Hi Arif, Ed,
Sorry, I didn't catch this thread until now. Simple green is one of the better cleaning agents to use. I remeove the trim pots, any heatsinks and electrolytic caps. Into an ultrasonic cleaner they go. After 3 min. or so they get a good water rinse. Drying is done with a heat gun (carefully), a hair dryer will work also.
100 % success every single time. New caps and remount the pots and that's normally it. Sometimes the op amp gets damaged, also the shunt IC's for the power supply regulation have been shorted
Arif, I hope that helps you out. That method has never failed me.
Be on the lookout for other transistors that have gone leaky but not outright blown. I've seen that a couple times too.
-Chris
Sorry, I didn't catch this thread until now. Simple green is one of the better cleaning agents to use. I remeove the trim pots, any heatsinks and electrolytic caps. Into an ultrasonic cleaner they go. After 3 min. or so they get a good water rinse. Drying is done with a heat gun (carefully), a hair dryer will work also.
100 % success every single time. New caps and remount the pots and that's normally it. Sometimes the op amp gets damaged, also the shunt IC's for the power supply regulation have been shorted
Arif, I hope that helps you out. That method has never failed me.
Be on the lookout for other transistors that have gone leaky but not outright blown. I've seen that a couple times too.
-Chris
Hi all,
I too have a 585 that started making some odd noises in one channel. When I did a few tests, I found it measures about 28 volts out of the bad channel so I replaced the leaky caps and cleaned up the boards as best I could.
It still measures the same so there must be more bad parts. I don't have a service manual as yet, but would appreciate any suggestions on what to check next.
Thanks in advance
I too have a 585 that started making some odd noises in one channel. When I did a few tests, I found it measures about 28 volts out of the bad channel so I replaced the leaky caps and cleaned up the boards as best I could.
It still measures the same so there must be more bad parts. I don't have a service manual as yet, but would appreciate any suggestions on what to check next.
Thanks in advance
So far I have only replaced the 220s which I had on hand. The old caps did not appear to have leaked all over the place, but they showed a little liquid on the cap and lead when I removed them. I cleaned the board with alcohol and rinsed with water.
I'll have to order the opamp and 100s and go from there.
Interestingly, the output fuses do not blow, but it sure did cook a cheap speaker I hooked up to it.
Thanks for the advice.
I'll have to order the opamp and 100s and go from there.
Interestingly, the output fuses do not blow, but it sure did cook a cheap speaker I hooked up to it.
Thanks for the advice.
And to get this slightly back on topic, these will drive any speaker you can think of to just about any level you can stand.
Back when these were current production, the store I worked in sold Adcom, Rowland, Thiel, and Maggie among others.
Quite a few customers actually preferred the $1800 Adcom 565s driving the Thiel CS5s over the $9000 Rowland amp. Now the Thiels went down to 2 ohms and the Rowland would shut down when we really had things cranking. The Adcoms never seemed to clip.
I was using mine to drive the woofer section of a pair of Carver Amazings, and it had great control and plenty of punch. At least until the right channel died.
Any more tips for fixing my 585 would be appreciated.
Anyone got a scanned readable schematic they could send me?
Back when these were current production, the store I worked in sold Adcom, Rowland, Thiel, and Maggie among others.
Quite a few customers actually preferred the $1800 Adcom 565s driving the Thiel CS5s over the $9000 Rowland amp. Now the Thiels went down to 2 ohms and the Rowland would shut down when we really had things cranking. The Adcoms never seemed to clip.
I was using mine to drive the woofer section of a pair of Carver Amazings, and it had great control and plenty of punch. At least until the right channel died.
Any more tips for fixing my 585 would be appreciated.
Anyone got a scanned readable schematic they could send me?
I have measured the 565 at 8 ohm clipping = 423 watts. At 4 ohms it was over 570 watts. I did not want to sacrifice any dummy loads at 2 ohms... But I trusted Adcom when they said it can drive 2 ohms.
If the 555 with 1200 watt OP dissipation can do sporadic 2 ohm loads, the 565 with 3000 watt OP dissipation capability certainly can.
I have only own one more amp with more OP devices, a Krell KSA-250 with more outputs than the Adcom 565. The KSA-250 has 24 pairs of the 15024/25 or an eye popping 6000 watt OP stage per channel. (Maybe it was more... I forget).
Granted these numbers are not real-life operational numbers but give you a fair idea.
If the 555 with 1200 watt OP dissipation can do sporadic 2 ohm loads, the 565 with 3000 watt OP dissipation capability certainly can.
I have only own one more amp with more OP devices, a Krell KSA-250 with more outputs than the Adcom 565. The KSA-250 has 24 pairs of the 15024/25 or an eye popping 6000 watt OP stage per channel. (Maybe it was more... I forget).
Granted these numbers are not real-life operational numbers but give you a fair idea.
Well, my speaker issue resolved itself. As the choice of speaker was for our living room, they had to meet my wife's approval.
I surfed around and showed her some pictures of likely candidates, and then everything went quiet. I was then surprised on my birtday weekend with a pair of used Magneplanar SMGa.
They required a little attention (loose wires on the bass/mid panel), but I now have them in good working condition again - tested using a woefully inadequate $40 CD/radio "music system" and they still sounded great. Hopefully, there will be time this evening for a first try out with the Adcom - I just cannot wait
It's fun that the speakers and amp are somewhat contemporary (semi-vintage, if you will) and that the system cost very little considering its quality level.
Cheers,
Ed
I surfed around and showed her some pictures of likely candidates, and then everything went quiet. I was then surprised on my birtday weekend with a pair of used Magneplanar SMGa.
They required a little attention (loose wires on the bass/mid panel), but I now have them in good working condition again - tested using a woefully inadequate $40 CD/radio "music system" and they still sounded great. Hopefully, there will be time this evening for a first try out with the Adcom - I just cannot wait
It's fun that the speakers and amp are somewhat contemporary (semi-vintage, if you will) and that the system cost very little considering its quality level.
Cheers,
Ed
Captaincrusty51
I have a service manual, but no way to scan. I broke down and purchased the manual from Adcom ($25 inc postage) a couple of weeks ago - they are very helpful if you contact them from their website:
http://www.adcom.com/contact.aspx
Cheers,
Ed
I have a service manual, but no way to scan. I broke down and purchased the manual from Adcom ($25 inc postage) a couple of weeks ago - they are very helpful if you contact them from their website:
http://www.adcom.com/contact.aspx
Cheers,
Ed
Ed Holland said:
Thanks for the info Ed. I was hoping to fix this quickly (and cheaply). I am not as skilled as I would like to be and was hoping after seeing this thread that my problem was similar to the others and a cap swap would solve the problem. Now that I have to go deeper into it, a service manual will probably be on the list.
The amp actually died about two years ago, and I threw it in the closet and forgot about it. Last week I ran into a $50 pair of Acoustats that definitely would benefit from the power of the 585, so now is a good time to resurrect it.
Ed, keep a careful hand on the throttle. You will bottom out those Maggies long before you run out of amplifier.
careful with the op amp!
I tried posting valid recommendations for this servo op amp here before. Apparently it went unnoticed. Here's what was/is involved with the associated ckt in the 565 and 585 amps (not any other Adcom amps):
1) The servo op amp must be a low power part, as the current it draws is supplied from a low power zener string (the series LM329 diodes, +/-13.8V). This fact alone rules out most std parts like 741s, 711s, etc. The LT1012 was the original Adcom 2A part, but has suffered excessive failures (not due to any circuit stress, for sure). A quality OP97 will substitute directly, and would be preferred from a no-other-changes-required point of view. Drop it in, and if the PCB is clean and nothing else is broken, it will work.
2) There may be some slow variations observed in the settled output DC level, under normal conditions. A few mV, +/-. Adcom did not provide any tracking or mechanical binding between the input pairs. There are two of these, so minor air currents around the PCB assy can/will modulate the instantaeous net Vbe, and cause the servo to correct. This is perfectly normal, and in no way a problem. Or audible.
3) The leaky capacitor problem is even more distressful from the point that it seems so preventable. Note that the problem parts here are labeled as Elna "Longlife" parts. No kidding folks, that's what they say. I would defer to those experienced Adcom repair techs here, such as Anatech, who advocate thorough and careful cleaning of the PCB. The high-Z inputs of the servo (and other parts of the front end) require clean, leak-free paths.
Hope this is helpful.
Walt Jung
565/585 design team member
PS: Don't sell these amps short. When they are working correctly, the sound is very good, indeed.
I tried posting valid recommendations for this servo op amp here before. Apparently it went unnoticed. Here's what was/is involved with the associated ckt in the 565 and 585 amps (not any other Adcom amps):
1) The servo op amp must be a low power part, as the current it draws is supplied from a low power zener string (the series LM329 diodes, +/-13.8V). This fact alone rules out most std parts like 741s, 711s, etc. The LT1012 was the original Adcom 2A part, but has suffered excessive failures (not due to any circuit stress, for sure). A quality OP97 will substitute directly, and would be preferred from a no-other-changes-required point of view. Drop it in, and if the PCB is clean and nothing else is broken, it will work.
2) There may be some slow variations observed in the settled output DC level, under normal conditions. A few mV, +/-. Adcom did not provide any tracking or mechanical binding between the input pairs. There are two of these, so minor air currents around the PCB assy can/will modulate the instantaeous net Vbe, and cause the servo to correct. This is perfectly normal, and in no way a problem. Or audible.
3) The leaky capacitor problem is even more distressful from the point that it seems so preventable. Note that the problem parts here are labeled as Elna "Longlife" parts. No kidding folks, that's what they say. I would defer to those experienced Adcom repair techs here, such as Anatech, who advocate thorough and careful cleaning of the PCB. The high-Z inputs of the servo (and other parts of the front end) require clean, leak-free paths.
Hope this is helpful.
Walt Jung
565/585 design team member
PS: Don't sell these amps short. When they are working correctly, the sound is very good, indeed.
Walt,
Great to read your recommendations. The 565's over engineering is impressive. 10 pairs of outputs... I'd say the amp could drive a 1 ohm resistive load though adcom never specified it. I have routinely measured an 8 ohm clipping figure of over 400 watts into 8 ohms at clipping. For a +/-83 vdc supply, thats impressive.
Great to read your recommendations. The 565's over engineering is impressive. 10 pairs of outputs... I'd say the amp could drive a 1 ohm resistive load though adcom never specified it. I have routinely measured an 8 ohm clipping figure of over 400 watts into 8 ohms at clipping. For a +/-83 vdc supply, thats impressive.
Hi Walt,
Thanks for the info. I spoke to Victor yesterday and he said you were interested in this subject - glad you found this thread.
I'm going to guess that all 585s have the leaky Elna caps as the 585 was made in limited numbers and likely with the same parts/vendors. Not all 565s have Elna caps (at least my pair doesn't, but I built/stuffed the boards while I was at Adcom), but I think the optional balanced input boards have quite a few. I'll take pics of the balanced boards and post them here this week.
Marvin,
In light of this new information, you are welcome to return those 711s. Also, I would be interested in hearing your La Scalas someday!
Happy Holidays everyone!
Thanks for the info. I spoke to Victor yesterday and he said you were interested in this subject - glad you found this thread.
I'm going to guess that all 585s have the leaky Elna caps as the 585 was made in limited numbers and likely with the same parts/vendors. Not all 565s have Elna caps (at least my pair doesn't, but I built/stuffed the boards while I was at Adcom), but I think the optional balanced input boards have quite a few. I'll take pics of the balanced boards and post them here this week.
Marvin,
In light of this new information, you are welcome to return those 711s. Also, I would be interested in hearing your La Scalas someday!
Happy Holidays everyone!
Ed Holland said:
Looks like you weren't provided with a huge amount of recommendations on speakers in this thread, however, still made a great decision. I would have recommended the Eminent Technology LFT-8, or LFT-8A's though. I love these speakers! However, you probably got your SMGa's for a bit cheaper than that though.
Have fun,
Brandin
Wow! This thread is so informative to 565 and 585 owners! I have learned a lot. But I have one question!
With Adcom amplifiers, you are NOT supposed to do any connections while the amplifier is on. With that said, how do you measure DC offset?
Do I just connect my voltmeter to the speaker output terminals? Can I hold them there and remove them from the speaker posts on the amp while it is still on? Someone please explain the process of measuring DC offset on my GFA-565 monoblocs! Thanks so much!
With Adcom amplifiers, you are NOT supposed to do any connections while the amplifier is on. With that said, how do you measure DC offset?
Do I just connect my voltmeter to the speaker output terminals? Can I hold them there and remove them from the speaker posts on the amp while it is still on? Someone please explain the process of measuring DC offset on my GFA-565 monoblocs! Thanks so much!
Manufacturers like to scare users because it is hard to explain each possible scenario the user will engage in.
It is OK to connect anything (inert) to the outputs except shorting the outputs. As far as the inputs go, you do not want to connect any ungrounded or floating source to the power amp as it might oscillate or feed massive amounts of RFI to the rest of the amp.
It is perfectly ok to make measurements to the output when the amp is ok.... Just use common sense as always.
because it is hard to explain each possible scenario the user will engage in.It is OK to connect anything (inert) to the outputs except shorting the outputs. As far as the inputs go, you do not want to connect any ungrounded or floating source to the power amp as it might oscillate or feed massive amounts of RFI to the rest of the amp.
It is perfectly ok to make measurements to the output when the amp is ok.... Just use common sense as always.
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