Service Manuals, User Guides, Schematic Diagrams or docs for : DYNACORD Audio DPA 4260 hfe_dynacord_dpa_4245_4260_service_de

<< Back | Home

Most service manuals and schematics are PDF files, so You will need Adobre Acrobat Reader to view : Acrobat Download Some of the files are DjVu format. Readers and resources available here : DjVu Resources
For the compressed files, most common are zip and rar. Please, extract files with Your favorite compression software ( WinZip, WinRAR ... ) before viewing. If a document has multiple parts, You should download all, before extracting.
Good luck. Repair on Your own risk. Make sure You know what You are doing.




Image preview - the first page of the document
hfe_dynacord_dpa_4245_4260_service_de


>> Download hfe_dynacord_dpa_4245_4260_service_de documenatation <<

Text preview - extract from the document
                      SERVICE MANUAL




DPA 4245 / DPA 4260 POWER AMPLIFIER
MEASUREMENT SPECIFICATIONS: DPA power amplifiers                                             complete appliance

Names of the individual printed board assemblies and their corresponding EDP numbers:

                                         EDP numbers of the main boards
                         DPA 4245                                                 DPA 4260
                          84 188                                                   84 189

                       Board section                                               Index
                         Main PCB                                                    1
                        Supply PCB                                                   4
                         LED PCB                                                     3

Input-PCB (index 1) and Output-PCB (Index 2) are located on the printed board assembly 81340.

Measuring conditions, unless differently specified:

-   measuring tolerance:                                           X    = 1.5dB
-   measuring frequency:                                           f    = 1kHz
-   all stated levels refer to:                                    U    = 775mV (0dBu)
-   level controls are set to their clockwise margin:
-   XLR connector pin-assignment:                                      PIN 1    = GROUND/SHIELD
                                                                       PIN 2    = + INPUT
                                                                       PIN 3    = - INPUT
- source impedance for the induction via the XLR-type connector:        R(Q) = 50 ohms

- the AMPLIFIER PCB is provided with service connectors:

                 CNS1                                   CNS2                                 CNRC
         PIN             Assigned to            PIN            Assigned to          PIN           Assigned to
          1                 -Vcc                 1            LIM A Switch           1            LIM Out A
          2               BIAS +A                2                -15V               2            LIM Out B
          3               BIAS -A                3            LIM B Switch           3          Standby via RC
          4             FAN Voltage              4                +15V               4           Standby LED
          5                +Vcc                  5               AGND                5               -Vss
          6               BIAS +B                6            Speaker Out A          6               +Vss
          7               BIAS -B                7            Relay/Protect          7                n.c.
          8            Temp Heatsink             8            Speaker Out B          8                n.c.

- Pin-assignment of the power amplifiers output connector:

          PIN                                      Function                                    Channel
            1           + pole of the 100V output and + pole of the 25V output
            2           - pole of the 25V output and + pole of the 70V output
            3           - pole of the 70V output and - pole of the 100V output                      B
            4           + pole Direct Output
            5           - pole Direct Output
          6,7           not assigned                                                                -
            8           - pole Direct Output
            9           + pole Direct Output
           10           - pole of the 70V output and - pole of the 100V output                      A
           11           - pole of the 25V output and + pole of the 70V output
           12           + pole of the 100V output and + pole of the 25V output

Pin-assignment of the Power Remote connector:           PIN 1 control voltage -
                                                        PIN 2 control voltage +




                                                          1
Nominal load impedances

                                    100V output                   70V output                   25V output
        DPA 4245                       28,5                          14                           1,8
        DPA 4260                        20                           9,8                         1,25



1. Operation voltage:                                          U(B) = 230V / 50Hz ... 60Hz

2. Deviation limit of the operation voltage:                   -30% .... +10%

3. Power consumption (both channels driven via the 100V output, f = 1kHz)

                                                                                DPA 4245             DPA 4260
idling condition power consumption                                               30-60W               40-80W
nominal power consumption (nominal load)                                         1580W                1950W
standard power consumption (nominal load)                                         470W                 620W
maximum power consumption (nominal load)                                         1680W                2180W
power consumption at 1/8 of the maximum output capacity                           600W                 870W

4. Settings

4.1. IDLING CURRENT ADJUSTMENT

Connect the DC-volt meter at the BIAS measuring points (refer to service connectors) and adjust the idling
current via the trim potentiometer VR101/VR301 (located on the Main PCB). Adjust both channels of the power
amplifier A&B to U(DC) = 7.5mV. Adjusting the idling current has to be performed at normal room
temperature. In case the power amplifier had previously been operated, it has to be given several hours to regain
its normal temperature.

4.2. VCA - OFFSET

Rhythmically open and short-circuit CNS2.1 and CNS2.2 for channel A as well as CNS2.3 and CNS2.2 for
channel B. The switches are located on the Main PCB. Using VR100 or VR300 respectively to adjust the power
amplifier's Direct Output to its minimum offset (with oscilloscope to minimal peak value or to the audible
minimal volume of the interfering pulse).

5. Functioning test

5.1. OUTPUT - offset voltage

DC-voltage measuring at the Direct Output A/B with U(DC) 10mV.

5.2. LIMITER

5.2.1. Voltage limiter

Both channels separately driven without load via the Direct Output with a 1 kHz signal up to U(A) = 38V.
Increase the input voltage by 10 dB. The LIMITER LED lights and the output voltage ascents by approx. 1.5 dB
or 2.5 dB respectively to approx. 44V or 52V, respectively. The distortion rate of the limited signal should not
ascent above 0.8%.

5.2.2. Distortion limiter

Both channels separately driven via the Direct Output at 2 with a 1 kHz signal up to U(A) = 20V or U(A) =
25V, respectively. Increase the input voltage by 5 dB. The LIMITER LED lights and the output voltage ascents
by approx. 1.5dB to approx. 25V or 29V respectively and it is slightly clipping. The distortion rate of the limited
signal is approx. THD = 2 ... 3%. Further increasing the input signal by +10dB should not result in a remarkably
higher clipping of the output signal.


                                                         2
5.2.3. Attack- and release times

separately testing the power amplifier channels is mandatory: Test has to be performed at the Direct Output
     without load.
1.) Drive the power amplifier's input with a burst signal (f = 1kHz, 10 cycles, rate : 3 sec.) and U(E) = +10dBu.
2.) Monitor the output signal via oscilloscope. After 1 - 2 signal periods, the limiter has reduced the major
distortion to a minor residual distortion (THD  1%)
    attack time: approx. 2 ms                release time: approx. 130 ms

5.3 POWER-ON DELAY

Feed the test signal to the power amplifier input. Switch the power amplifier ON using the "Power On" switch.
Approximately 2 seconds after pressing the "Power On" switch, the signal is present at the output.

5.4 POWER REMOTE

Switch the power of the appliance OFF. Feed a control voltage of +24V to the Power Remote input. The power
amplifier has to start operation and after disconnecting the control voltage has to go off again.

5.5 FAN CONTROL

Upon powering-on the power amplifier, the fans will run for approximately 2 seconds and stop when the power
amplifier has re-gained its "normal" temperature. In idling condition (power-on, no signal present) the fans are
switched between the SLOW and OFF mode, depending on the heat sink's temperature. Connecting the CNS1.8
via a 5k resistor to +15V lets the fans run in SLOW mode. A FAN VOLTAGE of 16.8V DC can be measured
between pin CNS2.4 and pin CNS1.4. When disconnecting CN5, the fans will run in FAST mode. A FAN
VOLTAGE of 28V DC is measured between pin CNS2.4 and pin CNS1.4.

5.6 SOAR-PROTECTION TEST

Channels separately driven up to 0dB via the Direct-Output, terminated with 4. Parallel connect an 1 resistor.
The protection circuit reacts and tries continuously to re-start! The protect-LED lights.

5.7 SHORT-CIRCUIT CURRENT-LIMITING TEST

separately testing the power amplifier channels without load is mandatory:
- drive the channel with a burst signal (f = 1kHz, 1-3 cycles, rate  1 sec.), at the Direct Output with
     U(E) = 0dBu.
- connect a load resistor of 1.
- the short-circuit current-limiter limits the output voltage at the load resistor symmetrically (monitor via
  oscilloscope!) to a peak voltage value of 15V or 20V respectively (approx. 15A or 20A respectively maximum
  peak output current).

5.8 DC-voltage and HF-Protection Circuit

- Testing the protection circuitry against the occurrence of DC-voltage and HF at the output is only possible
  directly via the Main PCB when it is not installed in the appliance.

5.9 INDICATORS TEST

Feed a 1kHz sine signal while slowly increasing the level. At approx. -30dBu the SIGNAL LEDs will light and
at approx. +1.5dBu the Limit LED will light.




                                                        3
6. Level CHANNEL A B

6.1. VOLTAGE AMPLIFICATION

       Appliance        Input           U(E)      Measuring point        vU         U(A)       Load      Frequency
       DPA 4245        CH. A/B          0dBu       Direct Out A/B      33.8dBu      37.8V        4         1kHz
       DPA 4245        CH. A/B          0dBu        100V Output        42.2dBu      99.2V      28.5        1kHz
       DPA 4245        CH. A/B          0dBu         70V Output        39.3dBu      71.6V       14         1kHz
       DPA 4245        CH. A/B          0dBu         25V Output        30.2dBu      25.1V       1.8V       1kHz
       DPA 4245         CH. A           0dBu      BRIDGED OUT          39.8dBu       76V         8         1kHz
       DPA 4260        CH. A/B          0dBu       Direct Out A/B      34.9dBu       43V         4         1kHz
       DPA 4260        CH. A/B          0dBu        100V Output        41.8dBu      95.2V       20         1kHz
       DPA 4260        CH. A/B          0dBu         70V Output         39dBu       68.8V      9.8         1kHz
       DPA 4260        CH. A/B          0dBu         25V Output        29.8dBu       24V       1.25        1kHz
       DPA 4260         CH. A           0dBu      BRIDGED OUT           41dBu       87.3V        8         1kHz

6.2.       MAXIMUM INPUT LEVEL:          U(E) = +21dBu

7. GROUND LIFT switch

The circuit ground (at the input or the output connector) is measured versus the common ground of the enclosure
(contact at the ground terminal, located on the rear panel - or common ground of the mains cord).
without input transformer GROUNDED               : R = 0  with input transformer GROUNDED : R = 0
                             NOT GROUNDED: R = 5                                     NOT GROUNDED: R

8. Amplitude - Non-Linearities

- MBW = 80kHz
- all channels terminated with nominal load at nominal power, Direct Output at 8 or at 4 respectively, at
  nominal power

Measurement                    DPA 4245                                  DPA 4260                      Remarks
                   100V      70V     25V        Direct      100V       70V     25V          Direct
THD+N              <0.1%    <0.2% <0.3%         <0.05%      <0.1%     <0.2%   <0.3%         <0.05%        1kHz
IMD-SMPTE          <0.1%    <0.3% <0.5%         <0.08%      <0.2%     <0.3%   <0.5%         <0.08%     60Hz, 7kHz
DIM 30             <0.2%    <0.2% <0.2%         <0.03%      <0.2%     <0.3%   <0.3%         <0.03%      3.15kHz,
                                                                                                         15kHz

9. Frequency Response

The frequency response is linear. (mind the border frequencies)

                         fU -1dB               fO -1dB                 fU -3dB                fO -3dB
       100V Output              60Hz                  17kHz                   45Hz                   26kHz
        70V Output              60Hz                  17kHz                   45Hz                   26kHz
        25V Output              60Hz                  12kHz                   45Hz                   22kHz
       Direct Output            60Hz                  22kHz                   45Hz                   30kHz

10. Insert Attenuation

Drive the power amplifier in idling condition via the transformer outputs up to the nominal output voltage.
Connect the nominal load and measure the level changes.

                                                   DPA 4245                               DPA 4260
             100V Output                            0,7 dB                                 0,7 dB
             70V Output                             0,8 dB                                 0,8 dB
             25V Output                             1,1 dB                                 1,1 dB




                                                        4
11.      Crosstalk

It is necessary to align the output transformers when testing the crosstalk. Therefore, turn the transformer outputs
by 90



◦ Jabse Service Manual Search 2020 ◦ Jabse Pravopis ◦ Other service manual resources online : FixyaeServiceinfo