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KA-7300 Problems

Hmmm. Well I didn't have as much of a problem twisting the leads for Qe3 & Qe4 as I thought I would, so I do feel confident that I could do it again if I had to.

I see Digikey has the Zetex transistors as well as the metalized polypropylene input cap I asked about before. I may dive into the rest of it and get cap values on everything I haven't hit and then I'll be able to have a fully recapped unit. Don't think I'll do the four 10k uf though.

After I placed my order from Mouser I opened the unit and started studying the amp boards, trying to learn what went where. I noticed that there was a bunch of fuzzy muck & grim between the three leads on Qe1 & Qe2, one board had more than the other. It was like a thick web. I used a wooden toothpick & magnifying glass to displace & remove the fuzz. After that I thought to myself I wonder if that somehow could have had something to do with the popping. Plugged the unit in, hooked up a cd player & headphones and not a pop since I cleaned it. I decided since I had already ordered the parts that I was going to replace them, but I guess they were actually better than what I bought.

Either way, this has been a great experience. I learned a lot and gained much needed confidence in doing something like this again. I now feel like instead of buying any more gear, I should just recap what I have and go from there. :thmbsp:
 
Well, since I have the meter for another night I decided to measure the transistors I took out of Qe1 & Qe2. To my surprise I have values of: 353, 374, 324, & 315 Hfe. So actually the parts I installed all have higher numbers(380 Hfe) than the old, not to mention much tighter ranges So how did the offset increase? :scratch2:
 
Maybe the ones you installed aren't as close as you suppose.

That's my lame way of saying that I don't have an answer. But, we're talking about millivolts here, so it doesn't take a lot to make an appreciable difference.
 
Here is a general form of the DC Servo. This is a non-specific example, and does not include the necessary supplies to the opamp.
 

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Trio KA 7300

Hey folks,
I posted on another thread along the same theme....
Excuse me doubling up a bit.
I picked up a Trio KA 7300 earlier, cleaned it, hooked it up... and now it's me that's hooked.
Playing through a set of cheap technics full range speakers.
Sounds great!

I'm expecting to have to replace capacitors at some stage and I'm looking for the service manual. I don't mind to pay (if I have to) but I would be very happy if someone can recommend a good reliable (the people that is) place to download before I fork out the beer vouchers.
Don't like giving my e-mail address to any of the plethora of unknown PDF Manual download companies which have sprung up over the last 18 months, but if someone has a site they can recommend from experience?

Ta very much!
Bill :smoke: ...actually I gave up...
 
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