Hey New here in advance thank you for any replys!
I have A MARSHALL 5213 MOSFET 100 Reverb Twin, 100W 2x12" combo that Was left in my basement of my house when i purchased it! I bought a step up transformer (external) but would like to swap the transformer for a 110v vs the 240v. I uses the same 3 ground plug as usa but on the back of the amp states 240v and the internal fuse is 2a for this as well, Wondering if any ones knows what transformer i need to make it 110v and besides swaping that and the fuse is thiere any other componets that need swapping?
O also it works with the step up on 220v but is noisy and the volume jumps from 0 to 100percent! randomly , the POTs are scratchy tho i think that is the issue what do you think!
Thanks Jeff
Hi Bass.
You are talking two different problems here.
The fact it jumps randomly to different volume levels, scratchy pots and the like, means dirty/rusty/grimey pots , jacks and switches, normal on any old amp and even more if it was unused for a long ime in a damp environement.
You can clean everything with Deoxit or any similar product.
About the voltage conversion, do your homework, search for the schematic and post it here (or a link to it) and we'll guide you for that conversion, if possible.
Good luck.
Thanks for the reply! Sorry I didnt post it first I already got the schmatic here is the link
http://www.schematicheaven.com/marshallamps/mosfet_100reverbtwin_100w_5213.pdf (http://www.schematicheaven.com/marshallamps/mosfet_100reverbtwin_100w_5213.pdf)
I will grab the cleaner thank you! , As far as the transformer more help would be great.
agreed it needs some seriously cleaning to start with , if you need a diagram for this amp go to http://www.schematicheaven.com there's one there . However it is for the export not the U.K.
Rock On
Using Hammonds "Design Guide for Rectifier Use" I come up with that you need a 70V CT transformer:
Bridge Rectifier...capacitor filter... So +50 -50 (according to the schematic) DC :
So 100 VDC/ 1.41 = 70
and you'd probably need about 250VA
Hopefully one of the super gurus here will check my math :D
Hi Bass. Your schematic shows a code 789-66 power transformer, with 3 color identified secondary wires (Red/Black/Red) and unidentified (on the schematic) primary wires.
It also shows that they correspond to 2 ¿120V? primaries, in this cas in series.
Take a couple pictures of the transformer-to-mains wiring and redraw that part, showing wire colors. Maybe you are lucky.
If you have only two primary wires, you are stuck. You might replace the power transformer with a new, modern one.
Bry's math is good; the schematic suggests a 190VA transformer.
Good luck.
Thanks for the double check. JM
If the transformer has 4 primary wires, they'd be wired in parallel for Europe. So they'd need to be wired in Series as per the schematic.
If the transformer doesn't and needs to be replaced a hammond 167N70 would work...it's actually 280VA I misread earlier. the choices from Hammond seem to be 140VA (too small) or the 280
Of course other are other brands too
FWIW Mouser has 2 of the Hammonds 167N70s in stock.
Hi Bry, 90% right this time.
The primaries, being 115 or 120V each , should be wired in parallel in the USA and in series in Europe. You must pay attention to the phase also.
Good luck.
ok sorry got confused there. SO that would mean the schematic referred in earlier posts is in fact showing European wiring... and isn't the "export" version after all?
Sorry for the dyslexia.
FWIW that's one of the reasons I usually buy Hammonds...they have nice pictorial instructions for their products.
heres the links to the photos so you dont have to scroll over in the forum
The arrows and circled wires on the PCB are the wires coming from the transformer , let me know if this is suficent for pics
The current Transformer Manufacturer is DRAKE (its hard to read in image)
Thanks again for helping me out greatly apreciated
http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1014.jpg (http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1014.jpg)
http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1021.jpg (http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1021.jpg)
http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1020.jpg (http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1020.jpg)
http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1018.jpg (http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1018.jpg)
http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1015.jpg (http://i815.photobucket.com/albums/zz78/bassforlife2007/IMG_1015.jpg)
As far as I know the only wires you would need to change are at the top of the transformer The brown ones and a blue one
consider the pic #14 at the top of the transformer in this pic you have 4 connections
Lets call them 1 2 3 and 4 left to right
I THINK you need to remove the jumper from 2 and 3
place a jumper between 1 and 3
place a jumper between 2 and 4
change the fuse to a 3 amp
You Might want to wait for a second opinion from one of the experts though. I'm a musician that fixes her own not an amp tech.
;)
So the transformer is capable of being used as 120 usa it has 2 120 rails? sorry if im mistaken i think thats what i gathered from your reply , please let me know
Bry got it right again.
As "a picture is worth 1000 words", here go my 1000 words:
(http://i50.tinypic.com/103h1nd.jpg)
By the way, nice amp. They don't make them like these any more.
Wow this worked out good huh no need for a replacement transformer! a local tech looked at it and wanted to charge me 200 for a transformer I knew he was scamming!
as for the amp I was very happy to open it up and see 1987 since thats my year of birth so its as old as me. and not seeing surface mount was even more joyus!
I will solder those points pop in a new fuse and let ya know how i make out.
Do you know if the POTS would be sealed in 1987? do you recomend compressed air vs deoxt?
Try the replacement transformer for the Marshall MG100Dfx I believe it use's the same transformer .
Rock On
Wait I can use the existing transformer correct? Kinda on a buget lol
Yes you should be able to rewire the transformer as marked up in the picture, and change to a 3 amp fuse and be good to go.
Hey guys hooked up the transformer its now running on 120v but i have a constant loud noise sounds almost like Road Traffic and sound like some one is plugging in a instrument cable while the amp is on every few seconds just alot of static and the volume of the static is rising and lowering intermintly , i also used contact and lube cleaner on all the pots before i checked the transformer (doh!) thanks ahead of time
Well, that's something else which will have to be checked.
Now I'm too sleepy, we'll see tomorrow.
Anyway, the worst part is over and for no cost.
Good luck.
No problem thanks again if i can donate to the site for your time spent let me know
Don't worry about that.
Let me study the somewhat unreadable schematic to see where can we start.
How far do you think you dare to dig into its innards?
Maybe get a nerdy friend (or your kid's friend) to help you?
"4 eyes see more than 2"
You should be able to follow the admittedly fuzzy schematic and find specific parts or points on the actual board, as in "ground the end of R47 which joins C21" or whatever.
Start by squirting a little cleaner into the send and return jacka, work a plug in-out a few times in each of them to clean the grime and plug your guitar straight into the return jack, ¿does it still make noises? The only control that should work is reverb.
If preamp and power amp are joined by plug-in cables, clean and work them also.
What you hear sounds like terrible contact problems, rather than "burnt parts".
Post results.
Sounds good , I used contact cleaner on all the jacks and worked them .will try plugging in my guitar into the send returns to see if that is the same result.
The schmatic is terrible! Im glad im not the only one who thought this.
I have a nice iron varible LCD small tip , decent bench setup (Im in IT) so Im willing to get into it as its exciting learning experience
If I post a mp3 of the noise would that be helpful?
Thanks again!
just some thoughts here...You said you found the amp in a cellar...
Does this noise continue with the reverb tank unplugged?
Do the pots all work smoothly now (or is it too noisy to tell)?
I've had to replace a lot of pots on my Marshalls due to noise (they get played about 20 or 30 hours a week; my newest Marshall amp is an 82)
your thoughts are most welcome'd :tu: . I did disconnect the Reverb Tank same deal :'( . It is wicked noisy! and the longer it runs it gets louder and more pop and cracks. all the pots will be at 0 and its still nosy as hell .Some of the pots seem looser to turn than others i noticed, cant really hear the scratcyness at this point, I will record a audio sample later tonight after work thanks!
OK guys LOL so I get home all bummin that cleaning the pots didnt work , fire up the amp and guess what clean as a whistle! just some minor hiss barly anything at all , no way like yesterday! , I guess it just needed to soak up and kill the scum
Thank you so much for all your help everyone. the amp sounds amazing!
:lmao: