Can anyone ID these part numbers?

[SteveFord]

This is what was done my 17LS before I bought it:

MJE340
MPSA42
MPSA92
IRF730
2MF-250V CJD

[admin]

The first 4 are transistors. The last is a capacitor. I guess you can open up the unit and look for what was replaced and match them with the part codes.

[SteveFord]

Thanks!

[AnotherJohnson]

Be careful. Capacitors can kill you. Seriously.

If you did not recognize these parts by their specs, you are probably not a good candidate for opening the unit and poking around willy nilly.

If you decide to go ahead, stand on an isolation mat, keep one hand in your pocket, and use a nonconductor to touch things.

Healthy capacitors can maintain charge even if the unit is unplugged. You are not safe just because it’s unplugged. You can safely discharge capacitors to ground if you know how … but if you’re not sure, don’t try. We’re not talking about messing up the unit. We’re talking about electrocution.

[SteveFord]

I'm not doing any work to it, this is work that c-j did to it shortly before I purchased it.
I simply wanted to know the starting point as it seemed to me that the sound had improved the longer I've used it.

[admin]

If there is no problem, then I don't think there is too much to do at this point. If you are interested in seeing what was replaced, again, opening up the unit and identifying the parts would be the next step. But as AJ mentioned, it has to be done carefully for safety reasons.

[SteveFord]

I'm well aware of the dangers of tube gear.
My questions were answered in post number 2 and now we have a tornado headed towards my location so time to go.

[roberto]

Hola Steve,
...the parts for your 17LS belong to a voltage regulator circuit. I did try to find where a 2uF@250V were used and I could not find it. Using that capacitance might be a voltage divisor but not sure. I hope that you got it back...the CT-5 is a great preamp.

Happy listening!

Prem17sch.pdf

[SteveFord]

I should back up a little bit: the original owner sent the 17LS to c-j for a going over and he had it drop shipped to the second owner, we'll call him Mike.
There was a packing slip in with the unit with a list of replaced parts.
Mike didn't know what was done. Mike contacted c-j and they wouldn't tell him what was done.
The sound appeared to be changing so I got curious what they did to the unit and I wrote to c-j who wouldn't tell me what those parts were because I was not the original owner.
If any place would recognize those part numbers it would be you fellows which is why I asked if anyone knew what those part numbers were.

I'm looking forward to that CJ5 but will keep the 17LS as I really enjoy listening to it.

[roberto]

Steve,
The list of parts are just for voltage regulation, and there is no signal path there...the numbers of the parts are correct. I do not know why he is claiming a difference in its sound quality. The parts get older and it is wise to change them to assure optimal operation. I assure you that those parts are just for voltage polarisation for the operation of the unit. His claim is very interesting. Perhaps ( with much respect ) he got used to a certain distortion that old parts might produce and when the new parts were installed, super clean sound might arise.

Did you have the chance to try it? If you did, what did you find? Is there another problem, or the sound quality is not right? Are both channels with the same problem if is there is a problem?

Happy listening!

[SteveFord]

I'm not making myself clear.

I am the one who thought the sound quality improved which is why I asked the factory what the parts were.
They said our policy is you're not the original owner so we won't tell you anything.
I said (to myself) you've got to be kidding me, you can't identify a few parts?
I asked here and my question was answered: a couple transistors, a cap.
I own the unit, it sounds fine.

I am told this particualar 17LS spent the majority of its life sitting unused so maybe it is still breaking in.
I like it so much I bought a CT5 to keep it company, that should be here late this week.

[AnotherJohnson]

I'm not making myself clear.

I am the one who thought the sound quality improved which is why I asked the factory what the parts were.
They said our policy is you're not the original owner so we won't tell you anything.
I said (to myself) you've got to be kidding me, you can't identify a few parts?
I asked here and my question was answered: a couple transistors, a cap.
I own the unit, it sounds fine.

I am told this particualar 17LS spent the majority of its life sitting unused so maybe it is still breaking in.
I like it so much I bought a CT5 to keep it company, that should be here late this week.

I understood what you said.

This would appear to be a relatively new policy. In my experience they’ve always been helpful regardless of whether or not you were the original owner.

I think there are several issues in play.

1. Intellectual property theft is becoming a serious threat, particularly as the Chinese pirate high value items into the marketplace. CJ won’t share schematics any more. They won’t sell parts to third parties. Now it appears that they will not discuss vintage products with unknown persons. It is sad, but not surprising. Note that on eBay you can buy some components that are advertised as “after Conrad Johnson.”

2. The company is VERY small. The vintage inventory in circulation is large and growing. There is good will to be gained by chatting with owners of used gear … but no money unless/until they buy something new. So the amount of time allocated for shmoozing with used customers is probably wisely rationed.

3. The phone jockey may not even know. He or she might have instructions to not disrupt the few skilled workers with questions that aren’t related to warranty work or units that were sold to persons in their customer database.

FWIW, you can often buy used CJ gear that has been factory refurbished, with a CJ warranty, through the dealer network. I’m sure they treat those customers as well as first owners. But I’ve never seen any 20th Century gear offered for sale in this way.

[roberto]

Ok, understood too.

The units that you have, the 17LS and the CT-5 are super great preamplifiers. Both have the Conrad Johnson signature Magic sound. The 17LS offers four 6922 in triode mode and the cT-5 use 2 6N30P tubed, and also configured in triode mode.

Both have a beautiful electronic design and they probably sound very alike, perhaps the CT-5 has more harmonic texture content. I had a CT-5 before of my ET-7, and the difference is that the ET-7 is more organic, I find more naturalness and like there is no preamp connected. Like it does not touch the signal, with a transparency that I never had before. The ET-7 V2 is a step ahead of mine.

I do know that you will be having a lot of fun listening any of those magical preamplifiers. They do sound very nice and both exhibit incredible musicality.

Happy listening!

[SteveFord]

It's going to be a fun comparison, that's for sure.
I've been thinking (always a dangerous thing) CT5 for 3.7s, 17LS for 1.7s, Classic 2SE for LRS.

I can see them being a small company, there are hardly any retail outlets left for high end audio gear here in the US.
The Great Recession really got it rolling, kids aren't interested in Big Stereo because their parents are so it's not cool and COVID bumped off most of the rest. RMAF (a really big audio event here) is gone for good unless someone else takes it over.

Like everyone else, I don't have an answer.

[AnotherJohnson]

I was surprised by the RMAF’s demise.

I guess they figured it would be best to cut losses.

[roberto]

It's going to be a fun comparison, that's for sure.
I've been thinking (always a dangerous thing) CT5 for 3.7s, 17LS for 1.7s, Classic 2SE for LRS.

I can see them being a small company, there are hardly any retail outlets left for high end audio gear here in the US.
The Great Recession really got it rolling, kids aren't interested in Big Stereo because their parents are so it's not cool and COVID bumped off most of the rest. RMAF (a really big audio event here) is gone for good unless someone else takes it over.

Like everyone else, I don't have an answer.

Hola Steve,

How the comparison went so far? I am with you with your chosen goods. How is your CT-5 doing?
Happy listening!

[SteveFord]

That CT-5 is the ticket, all right.
The other night I put on The Mothers Of Invention's Uncle Meat and by the time it got to King Kong I was paralyzed and couldn't open my eyes!
I was just rooted to the spot.
That kind of got me thinking about an EV-1 phono stage. That might be a good thing?

As for the other stuff, it's a work in progress.
The 17LS will NOT work in a small room with the LRS', it's simply too overpowering.
I know it will sound glorious with my 1.7s upstairs. I use a Sonic Frontiers SFL-2 up there and I need the tape loop for burning CD-Rs from albums.
However, it now sounds a bit thin and wimpy compared to the 17LS.
They didn't cram all of those caps in there because they were bored.