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Are Replacements Available for the ARC LS5 MKII Motorized Control Pot and Board?

I recently picked up an LS5 MKII. It has not been modified. I found a few issues that the seller didn't mention. I didn't question this as I paid very little and I really enjoy restoring old gear, any kind.

I have replaced all the electros, obtained 10 NOS Amperex 6DJ8 tubes from Brent Jessee, and replaced the output caps with 3.3 uf Vcap ODAMs. I am burning all this in right now. The sound is great!

However, there's more left to do. The Source/Monitor function does not work. I replaced the switch (gee, that was hard) but the problem persisted. I haven't done a detailed test of the control board yet. A problem for later as I have a work around right now.

The biggest problem is the motorized volume control. It doesn't work at all. I have the AR remote. The mute function does work, but not the volume control. I talked to Audio Research about this. After thinking a bit, AR said repair would be very expensive as they would have to re-engineer this function since replacement parts are not now available. AR didn't say which. Right now I'm using a Fosi P4 as volume control. I also use a GEQ, so the path is Preamp -> P4 -> GEQ -> Power amp (ML #27). I'd like to use the tape loop for these functions as I've done with the AR LS22.

Ideal would be a direct drop in replacement. I've seen the large variety of motor control pots and boards on Ali Express and eBay. I really would like a cleaner solution.
 

kevemaher
kevemaher's avatar
kevemaher OP
419 posts
 

I'm just going to listen to the LS5 MKII for a while. I like the sound. It is very similar to the LS22 I modified a few months ago. 

If I like the LS5 over the LS22, I can swap the working boards into the LS5.

I may buy one of the cheap motorized pots that are all over the place. All I would need to do is to replace the IR sensor and find +12VDC somewhere nearby.

Guess I could run on batteries!

Thanks everybody.

egrodsky
1 posts
 

Just reading this post. Similar issues with my recently acquired LS5 MKIII. The rear of the unit says it has the remote control option, and I just purchased an R1 remote from someone on this site. The remote I bought is silver, and has many more options than the one I saw described as the original R1 that was made for it. That black remote had only mute and volume; both say "R1". Will keep investigating similarly to what you described. I contacted Audio Research to ask if my remote would work; waiting on reply.

 

Thanks

Eric

bdalessio's avatar
bdalessio
9 posts
 

Happy that I found this recent thread about the ARC remote scenario.  I recently acquired an LS22 that I'm upgrading with tubes, diode's and caps. It also has the remote pot and circuit board factory installed, but I don't have a remote.  I would like to upgrade the pot to a better one, but could someone tell me how that can be accomplished while retaining the remote function?  Can I retain the original circuit board for the remote and just change out the pot?  I have a Goldpoint stepped attenuator in an SP3 with good results, but no remote control in that unit sadly.  Also, did someone figure out what remote to purchase that will work with the LS22?

kevemaher's avatar
kevemaher OP
419 posts
 

@bdalessio 

I also have an LS22 in addition to the LS5. I have changed both coupling and output caps and installed NOS Amperex 6DJ8 tubes. 

I have two remotes that both work on the LS22. I have a relatively inexpensive one and a much fancier more expensive one. I purchased both from ARC withing the last year. Send me a PM if you are interested in buying one from me.

I have explored several ways to fix the problem. I recently received a modern "equivalent" pot. It had all the correct markings and looked just like the one in the LS5. I installed it. No response when I tried either remote. I do not have the tools to effectively troubleshoot the control board, I have explored buying a complete package with pot, board and receiver. There are many options available. Some of them might be doable, but I would still need to find power somewhere inside the unit. Or I could go battery powered. I decided to put this problem away for now. I have also worked on the problem I have with the source/monitor function. I've replaced a bunch of transistors and have narrowed this problem to a (stuck?) relay. I can get a direct replacement, but I would have to remove several boards and most of the back panel in order to get to it. I decided to put the LS5 on the shelf for a winter day sometime.

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