Cant find the schematic so decided to carry on don't want to change anything that doesn't need changing or cost will be more than the amps are worth
I have tested the main caps in power supply and although still in spec one is leaking so both will be changed
looking at the output boards i have tested the caps and they seem ok see test results in pics
the small caps on left side of board are input caps and tested ok the one on the right tested ok
which ones would you change ?
20200113_123612 by glenn jarrett, on Flickr
20200120_103740 by glenn jarrett, on Flickr
I have tested the main caps in power supply and although still in spec one is leaking so both will be changed
looking at the output boards i have tested the caps and they seem ok see test results in pics
the small caps on left side of board are input caps and tested ok the one on the right tested ok
which ones would you change ?
20200113_123612 by glenn jarrett, on Flickr
20200120_103740 by glenn jarrett, on FlickrIf a 47uF cap tests as 82uF suggests its leaky. Increase in capacitance is a sign an electrolytic is degrading and leaking, as the oxide layer is dissolving and thinning. Testing in-circuit isn't ideal, and you can't measure leakage directly. Leaking caps can lead to other components failing so its wise to unsolder one end of each cap and test for leakage, or just replace.
How old is this? More that 20 years, replacing electrolytics is likely to be needed anyway.
Any datecodes?
How old is this? More that 20 years, replacing electrolytics is likely to be needed anyway.
Any datecodes?
Why? Is it broken?
Note that "47uFd +50%" caps can be 70uFd right from the start, and many were. And in this circuit a few ESR make no difference.
Haydn Cole at hc@hncelectronics.co.uk has helped me in the past with old Carlsbro service data; give him a try.
Well thats the first one done and tested
really glad i checked the heat sink compound it had gone that dry i had to get it off with ipa and a tooth brush
20200123_145816 by glenn jarrett, on Flickr
20200123_145809 by glenn jarrett, on Flickr
20200123_132029 by glenn jarrett, on Flickr
really glad i checked the heat sink compound it had gone that dry i had to get it off with ipa and a tooth brush
20200123_145816 by glenn jarrett, on Flickr
20200123_145809 by glenn jarrett, on Flickr
20200123_132029 by glenn jarrett, on Flickr
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Just finished the 2nd amplifier now to recap the tone boards
20200210_115745 by glenn jarrett, on Flickr
20200210_115745 by glenn jarrett, on FlickrThats the main amp back together
bored punk band in rehearsals, craft knife, and old Marshall badge
bored punk band in rehearsals, craft knife, and old Marshall badge
An externally hosted image should be here but it was not working when we last tested it.
20200210_135618 by glenn jarrett, on Flickr
Hi all,newbie here.
Ive just bought a 1978 Carlsbro Stingray combo similiar to the one detailed in this thread and have deduced the heat sink may have been removed.The back panel looks identical to the last pic in Page 1 of this thread...multiple holes on the backboard where,I assume,the original would have been.
My queston is this: is it safe for me to use this amp at low volume e.g. not above 9 o’clock on the Master Volume or should i get a heat sink added? If so do I just mount a new heat sink onto the back panel using TO3’s and a fin shaped heat sink or is it more complicated than that? I have no experience in this area so apologies if my questions are amateur.
Many thanks in advance for any help and advice offered.
Ive just bought a 1978 Carlsbro Stingray combo similiar to the one detailed in this thread and have deduced the heat sink may have been removed.The back panel looks identical to the last pic in Page 1 of this thread...multiple holes on the backboard where,I assume,the original would have been.
My queston is this: is it safe for me to use this amp at low volume e.g. not above 9 o’clock on the Master Volume or should i get a heat sink added? If so do I just mount a new heat sink onto the back panel using TO3’s and a fin shaped heat sink or is it more complicated than that? I have no experience in this area so apologies if my questions are amateur.
Many thanks in advance for any help and advice offered.
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