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dragonworks

dragonworks

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I have an amp that was made in Italy and needs a couple of components that are burnt up. Luckily there is one left that I can read but dont know what it is. I think it is a resistor but not sure, not color coded. I tried a search on the web but to no avail.
Now for a description. It is about 6mm in diameter and about 25 mm long, green, with metal ring on both ends.
Written on it is the following 5BB680 or 5BB580,
and the letters SRECO or BRECO

There are three of them in the power supply, two are burnt. They are not the diodes because I can identify them.
can anyone help me.
I tried searching all of the above but got nowhere.

Thanx :)
 
A quick guess...

From your description,it might be a 2-watt metal film resistor.
Can you post a pic or two of the piece itself,as well as of the place (PCB) or circuit where it belongs?
..or,can you recall where were originally placed these three resistors in the PS circuit?
What amp is that you have?(brand,type)
Regards,
 
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Le Basseur said:
From your description,it might be a 2-watt metal film resistor.
Can you post a pic or two of the piece itself,as well as of the place (PCB) or circuit where it belongs?
..or,can you recall where were originally placed these three resistors in the PS circuit?
What amp is that you have?(brand,type)
Regards,
Click to expand...

Follow this link for a picture

https://homerecording.com/bbs/showthread.php?t=145734

I is a "Sound" amplifier, made in italy. I am familiar with tube power supplies, this is a transistor power supply, and from the looks of it I would think it is part of the voltage divider network?
If it is resistors which I believe they are I don't know how to tell the values. I guess I should just pull the one out that still "looks" good and take a resistance meausement.

I was wondering if the SRECO or BRECO is the company name but could find no reference.

Thanx again. :D
 
it is an all transistor amp. I saw the reviews on harmony central.
I know where there is a Sound tube amp in a small local music store. The guy says it is on consignment, it has been there for about five years, I have tried to buy it for twenty five dollars american for the last five years but he won't sell it to me, he wants fifty I think. I would shell out the fifty no problemo but it has become kind of a game and a ritual, a tradition between us.

Here is the standard conversation when I come in.

Owner, how you doing, what can I do for ya?

Me- I need a rental with an option to buy, the payments going towards the purchase, no money down and six months till first payment due, and, by the way, I'll give ya twenty five dollars for that Sound amp.

Owner-What can I do for ya?
 
dragonworks said:
Here is the standard conversation when I come in.

Owner, how you doing, what can I do for ya?

Me- I need a rental with an option to buy, the payments going towards the purchase, no money down and six months till first payment due, and, by the way, I'll give ya twenty five dollars for that Sound amp.

Owner-What can I do for ya?
Click to expand...
Well,THIS is why your amp has a burned component! :D :D :D
OK,you said it's a Sound.Pretty rare in these days (I saw only one in the past 10 years but it wasn't your model) and impossibile to find schematics.
Let's say that the burned component is really a 2-watt resistor (again,post a pic of it!) from a voltage pi-network,as you said.The point is that such a resistor in such a place doesn't burn by it's own but for a (usually ugly) reason,meaning that it might be a mess somewhere in the audio chain wich caused this.Please carefully inspect the rest of the circuits:is there something else looking suspect?
Again,it's very hard to track down a SS amp's problems blindly.
However,judging by the amp's look,it might be produced somewhere in the early 70's (Sound might be very similar with some other famous brands,from wich the Italians might had borrowed the schematics) meaning that the circuit should be handy for a repair.
Get it to a good amp tech and revive the damn thing! :D
 
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i have looked the amp over pretty good and they are the only damaged components I could identify by eye. Does a wire wound resistor have a solid core? When you squeeze the damaged ones they kind of feel like a spring with
a canvas covering. The one that still looks good feels kind of solid.
On further inspection, the amp says on front, Sound, Model 4000, a product of sound musical insruments, N.Y.(New York) All the info I have read on them say they are of Italian origin.
The picture I posted came from an Ebay auction and the amp was listed as a tube amp, but it is the same front panel. I wonder if they had anything to do with Heil Sound.
I do believe it is a transformerless power supply, the filter capacitors are the biggest I have seen in any amp. They are the size of a can capacitor, about 75mm to 100mm long and 40mm in diameter. (I hope I am doing my metric conversions about right, I am doing them out of my head and dont normanlly work with metric) but they are only one capacitor each. Past these filter capacitors I have located the diodes in the bridge rectifier and another diode, may be for bias circuit, past those are the burnt components in question along with two electolytic 250 volt and I am not sure of the capacitance value cause all it says on them is 35, I will replace them along with the ones in question.
Also the amp gives off a slight shock to the touch when turned on so I have to look for an ungrounded ? condition before I kill myself. I have to go into my amp repair book and find the test for this.
Channel one hardly works, Channel two works with lots of distortion. When the amp is turned on and nothing plugged in, all pots down, there is a very loud steady hum that does not sound like 60 cycle.
I would really like to fix this without a tech. I have been trying to do this for years as you might be able to tell from my scanty knowledge. I do have Jack Darrs guitar amplifier repair handbook which goes into great detail. I have the meters which I know how to use and own a sillyscope that I don't know how to use.
I have an old fender Bassman in line for work, and then the rarest preamp ever, noone has ever heard of it, an old Teisco stereo, all tube, two channel guitar preamp with reverb, tremolo, low, mid, high. It is really the coolest thing and the cats meow.
I just love this stuff and gots to learn it even if it kills me ;)

PS, I don't have a digital camera, actually, I don't have any camera, why? I guess cause I can't play music on them so I won't buy one!
 
Upon further inspection, the burnt componets are part of a circuit that goes to a small transformer, the two leads coming out of the transformer go directly to the power output transistors PN# HEP247, the drivers are HEP203 transisitors.
This amp seems to have been gone in before. I had to remove the heat sinks to find the transforemer and one heat sink had phillips screws and the other had flat heads.
There are only two circuit boards in the amp, one for the power supply, one for the preamp circuits etc. On the preamp circuit board looks what might appear to be an aftermarket add in, hard to tell, just don't look right.
So far except for the filter caps the compenents in question are pretty cheap including the output and driver transistors.
 
arcaxis said:
Crap I turned this into an obsession to find info on this amp. I'm beginning to think a Sound Model 4000 is mythical. Come to think of it, Dragons are mythical too...... :D



I did find however some stuff on SRECO !! See attached pics. They are/were a manufacturer of wirewound resistors as can be seen on 2 of the pics. The pics that look like dog turds on a stick are actually vintage wirewound resistors made by a company called Sage (maybe Sage REsistor CO = SRECO ?).
I'm going to take a guess the burned up components are 5 Watt 580 or 680 ohm wirewounds. If the good one has the same markings, check it with an ohmmeter.



http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4664&item=3845793233&rd=1&ssPageName=WD1V

http://search.ebay.com/sreco_W0QQso...mZR10QQftidZ2QQftrtZ1QQftrvZ1QQfsopZ1QQfsooZ1
Click to expand...


Your the man
 
I took out the one that looks good and it measures 633 ohms.
Now to get the rest of them out I may have to unsolder all the leads going to the board so I can get under it. Every thing is hard wired with globs of solder.
The power supply has a transformer duh, I didn't look under the chassis at first.
It looks like a stacked output stage with a an input transformer.
 
arcaxis, thanx for all the help.

Do you do repair work?


the output transistors are hep247 and the drivers are hep703, I was wrong when I said 203. I was allready able to cross reference them with an NTE number and get some prices. Cheap. the 247s were under five dollars each and the 703s about a dollar fifty. I can probably find them cheaper.
I cut all the wires to the power supply board, got tired of trying to unsolder them, and I took the board out. There has been work done on it before. At one time there were four identical resistors I would think, the 630 ohm wirewounds. Right now there are only three. I assume one has been replaced with a ceramic that had not been wired into the circuit board but jumped across the top to its contact points. One of the leads has come loose and this may have caused alot of the problems. To much current was being drawn
at one time because you can see the brown burn on the circuit board underneath unless that was from the previous one. Hopefully I will get 4 resistors, put them in and she will fly but I doubt it, I never have that kind of luck. There are two other standard resistors together in this circuit wired with the wirewounds, I will replace them also, and maybe the two electrolytics. :)

Since I cut all the wires I was able to drop the transformer and the heat sinks with the output transistors on them, they are now out of the amp. I don't know how to check the transformer and the transistors so will have to do a little more reading.
 
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