I was handed this JL30 to look into an issue with the take up reel not pulling correctly.

On inspection there were additionally more faults identified :

1. Motor hum
2. Leaking capacitors
3. Corrosion on some solder connections
4. Azimuth not set correctly

Opening the JL30 it was clear from the flexible printed circuit board (PCB) and volume potentiometer that someone had previously worked on this unit a long long time ago. It wasn't clear what they'd actually fixed. The capacitors seemed to be the original ones.

The ALP tape transport was stripped and the slip disc degreased (I've since discovered that the tape transport used in the 303/505 is called the Α or ALPHA transport). It was then reassembled. Sorry no photos of that, maybe I do a separate write up of that for a separate thread. A calibrated test tape was inserted into the JL30 and a rough calibration by ear was also performed. The previous owner had screwed down tight the calibration screws on the bi-azimuth mechanism!

The capacitors were all individually checked for their ESR readings. The main culprits for the leaked electrolyte, the 220uF 4V unsurprisingly all read ESR readings off the meter and therefore pronounced dead on the scene. The 47uF 4V all read slightly higher values ~5 Ohm. The biggest surprise were the two DC blocking 220uF 2V capacitors which read an extremely healthy ~1 Ohm.

The 220uF 4V and all the 47uF capacitors were removed. Also removed were the volume potentiometer and the microswitch PCB - to allow better access to the capacitors. All the flexible PCB cables were removed to aid easier cleaning.

The PCB was then carefully cleaned with Bicarbonate of Soda and isopropyl alcohol (IPA). The solder contacts were also re-tinned.

New capacitors were fitted.

The JL30 was then reassembled

Following reassembly the JL30 was tested again. This time the motor hum has gone and the DSL is more stronger. Audio in general also has greater clarity.

EDIT : ALP is the abbreviation used to denote Α or Alpha by AIWA.

Ah, it's a shame mine is rather dead.

I was rather confounded by the resistor and brown wire in place of a capacitor on this model... like a last minute revision. Also note the red wire added for the power input.

How does it sound VS the 505 and its brethren?

I set up a listen test with my JX505 and the JL30. Both with DSL disabled and both with the volume set at roughly the same volume. BBE was disabled on the JX505. I then set up Stereo Tool to play through to a FM transmitter and tuned them both into the same channel.

The results are... indiscernible! Obviously the JX505 has the edge as it can also call upon BBE as well, and with that enabled you can hear the additional brightness and clarity that BBE brings. The conclusion is that with a matched pair of headphones (in this case a pair of open air wrap around Sony MDR-G72) with DSL enabled both sound very good. An interesting note is that both the JX505 and the JL30 share the same main amp IC a TA7688F. Pre amp chips are different however the JL30 uses a CXA1278, whereas the JX505 uses a TA8155FN.

There are two wires added to the power input. A red and also a black wire. Note that if the unit is placed in "REMOTE" the radio does not operate. The tape mechanism will operate briefly to reset it self to the correct position and that is it. Does the power led come on at all on your JL303?

The power LED on my JL303 is stuck on once I connect the battery. Logic is still ok, as the unit responds fine and also does the logic reset at the start. No sound from radio (This means that I may also have a problem along the flex cable/radio board) , massive motor hum on playback (did not bother to test with tape).