Crown xls 802 , wont turn on

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Crown xls 802 , wont turn on

Hello all, I have recently acquired a dead crown xls802. The
amp doesn’t power up. If it is plugged in and turned on there is a small flash
of the signal leds but then nothing. if you immediately try again the signal
leds do not flash. 

The amp has mains power from the input to the fuse and to
the switch but none to the transformer. The small capacitors on the psu board
(near the mains bit) get very hot. They are labelled PTC , pics can be added . 

It seems this is some kind of protection to stop the amp
turning on in the event of a failure. I think a/many output devices have gone
but I don’t know. 

Any advice would be appreciated. 

Cheers ed  

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wayward91 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 15 July 2010 Location: Leeds/Mancester Status: Offline Points: 319	Post Options Post Reply Quote wayward91 Report Post Thanks(0) Quote Reply Topic: Crown xls 802 , wont turn on Posted: 24 November 2011 at 1:55pm
	Crown xls 802 , wont turn on Hello all, I have recently acquired a dead crown xls802. The amp doesn’t power up. If it is plugged in and turned on there is a small flash of the signal leds but then nothing. if you immediately try again the signal leds do not flash. The amp has mains power from the input to the fuse and to the switch but none to the transformer. The small capacitors on the psu board (near the mains bit) get very hot. They are labelled PTC , pics can be added . It seems this is some kind of protection to stop the amp turning on in the event of a failure. I think a/many output devices have gone but I don’t know. Any advice would be appreciated. Cheers ed

simonp1100 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 01 September 2008 Location: Bristol Status: Offline Points: 309	Post Options Post Reply Quote simonp1100 Report Post Thanks(0) Quote Reply Posted: 24 November 2011 at 3:02pm
	The PTC is a getting hot, because the protection circuit is on. This is due to a faulty output device / devices (MJ15024 or MJ15025) putting out DC on the outputs or it also can be the bridge rectifier faulty. Once found & the right parts replaced, also check the 47ohm 25 watt soft start resistor is at 47ohms (as this tends to go open circuit as well). Please remember that there is very high voltages (+ & - 90 volts DC) on the amplifier & really should be repaired via a qualified repair guy. Hope this helps Edited by simonp1100 - 25 November 2011 at 12:37pm

wayward91 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 15 July 2010 Location: Leeds/Mancester Status: Offline Points: 319	Post Options Post Reply Quote wayward91 Report Post Thanks(0) Quote Reply Posted: 25 November 2011 at 10:36am
	Yup cheers for the warning and advice :) . It seems as you said, the transformer is fine, outputting the propper voltages. The low voltage circuit starts up correctly when there is no high voltage rails connected. We will test the DC high voltage rail in isolation .then go on to checking the output devices. I have emailed crown for a schematic just in case. Will be a few weeks till I'm back to repair it but will post following success or failure. I Thanks again

taurusty Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 09 January 2007 Location: Jamaica Status: Offline Points: 123	Post Options Post Reply Quote taurusty Report Post Thanks(0) Quote Reply Posted: 25 November 2011 at 11:38am
	Can pm me for service manual, if interested...

Wilsonsk Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 February 2012 Status: Offline Points: 14	Post Options Post Reply Quote Wilsonsk Report Post Thanks(0) Quote Reply Posted: 20 February 2012 at 12:33am
	I just had my XLS 802 do this last night. Can you walk me through what to check? I am capable of doing so safely, i work on tube amps. No solid state gear though. Thanks in advance, Steve

mike03 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 07 September 2009 Location: Jamaica Status: Offline Points: 151	Post Options Post Reply Quote mike03 Report Post Thanks(0) Quote Reply Posted: 20 February 2012 at 4:19am
	Simonp1100 has outline detail as to the do's and dont's brother. Safety first the filter caps can KILL you before you know you made contact with it.
	dc

Wilsonsk Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 February 2012 Status: Offline Points: 14	Post Options Post Reply Quote Wilsonsk Report Post Thanks(0) Quote Reply Posted: 20 February 2012 at 4:27am
	Cool, That would be great. I may seem a little dense here, but I'm new to this forum, how do i send a private message?

mike03 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 07 September 2009 Location: Jamaica Status: Offline Points: 151	Post Options Post Reply Quote mike03 Report Post Thanks(0) Quote Reply Posted: 20 February 2012 at 4:48am
	There is a down pointing arrow in front of the member name you wish to pm, click on it and there you will have the options available to you.
	dc

Wilsonsk Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 February 2012 Status: Offline Points: 14	Post Options Post Reply Quote Wilsonsk Report Post Thanks(0) Quote Reply Posted: 20 February 2012 at 11:23am
	There is an arrow after the names, but my options are "members profile" and "find members posts", neither of which seem to lead me anywhere to pm. There again, I may be completely missing this too. Is it possible that isn't available for me because I just registered?

kedwardsleisure Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Old Croc Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 1939	Post Options Post Reply Quote kedwardsleisure Report Post Thanks(0) Quote Reply Posted: 20 February 2012 at 7:11pm
	you have to amass more posts before you can PM
	K. Edwards Electronics Engineers North Staffordshire

Wilsonsk Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 20 February 2012 Status: Offline Points: 14	Post Options Post Reply Quote Wilsonsk Report Post Thanks(0) Quote Reply Posted: 20 February 2012 at 8:01pm
	I figured it was something like that, well hopefully simonp1100 catches this post and can get me started on this amp, or maybe I'll amass enough post through this process :) Thanks, Steve

simonp1100 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 01 September 2008 Location: Bristol Status: Offline Points: 309	Post Options Post Reply Quote simonp1100 Report Post Thanks(0) Quote Reply Posted: 20 February 2012 at 10:07pm
	If you have tested all the low voltage sections & they seem to work, then the fault is mostly down to one or more of the output transistors. The best way i found to find the suspect faulty device / devices without taking all the transistors off of all the heatsinks is to measure with a meter between the casing of each transistor & the collector of that transistor, when you find the short, then you need to desolder all the PCB pads to the transistors that are connected to that specific heatsink bank and then measure each transistor in that bank to isolate which one / ones are at fault. Please also check the driver transistors (TIP50 / TIP47 / MJE5731A) & the current limit circuit (BC184L / BC214L & the diodes) on each channel as well as these tend to go when one or more of the output transistors blow. Once the faulty transistor / transistors have been taken out, confirm that the amp powers back up and goes out of protect. If NONE of the transistors are found to be faulty, then the fault must be one of the bridge rectifiers. There could be a small chance that the drive circuit could be at fault, but this is very rare (if you have already checked the driver transistors & the current limit circuit). Don't forget to check the 47ohm 25 watt soft start resistor is at 47ohms (as this tends to go open circuit as well) & the PTC. Please remember that there is very high voltages (+ & - 90 volts DC) on the amplifier & really should be repaired via a qualified repair guy. Hope this helps Regards Simon Edited by simonp1100 - 20 February 2012 at 10:09pm