K4004B non functional after assembly

Kits Audio Hi Fi Projects
1

I just completed assembly of my K4004B amplifier kit and need help with getting it to work. Problem: no speaker output. None at all.

I did a little troubleshooting within my capabilities. I believe the following information will help someone diagnose my problems.

  1. There was no difficulty in assembling the kit. All the parts seemed to go in the right place. All of the solder spots look good.
  2. The two LEDs light up on the audio amplifier board. This presumably shows appropriate power input from the K006 power supply that I used. I measured the voltage on the K4004B board at the points of power input. They measure +24 VDC and -24VDC with respect to power supply ground.
  3. With the circuit powered-up, but no signal input or output cables plugged in, I measured the voltages on the pins of the two IC semiconductors of the K004B with reference to power supply ground. I used the numbering system of the chips and their pins as printed on the circuit board. All measurement are in volts:

IC …#1 …#2
Pin #1 … 2.26…0
Pin #2 … 0.76…0
Pin #3 … 0.76…0
Pin #4 … 0.76…-0.2
Pin #5 … 0.31… 0
Pin #6 … 23.9 … 0.4
Pin #7 … 23.9 …0.4
Pin #8 … 0 … 0
Pin #9 … 0.10… 0

Can anyone decipher this information and give me advice as to how to proceed?

2

This is a follow-up to my problem with the K4004B that I posted. I fixed the problem but, in doing so, discovered a problem with the assembly instruction manual that Velleman should look at and, I believe, correct.

For those who read the original note, recall that I found that, in essence, the ICs were missing their electrical inputs: one IC was not attached to the negative voltage supply, whereas the other IC was not attached to either the positive or negative voltage supply.

Looking more closely at the circuit board, the electrical supplies to the ICs are printed on separate “traces.” These traces require the user to place jumper wires between the traces that are connected to the electrical supplies that come to the board and the traces to the ICs. The user needs to solder four jumpers on the circuit board, all on the left side (the side near the ICs).

I placed those four jumpers and the amp now works. In fact, it’s a thing of beauty with respect to performance.

Now here’s the part that I want to make Velleman (or anyone who assembles this kit) aware of: there are no (zero) instructions in the assembly manual that refer to the user placing these 4 jumpers. The assembly manual very carefully, and in order, goes through placement of all the other parts (resistors, capacitors, ICs, connector lugs, etc). It also indicates the placement of some jumpers used for options (mono vs stereo and strength of input signal).

However, no where in the (English version) of my instruction manual is there referral to placement of these 4 obligatory jumpers. It is true that the letter “J” appears in four places between two solder points on the PC board. But, unless the user takes the time to interpret the traces and compares them with the circuit diagram, one would not know that these jumpers need to be placed in order to complete assembly.

Suggestion: Velleman needs to include this instruction – identifying the four places in which jumpers must be inserted – in the assembly manual.

3

If true, i agree!

4

Please check assembly step 1 on page 6 of manual.
It calls for 4 x J (jumpers) :slight_smile:

5

Electromaniac is (obviously) correct: there is the instruction to place 4 jumpers on page 6 of the manual.

My confusion, as somewhat of a novice in these assembly instructions, stemmed from the placement of that instruction in the manual (which is not optional) with other instructions for placement of optional jumpers in the same space. I thought, obviously foolishly, that the instructions only referred to the optional jumpers.

I failed to obey the old adage: when all else fails, read the directions.

6

Happy to read it works fine…

7

I modified the firmware to standard baudrate of 115200 and now it works on all my ubuntu computers without modifieng them

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8

I think you posted this in the wrong section.