitarsucks
Hey. You need an oscilloscope. Connect probe tip to TP5 ( its called out in the original TR-808 service manual - take TP5 from the correct side of R375 (470K) can't recall which side at the moment- you can also get a reading off components directly connected to R375) in the handclap section, connect ground from the probe to an accessible ground point. You're looking for 6 Vpp (Volts peak to peak).

Hope that helps.