PHILIPS MCD388 AUX IN how to ? - Page 1
Forum section: electronics / repair

author: tiesto23
author_rank: Contributor
timestamp: April 28, 2020, 10:01:40 pm
content: hii have PHILIPS MCD388it have wireless subwooferthe dvd player i lost iti want to to add aux in input to subwoofer and use it with jack cable not wirlessany sugg how to do itthis is schematic of amp boardTHNX

author: Manul
author_rank: Super Contributor
timestamp: April 28, 2020, 10:41:09 pm
content: Well, you can try something like that. If you have mono signal, you need only one resistor. You may need to change the value of resistors to get desired sensitivity.

author: Manul
author_rank: Super Contributor
timestamp: April 28, 2020, 10:47:49 pm
content: And if you will never use it wireless, you can remove this resistor.

author: tiesto23
author_rank: Contributor
timestamp: April 28, 2020, 11:55:45 pm
content: Quote from: Manul on April 28, 2020, 10:41:09 pmhi thnx for your helpi just make as you show mebut nothing in output no sound no distorationwhat is the problem ??

author: Manul
author_rank: Super Contributor
timestamp: April 29, 2020, 12:15:41 am
content: There can be two things.1. It is on standby (off)Make sure, that LED isnoton. I marked connection to this LED.2. It is on mute (disabled output)If there is voltage on resistor marked with arrow, it means it is on mute. Try to remove that resistor to disable mute.

author: Manul
author_rank: Super Contributor
timestamp: April 29, 2020, 12:29:47 am
content: Sorry, I got it backwards, when LED is ON it means it is ON.

author: tiesto23
author_rank: Contributor
timestamp: April 29, 2020, 12:41:05 am
content: Quote from: Manul on April 29, 2020, 12:29:47 amthe led is offi try also remove resistornothing happen

author: Manul
author_rank: Super Contributor
timestamp: April 29, 2020, 12:49:03 am
content: Ok, do you have voltages from power supply +24V, +12V, -12V?

author: tiesto23
author_rank: Contributor
timestamp: April 29, 2020, 12:54:27 am
content: Quote from: Manul on April 29, 2020, 12:49:03 amyes i test it nowall ok +12 -12 +24

author: coromonadalix
author_rank: Super Contributor
timestamp: April 29, 2020, 01:08:02 am
content: The TDA8947 has 2 modes of operation .... see table 5https://www.nxp.com/docs/en/data-sheet/TDA8947J.pdf

author: Manul
author_rank: Super Contributor
timestamp: April 29, 2020, 01:10:07 am
content: Good. The problem is that STANDBY and MUTE is controlled by microprocessor and because you do not have active wireless connection, it turns off AMP.But you should be able to force the AMP to work by removing these resistors.

author: tiesto23
author_rank: Contributor
timestamp: April 29, 2020, 01:17:37 am
content: Quote from: Manul on April 29, 2020, 01:10:07 amthnx very much now its workbut i notice sound its a bit lowany sugg how control sound ?i mean increase\decrease

author: coromonadalix
author_rank: Super Contributor
timestamp: April 29, 2020, 01:22:09 am
content: something like thissee the photos, instead of the fixed 10k ohms resistors you add this circuit

author: tiesto23
author_rank: Contributor
timestamp: April 29, 2020, 01:26:32 am
content: Quote from: coromonadalix on April 29, 2020, 01:22:09 amcan you show me exactly how connect variable resistor on ampi mean in schematic

author: Manul
author_rank: Super Contributor
timestamp: April 29, 2020, 01:35:36 am
content: So you want volume control knob to be outside, like in this picture?If you do not want this, then it can be done with lower resistors on AUX IN, like 4.7K, 2.2K, 1K... Lower resistors will increase sound.

author: tiesto23
author_rank: Contributor
timestamp: April 29, 2020, 01:40:32 am
content: Quote from: Manul on April 29, 2020, 01:35:36 amyes it will be good to use volume control knobhow to conect it ?

author: coromonadalix
author_rank: Super Contributor
timestamp: April 29, 2020, 01:46:15 am
content: You have to do some small work on your side, you have to understand how potentiometers works and how to connect them.We have laid out the works for you ... all your answers was in the post i have made with the 3 pictures ...You have a beautiful tutorial here:https://www.doeeet.com/content/eee-components/passives/basic-principles-of-potentiometers-variable-resistors/

author: tiesto23
author_rank: Contributor
timestamp: April 29, 2020, 01:58:57 am
content: Quote from: coromonadalix on April 29, 2020, 01:46:15 amthank you very much ,, i dont understand exactly how its work im a beginner thats why i ask how to setup it in schematic that way i can understand it very wellthanx

author: Manul
author_rank: Super Contributor
timestamp: April 29, 2020, 02:02:22 am
content: Well, something like that.

author: tiesto23
author_rank: Contributor
timestamp: April 29, 2020, 02:09:54 am
content: Quote from: Manul on April 29, 2020, 02:02:22 amthank you very much for your help & good assistancetommorow i will add this changment and tell you the resultthnx#staySafe