• Amplituner Daewoo DV-115 - nie włącza się

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Amplituner Daewoo DV-115 - nie włącza się

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#1 Amplituner Daewoo DV-115 - nie włącza się

by bpjl • 21 September 2020, 16:01
Witajcie.

Dostałem amplituner Daewoo DV-115 z wciśniętym do wewnątrz gniazdem słuchawkowym. Urządzenie włączało się a czy było sprawne? Tego nie wiem.
Otwarłem je, zamontowałem gniazdo na miejscu (nic nie było złamane, tylko wyszło spod śruby). Nie wiem co mogło się stać, wszystko jest podłączone tak jak było ale amplituner teraz nie włącza się. Kompletnie nic, jakby nie dostawał zasilania.
Może ktoś pomoże sprawdzić co może być nie tak, a co za tym idzie co mogło się stać?

Re: Amplituner Daewoo DV-115 - nie włącza się

by Google Adsense [BOT] • 21 September 2020, 16:01

#2 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by matic • 21 September 2020, 20:05
Measure the voltages on following components:
- Resistor R706
- Capacitor C705
- Voltage to ground on cathode (- pin) of D727

#3 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by bpjl • 21 September 2020, 20:34
R706 = 1,5V
C705 = 0V
D727 cathode to GND = 0V

I noticed that the input of IC702 is 13V and the output is 0V. It's some kind of fuse. Can I short it for further trials?

#4 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by matic • 22 September 2020, 07:46
bpjl wrote:I noticed that the input of IC702 is 13V and the output is 0V. It's some kind of fuse. Can I short it for further trials?
IC702 is damaged and needs to be replaced.

bpjl wrote:Can I short it for further trials?
Instead of a short circuit it is better to use a fuse, otherwise you may damage the transformer T701.
Replace the chip IC702 with a 630mA fast acting fuse (F 0.63A).

You can use a fuse in the plastic package as on the following picture.
Image

Before connecting power supply to the machine measure the resistances to ground on both pins of diode D727.

#5 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by bpjl • 23 September 2020, 05:05
matic wrote:Before connecting power supply to the machine measure the resistances to ground on both pins of diode D727.


anode=3,3k
kathode=no reading, as if a circuit break (i have front panel disconected)

#6 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by matic • 23 September 2020, 09:15
Remeasure both resistances with front panel connected.
If both resistances will be still high (in kΩ range or greater), replace the fuse and test the machine.

#7 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by bpjl • 23 September 2020, 16:56
After connecting the front panel on the D727 I got:
- anode: 3.3k
- cathode: 165k

I am waiting for the fuses to reach me to replace the IC702.

I don't understand one thing. The MUTE_B + signal from the motherboard comes out via the D727 diode. When I set the multimeter to the continuity mode, I have a direct connection between the D727 cathode and the MUTE+B pin in the CP711 connector (or at least where it should be). As my DV-115 is a version without a mic board, I don't have a CP711 connector, but a CP712. D727 has no connection to any pin in CP712. So where does the resistance on the D727 cathode come from when connecting the front panel? I am browsing and looking at the service manual and schematics and can't figure it out.

Image

#8 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by matic • 23 September 2020, 19:54
bpjl wrote:I have a direct connection between the D727 cathode and the MUTE+B pin in the CP711 connector (or at least where it should be).
I don't understand what is strange here. The diode D727 and connector CP711 are on the same board, so there should be connection between them according to the schematic.

Signal "MUTE_B+" is also connected to the DSP board with a wire from connector CP503 to CN503.

#9 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by bpjl • 23 September 2020, 20:27
matic wrote:I don't understand what is strange here. The diode D727 and connector CP711 are on the same board, so there should be connection between them according to the schematic.

I understand that. I mean the next part.

matic wrote:Signal "MUTE_B+" is also connected to the DSP board with a wire from connector CP503 to CN503.

Okay. When I measured the resistance on the D727, I had the front panel connected (CP903->CP903, CN901->PN902, CN904->CP712), but not the DSP board. So where do these 130k on the D727 cathode come from?

CP712 have only +5.6V, D-G and VFD signals.

-=edit=-

matic wrote:IC702 is damaged and needs to be replaced.

matic wrote:Replace the chip IC702 with a 630mA fast acting fuse (F 0.63A).


So I did. I decided to run the motherboard itself without any additional circuits or the front panel. I measured 5.6V signal on the CP712 connector and it turned out that only 4.92V is there. I thought that, propably, it is not the front panel shorting but something else.

I looked closely and it turned out that I have not disconnected one PCB yet -
PCB REGULATOR.

Image

After disconnecting it, the voltage jumped to its 5.6V. Interestingly, after reconnecting it is still 5.6V. There is also 5.6V on the anode of D905, and 4.8V on the cathode.

We are looking far while there is no voltage on the CP703. So if I am not mistaken the main transformer power supply. In fact, I have already checked the R707, Q702, D707 and the RY701 relay, but maybe it should go back to the beginning and go through it again? Maybe you will mark me or describe what voltages (more or less) I can expect on these elements? My measurements are as follows:

Image

#10 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by matic • 24 September 2020, 22:04
bpjl wrote:Okay. When I measured the resistance on the D727, I had the front panel connected (CP903->CP903, CN901->PN902, CN904->CP712), but not the DSP board. So where do these 130k on the D727 cathode come from?
130kΩ is pretty high resistance, so there is no connection between D727 and front panel. This resistance is caused by other components to which this diode is connected.

bpjl wrote:Maybe you will mark me or describe what voltages (more or less) I can expect on these elements?
Here are the voltages, which I expect. On the signal line "ST/BY_RLY" should be 0V in stand-by, when you press on the power button, there should appear 5V.

Image

#11 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by bpjl • 25 September 2020, 05:00
Here are the voltages I measured:

Image

Those on the R703 are measured with the ST / BY button pressed and not pressed.

#12 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by matic • 27 September 2020, 11:36
Measure the voltage to ground on pin 29 of chip IC904 (it is located on the front panel board) in the following cases:
a) Power button S907 released.
b) Power button S907 pressed.

#13 Re: Amplituner Daewoo DV-115 - nie włącza się. Szukaj w tym temacie

by bpjl • 27 September 2020, 11:50
In both cases, this voltage is 0V.

#14 Re: Amplituner Daewoo DV-115 - nie włącza się

by matic • 27 September 2020, 15:27
Measure the voltages to ground on pins 3, 28, 39, 40, 44 of chip IC904.

#15 Re: Amplituner Daewoo DV-115 - nie włącza się

by bpjl • 27 September 2020, 16:11
    3 - 4,7V
    28 - 4,4V
    39 - 2,3V
    40 - 4,6V
    44 - 4,7V


#16 Re: Amplituner Daewoo DV-115 - nie włącza się

by matic • 27 September 2020, 18:28
Measure the resistances to ground on pins 29, 30, 31 of IC904.

Measure the voltages to ground on both pins of diodes D904, D905 (both are located on the front panel board).

Do you have an oscilloscope?

#17 Re: Amplituner Daewoo DV-115 - nie włącza się

by bpjl • 27 September 2020, 19:46
matic wrote:Measure the resistances to ground on pins 29, 30, 31 of IC904.

29 - 17kΩ
30 - 17,2kΩ
31 - 17kΩ

matic wrote:Measure the voltages to ground on both pins of diodes D904, D905 (both are located on the front panel board).

D904 - anode = 5,57V, kathode = 4,86V
D905 - anode = 5,57V, kathode = 4,79V

matic wrote:Do you have an oscilloscope?

Unfortunately not

#18 Re: Amplituner Daewoo DV-115 - nie włącza się

by matic • 27 September 2020, 19:50
Measure the voltages to ground on pins 29, 30, 31 of IC904.

#19 Re: Amplituner Daewoo DV-115 - nie włącza się

by bpjl • 27 September 2020, 19:53
matic wrote:Measure the voltages to ground on pins 29, 30, 31 of IC904.

All three = about 0,1V (considering my multimeter it could be 0V)

#20 Re: Amplituner Daewoo DV-115 - nie włącza się

by matic • 27 September 2020, 20:24
Lift the pin 29 (or cut the copper trace to this pin) of chip IC904 and perform the following measurements.

Measure the voltage on capacitor C959 in the following cases:
a) Power button S907 released.
b) Power button S907 pressed.

Re: Amplituner Daewoo DV-115 - nie włącza się

by Google Adsense [BOT] • 27 September 2020, 20:24
 This topic is marked as ARCHIVAL. Please only reply if your message contains the solution (Terms and Conditions p. 12.1).
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