New (to me) amps

[quindecima]

I have moved on to the input board. This was going to be the most challenging but I looked at it and thought that if I was real careful I could work on it without removing the board. Hah, fat chance, there is no way I can remove some of those itty bitty parts without having the board mounted in a board holder. I replaced one trimmer but that is as far as I am going until the board holder gets here. I am going to have to number all the wires ( they are marked on the board) it doesn't look too bad mostly labor intensive.

[quindecima]

I managed to mount the input board on my bench today in a pretty secure manner and changed out 8 diodes to a higher value. The darn things are the size of a large ant, I had to break out my magnifying glass on a lamp that I use for tying flies so I could see the things. I back lit the board so everything stood out pretty well.

[Wagner]

Here we are today. The X2 caps I tried to get with the long leads actually came with them, not as described at all. I replaced the little caps you see that are 47uf at 160V with 120uf at 200V and bypassed them with 22uf at 600V orange drops. I also replaced the Ceramic bypass cap on the mains with one of the X2 caps. I am debating if I need to get to the bottom of those 4 boards to replace the 68pf at 500V film that are there with the same thing.

Addendum. I replaced the film that were there with Micas.

I really wish I understood what this deal/problem is you've got going with the caps' lead length?
I also have no clue what it is you are up to, but I hope whatever it is it all works out to your satisfaction!

I assume you are changing out all of the amp's electrolytics, yes?

Enjoy!
Thomas

[quindecima]

Yes, almost all electrolytics and other caps. the lead length was a problem on the bridge rectifier, I had to run a cap across the AC and the short leads on most caps wouldn't reach. It is not a problem anymore I resolved it forthwith. These amps have a known problem with a bunch of bad caps the manufacturer got from a supplier, they leak land screw up the boards and its a big job to clean them up afterwards. Lucky for me the two amps that I got don't have the caps leaking and I am making sure they are replaced before they do. I am also making a few other upgrades while I am into it.

[quindecima]

Still waiting for the rest of the stuff from Mouser but today a little package from China. I'm going to install a speaker protection board to protect the speakers and they make these little boards over there you just have to assemble them, takes about 1/2 hour at a slow pace. Each board fits in the bottom of the amp and controls two speakers.

[quindecima]

The last of my components arrived and I have upgraded the output terminals and the board is completed. Now to reassemble and fire it up.

[quindecima]

I had to replace 4 of the diodes I installed. I could tell the cathode end on the new ones I installed but the ones from Adcom were colored with a different band and I had a hard time discerning them. My right output boards have some bad output transistors so it looks like they are going to be replaced.

[quindecima]

Here is the final story, I dropped some solder down on the board and it fell between the collectors and bases on the left side (nice) and then I had a bad trace on the right that blew a couple on the right so I had to replace all of the output transistors there. I took the output board out so many times trying to figure out what was the problem that I screwed it up a little but it is in fine shape now due to some outside help I am a happy camper. If any of you have Adcom Amps and want some info give me a shout and I will steer you in the correct direction.

[Challenger604]

Hi Larry!
Seems you had a lot of fun!!
C

[quindecima]

Yes, I started on my other amp and it's turning out much nicer. I have the correct length caps and am doing it a little different as far as disassembling it. It will be a much cleaner job, won't work any different but cosmetically will be better.

[quindecima]

I'm done this is it.

[Challenger604]

I'm done this is it.

Is it working?? LOL!!
Nice!!
Pretty much a brand new amp!
Congrats!
C

[quindecima]

Oh yeah, it's working very nice. I ran it today at idle and it is dead quiet and less than 1mv at the speaker outputs. I learned a lot on this that I passed on to my other one. One thing left is I am going to replace the power cord with an IEC plug with a filter on it. I am waiting for a square chassis punch, I couldn't figure out how to do it without making a mess without the punch.

[quindecima]

Well, the chassis punch came today and I jumped right on it. Last time I am doing that!!!! 18ga steel probably a little much for it. I turned the nut as far as I could muster up the strength, even lubed it, then I took it out and cut it out with a small cutting wheel heck of a lot faster. Actually a PITA for what little I gained. The best way to do it is to unsolder the outputs and inputs and remove the panel, I need a small libation.

[Krunchy]

Here is the final story, I dropped some solder down on the board and it fell between the collectors and bases on the left side (nice) and then I had a bad trace on the right that blew a couple on the right so I had to replace all of the output transistors there. I took the output board out so many times trying to figure out what was the problem that I screwed it up a little but it is in fine shape now due to some outside help I am a happy camper. If any of you have Adcom Amps and want some info give me a shout and I will steer you in the correct direction.

Thank you sir, I'm gonna take you up on that offer, I have a GFA5802 that is not working, hopefully it is something that is obvious or stands out, I have not had a chance to look into it yet but will do so as I get a chance.