I bought a GFA535 on Ebay and it was DOA. Contacted the seller and asked him didn't you test it before you listed it. He said he didn't have a pre-amp, told him all you needed was a stereo mini rca to an rca cable and use your phone as a source. He gave me a full refund. The unit looked like a beast, dual mono design with single AC plug. Sent it to a local shop i know and for $160 he repaired it, that was 2 years ago and working great.
Nicely done sir! Not to spend your money, but if you do much more work like this, consider buying a HAKKO FR301 desoldering gun. Yes it's crazy expensive but it beats the hell out of copper braid for removing solder, particularly from old PC boards.
Agreed, it’s a game changer. I used an FR301 for about two years and it is now my backup. I grabbed an FR-410 with gun handle and boy oh boy it makes the FR301 seem like a cheap toy.
Great Video... I have the same amplifier, unfortunately the right channel has shorted output transistors. Can you share the replacement part numbers for the pair of output transistors? Thank You
BTW, the bias is incorrect on the 5200 schematic. As has been noted on one site, the 20mv value was transferred over from the 5300, which uses .33 ohm resisters for 60ma. So because the 5200 uses .1 ohm resisters, 20mv sets the current to about three times what it should be. So more like 6mv should be applied.
I own Adcom 5300 , bigger brother of 5200.... I can recap it but how much would you charge for testing it afterwards and adjusting DC and Bias as you did here?
Great videos and work! Thank you for that but I would like to make a note - this is an audio equipment. Please consider recapping with appropriate capacitors. Termal/temperature rating should not be the most important thing.
Nice work! I have the same amplifier GFA 5200. It runs very hot, but does work. Also have the GFA 5200 that has developed a high pitch crackling noise through the speakers when the music stops or it’s paused. Any idea what could be causing the noise?
I’m curious where you are located I have a pair of GFA 565 dual monobloc amps very large one has a dead rotten fish smell which I’ve been told has bad cabs the other one I’m sure he’s got bad cats also but the sound comes on only when you briefly plugged in the RCA cord but as soon as the ground sleeve of the RCA cord touches the ground on the RCA input sound goes away so anyway where are you located hopefully you’re close if not oh well I may drop these off and have you repair them
Nice work, I would have used a vacuum desoldering gun to remove all the transistors still mounted to the HS. Hakko or such, not one of those pad destroying hand solder suckers. Braid is fine, just risky for pads and expensive. Overall good job.
Hi there, I have a GFA 5500 for 19 years now. There is a very bad scratch like noise or like a newspaper crumpled up when I turn it on. The thing is: Even when there is no source connected, only the speakers, this noise comes up. Actually I am listening to music with this noise parallel to it. It is very annoying, because I don't turn it up usually. Do you have an Idea what is wrong? Thank you.
Why doing a third measurement for shorts if 2 sets of pins are already shorted? If B is shorted to A, and C to A, then by deduction C is shorted to B ;)
I bought a GFA535 on Ebay and it was DOA. Contacted the seller and asked him didn't you test it before you listed it. He said he didn't have a pre-amp, told him all you needed was a stereo mini rca to an rca cable and use your phone as a source. He gave me a full refund. The unit looked like a beast, dual mono design with single AC plug. Sent it to a local shop i know and for $160 he repaired it, that was 2 years ago and working great.
Thank you for the detailed trouble shooting in your videos.
I learn something new every time I watch one of these. Great stuff.
Nicely done sir! Not to spend your money, but if you do much more work like this, consider buying a HAKKO FR301 desoldering gun. Yes it's crazy expensive but it beats the hell out of copper braid for removing solder, particularly from old PC boards.
Agreed, it’s a game changer. I used an FR301 for about two years and it is now my backup. I grabbed an FR-410 with gun handle and boy oh boy it makes the FR301 seem like a cheap toy.
Great Video...
I have the same amplifier, unfortunately the right channel has shorted output transistors. Can you share the replacement part numbers for the pair of output transistors? Thank You
BTW, the bias is incorrect on the 5200 schematic. As has been noted on one site, the 20mv value was transferred over from the 5300, which uses .33 ohm resisters for 60ma. So because the 5200 uses .1 ohm resisters, 20mv sets the current to about three times what it should be. So more like 6mv should be applied.
For the sake of verification, did you test the mosfets to see if there was an issue that made them short out ? Thanks J K
Where do you repair guys get the schematics from?
Hats off to cleaning the pads after removing the components, that's a step many overlook.
Hi, where did you get those caps and fuse to buy? Any site online? Thanks
I own Adcom 5300 , bigger brother of 5200.... I can recap it but how much would you charge for testing it afterwards and adjusting DC and Bias as you did here?
What is the reason some of the rail caps are installed elevated over the board instead of touching the board?
Is it for better heat isolation ?
Great videos and work! Thank you for that but I would like to make a note - this is an audio equipment. Please consider recapping with appropriate capacitors. Termal/temperature rating should not be the most important thing.
Love your soldering skills, and watching the whole process!!!
Are you using rubbing alcohol to clean the board?
Yep usually just plain old ipa
@@dualityrepair4770 Hi ca
I sure do love multi-turn pots
Adcom 2535l ? What kind Caps ?
Nice work! I have the same amplifier GFA 5200. It runs very hot, but does work.
Also have the GFA 5200 that has developed a high pitch crackling noise through the speakers when the music stops or it’s paused.
Any idea what could be causing the noise?
Runs hot because 90% of its life is spent in Class A mode - tons of heat but a great workhorse :D
I’m curious where you are located I have a pair of GFA 565 dual monobloc amps very large one has a dead rotten fish smell which I’ve been told has bad cabs the other one I’m sure he’s got bad cats also but the sound comes on only when you briefly plugged in the RCA cord but as soon as the ground sleeve of the RCA cord touches the ground on the RCA input sound goes away so anyway where are you located hopefully you’re close if not oh well I may drop these off and have you repair them
Hi Marc,
I'm in Minnesota (Twin Cities area).
Good job as usual. With the exception of the 2 power mosfets, did you have other transistors shorted ?
Great work Sir. You need a Hakko 808 solder removing gun. It will change your life! What do you remove flux with? 👍
Hi, what kind of video equipment (camera) did you use to create this wonderful video? Thanks for sharing your work.
Just an Iphone 11.
Nice work, I would have used a vacuum desoldering gun to remove all the transistors still mounted to the HS. Hakko or such, not one of those pad destroying hand solder suckers. Braid is fine, just risky for pads and expensive. Overall good job.
Hi there, I have a GFA 5500 for 19 years now. There is a very bad scratch like noise or like a newspaper crumpled up when I turn it on. The thing is: Even when there is no source connected, only the speakers, this noise comes up. Actually I am listening to music with this noise parallel to it. It is very annoying, because I don't turn it up usually. Do you have an Idea what is wrong? Thank you.
To be clear, is this noise only present on power up, or is it always present?
Replacing those single-turn quiescent current- and DC offset pots with multi-turn ones would let you dial in the precise numbers called for.
Excellent! Well Done.
Hi, when will do some tutorial on hi fi troubleshooting?
Why doing a third measurement for shorts if 2 sets of pins are already shorted? If B is shorted to A, and C to A, then by deduction C is shorted to B ;)
how difficult to replace Adcom input board?also do you know where I can buy the input board?
Not sure on both questions. Sorry.
@@dualityrepair4770 I could send Adcom amp to U ? If U have the time.
What kind of problems is it having?
@@dualityrepair4770 bad input board
Send me an email: nick@duality-er.com
Another great informative video !...cheers.
sounds more like the circuit for the GFA 535 which is dual mono power supply!
That is an odd duck.
But I do like it.
Great job !
Nelson Pass designed this didn't he.
Exelent
Great job!