No output from 1964 Deluxe Reverb - Help!

[J M Fahey]

[QUOTE=Josephcarassojunior;432402]JM, some pictures...
thanks, clean sharp well illuminated pictures, we can straight work with them.

Tonight Iīll edit a couple pictures indicating points where tou should measure voltage, you post back what you find.

Incredibly clean amp, in all meanings of the word

I spot just a couple replaced parts (no, I donīt care about Mojo, but functionality, a modern working part bets 1000:1 a misbehaving old one), Iīm certain our USA based friends who see them on a daily basis can spot and comment on anything unusual they find.

OK, stay tuned, hope nobody needs to use *that* table for a few days

No small kids nearby?
If so stack a couple chairs around the work area so small curious fingers donīt get near and keep it unplugged (not just turned off) until you are actually working on it.
Same if you have a large dog.
Cats are safe , thatīs why you often find them at Tech labs, he he.

If that CD player is your sound source, you can downlod test audiotones from here Download Audio Tone Files and burn a CD with them, get the 30 second MP3 and play the one you choose , I suggest http://www.mediacollege.com/audio/to...6bit_30sec.mp3 setting the player to repeat or loop continuously; all this later when we start injecting and testing audio.

I suggest you also record some guitar playing track, straight into the computer, no pedals or anything, a squeaky clean track so you can test with it yet keep hands and mind free for measuring.

This is looking better every moment, Iīm VERY confident youīll solve it

[g1]

One more picture please?
On the bottom side of the amp is something referred to as the "doghouse". It is a rectangular metal cover with 4 screws.
Can you remove the cover and take a picture? There should be some large capacitors and a few resistors in there.

[52 Bill]

Lots of changes in the power amp section, coupling caps, added caps at the power tube sockets, the 47 ohm resistor in the P.I. has been replaced with a jumper, etc. All of the preamp cathode caps have been replaced, and there are a few changed resistors.

Please cover the top of your dining table with a small sheet of plywood or cardboard or something as you are bound to drop something onto the top and you will damage the finish. If you are married, the wife will not be amused.

[bob p]

No, you are right, thatīs exactly how itīs done, itīs called "cargo consolidation" , somebody fills a container to the brim, and pays some U$3500 to U$7000 for the full container, delivered practically anywhere in the World.

Since a typical 40' container can carry 61000 lbs, raw freight cost amounts to some 10 cents a pound if you fill it up wisely.

Handling and paperwork costs add up to way more than that , plus products *are* shipped by mail or other means inside USA to customerīs door, all that adds real cost, which I think can no longer be despised as insignificant, and *somebody* must pay for it.

My "fishy" label applies to Chinese being able not to pay cheap freight, but being able to offer *Free Delivery* .

Free as in free/nothing/zilch , and on products which often are NOT volume efficient, say a cloth teddy bear inside a bubble plastic and cardboard package , or a baseball cap which does not come flattened inside an envelope but with normal shape inside a cardboard box, both way too bulky relative to actual weight.
Containers have a maximum weight I mentioned above, but are also limited in internal volume, a 40' one is 67.7 m3 or 2,389 cu ft .

Numbers simply do not add up

The numbers add up if you look at in the proper perspective.

1. When a package gets shipped via International Mail, the originating country receives all of the fees, and the destination country receives nothing.
2. The destination country is obligated to use it's infrastructure to provide distribution and delivery of International Mail at a loss. They have to pay for all of the infrastruture and personnel time that's required to deliver the package, while receiving nothing in return.
3. The originating country (China in this case) is subsidizing their trade exports with the world by providing postage at below market rates. They aggregate all of the outbound mail to the USA at their post offices, and dispatch a container of mail to the destination country, where the destination country foots the delivery bill as described in (2).

It's obvious how this adds up: China subsidizes it's manufacturing and exports by offering International Mail at below market rates. They get away with doing this because they have a huge economy of scale at the mail collection end, and they have absolutely ZERO COST at the mail delivery end.

This is yet another case where the Chinese are screwing the people in the destination country by exploiting their country's domestic mail delivery service -- the destination country's postal service gets stuck footing the bill for package delivery while receiving nothing in return, and the people in the receiving country end up footing the bill for the operations of their domestic mail service while the Chinese get a free ride.

The technical name for the procedure is "Cost-Shifting." The cost of domestic delivery from the Chinese is shifted to those who pay for the operations of the receiving country's postal service, through their use of that country's mail.

The Chinese are smart. They're good at exploiting the system, while other people do nothing to protect themselves from the exploitation.

It's easy to provide FREE DELIVERY when you don't have to pay the delivery man.

[J M Fahey]

Hi Joseph Carasso, back in town, so to speak. Busy week.
Will post layout with suggested test points, first the DC ones, please check and write what *your* amp shows.

In general variations up to 20% are not that bad, say a preamp plate shows 160V, will work reasonably well actually measuring from , say, 140 to 200V , and so on.
One exception are main +B voltage or bias which are more critical.

OK, Iīll label the layout voltages and your pictures , stay tuned.

EDIT 1:
hereīs the amp right side, preamps and effects, measure the voltages suggested and write yours by them.
I used Windows Paint, very clumsy but what anybody has available for free, so we all use the same, these pictures will go back and forth a couple times


EDIT 2:
Phase Inverter


EDIT 3:
Power amp, supply and bias.



NOTE: some socket pins are hidden, I showed the approximate position, but you triple check that these match:
* Schematic
* Layout
* Your actual identifying pin 1 and counting clockwise

All voltages relative to ground, meaning black probe to chassis, red probe measures, multimeter on highest voltage scale (500 to 700V DC depending on brand) except for values *expected* to be less than 100V .
And even so, start on the highest scale.

When you add your values, do it in some contrasting colour, such as orange or pink or violet.

Good luck.

[Josephcarassojunior]

Hi all, problem resolved!!!

It was the classic 47 NFB resistor issue, as hinted by many members. The reason i had missed it was my amp doesn't have this resistor, it had been replaced by a "jumper". That combined with my total lack of knowledge led to my not identifying the correct spot where this issue occurs. A member somewhere in the thread mentioned that this resistor had been jumped, I finally identified it and as i pushed it sideways i was so happy to see it had come loose! Solded, problem resolved!

Many many thanks to all for the responses, particularly to Juan for the time spent in trying to help me. Most appreciated.

All the best,

Joseph

[Josephcarassojunior]

Hi all, problem resolved!!!

It was the classic 47 NFB resistor issue, as hinted by many members. The reason i had missed it was my amp doesn't have this resistor, it had been replaced by a "jumper". That combined with my total lack of knowledge led to my not identifying the correct spot where this issue occurs. A member somewhere in the thread mentioned that this resistor had been jumped, I finally identified it and as i pushed it sideways i was so happy to see it had come loose! Solded, problem resolved!

Many many thanks to all for the responses, particularly to Juan for the time spent in trying to help me. Most appreciated.

All the best,

Joseph

[Leo_Gnardo]

It was the classic 47 NFB resistor issue, as hinted by many members. The reason i had missed it was my amp doesn't have this resistor, it had been replaced by a "jumper". That combined with my total lack of knowledge led to my not identifying the correct spot where this issue occurs. A member somewhere in the thread mentioned that this resistor had been jumped, I finally identified it and as i pushed it sideways i was so happy to see it had come loose! Solded, problem resolved!

Good to see you got your Deluxe sorted. Curious that some tech replaced that 47 ohm resistor with a jumper - it boosts the gain just a little bit with no feedback. But with that jumper detached, no amplification at all in that stage. Maybe the jumper was the only practical "field fix" to get that amp going in a remote part of the world where spare parts are rare. Meanwhile, in amps where the complaint is "zero or very weak signal", that resistor and jumper to ground bus is the part of the amp I look at first after verifying all the tubes are lighting up.

[Josephcarassojunior]

Yes Leo and you had guessed it right from the start!

[robrob]

One of the most common trouble spots in old Fenders, and one that would cause the symptom you describe, is a disconnected feedback node resistor. In a Deluxe that's a 47 ohm resistor located sideways on the board, just behind the vib. channel's bass pot.

Leo nailed it in the second post, nice work.

Jose, with a jumper in place of the 47 ohm resistor your amp is running with no negative feedback at all. You might consider trying the stock 47 ohm resistor to get back to "real" AB763 blackface tone. Another option would be a 22 ohm resistor for half the standard feedback. Fender cut the NFB in half in their 68 Custom Deluxe Reverb (increased NFB resistor from 820 to 1.5K) and it gets great reviews.

[dchang0]

I can imagine companies putting together container loads. Container comes over and is broken apart on this end. A container full of 5000 packages is a lot cheaper per package than 5000 packages all racing across the pond individually.

On the other hand I may just be naive about it.

You're correct about it. One of my neighbors ran an import business from China. They were masters of running the numbers on bundling stuff into containers, sometimes sharing one container between multiple unrelated companies.

Somewhat related, a person in Hong Kong contacted me about buying an old $150 hifi amp I have--the shipping to him would have been $89 at best. I pointed him to a seller of a similar $99 amp in Hong Kong whose shipping to the USA was free (well, it had to cost them something, but the total cost of that amp was $99--it can't be $89 of that for shipping).

EDIT: just saw bob p's explanation--that explains a lot. I guess that explains part of the complex math my neighbor's business was doing. Some of it must've been the cost-shifting. He was a millionaire at 30-something, so obviously he had it all figured out!

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Congrats to the OP and Leo_Gnardo on the fix!