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Let's Get Technical => Troubleshooting Problems => Topic started by: RVLP on December 09, 2016, 04:14:22 AM

Title: MP-1 v.2 Not editable equalizer.
Post by: RVLP on December 09, 2016, 04:14:22 AM
When I try to edit the equalizer, the numbers on the display change but the sound does not change at all.
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: MarshallJMP on December 09, 2016, 06:04:25 AM
Does this happend on bass,mid,treble and presence ?
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: RVLP on December 09, 2016, 09:19:46 AM
Does this happend on bass,mid,treble and presence ?
Yes.
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: MarshallJMP on December 09, 2016, 11:20:30 AM
There are 2 TC9170AP chips near the front (they are in ic sockets); check if they get hot.
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: RVLP on December 09, 2016, 12:40:04 PM
They are barely warm.
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: MarshallJMP on December 10, 2016, 08:45:52 AM
Ok can you measure the voltage on pin 1 and pin 16 (to ground)?
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: RVLP on December 10, 2016, 10:48:31 AM
7.18 V - Is the voltage between pin 1 and pin 16. The voltage between pin 1 and ground is -6.1 V , between pin 16 and ground is +1V.
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: RVLP on December 13, 2016, 02:15:17 PM
I fixed the device today. Thanks to everyone who wanted to help.
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: MarshallJMP on December 13, 2016, 02:48:36 PM
So what was the problem, seems to me the voltage on pin 16?
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: RVLP on December 13, 2016, 08:45:08 PM
The is a  short-circuited ceramic capacitor H5M 104 ( seems a filter circuit of U19, U20). It connected in parallel with a diode and located near U20, on the left.
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: MarshallJMP on December 14, 2016, 04:03:20 AM
Ah ok I see so it was the cap that made the voltage go way too low.
Title: Re: MP-1 v.2 Not editable equalizer.
Post by: RVLP on December 14, 2016, 03:49:28 PM
I think it's just old age.I already replaced the electrolytic capacitors in the power supply circuits of tubes.