Hello,
This is my first post to DIYaudio and I'm not an electronics tech.
I have an opportunity to buy what looks like a nice Adcom GFA-555. The question is, how do I know? I'll listen to it and inspect the inside visually, but I've read here (my understanding that is..) and other places that there is a potential to fry speakers if the caps end up going bad. Is there some preventative maintenance that wouldn't be too expensive or some tests that I could do or take it to someone to certify its condition and have some insurance without spending too much money ($100 or less)?
In a perhaps related question, I have a 10yr old son and a 13yr old daughter who I would love to use this and/or general diy amp/electronics for education. How do we get started? Might this be a good project?
Thank you for your help.
This is my first post to DIYaudio and I'm not an electronics tech.
I have an opportunity to buy what looks like a nice Adcom GFA-555. The question is, how do I know? I'll listen to it and inspect the inside visually, but I've read here (my understanding that is..) and other places that there is a potential to fry speakers if the caps end up going bad. Is there some preventative maintenance that wouldn't be too expensive or some tests that I could do or take it to someone to certify its condition and have some insurance without spending too much money ($100 or less)?
In a perhaps related question, I have a 10yr old son and a 13yr old daughter who I would love to use this and/or general diy amp/electronics for education. How do we get started? Might this be a good project?
Thank you for your help.
FWIW, mine has been going for 30 years with no problems at all. It's a terrific amp.
If you want to be conservative, you could spend $150 or so and replace the power supply caps, but if the amp sounds OK, there's no hum, and the little rubber plugs on top of the caps aren't bulging, you're probably fine.
If you want to be conservative, you could spend $150 or so and replace the power supply caps, but if the amp sounds OK, there's no hum, and the little rubber plugs on top of the caps aren't bulging, you're probably fine.
that's enough ; if it sounds OK , it's in working condition
took some pics later and post them here
second question - myriad of useful things on net , YTube etc.
maybe someone will chime in with recommendation for some books , intended for school kids
one of places : Basic Car Audio Electronics
Thank you for the quick responses and the book recommendation.
So does that mean there is no or little risk of frying speakers if/when caps or something else goes bad?
So does that mean there is no or little risk of frying speakers if/when caps or something else goes bad?
one day sun will implode , for sure 
in a meantime , do what I told you - post pics here , so we can chat about cap replacement if needed
only drawback with them aging is - deterioration of sound and buzz/hum
in a meantime , do what I told you - post pics here , so we can chat about cap replacement if needed
only drawback with them aging is - deterioration of sound and buzz/hum
Post pics
Thank you again! I will definitely, post pics if I buy the amp. This is a pre-buy question. I'll look for bulged and corroded caps when I look inside.
I really appreciate the help. Hopefully it will turn out to be a good deal.
Thank you again! I will definitely, post pics if I buy the amp. This is a pre-buy question. I'll look for bulged and corroded caps when I look inside.
I really appreciate the help. Hopefully it will turn out to be a good deal.
You have gotten good advice. If you are still worried, then measure the DV voltage at the output (DC not AC and no source needs to be connected). It should measure less than about 20-30 mV and be comparable in both channels. If it is not, then get back and tell us.
Pictures
The original amp I was looking at was being sold for $300. It sold before I could get it and I thought I lost out on a deal.
Yesterday I picked up an entire system (pre-amp, amp, marantz CD, NAD tape, cabinet) for $200.00. Original owner! Mint! Booyaaa!! It sounds great too!
The original amp I was looking at was being sold for $300. It sold before I could get it and I thought I lost out on a deal.
Yesterday I picked up an entire system (pre-amp, amp, marantz CD, NAD tape, cabinet) for $200.00. Original owner! Mint! Booyaaa!! It sounds great too!
Attachments
- Status
- Not open for further replies.