Discussion in 'Yamaha' started by Bert 1100, May 16, 2017.
Thank you ! And yes, the CA-810 is definitely worth it !
Nice work on the speaker terminals, they look great.
My 810 has the same transformer hum, especially on startup. Like an overdriven guitar with the whammy pedal all the way down. It's barely noticeable after the first 5-10 seconds after powering on but still worries me a bit.
I'm also inspired here, great job with the IEC mod and speaker terminals. I'd like to do LEDs on my meters someday but that's probably a little above my head at the moment.
Excellent work, it was well worth the watch and wait. It must be very satisfying to successfully accomplish a task like that!
The amp has been in use on and off, it has seen maybe 1 month of everyday use.
Lately I noticed the meter lighting has become dull and with a cold light color.
So I opened the light housing and saw that all four of my leds, the warm-white 5mm "straw-hat" were all very dim and blueish
I'm not sure what happened here, those leds have a nominal current of 20mA, and that's the number I got with choosing dropping resistors.
At first I thought I had forgotten they are in series and that I had given them 80mA for the 4 of them, but no.
They are in series, so the current in the circuit is the same for all 4, at 20 mA....
So I put in other ones I had, 3mm bright warm-white, with the top sanded off for more diffuseness. And the nice warm even light is back.
I hope those will last longer...or maybe I should hope I did something wrong, since I used the same ones for a Marantz 2325 (function lights) I did for somebody
Does anybody see if I did something wrong here that would explain the leds going bad ? Maybe it's getting too hot in there ? Most likely not.
Did you increase the large 5 Watt resistors to limit the current to the correct value? I believe there's 75 or 80 Volts on it, so the current needs to be dropped with increasing those large resistors. I replaced those in mine and the LED's are fine for almost 2 years.
Yes, the resistors were changed (there are two of them for the 4 display lights, unlike the schematic which shows one).
When I do the swap to leds, I start with a high value resistor and monitor the current, changing the resistor to get the proper current.
Here I now have a total of 3.6 kOhm resistance, gives me 20.5 mA cuurent, the leds are rated nominal 20mA, max 30mA.
At first I thought I did something wrong, what else could cause all 4 leds to go bad ? But now I've realised maybe there was just one bad led in the lot that caused the current to drop to the other 3, since they are all in series...
I did not dispose of the "bad" ones yet, maybe I can check if it is just one that has gone bad.
Awesome work, Bert!
Hi Bert, I did the same transformation on my CA-810 several months ago with warm white straw hat LEDs and the lighting has also become very weak.
I didn't have the time to to check or replace the lights yet.
Here's a link to my post from back then.
Hmmmm ça c'est intéressant...
I'll leave the amp in use and report back if there are problems with the new leds. I wonder what is happening here.
What was your source for the straw-hat leds ? Mine were from bright-components.co.uk
I got mine from chinese seller on eBay. Probably you got the same make.
I did the LED conversion in order to avoir changing bulbs every 1-2 years… it missed.
What did you use in place of those 2.2uf 25v bp caps on the protection circuit?
As Willy mentions, these are BiPolar, the KL or PW are not bipolar.
I think I used Wima MKS2 film caps (the red square ones)
Panasonic ECW or ECQ will also be fine but they are bigger.
There is a 10uf 50V bipolar somewhere there also, I used a Nichicon Muse ES (the green one you can see)
Ya I saw the green nichicon muse ES in your pics but I wasnt sure what the red square ones were.Did you use the Wima MKS2 anywhere else in this amp?
Yes I did, any electrolytic of 2.2 uF and below was replaced with these film caps. All in all nine 1uf and four 2.2uf if my list was correct
Was that only the bipolar ones or can I use them in place of the polarized variety?
Yes, here all small electrolytics can be replaced by a film cap.
But of course size and price goes up very quickly once you go above a few uF...
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