Welcome to Solid State Guitar Amp Forum | DIY Guitar Amplifiers. Please login or sign up.

December 02, 2022, 08:44:17 PM

Login with username, password and session length

Recent Posts

 

does anyone have a schematic for a marshall 5010 jm78-2 pcb?

Started by pinkjimiphoton, March 03, 2022, 05:57:19 PM

Previous topic - Next topic

pinkjimiphoton

i picked up the pcb for a marshall 5010 a couple years ago on ebay.
its the two horizontal input, one headphone/line out, full tone stack with presence 30 watters.
the bottom of the pcb is marked jm78-2
it works, i hooked it up to test it and am gonna get a proper hammond transformer for it and roll my own little beast out of it hopefully, but its a little different from any schematics i've managed to find. seems like there's 3-4 different versions of the amp, but i can't seem to find any really helpful info with google, which seems to have covid brain these days .
if someone could help me out, i'd be grateful! thanks!
what the hell ya mean it ain't fuzzy enough <static>

Jazz P Bass

Did you search the web?
I found this.
Not sure of the particulars.

Loudthud

Quote from: Jazz P Bass on March 04, 2022, 01:12:43 AM
Did you search the web?
I found this.
Not sure of the particulars.
In the upper right Notes section it says PCB: JMP27A

pinkjimiphoton

oh yeah, i searched the web, and my own 35 gig archive of schematics.
this appears to be the "early" version that nobody has traced. which is kinda weird, as i recall seeing a proper schematic for this one years ago. i have three slightly different models of this amp, and none of them are the same.
i can try and contact marshall, i guess, and see if they can help. they've been great in the past.

its similar to that schematic, but the part numbering differs a little, and it has a subtly different number of parts.

most of the schematics have a pcb # on them, but the closest i've found is actually for a tube circuit as far as board numbers.

i have glaucoma, so tracing it myself may be a bit beyond what i think i can do. i may have to ask a friend to take a look at some pics to see if we can make up a working schematic.

thanks guys. if i pull it off, it will get posted for sure.
what the hell ya mean it ain't fuzzy enough <static>

Spm5010MLC

Hi, I also have been looking for a schematic for Marshall 30W Master Lead Combo.... the one with no headphone or output jack. Has gain/preamp, master, treble,mid, bass, and presence. 12" speaker. It's hard to find even a photo of the model I have. I purchased in 1985.
I recently opened it up to address a scratchy volume pot and decided to take some photos while I had it open... I came across something I have not seen before. Hoping someone can enlighten me as to why it would be this way.
What I thought was a capacitor in the middle tone pot area of the pcb only has one lead attached thru the hole in the board. It seems that it was just clipped after being attached. I have attached a foto. Does this seem right?
Any ideas why?
I'm going to trace the complete board in the near future and will post for anyone who's interested.

Seems I do not have access to the attachments function so I can't post the images... hmmm.

Thanks!

Tassieviking

There are no stupid questions.
There are only stupid mistakes.

pinkjimiphoton

i saw that, thanks.... different from mine! ;)
mine has two inputs, horizontal, with a 1m resistor to ground and two 68k resistors like a fender. all but the smallest caps are red box caps, and the layout doesn't quite match. very similar, but not quite. i'll try and get some pics to post later.
what the hell ya mean it ain't fuzzy enough <static>

pinkjimiphoton

ok, here's some pics of the board i have. i'm trying to draw up a schematic, gotta take a bunch of notes and stuff and connect the dots, but so far it looks really close to the other schematic other than some part values and how they're named.
the input are two 68k in parallel with a 1m to ground. i've gotta draw the rest. later, i'll try to upload a BOM with the values as shown on the boards for all the parts.
lotta stuff to do. and i suck at this.
but pics:
what the hell ya mean it ain't fuzzy enough <static>

pinkjimiphoton

what the hell ya mean it ain't fuzzy enough <static>

pinkjimiphoton

Quote from: Spm5010MLC on March 05, 2022, 03:56:07 AM

I'm going to trace the complete board in the near future and will post for anyone who's interested.

Seems I do not have access to the attachments function so I can't post the images... hmmm.

Thanks!

hey bro, if ya click attachments and other options, it should give ya the option to upload pics... if not, shoot me a pm and i'll upload them for you.
what the hell ya mean it ain't fuzzy enough <static>

pinkjimiphoton

here's the BOM from the board i have,
hope it helps someone. still working on trying to draw up the schematic, wonky eyes suck!

5010 early version BOM
board jm78-2

vr1 gain b22k
vr2 volume al00k
vr3 treble b220k
vr4 mids b22k
vr5 bass a1m
vr6 pres b22k

ic 1 mc1458e

q1 bc184
q2 bc182
q3 bc182
q4 bc212
q5 bc184

q6 mj3001 darlington
q7 mj2501 darlington

zd1 9.1v <4739>
u
db1 br62

r= red box cap
t= tantalum
e= electro
c= ceramic

c1 47n@250 r
c2 2.2u@35 t
c3 2.2u@35 t
c4 2.2n c
c5 100n c
c6 2.2u@35 t
c7 2.2n c
c8 220n@100 r
c9 4.7n c
c10 220p c
c11 47n@250 r
c12 47n@250 r
c13 22n@400 r
c14 2.2u@35 t
c15 100u@25 e
c16 100u@25 e
c17 220n@100 r
c18 22u@25 e, axial
c19 2.2n c
c20 220p c
c21 100u@25 e, axial
c22 non existant
c23 2200u@25 e, radial
c24 2200u@25 e, radial

all resistors 5% cc  1/4 watt unless specified

r1 1m
r2 68k
r3 68k
r4 10k
r5 100r
r6 22k
r7 10k
r8 470r
r9 non existant
r10 22k
r11 68k
r12 10k
r13 33k
r14 4.7k
r15 2.7k
r16 2.7k
r17 10r
r18 6r 1 watt
r19 270r 3 watt
r20 470r
r21 10k
r22 3.9k
r23 4.7k
r24 680r
r25 10r
r26 2.2k
r27 1.5k
r28 1.5k
r29 1.5k
r30 10r
r31 39r
what the hell ya mean it ain't fuzzy enough <static>

Tassieviking

#11
I might give you a hand with this one, its late down here now so it will have to be another day.
well,  later today maybe as it's 2.30am here now.
I did find another photo of the track side of a 78-2 PCB so I mirrored it and marked out the components quickly.
On the picture the inputs are on the left.
There are no stupid questions.
There are only stupid mistakes.

pinkjimiphoton

Quote from: Tassieviking on March 18, 2022, 11:42:41 AM
I might give you a hand with this one, its late down here now so it will have to be another day.
well,  later today maybe as it's 2.30am here now.
I did find another photo of the track side of a 78-2 PCB so I mirrored it and marked out the components quickly.
On the picture the inputs are on the left.

you are god like!
i've been stalled. i'm really not very good at tracing stuff out at all.
i got it working again,  bought an aluminum hammond chassis to mount it in since it's just the pcb.
just need a chance to reassemble it all.

but for all intents, other than part numbers, mostly its the same as the other schematic other than a few part values.

thank you so much tassieviking! epic and helpful!!
what the hell ya mean it ain't fuzzy enough <static>

Tassieviking

I found a couple of mistakes on the picture of the trackside I had marked components on.
I fixed the picture and put the good one up.
I cant see the part numbers for the main capacitors, the 2200uF ones.
I had to rename R22, I had it as R32.
I have a draft of the circuit made up in KiCad, still a bit messy but I think it is correct.
Please let me know if you see any mistakes.

Could you tell me what the measurements are between the Jacks, and between pots.
I could make up a PCB in KiCad if I know the component spacing on the front panel.
The Gain pot on the schematic should be Preamp Volume, I will fix it later.
There are no stupid questions.
There are only stupid mistakes.

pinkjimiphoton

holy cow, tass!
that was quick!

looking at without the pcb in hand, it looks to be correct, but i will check it when i hit my workshop in a little bit.
i can definitely give you measurements.

i have another one of this particular amp, complete, do you want measurements for the chassis as well? thinking that may help not only with the spacing for the parts to layout, but also maybe you can make a proper front panel drill guide for the project as well?

i need to do this anyways, as i'm gonna mount this spare board in a hammond chassis i just picked up.

thank you for this! in your debt, along with all the rest of us messing with this in the past and future ;)
what the hell ya mean it ain't fuzzy enough <static>