• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

No sound output from MC240

D

DonBattles

Well-Known Member
My second MC240 arrived late on Friday and today I finally had some time to set it up and much to my dismay no sound :sigh: Tried the other set of tubes from my other 240 as well as the stereo and twin amp inputs but still no sound, hum, static, or anything. No smoke, no bad or burnt smells from the amp. Took a few pictures of the insides and nothing seems to be loose. The only thing that looks odd (see first picture) is there is no fuse in this circuit but there is a place for one. This amp has been worked on my s few different technicians and according to the papers I have Terry DeWick was the last in July of 2010. Any feedback would be greatly appreciated :thmbsp:

photo1.jpg


photo2.jpg


photo3.jpg


photo.jpg
 
Register to hide this ad
So I e-mail the seller:

XXXX,
stopped by work today and found that the tubes had indeed arrived via USPS as you had indicated. So once I arrived home I hooked installed the tubes and hooked everything up and no sound. The amp does power up/on and the tubes all glow but so sound output. I tried the stereo connections as well as the twin amp inputs and still no sound, not even a hum no matter how much I turn up the volume. I then swapped all the tubes from my other 240 and still nothing. Reinstalled my other 240, with the tubes you send along and it all works fine. Needless to say I'm not very happy. Please advise as to how we will handle this on a go forward basis.

Regards
Don Battles

Does this e-mail seem out of line? Because the reply from the seller, a brick and mortar audio store was a bit out of line IMHO (I will post their reply later).
 
Last edited:
On my MC225, that missing fuse would cause the symptoms that you describe. It is not shown in the service manual schematics but it is in the secondary side of the power supply transformer and its absence would block all power to the tubes except for the filaments (which are supplied by a different secondary winding). It is possible that previous rebuilds of your amp may have eliminated the need for that fuse but, until proven otherwise, it is the most likely/obvious suspect.
 
JohnWilliams said:
On my MC225, that missing fuse would cause the symptoms that you describe. It is not shown in the service manual schematics but it is in the secondary side of the power supply transformer and its absence would block all power to the tubes except for the filaments (which are supplied by a different secondary winding). It is possible that previous rebuilds of your amp may have eliminated the need for that fuse but, until proven otherwise, it is the most likely/obvious suspect.
Click to expand...

I was told the bias was checked and adjusted before the amp was shipped to me, would this fuse be removed to check or set the bias? If so maybe they simply forgot to reinstall it :scratch2:
 
Last edited:
Looking at the schematic for the MC240, the bias supply is on a third secondary winding of the power transformer, separate from the main supply and the filaments. They could definitely check the bias supply voltage without that fuse in place (although that would not be the correct method since the tubes should be operating when checking the bias current).
 
Hey Don I would step back a take a breather. I would suspect if you have paperwork on this baby and Terry worked on it a year a go or so you aren't getting the shaft. It looks like a really clean and nice piece that has been updated and had work done right, so I would figure it out.

Sometimes things hit hard in transit, they get knocked around, and components sometimes fail at inopportune moments (ie. like when you get it). I think it really did work fine when they shipped it, but I would inspect things and my suspicion would be it will not be a hard fix it all - something has to be overlooked here and it shouldn't be much - like that fuse.
 
The paper cover+tape over that one cap looks awful, and I'd be surprised if a skilled tech (like Mr. DeWick) would let an amp get off the bench like that.

The new diode and the dropping resistor suggest that the bias supply was rebuilt. A couple of caps (like cathode bypass and C4) and the thermistor have been replaced too, so generally the amp looks fine.

If the circuitry hasn't been altered, the internal fuse is vital for operation. In my MC75s the internal fuses are rated the same as the main fuse IIRC.
You could check if without the fuse any voltages are present at all. Or just pop in a properly sized fuse and see if the amp comes alive. Good luck!
 
The bias update and capacitor update look like mine, the can with the paper cover is not. Look for the fuse in the case, if you can not find it put in a 3A slo-blo and all should be fine.
 
dewickt said:
The bias update and capacitor update look like mine, the can with the paper cover is not. Look for the fuse in the case, if you can not find it put in a 3A slo-blo and all should be fine.
Click to expand...

Terry I'm glad you read this and I was hoping you would jump in,thanks!
I was pretty sure all would need is the fuse and will pick up one today on my way home, I just wasn't sure if the update somehow eliminated the need for the fuse. I had already had a good look in the chassis and did not see the fuse, anyway thanks again!
 
By the way here is the reply from the seller:

Don,

Glad that the tubes arrived yesterday and I'm very sorry that it did not fire up. Especially because, as you know, we tested this item and, moreover, it was gone through by Terry DeWick.

Your comment "needless to say I'm not very happy" is more than disappointing. We have always provided the best packaging and extreme care in offering quality components. I will pay any price to have this item brought back to me but you and I will never do another business transaction again.

Just have it shrink wrapped and packed beautifully. I will either have it shipped on our UPS/FedEx Acct or drive down to pick it up personally.

Rather than nicely say that something strange must have happened during shipping, you chose to say how "unhappy you were" with my business -- and that is unforgiveable. I'll get it back from you and pay for any trouble that you encountered just to avoid another dealing with you in the future

We offer a 90 day gauaranteed on every itiem because there are biased, tested and ran to full power. XXXX prep's it to got full safe return to XXXXX. I'll let you know when it arrrives safely back . Thankyou!

Sent from my Verizon Wireless BlackBerry

So he feels slighted by my e-mail and feels I should have handled if differently. My reply back to the seller:

XXXX,
would you be happy if you were me? It's a simple statement really and not intended to paint XXXX XXXX in a bad light, believe me if this was my intent my words would have been much sharper. It is I that should take offense especially given your less than professional reply. You might want to read my message again as I don't believe I made ANY mantion of wanting to send the unit back. I'm simply looking for some help if figuring out what it's not working. Now rather than this getting nasty on a personal level how about we come up with a way to solve the problem?

Regards
Don Battles

Based on the input from forum members here I'm sure the solution is the missing fuse. We shall see :thmbsp:
 
If I were the seller, I'd be frustrated to see this comment "needless to say I'm not very happy" as well.

At this point in the conversation, I'd hope a buyer would keep to constructive comments that would resolve the issue. ie. missing fuse, etc.

As others have said, many things can happen during shipping, no matter how well something is packed. To say you're unhappy with the transaction is potentially putting unfair blame on the seller.
 
fdejong said:
If I were the seller, I'd be frustrated to see this comment "needless to say I'm not very happy" as well.

At this point in the conversation, I'd hope a buyer would keep to constructive comments that would resolve the issue. ie. missing fuse, etc.

As others have said, many things can happen during shipping, no matter how well something is packed. To say you're unhappy with the transaction is potentially putting unfair blame on the seller.
Click to expand...

The above is VERY true, keeping comments to a dignified and constructive level really helps in the long run - and comments like the above put the seller in defensive mode. I would not attack the seller right away, and would leave this kind of language 'like not being happy', etc, for later on down the road when a refund or warranty would not be honored. In this case, it looks like both a refund OR a warranty would be honored so the seller looks legit to me.
 
Don, I think the email you wrote was perfectly fine. And given that you paid the seller some thousands of dollars and found the amp to be in non-working condition (plus the paper cover over the cap, that's inexcusable and dangerous), your choice of words "needless to say I'm not very happy" was more than justified.

The seller's response was an insult in my opinion. It sounds like some angry teenager on the internets wrote it. Not very professional.

And triple-check that the fuse is not stuck somewhere inside the amp. They're pretty big so they can't hide as easily like a piece of wire, but they can still produce a fatal electrical short.
The paper-cover over the cap was installed because the can is on a negative potential, and touching it is/could be lethal. You'll notice that the other caps sit there naked, that's because their can is at ground potential. The original caps in that position had a thick cardboard tube glued over the cap, it's the black ones if you're looking at pictures of original Mc power supplies. Modern caps use heatshrink tubing and a circular piece of plastic for isolation.
 
OK so I should not be comcerned with the paper over the capacitor? As for the fuse yesterday was a long day and I didn't get home until after 7pm and with family activities and a 6:30am work start time I simply could take time to pop the fuse in. Should be able to do so after work today however and I'll let you all know how it goes. As for the seller's position and mine perhaps we were/are both right and wrong to some dsegree. I myself mave been in customer service for over tywenty years and I've had my share of angry customers over the years. I will simply say that way Mr. X came across from a CS stant point was not right. Rather than punch back something to calm a diffuse the situation would have been more in line, at least that's what I would have done. Anyway whats done is done and I'm more concerned at this point about getting this puppy fired up :)
 
Don, on the interactions you have shared regarding your transaction, let me get this straight:

- You have purchased an older Mac amp from a seller.
- The seller represented it as being in first-class operating condition as evidenced by some level of restoration having been done to it.
- You have paid an agreed upon sum for the amp with those considerations.
- The amplifier was shipped to you in a condition that caused it to be inoperable upon receipt.
- Your own inspection, as revealed in the pictures posted here at AK, indicates that a fuse is/was completely missing. Diligence on your part has not yet revealed where this fuse has gone.
- Further inspection of the amp, including one of the potential people involved in _part_ of the restoration work, indicates that remedial work has, indeed, been done. (My observation: One capacitor with potential lethal voltages has been somewhat secured for safety but not too well and indicating low attention to detail.)
- Upon notification of the discrepancies, the seller has reacted in a less than professional manner but has indicated they would take the amp back with no other options offered.
- You have resolved to go ahead and try to power up the amp with a fuse of your own choice.

At this point, I'd suggest that you consider not doing this until you give the seller a complete chance to make things right. That is, if you power it up without full and written agreement from the seller and it fails in some way, you really will have _bought_ it. I'd suggest that you work with the seller in such a way that he remains fully responsible for the discrepancy regarding the amp's non-operational status.

I, too, have worked in customer service capacities from the vendor standpoint and the vendor of used gear in a transaction such as this _owns_ the option of repair/replace or refund your money.

I am not a lawyer so cannot speak to the details in that way, but look at your situation as if it were a used car that does not run even though the seller said it does. The seller appears to have failed to complete their part of the transaction at this point.

From a technical standpoint, that the seller did not verify the amp's operation prior to shipment is beyond me. Where, exactly, did that fuse go? Perhaps he needs to have a discussion with whomever did the last round of work on it.

Hope that helps.

Cheers,

David
 
Last edited:
dshoaf said:
Don, on the interactions you have shared regarding your transaction, let me get this straight:

- You have purchased an older Mac amp from a seller.
- The seller represented it as being in first-class operating condition as evidenced by some level of restoration having been done to it.
- You have paid an agreed upon sum for the amp with those considerations.
- The amplifier was shipped to you in a condition that caused it to be inoperable upon receipt.
- Your own inspection, as revealed in the pictures posted here at AK, indicates that a fuse is/was completely missing. Diligence on your part has not yet revealed where this fuse has gone.
- Further inspection of the amp, including one of the potential people involved in _part_ of the restoration work, indicates that remedial work has, indeed, been done. (My observation: One capacitor with potential lethal voltages has been somewhat secured for safety but not too well and indicating low attention to detail.)
- Upon notification of the discrepancies, the seller has reacted in a less than professional manner but has indicated they would take the amp back with no other options offered.
- You have resolved to go ahead and try to power up the amp with a fuse of your own choice.

At this point, I'd suggest that you consider not doing this until you give the seller a complete chance to make things right. That is, if you power it up without full and written agreement from the seller and it fails in some way, you really will have _bought_ it. I'd suggest that you work with the seller in such a way that he remains fully responsible for the discrepancy regarding the amp's non-operational status.

I, too, have worked in customer service capacities from the vendor standpoint and the vendor of used gear in a transaction such as this _owns_ the option of repair/replace or refund your money.

I am not a lawyer so cannot speak to the details in that way, but look at your situation as if it were a used car that does not run even though the seller said it does. The seller appears to have failed to complete their part of the transaction at this point.

From a technical standpoint, that the seller did not verify the amp's operation prior to shipment is beyond me. Where, exactly, did that fuse go? Perhaps he needs to have a discussion with whomever did the last round of work on it.

Hope that helps.

Cheers,

David
Click to expand...

David, seems like you have a pretty good grasp on how this went down. The seller did make it a point to drop Mr. DeWick's name on more than once, afterall his reputaion speaks for itself. The seller did indicate this unit was tested and bias checked before it was shipped and the general feeling I get and that it not working isn't really possible, in other words I'm making it up or lying perhaps. I e-mailed the seller the same picture I posted here and got a "could be" reply. Now I wil admit I might have used other words initailly but it's not like a said "hey A$$hole, whats with this piece of cr@p amp you sold me"! In the end we both could have taken a different approach. As for the rest of your advise it's appreciated but since I already opened up the chassis with his "permission" I may as well put the fuse in and see what happens :para:
 
OK, Don, sounds like the situation has been fully explored, then. Got a variac or a dim-bulb tester for that amp, by chance?

Cheers,

David
 
It looks like a very nice amp with it's skirt pulled up. Is it as nice when you flip it over. I am betting it is. Anything in that amp can be repaired/replaced except, God Forbid, If something happened to the power or OP transformers during shipping.

The sellers response was rather immature. I would be very unhappy too, if a very expensive amp showed up on my doorstep DOA. They should have not inflamed the situation by insisting you return the amp for a refund. They even offered to pick it up personally. That is odd don't you think.

Here is my conspiracy theory. They sold the amp to you and then got a much better offer, maybe from an Asian buyer. So, they shipped it DOA waiting for your email complaining that it was DOA. Then they responded by offering you a refund and, as I mentioned before, to personally pick the amp up. Then they stated they wanted to terminate any future business dealings with you. Why? So you would not find out what they did?

Something is rotten in the state of Denmark.

It is just a thought.

Send it to Terry and let him do a full monty recap/repair on it and enjoy your great amp. I can guarantee it will not come back with cardboard around the the can com pos cap. I have pictures if you want to see them.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom