In praise of Ashdown Engineering support

[Minininjarob]

1 hour ago, DGBass said:

The relay is I'm sure part of the output soft start circuit and not the fan circuit. I have one of these and the fan has never come on ever, not even when I've used the amp very hard. I think the amp modules in these are stripped down budget versions of the Powersoft DigiMod class-d modules, though I can't be sure. I'd like someone to tell me otherwise! I've asked Powersoft and they aren't sure either. If the schematic for the Digimod units are anything to go by, the fan should activate when the unit reaches approx 50C. My amp is eighteen years old, so in class-d terms that's a long while ago and even the Digimod versions are now obsolete.  As has been mentioned, as long as they don't get heavy use, the chunky heat sink seems to cope well. They make nice home and studio amps as they are very clean but warm sounding.  I've never had mine cut out at all.  I think from Ashdown's perspective I can understand there isn't a lot they can do to repair these, and replacement modules don't seem generally available. Faulting surface mount tech like this is beyond my capabilities, and I expect very time consuming for folks who do have the capabilities. It's the old chestnut of being easier to swap an entire unit, than fix it. Throwaway technology.  If you can find a used and working Digimod 500/1000 module, I believe the original PSAMP350 modules will swap out easily with them. 

Thanks for that. Without a schematic I just assumed the relay was for the fan as it’s a 12v one same as the fan, and it’s next to the fan header. Really interesting info, thanks very much - I wouldn’t expect a low stressed relay to go that easily anyway so the fact it will probably be something else is bad news but might save me a lot of time. Will sell it for parts probably. 
I did read up that the fan should come on briefly when you start it up and it doesn’t do that so I am assuming that it’s something to do with the fan control, but if it’s heating up and cutting out so easily then maybe there is multiple problems - maybe the amp sections are struggling and getting too hot, then the fan circuit or temp sensors have given up from overuse. Who knows? 

Edited 4 hours ago by Minininjarob

[Minininjarob]

3 hours ago, Ruarl said:

You mentioned up the thread that this was only for bedroom practice. Since the owner can’t afford anything else, why not just use the amp as-is at low volumes? And just keep an eye on the temperature. Or take regular breaks? Or are there other problems besides the fan not coming on? 

It’s used for bedroom practice and for gigs too, I can’t remember when he said it cuts out but it’s enough to make it fairly useless. 

[DGBass]

38 minutes ago, Minininjarob said:

Thanks for that. Without a schematic I just assumed the relay was for the fan as it’s a 12v one same as the fan, and it’s next to the fan header. Really interesting info, thanks very much - I wouldn’t expect a low stressed relay to go that easily anyway so the fact it will probably be something else is bad news but might save me a lot of time. Will sell it for parts probably. 
I did read up that the fan should come on briefly when you start it up and it doesn’t do that so I am assuming that it’s something to do with the fan control, but if it’s heating up and cutting out so easily then maybe there is multiple problems - maybe the amp sections are struggling and getting too hot, then the fan circuit or temp sensors have given up from overuse. Who knows? 

Actually, I've just found some more detail on the module, it is a Powersoft product called PowerMod II. Thermal protection shuts the unit off at 85C. It will work fine with the heatsink according to Powersoft up to an ambient temp of 45C. The temp sensor is apparently underneath the main board attached to the heatsink. No schematic available unfortunately. These were originally designed back in 2002 and have been obsolete for some years. You might find a manual online if you search PowerMod II . 

[Minininjarob]

2 hours ago, DGBass said:

Actually, I've just found some more detail on the module, it is a Powersoft product called PowerMod II. Thermal protection shuts the unit off at 85C. It will work fine with the heatsink according to Powersoft up to an ambient temp of 45C. The temp sensor is apparently underneath the main board attached to the heatsink. No schematic available unfortunately. These were originally designed back in 2002 and have been obsolete for some years. You might find a manual online if you search PowerMod II . 

Thanks. I wonder if the temp sensor is cooked? I will see if I can find it and test it.