Hi MJR,
I'd suggest first getting the amp completely operational staying with the parts you've already purchased.
Once it's working and stable, if you want to get fancy and start bypassing, replacing with Black Gates, playing with cooling, etc then go for it but only change one thing at a time and then evaluate.
What we don't want is too many variables changing at once.
These amps are known for being touchy anyway. You can bet that Adcom worked very hard at making these as stable as they are.
Get them working and stable FIRST, then and only then start changing things.
Just my opinion...
Good luck!
I'd suggest first getting the amp completely operational staying with the parts you've already purchased.
Once it's working and stable, if you want to get fancy and start bypassing, replacing with Black Gates, playing with cooling, etc then go for it but only change one thing at a time and then evaluate.
What we don't want is too many variables changing at once.
These amps are known for being touchy anyway. You can bet that Adcom worked very hard at making these as stable as they are.
Get them working and stable FIRST, then and only then start changing things.
Just my opinion...
Good luck!
Rebuilt and running perfectly
Gentlemen,
I have finished rebuilding the input boards on both amps.
The function of the amp which I rebuilt entirely is smooth and solid. Upon powerup, DC offset at the speaker terminals is at ~20mV, which reduces to 5mV after 10 seconds and 0mV after 30 seconds. The amp settles down very quickly and stays that way.
With the thermistor on the predriver heatsink, the fan kicks on after about 15 minutes of operation and runs at a high speed, then slowing down and running at low speed, it no longer stops and starts, unless ambient temperature is exceptionally low.
Bias hovers around 24mV at startup and remains steady at a solid 24mV after 1 hour of warm-up @ 100-watts with cover on (as the service manual instructs).
The inside of the completely rebuilt amp looks clean, works clean, and here is the surprising part. Prior to the rebuild, I was hearing a radio station on both amps when powered up and connected to a source (source ON/OFF or even unplugged)...
I can still hear radio stations on the other amp, but the rebuilt amp with EMI/RFI shielding foil has attenuated the audibility of the radio station by more than half in listening tests conducted by me. I am unsure if the EMI/RFI foil is responsible for this attenuation, but the difference only came after the rebuild while the other amp without EMI/RFI foil has a noticably louder radio station pickup (note, it is not the speaker leads, i tried a 100pF capacitor across the speaker wire, no difference)...this leads me to assume that the EMI/RFI foil did make a difference. In addition to installing it and experiencing the audible attenuation, logically RFI/EMI has no place inside of an amplifier chassis, where transistors may pick up and amplify them. I believe the foil has made the difference. Thoughts?
Here are pictures of the rebuilt amp:
PIC 1: Rebuilt amp with a rebuilt input stage, new filter capacitors, a new bridge rectifier, completely recapped with 105-degree Mallory SEK-series electrolytic capacitors, fitted with EMI/RFI shielding, and completely rewired with silver-plated-copper wiring with teflon dielectric.
PIC 2: Rewired and rebuilt input stages use all modular connections.
PIC 3: A close-up of the rebuilt input stage, installed.
PIC 4: New filter capacitors, new wiring, new connectors, clean installation.
This brings an end to my project, for now. It's been fun gentlemen, I thank you once again for your kind help and dedication to making diyAudio.com truly the best internet resource for DIYers. This thread alone has set a new internet standard for helping other GFA-565 owners understand their amplifiers and hopefully, be able to fix them themselves.
I'm beaming.
Tata,
--MJR
Gentlemen,
I have finished rebuilding the input boards on both amps.
The function of the amp which I rebuilt entirely is smooth and solid. Upon powerup, DC offset at the speaker terminals is at ~20mV, which reduces to 5mV after 10 seconds and 0mV after 30 seconds. The amp settles down very quickly and stays that way.
With the thermistor on the predriver heatsink, the fan kicks on after about 15 minutes of operation and runs at a high speed, then slowing down and running at low speed, it no longer stops and starts, unless ambient temperature is exceptionally low.
Bias hovers around 24mV at startup and remains steady at a solid 24mV after 1 hour of warm-up @ 100-watts with cover on (as the service manual instructs).
The inside of the completely rebuilt amp looks clean, works clean, and here is the surprising part. Prior to the rebuild, I was hearing a radio station on both amps when powered up and connected to a source (source ON/OFF or even unplugged)...
I can still hear radio stations on the other amp, but the rebuilt amp with EMI/RFI shielding foil has attenuated the audibility of the radio station by more than half in listening tests conducted by me. I am unsure if the EMI/RFI foil is responsible for this attenuation, but the difference only came after the rebuild while the other amp without EMI/RFI foil has a noticably louder radio station pickup (note, it is not the speaker leads, i tried a 100pF capacitor across the speaker wire, no difference)...this leads me to assume that the EMI/RFI foil did make a difference. In addition to installing it and experiencing the audible attenuation, logically RFI/EMI has no place inside of an amplifier chassis, where transistors may pick up and amplify them. I believe the foil has made the difference. Thoughts?
Here are pictures of the rebuilt amp:
PIC 1: Rebuilt amp with a rebuilt input stage, new filter capacitors, a new bridge rectifier, completely recapped with 105-degree Mallory SEK-series electrolytic capacitors, fitted with EMI/RFI shielding, and completely rewired with silver-plated-copper wiring with teflon dielectric.
PIC 2: Rewired and rebuilt input stages use all modular connections.
PIC 3: A close-up of the rebuilt input stage, installed.
PIC 4: New filter capacitors, new wiring, new connectors, clean installation.
This brings an end to my project, for now. It's been fun gentlemen, I thank you once again for your kind help and dedication to making diyAudio.com truly the best internet resource for DIYers. This thread alone has set a new internet standard for helping other GFA-565 owners understand their amplifiers and hopefully, be able to fix them themselves.
I'm beaming.
Tata,
--MJR
Hi MJR,
That is truly good workmanship, very neat. You have every reason to be proud of your effort.
Your reduction in RFI may also be simply due to the fact that you've redone all the connections. Any oxides in your screw connections were eliminated when you rebuilt it.
Excellent work!
-Chris
That is truly good workmanship, very neat. You have every reason to be proud of your effort.
Next time, use a small RFI choke between the capacitor and the amp. Amplifiers do not like caacitive loads and some are more sensitive than others to this.
Your reduction in RFI may also be simply due to the fact that you've redone all the connections. Any oxides in your screw connections were eliminated when you rebuilt it.
Excellent work!
-Chris
Circuitry error leads to Thermal Shutdown
Greetings to all diyAudio members and to those select few who were instrumental in assisting with my GFA-565 rebuild (Chris, Steve, Arif).
Status Report
It has been almost 7 months since the completion of my rebuilds and both amps have been functioning very well, running with active fan cooling and just warm-to-the-touch when I rarely push the amps to amplification levels (loads). 90% of the time, I run them at low amplification levels (or approximately 10-20% of capacity @ 8 ohms).
The rebuild has been a complete success.
Thermal Shutdown
However, during my last listening session two nights ago, one amp kept producing minor audible disruptions in its output. The sound is similar to what you frequently hear on analog amps when a power spike or surge is created in the electrical circuit upon power-on of another electrical device (i.e. turning another high power device on which is on the same circuit {JUST an example of the sound i heard, I wasn't doing this}).
Today, I powered up both amps and was running them for about 10 minutes at ~15% amplification levels when one amp started to produce the same audible disruptions (almost like clipping), then in a matter of seconds the disruptions became more frequent and then the Thermal Protection L.E.D. illuminated, signalling an emergency shutoff had occurred.
Based on my experience and limited knowledge of the internals of this amp, I am inclined to suspect that one (or both) of the UP62 (85 degree Celsius) thermostat thermal breakers has (have) opened, resulting in the GFA-565's thermal protection circuitry to be enabled. Now, remember that when this happened the amp was running cool, it was not even warmed up (in addition I have active cooling on the amp, it is virtually impossible to overheat). I believe that the thermal breakers are old and have simply failed.
Here is a description of the thermal protection circuitry in the GFA-565 from the Adcom Service Manual:
Remember that the amp was not overheating, it was running cool. In addition I sniffed all areas of the amp and could not detect any foul odors. I am highly confident that this problem is with either the thermal breakers or with a part of the thermal protection circuit.
I haven't yet opened the amp to give it a visual inspection, but once I do, I will post any noticeable observations.
Based on this preliminary information and your knowledge of these amps, what do you think is going on with the amp? Where should I target my inspection and troubleshooting?
Thank you for your help once again, gentlemen.
Greetings to all diyAudio members and to those select few who were instrumental in assisting with my GFA-565 rebuild (Chris, Steve, Arif).
Status Report
It has been almost 7 months since the completion of my rebuilds and both amps have been functioning very well, running with active fan cooling and just warm-to-the-touch when I rarely push the amps to amplification levels (loads). 90% of the time, I run them at low amplification levels (or approximately 10-20% of capacity @ 8 ohms).
The rebuild has been a complete success.
Thermal Shutdown
However, during my last listening session two nights ago, one amp kept producing minor audible disruptions in its output. The sound is similar to what you frequently hear on analog amps when a power spike or surge is created in the electrical circuit upon power-on of another electrical device (i.e. turning another high power device on which is on the same circuit {JUST an example of the sound i heard, I wasn't doing this}).
Today, I powered up both amps and was running them for about 10 minutes at ~15% amplification levels when one amp started to produce the same audible disruptions (almost like clipping), then in a matter of seconds the disruptions became more frequent and then the Thermal Protection L.E.D. illuminated, signalling an emergency shutoff had occurred.
Based on my experience and limited knowledge of the internals of this amp, I am inclined to suspect that one (or both) of the UP62 (85 degree Celsius) thermostat thermal breakers has (have) opened, resulting in the GFA-565's thermal protection circuitry to be enabled. Now, remember that when this happened the amp was running cool, it was not even warmed up (in addition I have active cooling on the amp, it is virtually impossible to overheat). I believe that the thermal breakers are old and have simply failed.
Here is a description of the thermal protection circuitry in the GFA-565 from the Adcom Service Manual:
Remember that the amp was not overheating, it was running cool. In addition I sniffed all areas of the amp and could not detect any foul odors. I am highly confident that this problem is with either the thermal breakers or with a part of the thermal protection circuit.
I haven't yet opened the amp to give it a visual inspection, but once I do, I will post any noticeable observations.
Based on this preliminary information and your knowledge of these amps, what do you think is going on with the amp? Where should I target my inspection and troubleshooting?
Thank you for your help once again, gentlemen.
Hi MJR,
Solder joints to those sensors. I have not seen one fail, but that doesn't mean it can't happen.
Take the top off and gently nudge the wires with a non-conductive object. Work gently and you may find the fault.
Try tapping the PCB also, again look for bad solder joints. Another possible cause would be an intermittent transistor in the CCS circuit.
-Chris
Solder joints to those sensors. I have not seen one fail, but that doesn't mean it can't happen.
Take the top off and gently nudge the wires with a non-conductive object. Work gently and you may find the fault.
Try tapping the PCB also, again look for bad solder joints. Another possible cause would be an intermittent transistor in the CCS circuit.
-Chris
Alternately you can also check for continuity of the sensors.
Run the amp via an AC series bulb, short one or both sensors, then power up and run the amp at 10% power.
If signal is undistorted then you know the thermal switches are bad. I have had to replace only 1 switch since I began tinkering with Adcoms so you know they don't fail often as Chris says.
This is not a fool proof method, but gives you a negative test.
K
Run the amp via an AC series bulb, short one or both sensors, then power up and run the amp at 10% power.
If signal is undistorted then you know the thermal switches are bad. I have had to replace only 1 switch since I began tinkering with Adcoms so you know they don't fail often as Chris says.
This is not a fool proof method, but gives you a negative test.
K
Hi Mjr,
Nice that you could fix your broken 565 well.
I'm in the process of putting together a system with a DAC-1, and the recently bought preowned 565s (serial # 007214094, and 007214101).
Though I havent got the speakers, just to check, I powered them and found that one gave out a horrible smell, on which I promptly powered it down.
I feel strongly that its a capacitor leak problem. Instead of taking it to a technician, I want to do it myself, learn things in the process, with your support.
Could you share with me the details of the kind of tools I'd require to fix this as you did? If you can send me a pic of your work table, much better.
Reading the posts from you, Chris, apogee and others, I gathered and summarized the list of possible tweaks that can go in to the 565:
ADCOM GFA-555 Mk-II Power Amplifier upgrades
black gate electrolytic caps and auricap film caps
Panasonic FC's from Digikey and Nichicon HE or PW's from Mouser
Input Board Upgrades
1. Input board Electrolytics (470uF and 4.7uF (four total)) replaced with BLACK GATE capacitors.
2. Input board Film caps replaced (.01uF (8-total)) replaced with Hovland (Film and foil) “Musicaps”
3. Input board Film coupling caps (1.0uF (2ea)) replaced with Auricap metalized polypropylene caps.
4. Input board Mica caps (330, 15, 50pF (6 total)) replaced with Hi temp silver mica caps.
5. Input RCA connectors replaced with “Cardas” connectors
6. Input board RCA to PCB hook up wire replace with D.H. Labs Revelation Series - 18 awg. Solid Core silver wire. The rest of the input board wire harness was replaced with Kimber AGSE hook up wire
Output Board Upgrades
1. Output board Electrolytics (47uF (four total)) replaced with BLACK GATE capacitors.
2. Output board Mica caps (68pF (4 total)) replaced with Hi temp silver mica caps.
Replace both of the ADCOM 100V / 35,000uF capacitors with BLACK GATE 100V (or higher) / 39,000uF capacitors
The 3504 bridge can be replaced by any other 3504 bridge, regardless of manufacturer or prefixes, suffixes, etc......
the first 2 digits tell you the rated current, in this case 35A, and the second two digits tell you the voltage in hundreds, in this case 400V.
Replace 3504 bridge rectifier (part # KBPC3504P) with:
- 400V/35A or
- 40A/400V (4004) or
- 40A/600V (4006) or
- 60A/600V (6006) bridge rectifiers regardless of manufacturer or prefixes, suffixes, etc......to get the higher Peak Inverse Voltage 600V . This is another safety precaution and will in NO way affect the operation of the amp , just add some more safety.
Replace the electrolytic caps on the AC Input/Bias Time-delay (soft start) boards in BOTH amps with shiny and brand new Mallory electrolytic caps, as well as the bridge rectifiers with higher quality HVCA models. The HVCA is recommend because it is glass encased, the bottom and sides are metal, which can conduct heat better and pass its own heat to the heatsink to which it is attached to in the 565.
Replace the two electrolytic capacitors on the output stage with Mallory caps.
Rewire the entire amp (everything that is possible) with the same guage wiring, but MILSPEC (Silver coated copper stranded).
Line the internal planes with EMI/RFI shielding foil.
Bypass the Large caps with 1000uF then 100uF then 5uF then 0.5uF caps.
Install distributed caps near the OP devices of 1000uF to 2000uF.
Input Stage cleaned with ultrasonic cleaning, completely rebuilt with brand new Mallory SEK series 105-degree-rated aluminum electrolytic capacitors, WECO PCB screw-down terminals (epoxied to the PCB with cyanoacrylate, then soldered), gold headers for all LED connection points, an upgraded Analog Devices OP97 op-amp IC, a Copal 100 ohms Cermet variable resistor, and silver-plated copper patch wires with teflon dielectric.
Regrease Sanyo 150W Predriver Transistors (using Arctic Silver 5 thermal compound).
Bathe the GFA-565 input stage PCB through 3 Simple Green washes and 4 cold water rinses inside of this ultrasonic cleaner, yeilding a wash cycle of 1 full hour. The tank needs to be drained, rinsed, and wiped-down after each wash cycle, to prevent any remaining electrolyte from reattaching to the PCB.
Modify Optional Top Cover & Cooling Fan (EMI/RFI Aluminum/Polyester Shielding Foil installed for over 60dBA attenuation of 600MHz-1GHz frequencies.
Upgraded bypass capacitors to 105 degree Celsius-rated aluminum electrolytics & custom gold-plated copper headers installed with brass-female connectors crimped into the AC input and DC output leads for modular connections. In addition, the thermistor for the fan circuit is placed on the input stage predriver transistors, which force the fan to flush out the hot air every 5 minutes, environmental noise from the fan is negligible at normal listening levels.)
CHECK:
The GFA565 is a direct coupled amp using a DC feedback servo to null out any DC appearing at the speaker output terminals. IC101 (Adcom part no. 2A) is part of this nulling circuit. If this IC fails there will be some DC (~1 volt) on the speaker output and this will cause a "thump" in your speakers when the amp is turned off. If needed, you can order a replacement 2A IC directly from Adcom -- or get a Linear Technology LT1012 from Digikey for a lot less money.
In addition to IC101 and associated components, you may want to check the two 10-Ohm fusible resistors R121 and R157 on the main signal input PC board. Also check the 100-Ohm R803 fusible resistor on the small PC board atop the filter caps. These resistors are sacrificial devices which open when subjected to current spikes in the circuit grounds.
R121 and R803 can be easily checked from outside the amp as detailed below:
Troubleshooting two of the fusible resistors by external measurements:
DC resistance from speaker output black terminals (grounds 1 and 2) to AC power plug third pin safety ground should be 100 Ohms (checks 100-Ohm fusible R803).
DC resistance between signal input ground 3 and speaker output black terminals (grounds 1 and 2) should be 10 Ohms
Nice that you could fix your broken 565 well.
I'm in the process of putting together a system with a DAC-1, and the recently bought preowned 565s (serial # 007214094, and 007214101).
Though I havent got the speakers, just to check, I powered them and found that one gave out a horrible smell, on which I promptly powered it down.
I feel strongly that its a capacitor leak problem. Instead of taking it to a technician, I want to do it myself, learn things in the process, with your support.
Could you share with me the details of the kind of tools I'd require to fix this as you did? If you can send me a pic of your work table, much better.
Reading the posts from you, Chris, apogee and others, I gathered and summarized the list of possible tweaks that can go in to the 565:
ADCOM GFA-555 Mk-II Power Amplifier upgrades
black gate electrolytic caps and auricap film caps
Panasonic FC's from Digikey and Nichicon HE or PW's from Mouser
Input Board Upgrades
1. Input board Electrolytics (470uF and 4.7uF (four total)) replaced with BLACK GATE capacitors.
2. Input board Film caps replaced (.01uF (8-total)) replaced with Hovland (Film and foil) “Musicaps”
3. Input board Film coupling caps (1.0uF (2ea)) replaced with Auricap metalized polypropylene caps.
4. Input board Mica caps (330, 15, 50pF (6 total)) replaced with Hi temp silver mica caps.
5. Input RCA connectors replaced with “Cardas” connectors
6. Input board RCA to PCB hook up wire replace with D.H. Labs Revelation Series - 18 awg. Solid Core silver wire. The rest of the input board wire harness was replaced with Kimber AGSE hook up wire
Output Board Upgrades
1. Output board Electrolytics (47uF (four total)) replaced with BLACK GATE capacitors.
2. Output board Mica caps (68pF (4 total)) replaced with Hi temp silver mica caps.
Replace both of the ADCOM 100V / 35,000uF capacitors with BLACK GATE 100V (or higher) / 39,000uF capacitors
The 3504 bridge can be replaced by any other 3504 bridge, regardless of manufacturer or prefixes, suffixes, etc......
the first 2 digits tell you the rated current, in this case 35A, and the second two digits tell you the voltage in hundreds, in this case 400V.
Replace 3504 bridge rectifier (part # KBPC3504P) with:
- 400V/35A or
- 40A/400V (4004) or
- 40A/600V (4006) or
- 60A/600V (6006) bridge rectifiers regardless of manufacturer or prefixes, suffixes, etc......to get the higher Peak Inverse Voltage 600V . This is another safety precaution and will in NO way affect the operation of the amp , just add some more safety.
Replace the electrolytic caps on the AC Input/Bias Time-delay (soft start) boards in BOTH amps with shiny and brand new Mallory electrolytic caps, as well as the bridge rectifiers with higher quality HVCA models. The HVCA is recommend because it is glass encased, the bottom and sides are metal, which can conduct heat better and pass its own heat to the heatsink to which it is attached to in the 565.
Replace the two electrolytic capacitors on the output stage with Mallory caps.
Rewire the entire amp (everything that is possible) with the same guage wiring, but MILSPEC (Silver coated copper stranded).
Line the internal planes with EMI/RFI shielding foil.
Bypass the Large caps with 1000uF then 100uF then 5uF then 0.5uF caps.
Install distributed caps near the OP devices of 1000uF to 2000uF.
Input Stage cleaned with ultrasonic cleaning, completely rebuilt with brand new Mallory SEK series 105-degree-rated aluminum electrolytic capacitors, WECO PCB screw-down terminals (epoxied to the PCB with cyanoacrylate, then soldered), gold headers for all LED connection points, an upgraded Analog Devices OP97 op-amp IC, a Copal 100 ohms Cermet variable resistor, and silver-plated copper patch wires with teflon dielectric.
Regrease Sanyo 150W Predriver Transistors (using Arctic Silver 5 thermal compound).
Bathe the GFA-565 input stage PCB through 3 Simple Green washes and 4 cold water rinses inside of this ultrasonic cleaner, yeilding a wash cycle of 1 full hour. The tank needs to be drained, rinsed, and wiped-down after each wash cycle, to prevent any remaining electrolyte from reattaching to the PCB.
Modify Optional Top Cover & Cooling Fan (EMI/RFI Aluminum/Polyester Shielding Foil installed for over 60dBA attenuation of 600MHz-1GHz frequencies.
Upgraded bypass capacitors to 105 degree Celsius-rated aluminum electrolytics & custom gold-plated copper headers installed with brass-female connectors crimped into the AC input and DC output leads for modular connections. In addition, the thermistor for the fan circuit is placed on the input stage predriver transistors, which force the fan to flush out the hot air every 5 minutes, environmental noise from the fan is negligible at normal listening levels.)
CHECK:
The GFA565 is a direct coupled amp using a DC feedback servo to null out any DC appearing at the speaker output terminals. IC101 (Adcom part no. 2A) is part of this nulling circuit. If this IC fails there will be some DC (~1 volt) on the speaker output and this will cause a "thump" in your speakers when the amp is turned off. If needed, you can order a replacement 2A IC directly from Adcom -- or get a Linear Technology LT1012 from Digikey for a lot less money.
In addition to IC101 and associated components, you may want to check the two 10-Ohm fusible resistors R121 and R157 on the main signal input PC board. Also check the 100-Ohm R803 fusible resistor on the small PC board atop the filter caps. These resistors are sacrificial devices which open when subjected to current spikes in the circuit grounds.
R121 and R803 can be easily checked from outside the amp as detailed below:
Troubleshooting two of the fusible resistors by external measurements:
DC resistance from speaker output black terminals (grounds 1 and 2) to AC power plug third pin safety ground should be 100 Ohms (checks 100-Ohm fusible R803).
DC resistance between signal input ground 3 and speaker output black terminals (grounds 1 and 2) should be 10 Ohms
Hi, I'm facing a similar problem of smoking caps in one of my 565s. Checking out for solutions, this's a aggregation of mods for the 565 I came across while reading the posts in this thread till date.
Also included are mods for the 555 mkII, as its from the same stable.Thought its a good idea to share the list so that anyone in future can save time while solving a similar problem. I'm just another novice trying to find my way through the maze.
Also included are mods for the 555 mkII, as its from the same stable.Thought its a good idea to share the list so that anyone in future can save time while solving a similar problem. I'm just another novice trying to find my way through the maze.
I bought a pair of 565s a week ago. When I powered the amps, suspecting some kind of trouble, both the green LEDs in the input area glowed. However, one of the amps gave up a horrible odour, on which I immediately switched it off.
On taking off the top cover, I did not find the Fan. Is this normal? Is it perhaps some 565 batches didnot carry the fan? These 565s do not've captured power cords either.
Contacting ADCOM service, I was sent an article that told that there's a capacitor leak on to the printed circuit board, causing a DC offset, that if left unattended, could damage my loudspeakers.
I did not find any of the 2 massive 100V 35,000uF ADCOM capacitors smoking.
As there's dearth of good service technicians in my area, I'm fixing this amp myself, though a novice in the art of soldering.
Now to work on the 565, do I require a hobbyist soldering iron or a soldering station with temperature control?
Do I need a usual DMM or a professional one which reads capacitance and temperature as well? I bought the FLUKE 179 which does both.
I found that the input board, indeed had cap fluid leaked all over the area. Now, in order to clean this PCB, do I remove all the components from the input board or can I wash them with the resistors and diodes?
Can I wash the PCB with 100% alchohol/ESD brush and then distilled water and then dry it with compressed air
Or is it enough if I use dish soap for then purpose?
Please help with ideas and suggestion!
On taking off the top cover, I did not find the Fan. Is this normal? Is it perhaps some 565 batches didnot carry the fan? These 565s do not've captured power cords either.
Contacting ADCOM service, I was sent an article that told that there's a capacitor leak on to the printed circuit board, causing a DC offset, that if left unattended, could damage my loudspeakers.
I did not find any of the 2 massive 100V 35,000uF ADCOM capacitors smoking.
As there's dearth of good service technicians in my area, I'm fixing this amp myself, though a novice in the art of soldering.
Now to work on the 565, do I require a hobbyist soldering iron or a soldering station with temperature control?
Do I need a usual DMM or a professional one which reads capacitance and temperature as well? I bought the FLUKE 179 which does both.
I found that the input board, indeed had cap fluid leaked all over the area. Now, in order to clean this PCB, do I remove all the components from the input board or can I wash them with the resistors and diodes?
Can I wash the PCB with 100% alchohol/ESD brush and then distilled water and then dry it with compressed air
Or is it enough if I use dish soap for then purpose?
Please help with ideas and suggestion!
'novice at the art of soldering'
I feel obligated to mention that you can kill yourself by 'repairing' amps if you're a 'novice at the art of soldering'.
Notice to whomever suggested ultrasonic cleaning: Adcom does not recommend this.
I've got a pair of GFA-565's sitting in Minnesota. Considering selling them or shipping to Germany if the customs won't rape me shipping defective amps.
If anyone here is interested and capable of doing repairs, drop me an email.
I feel obligated to mention that you can kill yourself by 'repairing' amps if you're a 'novice at the art of soldering'.
Notice to whomever suggested ultrasonic cleaning: Adcom does not recommend this.
I've got a pair of GFA-565's sitting in Minnesota. Considering selling them or shipping to Germany if the customs won't rape me shipping defective amps.
If anyone here is interested and capable of doing repairs, drop me an email.
Mnay thanks pupnik, for words of caution.
My soldering skills are not that of an expert, though I've done small jobs before. Besides, the amps've been lying disconnected from the mains for around 2 months. Guess, thats time enough for the 35000uf caps to discharge completely.
I desoldered the input board of the broken amp, washed it throughly in Isopropyl alchohol, dried the board with compressed air, and resoldered it with new Rubycon caps. I'm waiting for sliver RCA jacks to arrive.
However, I noticed that in the unbroken amp, the input board has the C109, C118, C119 with 35V/220uF, instead of 25V/220uF. Will this difference of 10V in these caps create future problems? Is it advisable to change them to 25V/220uF as mentioned in the service manual?
Seems the previous owner had them changed because of cap fluid leak, which means I've to wash this board too.
--Katza
My soldering skills are not that of an expert, though I've done small jobs before. Besides, the amps've been lying disconnected from the mains for around 2 months. Guess, thats time enough for the 35000uf caps to discharge completely.
I desoldered the input board of the broken amp, washed it throughly in Isopropyl alchohol, dried the board with compressed air, and resoldered it with new Rubycon caps. I'm waiting for sliver RCA jacks to arrive.
However, I noticed that in the unbroken amp, the input board has the C109, C118, C119 with 35V/220uF, instead of 25V/220uF. Will this difference of 10V in these caps create future problems? Is it advisable to change them to 25V/220uF as mentioned in the service manual?
Seems the previous owner had them changed because of cap fluid leak, which means I've to wash this board too.
--Katza
Hi pupnik,
Take it from me. You are not going to get the electrolyte off those boards without an ultrasonic cleaner. You must also use an aqueous cleaning agent or risk fire / explosion. I was authorized warranty for Adcom until I sold my shop.
I could repair your amps, but I'm in Canada. The extra shipping is not worth while.
Hi Katza,
The higher voltage rating on the capacitors is fine. I normally stock 35V and 63V rated units. The Quality factor on capacitors is generally better with the higher voltage rating too.
-Chris
Yes they do as long as you take intelligent precautions. I spoke directly to them on the phone a while ago. You must remove the pots (and label them) and heat sinks. Be careful not to over clean them.
Take it from me. You are not going to get the electrolyte off those boards without an ultrasonic cleaner. You must also use an aqueous cleaning agent or risk fire / explosion. I was authorized warranty for Adcom until I sold my shop.
I could repair your amps, but I'm in Canada. The extra shipping is not worth while.
Hi Katza,
The higher voltage rating on the capacitors is fine. I normally stock 35V and 63V rated units. The Quality factor on capacitors is generally better with the higher voltage rating too.
-Chris
Hi Gentlemen,
It's nice to see this thread alive and well with a new 565 owner going through the same learning process I went through when I bought my 565s over a year ago.
I recently finally replaced the other amp's filter capacitors and can now relax and turn up the volume.
Interestingly, thanks in large part to all of you, I've decided to launch a little amp repair business dealing primarily with the 565s. So I just want to formally thank all of you for your help and support with my rebuild. I've been getting at least 4-5 emails per month since I posted the pics on Flickr from troubled 565 users asking for help with their amps, and I always give them the advice that was given me through this thread!
@Katza: Regarding your compiled list of possible upgrades, the only place you may not be successful in is finding replacement filter capacitors from Black Gate Rubycon. As far as I am aware the company had some difficulty and is not longer producing the Black Gate range of electrolytics. Even so, I don't think they even make a 100VDC 39,000uF electrolytic that is 2.5" in diameter. I would have personally loved to put Mundorf M caps in my amp, but they are also too large. I would strongly advise you to stick within the 565's size restraints and get a 2.5" capacitor.
Also, don't touch ANYTHING inside the amp while it is charged up. The filter capacitors carry their current to many other solder points in the amp and you do not want to risk death or serious injury. I wore gloves
Katza it will be interesting to discover how much of a difference your amp will sound with Silver connection points and high-grade capacitors. If I could have afforded to do it, I would have, but alas, I'm just a recent college graduate with student loans
Good luck with the rebuild and keep the questions coming, I like to see this thread alive and thriving for all the 565 owners out there to benefit from.
It's nice to see this thread alive and well with a new 565 owner going through the same learning process I went through when I bought my 565s over a year ago.
I recently finally replaced the other amp's filter capacitors and can now relax and turn up the volume.
Interestingly, thanks in large part to all of you, I've decided to launch a little amp repair business dealing primarily with the 565s. So I just want to formally thank all of you for your help and support with my rebuild. I've been getting at least 4-5 emails per month since I posted the pics on Flickr from troubled 565 users asking for help with their amps, and I always give them the advice that was given me through this thread!
@Katza: Regarding your compiled list of possible upgrades, the only place you may not be successful in is finding replacement filter capacitors from Black Gate Rubycon. As far as I am aware the company had some difficulty and is not longer producing the Black Gate range of electrolytics. Even so, I don't think they even make a 100VDC 39,000uF electrolytic that is 2.5" in diameter. I would have personally loved to put Mundorf M caps in my amp, but they are also too large. I would strongly advise you to stick within the 565's size restraints and get a 2.5" capacitor.
Also, don't touch ANYTHING inside the amp while it is charged up. The filter capacitors carry their current to many other solder points in the amp and you do not want to risk death or serious injury. I wore gloves
Katza it will be interesting to discover how much of a difference your amp will sound with Silver connection points and high-grade capacitors. If I could have afforded to do it, I would have, but alas, I'm just a recent college graduate with student loans
Good luck with the rebuild and keep the questions coming, I like to see this thread alive and thriving for all the 565 owners out there to benefit from.
Adcom GFA-565 fuses
Hi Mjr,
This is my first post here so if I don't do it right don't beat up on me too much!
Correct me if I'm wrong, but my Adcom GFA-565s say on the back panel that the AC fuse is 125V/15A (1875W), and the DC rail fuses are 125V/12A (1500W). Your 250V/12A fuses would be protecting against 3000W! I'm not an electrical engineer, but I would think that 10A fuses would be on the safe side and not cause damage - a higher rated (15A instead of 12A for the DC rails) could cause damage, allowing more current to flow than should be allowed. Your belief that 250V is correct sounds very wrong, unless of course your GFA-565 is different than mine.
And I would think that the only reason a correct fuse would blow is if something was very wrong, in which case you should shut down immediately and let an authorized repair-person fix it.
What does it actually say on the back of your amps, and what do the fuses actually say?
Thanks!
Gary
PS - the reason I looked at this thread in the first place is that I want to put some audiophile-grade fuses in instead, wondering if that would make a sonic difference.
I do have an electrical engineer question: is it the total watts that really matters in fuse rating? In other words, is a 125V/12A fuse equivalent to a 250V/6A fuse, or a 500V/3A fuse? Will they perform the same? They all seem to add up to 1500W. The reason I'm asking that is that the fuses I want to get don't come in 125V, and I want to make sure they will perform the same as the amp expects.
Thanks again!
Adcom GFP-565 pre
Adcom GFA-565 monos
Paul Speltz zeros, anti-cables, anti-ICs
Magnepan 1.6 speakers
Hi Mjr,
This is my first post here so if I don't do it right don't beat up on me too much!
Correct me if I'm wrong, but my Adcom GFA-565s say on the back panel that the AC fuse is 125V/15A (1875W), and the DC rail fuses are 125V/12A (1500W). Your 250V/12A fuses would be protecting against 3000W! I'm not an electrical engineer, but I would think that 10A fuses would be on the safe side and not cause damage - a higher rated (15A instead of 12A for the DC rails) could cause damage, allowing more current to flow than should be allowed. Your belief that 250V is correct sounds very wrong, unless of course your GFA-565 is different than mine.
And I would think that the only reason a correct fuse would blow is if something was very wrong, in which case you should shut down immediately and let an authorized repair-person fix it.
What does it actually say on the back of your amps, and what do the fuses actually say?
Thanks!
Gary
PS - the reason I looked at this thread in the first place is that I want to put some audiophile-grade fuses in instead, wondering if that would make a sonic difference.
I do have an electrical engineer question: is it the total watts that really matters in fuse rating? In other words, is a 125V/12A fuse equivalent to a 250V/6A fuse, or a 500V/3A fuse? Will they perform the same? They all seem to add up to 1500W. The reason I'm asking that is that the fuses I want to get don't come in 125V, and I want to make sure they will perform the same as the amp expects.
Thanks again!
Adcom GFP-565 pre
Adcom GFA-565 monos
Paul Speltz zeros, anti-cables, anti-ICs
Magnepan 1.6 speakers
actual fuse rating vs power ratio can vary a lot. the fuses are there to protect against OVERcurrent. guessing the output power by fuse size isn't a very accurate method at all. it depends on the efficiency of the amp (is it class A?, B?, D?). and it includes any "whistles and bells" that might be included in the amp (digital circuits are power hungry). another thing to consider is am amp with large power supply caps. the turn on surges are usually very high currents while the caps charge (which is why the fuses tend to be slow blow types). if it's a tube amp, the filaments cause a turn on surge while they heat up. fuse rating vs power is also about useless if it's a multichannel surround receiver (and you can usually ignore the "1500 WATTS!!!!" claims on the advertising blurb as well, as most of these receivers only have about 200 watts worth of power transformer). the only real way to know the output power is to run all channels up to clipping into loads simultaneously and measure.
"I do have an electrical engineer question: is it the total watts that really matters in fuse rating? In other words, is a 125V/12A fuse equivalent to a 250V/6A fuse, or a 500V/3A fuse? Will they perform the same? They all seem to add up to 1500W. The reason I'm asking that is that the fuses I want to get don't come in 125V, and I want to make sure they will perform the same as the amp expects."
No. The voltage is the maximum voltage the fuse is designed to break, nothing else. Substituting a 250V 12A for a 125V 12A is OK but not the other way round. There are some other parameters too like fast blow/slow blow that must match and ceramic fuses with high current breaking capacity should not be substituted by glass fuses. The glass fuses can explode or fail to break if the short circuit current is too high.
No. The voltage is the maximum voltage the fuse is designed to break, nothing else. Substituting a 250V 12A for a 125V 12A is OK but not the other way round. There are some other parameters too like fast blow/slow blow that must match and ceramic fuses with high current breaking capacity should not be substituted by glass fuses. The glass fuses can explode or fail to break if the short circuit current is too high.
Hi
Any success in removing the dc out of the speaker terminals ?
I am repeairing a 565, amp, which had the electolityic caps on the input board pourde some nasty substance over the board. I cleaned it and replaced the electrolytic caps and the LT1012.
I have about 0.7 dc at the output...
any suggestion will be appreciated.
I do not have the schematic..
regards
Alexander
Any success in removing the dc out of the speaker terminals ?
I am repeairing a 565, amp, which had the electolityic caps on the input board pourde some nasty substance over the board. I cleaned it and replaced the electrolytic caps and the LT1012.
I have about 0.7 dc at the output...
any suggestion will be appreciated.
I do not have the schematic..
regards
Alexander
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