Bang & Olufsen Beogram 4004 Linear Tracking Turntable Will not power on

Bang & Olufsen Beogram 4004 Linear Tracking Turntable Will not power on, unit is dead. First thing I did was check the fuses. After looking all over the place for the fuses.I found them located under the platter. And yes they were blown. So I replaced them.

 Being that I did'nt know why they blow. I figure I'd use my varible tranformer incase there's a short. I cranked the power up to about 60 volt, then I saw smoke coming from under the control panel. looks like I burnt out a diode in the process. 

I replaced the diode and after further inspection I found the original problem, a burnt 22 uF capacitor. The one shown in my photos. Problem solved.

Harmon Kardon FL 8450 CD player display is dark and disk motor spins continuously

When powered on the display is dark and disk motor spins continuously. Possible Power supply problem.

Checked positive and negative 12 volt regulators, both check good.

Checked positive and negative 5 volt regulators, the negative was good but the positive 5 volt was outputting  zero volts. So I checked the input to the regulator. It was suppose to be 13 volt but it was sitting at 1.2 volts. So it's not the regulator, it the input to the regulator.

 I traced the input leg back, and I found a bad 1 ohm resister. (R312) was open. Replaced resistor and problem was fixed.

Mitsubishi M R8010 Receiver, Left channel has no output sound

When an amplifier or receiver has an output problem. (no sound from either of the channels) It's usually bad output transistors in the amplifier section. But before you just assumed that, you need to make sure the problem is not in the preamp section of the unit. Lucky for me this particular receiver had the jumpers between the preamp and Amplifier, so it was easy to check the two sections.

Output of the preamp section was good on both channels. So this means the problem is in the amplifier section. Possible output transistors. All output transistors and the surround sound power module was good. This particular unit had an STK3122II Audio Power amplifier IC that feeds the left and right output transistors.

I removed and tested it. I found that the left side was defective. Replaced it and problem was solved.  

PIONEER PD M423 Multi-Play Disc Player skips and gets hung up in certain spots when playing CD's

PIONEER PD M423 Multi-Play Disc Player skips and gets hung up in certain spots when playing CD's. I first thought it was the laser assembly getting hung up on the guide rail, so I cleaned and lubed the rail. However that still did fix the problem. After further inspection I found that the gear that controls the laser assemblies motion would stop moving at times. So I removed the gear for inspection. I found that some of the teeth on the gear were worn out. After replacing the gear, the unit works like new.

                                          PIONEER PD M423 Multi-Play Disc Player

              Remove a total of six screws to remove the case, two on each side and two in the rear.

 Remove the three screws circled in the photo, then remove the two brackets. The gear can be easily removed by lifting it out of the slot. An arrow is pointing to the gear in the photo.

                Here is the gear after removal, the top portion of the shaft is where the teeth are worn.

Is your Marantz Model 500 missing that little door?

Well,  maybe this will help you out. Here are the dimension so you can have one made. 

 

All measurements are taken in Millimeters

a) 13.2  b) 6.0  c) 15.5  d) 2.0  e) 2.1  f) 3.1  g) 3.0 

 h) 1.4  i) 0.5  J) 0.5  k) 0.5  l) 0.3  m) 1.2  n) 1.9

KENWOOD KX 630 Stereo Cassette Deck ( No sound output from Left channel)

I originally thought the unit probably needed a simple head cleaning, but I quickly found out, this was a more serious problem. Tracing the input signal, led me to the processor chips. one of them accepted an input signal and produced an output. The left one did not... BINGO!

 I found a bad LM1011 DOLBY NOISE REDUCTION PROCESSOR chips (seen in picture below)  This unit comes with two of them, a left & right. I replaced the left processor chip and the problem was solved! 

The LM1011 DOLBY NOISE REDUCTION PROCESSOR chip, is the same as the NTE 2003.

Sansui A 910 Integrated Amplifier (stuck in PROTECTION mode)

Stuck in protection mode. (The speaker relay does NOT click on) I checked voltages at the output transistors. The right side voltages looked good, but the left side voltages were bad ( that's why the relay doesn't click on)

I found a bad 45580 op-amp chips (seen in picture above)  location on the board (IC2) Replaced Chip and unit is working great now. Very nice sounding amplifier!

Pioneer QX 8000A QUADROPHONIC Receiver (no sound from Channel 2 & 3)

This is a four channel receiver, it had a problem with channels 2 & 3. Their was no sound output from either of these channel. The problem was on the control Amp Board. Capacitors C2 & C3 were found to be bad. Rate 0.47uf @ 25 volt.

Here's a Diagram of the bad capacitors

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Technics SU V98 Integrated Amplifier. (Volume Problem)

This unit came to me with a volume problem. When powered on, it goes though it's checks and the speaker relay clicks on. I connected a CD player and speakers to it. volume was about 30 percent, no matter how high you turned up the volume knob.

I found a defective TC9212P ELECTRONIC VOLUME CONTROL IC. after replacing it, I was able to turn the volume all the way down and all the way up with no problem. I hope this repair can help someone in the future.