Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Andre Oliveros on November 08, 2010, 10:50:10 am
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Guys im the owner of the JCM 800 2210, and i was thinking, could be posible to remove the board of this amp, and install the ceriatone jubilee clone, doing the respective mods? i mean can i use the parts of the 2210, to complete the ceriatone board?
any ideas thanks
Dre.
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I wouldn't mod a JCM. Keep it in stock form if you like it, resell it and buy another amp if you don't. BTW the 2210 is a reverb model, the JS aren't, so your existing chassis would be full of unused holes...
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well, the problem is , that the jcm doesnt work, a lot of people have seen that amp and no one can fix it, also i the transformers are new because it supoussed to be that, as well as the filter caps, it has pretty much everything but the board new, Transformers, filter caps, switches, tubes, and it has the same problemthat doesnt work the amp properly , so im pretty tired of that, thats why i was thinking about that idea, i dont mind the unused holes, or the reverb i just want an amp that works using the things that i already buy.
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Converting that amp to another amp is doable but it's going to be much more complicated and involved than fixing the simple bias problem in that amp. Anyone that can successfully convert that amp should also be capable of fixing the bias problem.
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well, the problem is , that the jcm doesnt work, a lot of people have seen that amp and no one can fix it
It seems that the problem is bias-related, something pretty simple to fix. Building a whole amp is much more difficult.
Have you contacted Cesetec? They're supposed to be really good and are the official network of service centers for Marshall products in Brazil.
http://www.cesetec.com.br/
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i posted a thread well various threads, about this amp, but no one can help me , the last thing that our friend renzc suggested was that was something wrong with the ground , because we already change the transformers and also checked the bias section, the whole problem is in this thread... http://www.el34world.com/Forum/index.php?topic=6512.msg92968#msg92968
but im kinda desperated with this theme, and no solution for years... ill be happy to post pictures and everything if someone wants to help me , ill be the hands. but i do want to repair this amp, and like it says in the whole thread the amp has almost everything new, and acording to the last guy that tried to repair the amp, every component its in good shape if not new.
thanks ill be very happy if someone can help me to fix this for good
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Dre.
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The bias issue with that amp was never resolved. Just because the PT was changed doesn't mean that the new one is still working properly. The bias will be an issue until you can measure approx. -50vdc on the output tubes grids. There have been a lot of inexperienced hands inside that amp. You really should take it to a competent shop and pay to have it fixed.
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well believe it or not theres no shops in my country, thats why am asking for help since it got bad, because i already took that amp to stores that sell amps, and has "service" but they dont want to try to fix my amp because "they are afraid, to not fix it" thats my main problem believe me ill rather pay for someone than all that headache and bad spended money but here no one fix tube amps, i already asked for electric techs and no one wants to fix that amp, i mean no one really and believe me i have search like mad for someone that can or in my case wants to fix the amp.
Dre.
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Send it to the states.
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well shipping its a big issue since they ll charge 200$ aprox for send it and another 200$ for bring it back, plus the price of the repair would be a expensive choice dont you think?, but thanks anyway for your solutions man.
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Did you have any pictures?It is really easy to do the bias supply in those amps.
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well believe it or not theres no shops in my country, thats why am asking for help since it got bad, because i already took that amp to stores that sell amps, and has "service" but they dont want to try to fix my amp because "they are afraid, to not fix it" thats my main problem believe me ill rather pay for someone than all that headache and bad spended money but here no one fix tube amps, i already asked for electric techs and no one wants to fix that amp, i mean no one really and believe me i have search like mad for someone that can or in my case wants to fix the amp.
Você já contactou Cesetec? Eles deveriam ser muito boa e são a rede oficial de centros de serviços para produtos de Marshall no Brasil.
http://www.cesetec.com.br/
(In Portuguese this time)
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thanks for that page but am from guatemala, i dont see how this page would help me since im in central america and this directory its from brasil wich is in south america, or they can help me anyway, if so how?
Dre.
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Hey, Im having a hard enough time understanding some of this stuff in english. :laugh:
Now Poruguese ! :confused2:
Brad :angel
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thanks for that page but am from guatemala
Sorry. I thought you were from Brazil. My bad.
I've no local service center or repair facility listed in my files. All operations for major brands are handled thru hubs in Miami or the US SE. The largest local distrib seems to be Preludio Domisol in Guatemala City, but I've no further info.
You may contact Marshall in the UK, maybe they can help you.
If not your options are quite limited: ship the amp to a qualified service center abroad, have it repaired and sent back.
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Hi,
post some pictures so that we can see the current condition of the amp.
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ok ill post pictures of everything, that can be usefull i remember that i had some photos uploaded but the servers are down the only one by now is this one that took the last guy that tried to fix the amp.
https://tech502.com/Archivos/Components.jpg
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dammit this one is down to, ill upload new photos as soon as i can.
Dre.
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Dre, my suggestion to ship to the states was not helpful. It was also not meant literally. I understand your frustration with this amp and having no one in country that will fix it for you just adds to that frustration. I worked with someone called hctrjs during the entire month of April. We danced around the bias circuit the entire time and I don't believe we ever got in sync together. I'd ask this, he'd report this. I'd ask that, he'd answer that. But, the info he was reporting was often conflicting, so I could never quite trust which answer was correct.
Refer to this schematic... http://www.el34world.com/charts/Schematics/files/marshall/jcm800_splitch_100w_2210.pdf
We need to know unconditionally if the PT bias winding is good. Disconnect the PT bias wire (white) and just let it dangle in the air. Now measure the AC voltage between that wire and chassis ground. What do you get?
CAUTION. UNPLUG ALL OUTPUT TUBES UNTIL THE BIAS PROBLEM IS FIXED!
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ok ill do that, i think the problem was that he doesnt know about amps, and my problem is that i dont know to much about electronic things but i get a pretty good idea of it, also the lenguaje doesnt help me to much to understand , so be free of explain to me (if you would be to kind) with wire colors, shapes, or simply telling me how do i have to set the voltmeter, whatever that can help ill do it also im not that afraid of electrical shocks, not because am a dumbass but because i already know the basics to work with amps, also soldering, and im very perfeccionist , so basically i want to fix this and also do it in the best and clean way posibble, -time is not an issue for me ill take the time to do the right things.
thanks very much for your time also , because i know you were trying to help the guy.
Dre.
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Hi Andre. I remember your amp well. Slucky is the Best! yes, I think it is good "You" do this with
Slucky. I'm sure you can fix it. :smiley:
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Intente http://babelfish.yahoo.com/ (http://babelfish.yahoo.com/) para las palabras y las frases que son duras para que usted traduzca al inglés. Puede ser que no trabaje siempre la manera que esperamos, pero puede ser que sea más fácil que teniéndolo interpretó mal
I used that site for the above translation to Spanish from English.
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Puede ser que no trabaje siempre la manera que esperamos, pero puede ser que sea más fácil que teniéndolo interpretó mal
Do you really want to order a steak and kidney pie with plaster and strawberries on the side, served by a blind dwarf riding a unicycle?
Friggin' automatic translators...
:wink:
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well today im taking the pictures, i was watching the amp yesterday, i have not watched it since the guy bringed it back to me , and hell, its worst than it was, bad soldering in some areas , wich a fixed yesterday, ill post the pics, of everything, to me look suspicious in some areas, so ill be happy to show you guys the pics and maybe you guys can circle and tell me whats wrong and what i have to change and redo, also maybe would be great if we can fix this one i have another amp... a fender Bassman 100 wich its doing a horrible hum, ill post pics of that one too but maybe later, after we fix the marshall, thanks to everyone and lets get started.
Dre.
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So, no joy yet?
Oh man... I feel you pain... how long have you been trying to put it together?
Best Regards
Rzenc
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almost 3 years now, i only used the amp like 4 months and it was enough for falling in love.
hopefully anytime soon ill fix it by myself, the bright side is that am going to be the only Guatemalan, who repairs tube amps :D.
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Puede ser que no trabaje siempre la manera que esperamos, pero puede ser que sea más fácil que teniéndolo interpretó mal
Do you really want to order a steak and kidney pie with plaster and strawberries on the side, served by a blind dwarf riding a unicycle?
Friggin' automatic translators...
:wink:
:toothy9: I never said to constantly use it. :tongue3: I know translators are not perfect, but the worst I've ever seen only seem to mangle sentence structure leaning towards the original language... Then again a bad translator can have your head on a platter in some places (Human or machine). :evil3: Then again, the life most people think rock stars have might benefit from the translation work of Corey Feldman in "The Goonies."
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OK HERES THE WHOLE ALBUM WITH A BUNCH OF HIGH RES PHOTOS, ANY IDEAS OR SUGGESTIONS ARE WELCOME!
http://s281.photobucket.com/albums/kk235/Guayajilla/JCM%20800%202210/
(let me know if the link work for you guys)
thanks
Dre.
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Dre, I've looked at your pics. Seems that the wiring around the rectifier end of the board has changed since I last saw this amp. Looks like the amp will blow the mains fuse immediately when you flip the standby switch. Look at picture DCS00822. See the two light blue wires on the lower right side? Those wires come directly from the STBY switch and the other side of that switch is connected directly to the HT winding of the PT. Back to the board. The light blue wires are connected in such a way as to have a direct short across them. That's wrong! According to the schematic, your amp uses a bridge rectifier. But the board is set up to run either a bridge or a conventional rectifier, simply by changing some jumpers (links) on the board. Of course, you would have to use an appropriate PT also. Also, the yellow (HT center tap) wire should not be connected to the board for a bridge rectifier.
It would be a simple matter to determine which PT you have and to wire it to the circuit correctly if I had the amp on a bench. I don't think I can explain to you how to do this though. And there's a chance that PT is bad by now also.
The wiring to the cap cans looks terrible, especially the grounds.
Probably, if the PT is still good, the bias problem will also be fixed if/when the PT is wired correctly.
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Hi Dre,
here's some pictures that show how the amp was originally wired:
http://www.amparchives.com/album/Marshall/JCM%20800%20Series/2210%20JCM%20800%20MV%20Split%20Channel%20100W/87%202210%20JCM%20800%20MV%20Split%20Channel%20100W%20SN%20SAV24088/index.html (http://www.amparchives.com/album/Marshall/JCM%20800%20Series/2210%20JCM%20800%20MV%20Split%20Channel%20100W/87%202210%20JCM%20800%20MV%20Split%20Channel%20100W%20SN%20SAV24088/index.html)
That is, if this is the same model that your amp is.
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do you think the PT is bad? it hasn been turned on the amp after the guy bringed back to me , and i just put the wires when they was, but i also knew that this isnt how i left the board the last time, so i guess that cables are just there because a "quick i have to return your amp fast thing" so just let me know what you need , so i can re wire correctly the PT, or change what i have to change to get started, what you need to know ?? ill bring that info
thanks
Dre.
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http://cgi.ebay.com/Mag-100w-Power-Transformer-Marshall-JCM800-JMP-Amp-/110603528623?pt=LH_DefaultDomain_0&hash=item19c07be9af#ht_811wt_885
this is the transformer i buyed.
this is the one that is on the pics, its a new one and also i doubt has been used by the guy that was "fixing" the amp
Dre.
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I named some wires on this picture so that it would be easier to follow.
What do you guys think, does the black wire from the rectifier go to that point near the potentiometer?
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that black goes to ground, as i remember that my amp was has that one to ground and the other one its at the last hole from left to right in the up side of the board.
Dre.
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Ok, according to this thread, both of those black wires should go to ground:
http://www.el34world.com/Forum/index.php?topic=10272.msg93979#msg93979 (http://www.el34world.com/Forum/index.php?topic=10272.msg93979#msg93979)
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well, everything in my amp is now conected as the picture, and as it has to be, question where should i start? also in that thread the tubes are a problem, should i try another Quartet in some point? remember that the main problem in my amp started where it blowed the fuse, and then the tubes started to glow pretty red till blowed the new fuse, so where i start now with the readings?
Dre.
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CAUTION. UNPLUG ALL OUTPUT TUBES UNTIL THE BIAS PROBLEM IS FIXED!
The bias problem will be fixed when you can measure approximately -50vdc on pin 5 of each of the output tube sockets.
Can you show us another picture of the rectifier end of the circuit board now that you have corrected the wiring errors?
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yes ill bring that pics, am hoping to clean up all the amp, i mean all that ugly soldering job, and also the cables not to be that mess¥ ill bring the photos, where should i put the voltmeter (mode) just to be sure? to do the right readings?
Dre.
also how can i set the voltmeter to test the components to be sure that are ok?
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Put one meter probe to chassis. Put the other probe to pin 5 of one of the output tube sockets. Set your meter to read -50vdc. I don't know which meter you have. Read your instruction manual if you don't know how to set your meter.
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ok to not kill the thread, news... im cleaning all the amp, i found things doing this, it was a loose ground in a tube socket, also a pin was about to break in other tube socket wich actually broke when i pulled the cable out, so i ordered yesterday 4 new tube sockets for the power tubes, also i found a lot of horrible solders in the tube sockets, i also re wired the cables that are atached to the filter caps ,so im cleaning everithing, but i have to wait till the sockets arrive to keep doing everything, ill post pics when i finish the amp, and then i can start with the correct readings. i was thinking that maybe something simple like that ground loose, and the bad pin in the tube socket might be causing all the trouble, dont you guys think so...
thanks for all, ill be posting some news
Dre.
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yes this is possible. keep up the good work. :smiley:
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ok, i just finished to clean and rewire the amp, tube sockets, PT, and the filter caps, i measured pin 5 and nothing, so here are the pics of how is the amp now check and iam ready to start back with the readings, by the way i just electrocuted, and my hands hurt like hell :S but everything AOK, it also arrived my new book the last thursday, "all about vacuum tube guitar amplifiers" :) so am learning more. here the link for the album:
http://s281.photobucket.com/albums/kk235/Guayajilla/JCM%20800%20new%20pics/
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Your rectifier diodes are still not connected properly!
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no? whats wrong? im having a hard time figuring out where or how they should be conected, im connecting them how the last guy did and also like the picture that a guy posted here recently, how they should be conected?, (note: in this areas the pcb to me just dont seem to be right, it look like the conducting material has gone kinda bad wich brings me to another question that crossed my mind, is there a way to build a separate to the pcb bias supply? and if so, isnt more easy to do that?
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Note: that red cable that you see that goes to the diode its coming from the STBY switch, because in the back of the pcb was impossible to solder that cable but the path goes to the same place... that leg of the diode, wich its not connected to anything else that affects.
Dre.
(http://i281.photobucket.com/albums/kk235/Guayajilla/JCM%20800%20new%20pics/Picture4.png)
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Ok, show us a picture that shows the amp as it is wired right now.
There shouldn't be a red wire on a standby.
I think you have the wiring correct on this picture.
You could disconnect the white bias wire and measure if you get ~100VAC from that.
Make sure that nothing is connected to that yellow wire that I marked CT tie point.
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Where did that pic come from? It isn't part of the new set of pics you posted.
There are two blue wires twisted together and connected to the STBY switch. Both of those wires must correctly connect to the diode bridge rectifier on the board. Your new pic "DSC00855.jpg" clearly shows only one blue wire connected. So where is the other blue wire really connected?
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ok, the new blue wire is connected to the first (left to right) "green spot" in the picture i posted now, the pic is an old one but i used to show you guys were is now the blue wire connected, the tip of the cable is now red because the blue was burn, so i putted red one to cover the wire where it was more abused,
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theres no missing wire its attached in the back of the pcb , its a yellow wire
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Ok, I think the wiring is correct.
Now you should measure the voltages.
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I agree with VMS, based on the pic he posted that shows two blue wires connected properly. However, I jumped on your best pic, the close-up of the diodes and there's only one blue wire connected in that pic. That's very confusing and frustrating.
(http://i281.photobucket.com/albums/kk235/Guayajilla/JCM%20800%20new%20pics/DSC00855.jpg)
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As I understand this, the red wire (above C37) is the other blue wire. He couldn't solder it to the old place.
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Makes sense to me. But the pic you posted showed both blue wires correctly connected while the pic I posted only has one blue wire connected. And all pics of the STBY switch show two blues. I guess the red splices to a blue underneath the board? There's been some soldering going on between photos.
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well one pic, the one with both blue wires side by side was when i finished the sockets, but when i was inspecting i found that blue wire was cold solder, and was not making contact, also i found that par of that cable was damaged ( ruber burned) so i re-cover the blue wire with a red, and connected it where i put the "green dot" in the pic for the porpouse of explain where i soldered now, to also know if im correct to connect that cable over there since it follows the same path as the other point "the 3rd green dot" wich now for some reason i cant solder over there, so resuming the old blue cable now is half blue half red, ill paint it for better understanding (color blue) , its correct sluckey that its the last pic, VMS its right soldered there because i could soldered it to nowhere else that seems logical, its ok where i soldered it now?, makes any difference?, if its correct, what are the readings that i should take?
thanks and sorry for the confusion sluckey and VMS
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that seems logical, its ok where i soldered it now?, makes any difference?, if its correct, what are the readings that i should take?
I think it's correct.
Here is a pic to help you with your DMM. When you measure Plate, Screen and Bias voltages the black test lead goes to ground bolt.
Pin numbers are for power tubes.
I'll let sluckey explain the procedure, because my English is not so good and I don't want you to electrocute yourself again.
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im going to do the readings, but i was thinking in another solution, do you guys know someone in LA, a friend of mine is going this december 10, so i was thinking to ask her to take my amp to a tech over there, also how much would this repair cost aproximately, and how many time because i think she would be over there like 15 days. thanks
Dre.
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im not getting any readings, for pin 5, its in 0.00
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Read this entire thread again. You'll see what your next move should be.
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bias (white cable)? ill do that today, yesterday i went to late home i just did fast the things, also i fixed that blue/cable mod, now the cable is where it supoussed to with no mixed cables.
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bias (white cable)?
Yes
Disconnect that white wire from the board and just let it dangle in the air without touching anything.
Set your meter to the 200VAC position (that's two clicks clockwise of OFF position).
Connect the black lead to the chassis.
Connect the red lead to the dangling white wire.
Turn the amp on.
You should have between 50VAC and 100VAC. What do you actually measure?
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i measure 0.00 with a titling minus. this mean that my new transformer is bad?
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Yes. We reached that same conclusion back in April.
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this mean that my new transformer is bad?
If you have checked your fuses and you have correct voltage on the primary side of the PT but nothing on the secondary side, then your transformer probably is bad.
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how do i test the transformer? ill like to know if i just spilled 150$ for nothing if so ill burn that haunted amp, not really, but ill like to know if its good because i found a place where sell a 2210 board PTP, and am pretty tired of looking for components, that i just want to know if the tranny its ok then i buy the board install it and forget about problems, since the board its one of the things that i havent change, and also knowing that the Choke, Ot, and preamp sockets are ok,
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GEEZ! WHAT DO YOU THINK WE JUST WENT THRU ALL THIS SHIT FOR? The transformer is bad. I don't think it was bad when you bought it. I think you killed it because you don't have a clue what you're doing. Accept it and move on. I'm done!
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well sorry if youre getting mad, everytime your answer seems to be a big problem to you, so why you bother to answer anyway? if i ask its to double check everything i read, and also im learning how to do it, if this bothers you in some way just dont answer to me anything, saying that i killed the transformer when i just have been doing what you guys say to me its kinda rude, im asking because the other guy put his hands on the amp, i want to know why if i spend money in a new transformer it doesnt work (maybe the guy killed it if so ill tell him to pay for it), i dont think i killed the transformer since ill be doing only what you and the other nice guys tell me to try and do, so really im sorry if you misunderstand me, or you are just tired, or you just dont feel like help, if thats the case im sorry to bother you, but really no one its forcing you to write any answer to me, ill not just move on till i fix, and understand everything, doesnt matter if you help me or if i have to buy books or read everything online, sorry but i really want to learn, and no one has the authority to make me feel like i cant, because you didnt born knowing everything you know, you should try to be more polite or just ignore what i ask.
thanks anyway because people like you just make me want to try harder , and also for taking the time to help, sorry for any problem that i caused to you.
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No problems. Just tons of frustration. Someone killed that PT a long time ago. You didn't kill it because of any advise you got on this forum. That amp had the very same problem back when you posted the first thread in April. Didn't you initially install that PT? Regardless of who did it, it was installed wrong and the bias winding died as a result.
I know you were told this back in April. You ask for help, then don't believe the logical answers you get. That's very frustrating to the people trying to help you. Your PT is bad and you probably caused it. It's unfortunate, but it does happen, even with knowledgeable people. So, if you want to fix that amp you will have to buy another PT. I hope you get it fixed, but I really don't care if you do burn it. Either way, I'll stay out of your threads. I feel I've danced with the Borg far too long.
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Just to make sure that the problem is not between mains switches and the PT primary, do these following measurements.
1st: Measure that you have the wall voltage between blue and brown.
2nd: Flip the mains switch on and measure VAC between orange and red wire.
3rd: Report the voltages.
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117 VAC in both
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117 VAC in both
Those seem to be OK.
Next flip the mains switch on and take following measurements:
VAC between gray and blue at the standby switch.
VAC between pin2 and pin7.
Report voltages.
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between blue and grey 361 VAC
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between blue and grey 361 VAC
This is good.
What is the voltage between pin2 & pin7?
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thats ok 6.3 VAC
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Ok, so the transformer is not completely bad.
Are you 100% sure that you don't get VAC reading between white wire (disconnected from pcb) and ground bolt (where the green wires are)?
If so, then we have to use a different method to get the bias voltage.
Easiest way is that you buy a small 120V:6V transformer and wire this in reverse to heater supply.
Second choice is to use a similar circuit that is in Ampeg V4 amp.
Good news is that you probably don't have to buy a new PT.
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ill triple check readings in that cable today so we can be completily shure... but hey yes they are good news, however would you mind to tell me how to do this what are you asking me and where can i find the transformer 120V:6V?
thanks man
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however would you mind to tell me how to do this what are you asking me and where can i find the transformer 120V:6V?
Check first. I'll tell you what to do after that.
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ok, ill do that again
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Hey - I know you said you loved the tone of the 2210 before it broke on you, but if you loved it you'll absolutely go nuts over that amp converted to a 2204.
Trust me I know as I just finished one and it only took me a few days.
I ended up using odds and ends I had in my shop, but I could have easily done it with cheap radio shack terminal strips as well. There's a complete layout and schematic at Dreamtone amps.com and the only thing I took off the 2210's preamp board was the bias pot. I also had to configure a full bridge rectifier like is one the 2210, but that's child's play. This amp rocks and has balls like Malcomb Young would want.
I can send you a picture if you're intersted. You see at least part of the problems with the 2210 series was by that time (or at least for that model) Marshall cheapened the preamp board making it very fragile and almost as bad as Fender Hotrod series boards. Unless you are very good with an iron and have one with dial settings, you can look crooked at that board and fry the weld pads. Maybe I'm old fashioned, but why rehab something that is so weak to start with? Even with radio shack terminal strips you can weld and unweld componets to your heart's content. Not only dies this render a more durable amp, but infinitely mortweakable and moddable.
Best of luck to you. I'd bet you money there's not a thing wrong with the transformers you have!!!! Believe me I've been there, I thought my 2210's trannys were toast too, but by looking at how much that board and amp have been messed with.............just saying.
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Plus don't forget that PT only puts out low voltage compared to some because it's designed for a full bridge rectifier. Stupid me I tried to use the normal 2204 hook up and couldnt figure out why the voltage was so low since I grounded the CT even. Doesn't matter........it's not the PT trust me. I've been excactly where you are with this amp. Just convert it to a far superior 2204 and if you think you like the 2210....just wait until you here it as a 2204.
Just remember to build a full wave bridge rectifier and it will put out at least 450VDC at the plates. That's where mine is running right now. Very few folks understand these 2210's until you've actually worked on one, they suck to work on. I've built and repaired quite a few amps and none were more challenging than the 2210. Not because it's that complex, but because there's so much going on with the preamp board, tracing it's exact problem is only for the best, most well equipped techs, which I'm not and it doesn't look or sound like you are either. Try the link below and build this exact amp and your problems will be over. Took me about 3 days to finish and another two to trouble shoot because I'm an idiot soemtimes.
http://www.dreamtone.org/pdf/NEW2204LayoutSchemBomDreamTone.pdf
Heck, when I was in your shoes working on the 2210...first I thought it was the choke, then I thought it was the OT...then I thought it was the PT. But then I got rid of that damn board after removing and testing the tranny's out of circuit to see they were most likley just fine...even though the PT's secondary HT's threw me for a lop at first because the voltage is designed for a full wave bridge only. Also the 2204 will save you on both preamp tubes and in my case power tubes as well as I converted to a 50 watt using only two power tubes.
I'm using all the original trannys and choke. I got rid of the reverb and the extra 2 preamp tubes. The 2210 is an okay amp, but nowhere near as cool and ballsy as a 2204. I also opted for a couple small tweaks to make the 2204 more ballsy that are available on the "ultimate JCM 800 website" just a couple different resistor values here and there.
Oh...and as a side note....I get 97.0 VAC from my white wire bias tap. I just cut the center tap and heat shrinked it off since it's not used for a full wave bridge. And don't even think you're going to ground that CT and use a half wave.
Nope, that tranny is designed specifically for a full wave bridge - I already made that mistake. Oh you get voltage alright, just nowhere near enough to power the amp. Must be full wave bridge. When I received my 2210 it had been modded enough to have it's board meesed up in places I still don't even know about. But funny how everything I thought was broken now works perfectly in my redesigned 2204, tranny's and choke included. Jeez...I thought it was everything from tubes to tranny's - those boards SUCK!!!!
I even tested the board and ohmed out the entire thing....never did find a problem with it-lol! That's why I say unless you are highly skilled and ready to be so frsutrated you want to throw the entire amp out the window, do yourself a favor. You'd be done by now and playing if you listen to me.
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ok, can you help me then? i pm you.
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Hi Andre.
Is there a reason you don't check the bias voltage for me?
Anyway, if the bias winding really is dead then here are two options for the bias supply:
Option 1. The easy way:
http://www.el34world.com/Forum/index.php?topic=6512.msg83232#msg83232 (http://www.el34world.com/Forum/index.php?topic=6512.msg83232#msg83232)
if you choose this one, I can give you a picture where to solder the components.
Option 2. With additional transformer:
http://lenardaudio.com/education/14_valve_amps_6.html (http://lenardaudio.com/education/14_valve_amps_6.html)
Picture from lenardaudio:
(http://lenardaudio.com/education/images/a14/a14_ps_bias-tranny.gif)
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i did, i found this: 0.00 VAC, but its something weird, i spoke with the guy that replaced the transformer, he told to me that he tested that part with both sides (white cable) and (green cables) unpluged, and it use to give him something like 150VAC, but when he atached to the amp (the green cables) the 150VAC just drop dead. what do you think?
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ok would you please give me the pic where to solder i want to try that one, i think ill going to spend first this solutions.
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but when he atached to the amp (the green cables) the 150VAC just drop dead. what do you think?
I don't know. Check those bias caps C35 and C36.
Here is the way it is done in JCM900:
http://www.el34world.com/charts/Schematics/files/marshall/jcm900_21xx_25xx_100w.pdf (http://www.el34world.com/charts/Schematics/files/marshall/jcm900_21xx_25xx_100w.pdf)
(http://www.el34world.com/Forum/index.php?action=dlattach;topic=6512.0;attach=14002;image)
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That white wire should go to at least a 100K resisitor then to the anode of a IN4007 diode. The place the white wire is attached is near the bias section of the 2210's board on the controls side near the green and orange wires goin to the 220K r's. You also need to remove that silver diode/cap looking thing labeled 546 in small black numbers as that part never existed on that board.
If I were you I'd completely scrap this project before you really do screw up your valuable trannys and stuff., Just gut it and build a 2204/2203. I converted mine into a 2204. Only difference is a full wave bridge rectifier - it was painfully simple to do. That 2210 PCB board is tough even for very good techs- junk it!
here's some cell phone pix-its not pretty but sounds killer. Made from scraps around shop.http://i5.photobucket.com/albums/y183/jogman/Mobile%20Uploads/DSC01243.jpg
Here's the full wave bridge rectifer put on an old organ terminal board that had a chunk broken off just the right size-lol!:
http://i5.photobucket.com/albums/y183/jogman/Mobile%20Uploads/DSC01244.jpg
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The amp isn't pretty because I had to make due with what I had between a piece of wood/terminal strips and part of an old organ board, it worked but is pretty crowded, especially on the organ board. But what's cool is it runs dead quiet and is the most quiet running amp I've ever built - who'd think?
Anyway you could even used the wired already in place on most the tubes.
Just gut the two on the end leaving you with 3x9 pin preamp sockets.
I made mine a 50 watter to conserve tubes for one thing.
If you use that dream tone PDF I sent you it will be easy. Hardest thing was removing the board. Don't even try to salvage the pots off the PCB board because they are extremely hard to remove.