I have an Audio Research D-100 that needs an overhaul. I emailed A R about it and received this response: I'm sorry, those capacitors are no longer manufactured and we do not have anything in stock that will work. Unfortunately, the D100 in any version is no longer serviceable by Audio Research due to these parts and a few others that are no longer manufactured and there are no modern equivalents that will work as substitute parts. Has anyone around here restored one of these? I could use some guidance on getting around the obsolete parts.
Yeah, it looks like the 340's are backwards on your modules; the heat sink should face the broad solid line of the silk screen, if I understand the updated instructions correctly: The boards weren't labeled correctly in the initial pcb layout builds, the square pad that normally indicates the base orientation was placed on the incorrect pin for the 340's (it was ok on the 350's). And if I'm understanding, it was easier to address the issue in the silk screening rather than redoing the pcb layout...Anyway, both you and "Deafby" have way more experience in electronics than I do, I'm just a tinkerer, and I sometimes get harsh criticism too when I'm slow to pick up on a point so I can understand your feelings -- "Deafby" has a real job, plus he's doing all of this design and support for our community, so I cut him a lot of slack. I think you're doing great and you're so close to finishing; and just think how sweet the amp will sound when you're finally done! Plus you'll have a great "I survived" story to tell to friends. ;-)
What obsolete parts are you talking about? The AM1-4 modules have replacements, you just have to build them yourself. As to the [filter] capacitors, there are replacements, just not the exact values, but close enough. The issue I had was that the posts on the replacement filter caps are the long style vs the short style used on the originals. This means that you have to correct for that extra length somewhere...I made some nylon spacer rings on my lathe to offset them enough that the original mountings all worked, but there are other ways to go about that if you don't want to use my approach.
If you go to page 8 you will see all the 340 modules are to be placed backwards. So I put them in as indicated. The silk screen on the board is on both 340 and 350 modules. The 350 go with the silver back towards the line, the 340's go the other way. The silk screening was not changed on the board.
Since I know the power section on both channels now has all new transistors and my DC off set is like 25mv , I don't have more 340/350 transistors.
So I am going to put back in my original AM-1 and AM-2 as they were ok, I tested them a while back.
Since I know the power section on both channels now has all new transistors and my DC off set is like 25mv , I don't have more 340/350 transistors.
So I am going to put back in my original AM-1 and AM-2 as they were ok, I tested them a while back.
I replaced my 1900/100 with 2200uf/100 and just put rubber o rings on the longer shafts, they fit great.
No, I think you have this backwards...
"...I basically installed half the transistors backwards. He then told me there is a heavy line on the the board on the side of the would be transistor heat sink side. So I pulled the half of them and reoriented them and the amp functions perfectly..."
I believe this means that the heat sink side should face the heavy line, but I think we'll have to wait for Deafbykhorns to chime in to be sure.
BTW, I don't believe that you'll need to replace the 340's, unless they test bad when you remove them to reorient, your resistors 'died' to save them....
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Well looking over the pix on page 8 I take it the 350 heatsink side face the white line, but the 340 go the other way. He shows that in the second pix.
So you have the same boards and all your heatsink side face the white line?
So you have the same boards and all your heatsink side face the white line?
Well looking at the pix again on page 8 maybe all the 340 and 350 all the silver heat sink side go to the white line on the baords. I was under the impression the 340's went the other way. I looked and there is no schematic or I could verify this.
I think those images show the incorrect configuration for the 340's...I know it's confusing, but reading farther into that particular thread you find the following, " ...So when you insert the transistors all of the heatsink sides point toward the heavy line on the board below them...", and that's what I did.
However, I've been chasing output shorts on the backend so I can't say that I've actually run this configuration yet. I will soon, and I'll bring it up slowly on a variac, while connected to a dim bulb setup, with my fingers crossed.
However, I've been chasing output shorts on the backend so I can't say that I've actually run this configuration yet. I will soon, and I'll bring it up slowly on a variac, while connected to a dim bulb setup, with my fingers crossed.
A college degree doesn’t automatically turn you into an expert in electronics; it’s merely a stepping stone on a much deeper and more intricate journey. True mastery comes from hands-on experience, relentless curiosity, and a burning passion to understand every nuance of the craft. I never meant to make you feel diminished. Truly, I believe your time might have been better spent on something else like a cool DIY Pass amp. While I admire your perseverance, I can’t help but think that letting a professional handle the repairs would be a wiser choice. I know it’s been a journey of learning for you, but honestly, I would have been tempted to take that amp and throw it into the street, running it over a few times just to unleash some pent-up frustration (that’s the Sicilian in me)…
I truly feel your pain, we’ve all been there during the learning process
I truly feel your pain, we’ve all been there during the learning process
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The heavy line is always the heat sink side, sometimes a tab with a TO220. I see at least three transistors on each board installed wrong which led to your catastrophic failure. A variac or light bulb is a basic troubleshooting device and must always be used or you will keep buying parts.
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Well, I gots me a college diploma - but I think my wife lost it when she was cleaning up the house... figures...
(Zappa. Dummy Up)
...Wait a minute!...
College!
College!
That's college-rhythm
You mean if I smoke that, it's the same as this
As if I was at college?
Roll it on up!
Roll it on up!
Roll it on up!
Give me that!...
No no, the college degree is stuffed with absolutely nothing at all
You get, you get nothing with your college-degree...
I won't bother with any comments about knowledge etc in electronics. We are not here to do this and appreciate the time you have spent to help out, and I am not feeling diminished, more uncertain of the way these 340/350 devices go. So anything I have built with those type of transistors/rectifiers, the heavy white line means the device with the heatsink side goes that way. Then where did I read that the 340's went the other way? So both the 340/350 all have the heatsink side towards the line? Appreciate if you can answer this as Karlzim was also not sure. If you look below what you listed I was under the impression the 340's went the other way. I guess this is where the disconnect is. You are Sicilian decent...I was born not far from Naples..more inland.
I went by this post you out on page 8 by another fellow butch??
Butch discovered that the square pads are inconsistent between the MJE340 and MJE350
The square pad on MJE350 is correct, the MJE340 is wrong. I pointed this out in some earlier threads, these boards are a revision from "Jayfree" design. Use the silkscreen for orientation, do not pay attention to the square pad. The footprint files in EasyEda are open source and inconsistent, it was easier to add the silkscreen in lieu of revising the board.
See screenshot of the boards below pointing out a couple of the MJE340 oriented wrong
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It seems Karlizm also originall placed all the 340 's in wrong. So I change all the 340's so the heatsink side is on towards ther white line.
This has been confusing as I read it the 340's were to go the other way.
This has been confusing as I read it the 340's were to go the other way.
I have shared, sold and helped repair at least 30 of these old amplifiers. Only 2 people have soldered these wrong so I think it was just a mistake not understanding the silkscreen. Butch assumed the sq pad was the collector, you just didn’t pay attention to the silkscreens from what I gather or used Butches pictures to stuff the devices and not the silkscreen.
Butch was lucky and didn’t blow anything because he used a current limiter
Butch was lucky and didn’t blow anything because he used a current limiter
I think the mistake happened when I was reading that the 340's were to be put in backwards with the heat tab away from the heavy white line.
Somehow looking at the boards that Butch made and then a folllowing pix showing the 340's were backwards...I somehow got confused...I have always placed any devixes like that towards the heavy line.
If I had a schematic to follow I would have been able to double check everything.
Thanks Again for all your help!!
Somehow looking at the boards that Butch made and then a folllowing pix showing the 340's were backwards...I somehow got confused...I have always placed any devixes like that towards the heavy line.
If I had a schematic to follow I would have been able to double check everything.
Thanks Again for all your help!!
Yeah, Karlzim did it wrong (like butch) the first time too, I was also confused by the square pad and used the wrong reference; however this caused some voltage issues, and after I did more reading in this thread, I discovered my error...Unfortunately, I've been working on car stuff (which actually makes sense to me) for my wife, so I won't be back on this little project till the weekend -- Oh, I'm close, so close, I can hear the amp in my dreams...Now if I can only hear it when I'm awake life will be good!
Ya, I would of put them with the heat sink side to the white line like most other types I have installed, then got confused that the 340's on a few others were put in wrong so I flipped mine around. Anyway it took out 2 resistors, and 3 transistors. I just got some more from Digikey, same ones.
So hopefully soon everything should be ok.
So hopefully soon everything should be ok.
Well, finally got the ARC amp reassembled and did a first power-on...Had a short but on the other channel, thank god for dim bulbs and variacs! I didn't get past 35V so I powered it off and rechecked the wiring, and sure enough, I there was a problem on one of the common connections. So I fixed that and tried the power-on again, and voila! Not even a flicker on the dim bulb at full voltage. I need to tidy up the wiring a bit an then check the dc offsets but I think this is decent progress for this weekend.