@Zen Mod, @Mooly, @6L6. Thank you all for your feedbacks. Repairing the Adcom was my first priority. After two years of inquiring at various local techs/shops, no one was able to get the parts for this repair. Apparently, it's quite a common problem for this vintage to have input/output transistors issues. I've been told that it's "impossible" to get parts for transistors and boards. Would love to have it repaired, but alas, couldn't get it done.
What transistors are inoperative? Has it been diagnosed with actual failures or are techs just throwing up hands saying, “woe is us!” ?
@6L6 - I was quoted $328Cad to replace the output transistors back in spring of 2021. Every time I did a follow up, it was the same reply..."still waiting for parts to arrive". Finally, a year later, the shop gave the news of parts not available for my amp AND that there's no substitute parts either. As for throwing up hands, can't say for sure as we're at their mercy when it comes to repairs. I've contacted three more repair outfits, they all refused to look at it the moment I mentioned the make and model of the amp.
@Zen Mod - ha ha, you're right, wood is over 4000 km away.
Hi Watts-Up,
Yes, I would repair that one. We never did see an output failure with those in Toronto in my shop. I was authorized warranty for Adcom.
Okay, $328 is cheap, too cheap. When you have output transistor failure, you change all of them in that channel. This goes for any amplifier. They also have to be matched. This will give you a reliable amplifier with lower distortion. These days I'm not sure what the parts would cost.
Thank you Zen Mod. Yes, Canada is huge (big woods).
-Chris
Yes, I would repair that one. We never did see an output failure with those in Toronto in my shop. I was authorized warranty for Adcom.
Okay, $328 is cheap, too cheap. When you have output transistor failure, you change all of them in that channel. This goes for any amplifier. They also have to be matched. This will give you a reliable amplifier with lower distortion. These days I'm not sure what the parts would cost.
Thank you Zen Mod. Yes, Canada is huge (big woods).
-Chris
@anatech - Hi Chris,
If only I was a little closer, would've gladly drop off my amp at your shop.
Assuming the diagnostic by my local techs was accurate, and it is indeed the output transistors, would you be able to get replacements? If you are able to get them, please provide estimate cost for needed parts. I'll look into the cost of shipping costs to and from Toronto area (I'm in Vancouver). Once again, my amp is the Adcom GFA-8520.
Thanks!
If only I was a little closer, would've gladly drop off my amp at your shop.
Assuming the diagnostic by my local techs was accurate, and it is indeed the output transistors, would you be able to get replacements? If you are able to get them, please provide estimate cost for needed parts. I'll look into the cost of shipping costs to and from Toronto area (I'm in Vancouver). Once again, my amp is the Adcom GFA-8520.
Thanks!
I'm looking for preamp suggestions for use with my ACAs. I'm currently using the preamp from my Marantz 1060, which works fine, but I would like to have a dedicated pre, preferably with a remote (I'm lazy and don't want to have to get out of my comfy listening chair to adjust the volume every song). Ideally, I would like a DIY project that is within my capabilities. I also have a stand-alone phono amp, so I don't necessarily need that as part of the preamp.
I'm currently running the ACAs as monoblocks into Klipsch Forte IIIs (99 dB efficiency). As I've posted before, I also have a Fisher X-101-B and think the mono ACAs compare favorably, but feel the Fisher has a slightly (very slightly) more appealing sound, so I wonder if a tube preamp might be more to my liking. Not locked into that, but certainly open.
Thoughts? Thanks in advance!
I'm currently running the ACAs as monoblocks into Klipsch Forte IIIs (99 dB efficiency). As I've posted before, I also have a Fisher X-101-B and think the mono ACAs compare favorably, but feel the Fisher has a slightly (very slightly) more appealing sound, so I wonder if a tube preamp might be more to my liking. Not locked into that, but certainly open.
Thoughts? Thanks in advance!
Take a look at the Bottlehead Moreplay preamp kit. It is fun to build, sounds fantastic and you can roll several types of tubes. Here is a link:
https://bottlehead.com/product/moreplay-preamplifier-kit/
https://bottlehead.com/product/moreplay-preamplifier-kit/
Another option that costs much less is to build a clone of the Bottlehead Quickie which is a battery powered preamp, using 3S4 tubes in triode mode. Very simple to build and as always great sounding. You can build it for less than $120, batteries not included. The preamp utilizes a total of four caps and eight resistors. Here is a photo of mine:
Haven't been around this thread since I built my ACA.. maybe 2 years now. It's been up my shed happily keeping me toes tapping while doing whatever. Hasn't missed a beat other than the left LED blowing which I must fix
Decided to bring it back into the house and see how goes with a Supratek Cabernet 6SN7 pre, high gain. The ACA's some stiff competition!
First tried some 95db Summoner speakers, was impressive. Then tied in a pair of Harbeth SHL5's.. completely blown away! So musical it's ridiculous and these Harbeths are 86dB efficient, the ACA can hold its head high with pride.
Now where's that F5 I was in the middle of removing the current limiters on...
Decided to bring it back into the house and see how goes with a Supratek Cabernet 6SN7 pre, high gain. The ACA's some stiff competition!
First tried some 95db Summoner speakers, was impressive. Then tied in a pair of Harbeth SHL5's.. completely blown away! So musical it's ridiculous and these Harbeths are 86dB efficient, the ACA can hold its head high with pride.
Now where's that F5 I was in the middle of removing the current limiters on...
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I started working on a 1.8 kit and noticed on one board the mask was a bit scratched away below R18 and nearby around the perimeter of C1 (see bottom center of picture). I don't think that will present any risk of shorting, but I was wondering if there is any simple way to cover those spots up?
Attachments
Pictures can be tricky to work with. It looks for all the world like unetched copper remaining on the PCB in several areas.
Can't tell from the picture. Is that the base colour of the board you are looking at or left over copper?
Can't tell from the picture. Is that the base colour of the board you are looking at or left over copper?
To me it looks like some of the green layer is missing (scratched off?) next to the inside through hole of R15 and nearby on the trace going in to C1. (The shininess on the left side of C1 is from the picture lighting, the board looks fine there).