Job Number

0202-39

Equipment type

Portable, stereo tuner/cassette recorder

Maker + Model #

Sanyo  M4500k

Made in

Japan

Comments

Very old style and large model

BAD

1

Does not record (reported by client)

2

Counter not working *

3

Sounds from one speaker and one VU meter working *

4

Pause Button does not hold into down position *

                                *   (other faults noted later)

GOOD

1

Powers up and good radio functions

2

Cassette playback, FF and REW OK

Full repair description and observations

1

Immediately, it was noted that the record was functioning well, and probably the client inserted a rec-protected cassette and so the rec button could not go down

2

Since of the state of the player, a service was strongly needed. The cassette unit was under the pcb circuitry, and to remove the PCB required desoldering about 22 wires. The location of the wires were noted on paper.  

3

The 3 belts found were replaced, however it was found that the tape stops after playing for few seconds. The auto-stop at end of tape mechanism was not assembled/working properely. Numerous attempts and commen-sense guess work was done to fix this problem but all attempts were in vain. It was hence decided to eliminate the aut-stop mechanism because it was hindering problems to the playback.

4

Various servicing tasks were performed such as cleaning of the switches and user potentiometers, cleaning of the tap audio head and erase head, cleaning of the pinch roller, etc.

5

The Counter was found that it was slightly out of place, and when arranged in the original position, it began to count well. The belt which controlled the counter was becoming loose (overstretched) but it was very very difficult to remove it (it would have involved disassembling the whole parts of the cassette unit) so it was left there.

6

The faulty speaker made noise on touching its terminals with a 1.5V battery. Hence the speaker is good. Whith some guess work it was found that previously it was connected at a wrong place on the circuit, and the ‘correct’ place was found, or at least it did produce sound well now.

7

The case PCB circuit was re-assembled back, but the recorder was not recording and on microphone mode, it was making huge feedback noise. Finally it was found that the one of the wires (the erase voltage) was connected to a wrong place. It was a careless mistake while writing the wire connections, since this wire concerned was orange, while I wrote pink. With this wire connected to the right place, the recording worked perfectely on microphone, radio and Long Play/CD/Aux input.

8

The unit was closed, and the outer case was cleanned and polished, while the user knobs were cleaned with soap.

Repair summary

Servicing of belts and pots

Precautions, fouls and advises

1

Always pay great care when desoldering numerous wires and note extremely well the order and position. A picture with the digital camera will help a lot