Aiwa schematics ... ?

Arfa Daily ha escrito:

have you tried eserviceinfo?

Nothing listed for this model. I'm not desperate, as the system is not worth that much, but as it was apart on the bench, and I had sorted the missing -24v problem, it was a bit annoying that I still had trouble with the filament supply. This appears to be switched with a couple of transistors near to the -24v reg. They actually derive the -24 on this model, direct from a rectifier, rather than by the more traditional Aiwa voltage multiplier. I don't really know why they bother switching the filament supply to unused displays when the unit is off. Possibly to preserve their life, I guess, but I have seen plenty of units where the filament supply is always on. Anyway, having found these transistors, I went looking for a control signal, but I couldn't find anything in the area that moved when you switched from standby to on. There is a little surface mount digital transistor that looks as though it ought to control this lot, and what should be the base leg, has print disappearing off towards the front panel, but as I say, no movement of voltages around it. Just for sport, I tried shorting across the switch transistor, and this immediately restored filament volts, and display on the amp, but still no filament volts up the bus to the graphic, so that remained dead. That was the point that I called it a day, and posted the request just to see if anyone had a manual.

No matter though, I have wrapped it back up now, and told the shop that booked it in that the only way that it is going ahead, is if a service manual could be found. They have indicated that they don't think that their customer will want to be bothered, so it will finish up now as just another of those jobs that end up only just about covering their time ... Thanks for the suggestion anyway.

Arfa

Arfa Daily ha escrito:

I've generally found mini systems horrible things to work on. if it's not dismantling the thing to access the front bit, its the awful audio output stages and board layout etc. Often, for anything more complicated than cap replacement, mechanical or electro- mechanical stuff, a service manual seems to be the order of the day..... good luck

-B

Yep, know what you mean, This one is actually a big stacking 5-piece, about the same size as those hateful Kenwood stackers that were so popular a few years back, but still it is a pain to work on. To do anything to the main board in the amp unit, it has to come out, which involves removing the front and back panels. Happy days ...

Arfa