Samlowe Posted January 14, 2012 Share Posted January 14, 2012 Evening All. I have recently decided to try and get my old Warwick solid state amp up and running again for use as a back up but when I was last using it on a regular basis a few years back I managed to break it some how... When I first turn the amp on all is okay but after perhaps 10-20 minutes of play the clip LED starts to come on and the amp starts to cut in and out in quick bursts untill I have to turn it off and let it cool. After cooling the same sequence of events will happen once more. I'm fairly sure it's going to be a tech that needs to take a look at it but if you guys have any ideas I'd like to hear them! Thanks! Quote Link to comment Share on other sites More sharing options...
MarkBassChat Posted January 14, 2012 Share Posted January 14, 2012 (edited) Most probably the quiescent current is set incorrectly. Another possible problem could be a cold solder. In any case this should be corrected by a tech. Mark Edited January 14, 2012 by MarkBassChat Quote Link to comment Share on other sites More sharing options...
icastle Posted January 14, 2012 Share Posted January 14, 2012 Well if it cuts out when warm and then works again when cold my guess is a dry joint somewhere on the preamp board (as the clip indicator is controlled from there). As the amp heats up, the joint expands and a circuit is broken. Once the amp cools down again then the joint goes back to where it can make contact - we're talking fractions of a millimetre here. If you have soldering skills then you could take a look and see if you can spot the dry joint and resolder it, along with any others that look suspect. If you don't then it's time for an amp tech to take a look at it. Quote Link to comment Share on other sites More sharing options...
Samlowe Posted January 14, 2012 Author Share Posted January 14, 2012 When it is in the process of cutting out I get the feeling it's some sort of digital cut out. It starts to cut in and out at a slow pace and quickly speeds up. Thuis happnens within the space of around 10sec. If i were to leave the amp on it would keep cutting in and out a a very quick rate. It seems to me like some sort of protection device is cutting in? Quote Link to comment Share on other sites More sharing options...
icastle Posted January 14, 2012 Share Posted January 14, 2012 [quote name='Samlowe' timestamp='1326576822' post='1499151'] When it is in the process of cutting out I get the feeling it's some sort of digital cut out. It starts to cut in and out at a slow pace and quickly speeds up. Thuis happnens within the space of around 10sec. If i were to leave the amp on it would keep cutting in and out a a very quick rate. It seems to me like some sort of protection device is cutting in? [/quote] Having looked at the scematic ([url="http://www.warwick.de/media/manuals/ProFet/PROFET_3.2.pdf"]http://www.warwick.de/media/manuals/ProFet/PROFET_3.2.pdf[/url] in case anyone needs it in the future) there are cutouts that occur if: 1) Output shorted (faulty cab or duff speaker cable) 2) Thermal cutout - make sure you have plenty of airflow around the amp. If either of those two things happen then, according to the manual, the Mute LED will come on even if you haven't selected it previously. If it's a protection circuit kicking in then you should hear a mechanical 'click' from the amp as the relay switches. Incidentally, does the fan run? Quote Link to comment Share on other sites More sharing options...
Samlowe Posted January 14, 2012 Author Share Posted January 14, 2012 It's been so long since i've had it hooked up to a cab i can't remember if the fan cuts in or not, I'll check it out next time I'm in our room with cabs. I'm sure the cab isn't the issue though because it's the same one i'm using now with out any issues. The thermal cut out is definitely something I haven't considered so will be on the look out for when I use it next. Yeah, a mechanical kick is kind of how i would describe it. The kick gets amplified through the speaker also. Thanks for advice icastle! I'll report back next week sometime... Quote Link to comment Share on other sites More sharing options...
Samlowe Posted January 14, 2012 Author Share Posted January 14, 2012 While I have the amp here with the cover off, is there any way of testing the fan? Cheers. Quote Link to comment Share on other sites More sharing options...
icastle Posted January 14, 2012 Share Posted January 14, 2012 [quote name='Samlowe' timestamp='1326578871' post='1499196'] It's been so long since i've had it hooked up to a cab i can't remember if the fan cuts in or not, I'll check it out next time I'm in our room with cabs. I'm sure the cab isn't the issue though because it's the same one i'm using now with out any issues. The thermal cut out is definitely something I haven't considered so will be on the look out for when I use it next. Yeah, a mechanical kick is kind of how i would describe it. The kick gets amplified through the speaker also. Thanks for advice icastle! I'll report back next week sometime... [/quote] No problem. The fan looks as though it cuts in and out as the temperature goes up and down so what you should find is that when the amp starts cutting in and out the fan should be running - if it's not then there's a chance that what you're seeing is a thermal cutout because the fan isn't working (if all those double negatives make sense?!?) As a way of eliminating another potential issue, try swapping speaker leads over just in case you've got a duff connection in there. Quote Link to comment Share on other sites More sharing options...
Samlowe Posted January 14, 2012 Author Share Posted January 14, 2012 Ok, yeah i think that makes sence... I'll have play next week sometime and be on the look out for a dodgy fan! Thanks again! Quote Link to comment Share on other sites More sharing options...
icastle Posted January 14, 2012 Share Posted January 14, 2012 [quote name='Samlowe' timestamp='1326579084' post='1499197'] While I have the amp here with the cover off, is there any way of testing the fan? Cheers. [/quote] It really depends on what you have available. The fan runs off of the 15V supply rail so, if you have a suitable bench power supply, it is possible to disconnect one of the cables from the pcb and stick 15V directly onto the fan (thereby bypassing the control circuitry). If that works then you need to fool the control circuitry into trying to switch the fan on, I'd do something hi tech like heating the sensor with a hairdryer - at which point you'll find 15V appearing where the fan joins the pcb. Quote Link to comment Share on other sites More sharing options...
Samlowe Posted January 14, 2012 Author Share Posted January 14, 2012 Unfortunately I don't have a suitable bench supply or a hair dryer to hand! It will have to wait till it's hooked up with a cab next week. I have a funny feeling the fan may well be what's causing the issue... Quote Link to comment Share on other sites More sharing options...
Samlowe Posted January 18, 2012 Author Share Posted January 18, 2012 Ok, I haven't had a chance to use this properly yet but having sourced a hair dryer I can say the fan works then internal components are heated. I'll still try and get it hooked up to a cab soon but any ideas in the mean time? Cheers. Quote Link to comment Share on other sites More sharing options...
.gif.9ad672bb8b84505709f76b39c8c256ec.gif)
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.