I just took a closer look at your pic - too bad you can’t solder aluminum bond wires. I’ll bet it still works.
Quick question these tan caps I want to play around with what parts I have is there a way I can know what size they are by what's printed on them of course I want to get one of them cap tester things you guys was talking about but that will be when I have the money to get one thanks for any info you guys share with me Aaron.
Hey there,
I worked in the tech. service dept. of the original Australian BGW importer.
Some 'silly' (not me) repaired a BGW 750 with 2N3773's instead of the proper Motorola (coded) devices >
and the amp. BLEW ITS BRAINS OUT - highly embarrassingly during an AES listening demonstration 😵
It blew on the 'cannon fire' of the 1812 overture !
A case of insufficient SOA
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Whose 2N3773? Motorola/ON will usually pass 200 VCEO, which is what is needed. The 100V/1.5A SOA rating of the original Motorola is plenty sufficient, and that’s 100% production tested. Second-source units may or may not be as robust. RCA hometaxial is just as good if not better about the 100V/1.5 A rating, but they have more trouble with VCEO>140V. They used those too, but I’m sure yields were lower at the factory so they were probably pricey. Other makers could be all over the map. I would have only used Motorola, and tested them myself first. VCEO test is easy, and non destructive. And would have saved embarassment. If you used some no-name “2N3773” you deserve your fate.
Today you just use MJ15024 and be done with it. On semi, of course.
Well I just checked your guys store out I'm so glad I found this forum or message board I don't wanna call it the wrong thing just glad to be here to learn all I can love reading your guys post even tho some of it I clearly have no clue what y'all are talking about lol hopefully your new friend in the world of sound Aaron
Here is a little amp I was working on last night it's a mb3712 I call it the cash card amp lol 😂 was testing it out hooked my 4 ohm speaker cause that's what they used in data sheet and when I hooked up power it makes this wub wub wub wub wub sound all the time and when I would unhook the power when it was losing voltage you could hear it start to play what I was playing threw it but faintly anyways I don't know either the chip is bad or I don't have enough parts to filter whatever it is
Attachments
Probably needs a 470 or so uF cap directly across the + and - supply pins of that IC.
That can create other minor problems, but probably solve the one you’re having at the moment.
Those little single supply IC amps are notoriously difficult to work with, despite their supposed simplicity. There are about 10 or 12 cardinal rules concerning proper grounding, and with IC amps that share a power and signal ground (same pin) it’s physically impossible to follow them all simultaneously.
That can create other minor problems, but probably solve the one you’re having at the moment.
Those little single supply IC amps are notoriously difficult to work with, despite their supposed simplicity. There are about 10 or 12 cardinal rules concerning proper grounding, and with IC amps that share a power and signal ground (same pin) it’s physically impossible to follow them all simultaneously.
Are you talking about a cap like I am using or the ceramic tan ones and thanks for helping me man I'll try that tonight after my movie and let you know my results oh and if I record a short 10sec video or mp3 sound file can they be uploaded like the pictures?
Ps. Do I need to leave the other one I already have and add the other cap?
Ps. Do I need to leave the other one I already have and add the other cap?
Sometimes one of those 0.1 uF “tan ceramic ones” is big enough. Sometimes it isn’t happy until you stick a big electrolytic on it.
I don't know how you guys are about posting sites if this is wrong just let me know but this is what I went by I may make me a amp next I can play my guitar threw https://www.diystompboxes.com/smfforum/index.php?topic=110349.0
Well them tan caps all the ones I have have a 103 and 102s on them and I don't know how to figure out what size they are but that guys circuit is what I went by the 100 uf one I didn't have that so I used a 220uf one I'm using all ones that have a + and a - side anyways have to learn how to spell the word you call them
They are ”color coded” like resistors, just using numbers. 102= 1000, and 103 = 10,000. Value is in PICOfarads. Too small to be an effective bypass cap for any audio power amp - even a 2 watt IC. A 220 uF electrolytic type SHOULD work. If it’s still oscillating with one of those in place your layout is somehow poor.