Cool, thanks Rick!
And here's my parts list for the GFA-565/GFA-585, meant for use with my replacement circuit boards.
Dropbox - GFA-565 parts list.xls
And here's my parts list for the GFA-565/GFA-585, meant for use with my replacement circuit boards.
Dropbox - GFA-565 parts list.xls
Just also wanted to also express my appreciation to the folks who shared this info. I've got some Adcom gear that has been patiently waiting for me to get back to it. This will be a huge help.
Thank you!!!!
Thank you!!!!
A couple of additions I have discovered in recent years!
The ADCOM 3A / LT1006 /AD820 opamp in the GFA-555 II servo circuit can be replaced with ADA4622-1 on an SO08 to DIP-8 adapter board. The adapter board won't cause any stability issues, the circuit operates slow as molasses.
The ADA4622 is marketed as an improved AD820, which is itself a direct competitor to the LT1006. And it's cheaper. I've been using the ADA4622-1 with my BFA-555 MK2 boards with excellent results. They support the SO08 footprint as well as DIP-8.
KB262 and KB362 Stabistors in GFA-565 and GFA-585: Unfortunately the CMXSTB400 is now obsolete and hard to find, but the BAS17 is still an active part. It's a single diode in a SOT-23 package, so would be difficult but not impossible to adapt to an original board that takes through-hole diodes. BFA-565 board versions since 2022.02.14 have footprints for the BAS17 on the under-side. Quantity of 10 is required for one board. SOT23 package is somewhat easier to solder than SOT26 CMXSTB400. BAV17 stabistors have slightly higher forward voltage vs. current than KB262/KB363 or CMXSTB400. This does not significantly affect the circuit, but expect a higher voltage drop if using these type stabistors. Ten BAS17's are beer money cheaper than four CMXSTB400.
The ADCOM 3A / LT1006 /AD820 opamp in the GFA-555 II servo circuit can be replaced with ADA4622-1 on an SO08 to DIP-8 adapter board. The adapter board won't cause any stability issues, the circuit operates slow as molasses.
The ADA4622 is marketed as an improved AD820, which is itself a direct competitor to the LT1006. And it's cheaper. I've been using the ADA4622-1 with my BFA-555 MK2 boards with excellent results. They support the SO08 footprint as well as DIP-8.
KB262 and KB362 Stabistors in GFA-565 and GFA-585: Unfortunately the CMXSTB400 is now obsolete and hard to find, but the BAS17 is still an active part. It's a single diode in a SOT-23 package, so would be difficult but not impossible to adapt to an original board that takes through-hole diodes. BFA-565 board versions since 2022.02.14 have footprints for the BAS17 on the under-side. Quantity of 10 is required for one board. SOT23 package is somewhat easier to solder than SOT26 CMXSTB400. BAV17 stabistors have slightly higher forward voltage vs. current than KB262/KB363 or CMXSTB400. This does not significantly affect the circuit, but expect a higher voltage drop if using these type stabistors. Ten BAS17's are beer money cheaper than four CMXSTB400.
Like, seriously?? This is information I gathered in the operation of my business. It's relevant to the DIY community, many of whom are using my boards to fix their amps. They are doing DIY audio with my products. I am helping. It's relevant information.
Yes, interacting with my customers on forums helps my sales because it shows I actually care.
I'm not getting rich at it by the way.
Yes, interacting with my customers on forums helps my sales because it shows I actually care.
I'm not getting rich at it by the way.
Commercial promotion is not allowed in threads outside of the Marketplace. Promotion of products in the regular forums is not in the spirit of diyAudio and is also against the rules. Please do not promote products in the threads.
Just one more add. I know for a fact that Adcom also used the Burr-Brown at the time, TI now, OPA604 and OPA2604 I just can't remember how they were designated. Might have been the 6AA and 7AA but white dot vs green dot? I just can't remember but do know they were used.
I would use LT1113 dual JFET op amp next time I open up my GFP-565. It's a bit quieter than the OPA2604, although more expensive.
