Panasonic A1F - sound issues

By Crash

Supporter (1)

Crash's picture

23-11-2019, 02:04

Greetings everyone!

Recently I became the owner of a Panasonic A1F MSX machine. While everything seems to work like a charm (video, keyboard, FDD, loading stuff via MegaFlashRom), I have a weird issue with sound, both on the RCA and RF out.

It starts absolutely normally, with sound playing on both the Panasonic firmware or the game. However after a small amount of time (around 5 to 10 minutes) the sound volume starts to go lower and lower by itself, almost like somebody was lowering the volume on the TV, until it's so quiet I have to crank the volume on the TV to 60-80% in order to hear anything. It will stay like that until I power the machine down, wait for a short while and power it up again - the sound volume will be back, but again - only for 5 to 10 minutes.

Checked the MSX on two different CRT TVs, two step down transformers (I live in Europe), and two sets of RCA/RF cables - unfortunately the issue persists. I opened the machine up to check for any bulky or leaking capacitors but haven't found any issues (the seller has apparently replaced the FDD belt and checked the computer before sending it to me) at the first glance. Should I look for a specific capacitor/place on the motherboard, or is it a completely different issue altogether?

Cheers,
Crash.

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By Palver

Rookie (28)

Palver's picture

24-11-2019, 16:37

Damn, thats weird. I would start looking for a bad solder joint, starting from the PSG chip. You can use a hairdryer to heat a small area in the pcb and find where the problem is.

By Josevil

Master (157)

Josevil's picture

05-12-2019, 23:43

the capacitors degrade over time you will have to perform the maintenance, also your msx assembles the famous hic plate that usually loses acid these plate counters did you can mount ceramic tiles

los condensadores se degradan con el tiempo tendras que realizar el mantenimiento ,tambien tu msx monta la famosa placa hic que suele perder acido ,estos condesadores de la placa hic le puedes montar ceramicos perfectamente

By sd_snatcher

Prophet (3135)

sd_snatcher's picture

06-12-2019, 01:58

The Panasonic FS-A1F is another machine that has the famous HIC-1 daughterboard with its suicide capacitors. If the sound is failing, you can be sure that they're already leaking, so you should replace those ASAP.