Orange Crush 15R

[J M Fahey]

Dear BluesDog/dogie
To begin with, congratulations on your work.
And I must recognize it's *real* complex .... which can also bring all kinds of problems on its own 
Spud asked me not to "spread the Orange schematic all over the Internet" so I am respecting his wishes, posting stricly whatever's needed for servicing your unit, but no power amp, nor power supply, etc.
The incomplete schematic is:

The first problem I see is that it is *not* a two channel amp, but a single channel one, with a "distortion pedal" added, which, to boot, is *always* on circuit, always passing signal, even the clean one.
The second (and quite important) problem is that it's not at the beginning of the signal path, as most dirtortion pedals are, which would allow you to replace it with your own "Big Butt", but *after* the clean amp.
Modding it and building a new one from scratch will be about the same, sorry.
Having the schematic, you may try to find a way around this, but personally , seeing that you design and make your own boards (including the individual pot. mini-boards, very neat) I would walk a little further and make a new general-purpose "clean channel" plus switching, so you may build different amps with said clean channel plus any of your distortions.
It would be a very flexible project.
You might include a generic reverb circuit in it (similar to Orange's own) or as a stand-alone board.
With these boards plus your many pedals, you may offer dozens of variations, think about it.
I am intrigued by your chassis.
At first sight I had thought you were modding a JCM900 ... but it has no socket or transformer holes 
Is that one of those Made-in-Malaysia clones which are offered in kits?
If so, I'm interested, can you provide a link and some info?
Thanks.
PS: I am also intrigued at your 8 output transistors power amp, any comments?
Good luck.
PS2: Switching with relays and with so many flying wires plus intermixing different boards,  it takes some time twiddling the layout , grounding and wire dressing until you cut interference down.
You are not doing nothing "bad", but will need to move wires here and there .... and as I said, with that Orange you *always* go through the distortion, so ....

[blues dog]

My main problem is that my customer insisted on Low Budget cost... 
And it's kinda frustrating me..

If it's my Amp, I will do exactly what you said.
It will be muuuuch more easier to build an all new preamp section.

But the owner also have problem. He already spend a lot of money for the head cabinet amp until he found that the tone and the feature is awfull. When first came, the amp goes like this:
* the Vol of channel A and Ch B interact each other
* the Gain of Ch A and Ch B interact each other
* the REVERB of Ch A and Ch B interact each other
* The connection of the "LineOut", "SEND" & "RETURN" jack is not proper.

So what I do is try to minimize the bad things.

About the PCB tracing & channel wiring; I spend 2 nights doing that.. 

About the chasis & the cabinet, they're all made here in Indonesia.
I might find some details about the manufacturer & will email you later.

[J M Fahey]

My main problem is that my customer insisted on Low Budget cost...  Cry
And it's kinda frustrating me..

You bet.
In his own words, your customer is saying: you can't do it .(I ain't paying)
I'm talking $$$$$ , not knowledge.
Don't get hooked into it; the mistake was made by somebody else, you are not allowed to solve it, sorry.

If it's my Amp, I will do exactly what you said.
It will be muuuuch more easier to build an all new preamp section.

Yes, it doesn't pay to design , debug and build *just one*.
If you had a kit it would mean soldering and wiring, but not that much else, but designing? ... forget it.

But the owner also have problem. He already spend a lot of money for the head cabinet amp until he found that the tone and the feature is awfull.

He did not spend that much money with you. 

When first came, the amp goes like this:
* the Vol of channel A and Ch B interact each other
* the Gain of Ch A and Ch B interact each other
* the REVERB of Ch A and Ch B interact each other

That's *exactly* what the Crush 15R does.
It's a cheap generic beginner's amp, its features are adequate for what it is, but not more.
I bet it's built by a monster factory in mainland China which supplies 30 or 40 other distributors under many trademarks.
I recently learnt that the same company, with the same schematic, supplies many models of famous expensive amps, among them Randall, Egnater, and similar high level ones.
The supplied schematic is the same, only rewriting the small "box" in the drawing which states the model.
Couldn't believe it ! :loco :duh
What's the best part?
1) they are all Marshall JCM 900 copies .... with errors 
2) even better: in some forums musicians discuss to death the sonic advantages of one against the others 
In your case, I think the best would be to leave the modded amp as-is, and sell the customer one of your Fat Ass (or any other) pedals, external, to use at will.
But don't waste more time on that amp.

[blues dog]

 :tu:
speechless.. but really thinking hard..

thank you sooo much..
What you've said really really open a new perspective to me.

I'll sent the progress here.

[blues dog]

Done!
Just after got the schematic, get into the board, around 90minutes, all is done.. 

I've complain about some "fuzz leak" ini my own built clean channel. And no reverb at all.

My biggest interest is in reverb. So I check the reverb section. Getting frustrated, I cut the dry signal. I want to check how the reverb signal work. Then I found out: no signal. Only a tiny fuzzy tone goes out there. But shaking the reverb tank will gives a big rumbling reveb sound.

Looking at the schematic I found out that one single IC work as the driver and receiver of the reverb. I'm curios: is it posible that the first opamp is broken while the second one is not? I just replace the IC (TL072 in schematic, but TL082 onboard) with a new TL072. Done!!! There's an obvious reverb now!

Then I put back the dry signal. Just as I expected. The tiny fuzzy tone is also gone! Now I have a pure clean british channel.

Then I goes to the drive section. The original signal path of Crush 15 (drive channel). The reverb is also there.


The signal path goes like this:
IN
(switch)
- channel A: Big Butt (GAIN, VOL, PRESENCE = TONE)
- channel B: Crush 15 drive channel (GAIN, VOL)
(switch)
back to Crush 15 board: EQ section
SEND jack = End of EQ section
RETURN jack = back to MASTER VOLUME*
to REVERB driver & receiver
(switch)
- channel A REVERB pots
- channel B REVERB pots
(switch)
back to mixing section
goes to power AMP**


*I bypass this pots, since each channel already has one
** In Crush 15 board, the signal path ended going in TDA2030, the TDA 2030 is already cut out when the unit came. But not wired properly. So now, I wired this point to the power amp board.


That's it. I might want to make a video about it.. Still not decide yet.. 

Tks guys.. Tks JMF. You're the best! 

[J M Fahey]

It's too kind of you, you'll make me blush.
The good thing is that you could finish the job as the client wanted, sometimes it's not possible.
Another important factor is that you could justify all the hours of work you had already lost working on it, which nobody can give you back.
As they say: "all is well that ends well"
Congratulations  :tu:

[joecool85]

Congrats!  Another amp saved from the dumpster!   

[zoltrano]

Hi all, can anyone please tell me the value of the resistor in R8?
My amp got her "toasted" and I'm Having difficulties in reading that from the PCB
Thanks in advance...

[J M Fahey]

I have the preamp schematic and parts numbers start from 100 up 

In general even the same basic design goes through different variations and upgrades, so unless somebody has the exact same schematic and version of yours, "R8" does not mean much.

Please post a closeup picture showing the damaged resistor and the parts surrounding it, from both sides of the PCB, top and bottom, we *might*  deduce its function and hence its value.

That said, if you have a burnt resistor, "something" burnt it, so just replacing it won't be enough.

What are the actual symptoms of the failure?