Jordan J-700 Distortion

[c.wright]

Jordan J-700 Distortion ... is this the same Jordan as the Jordan Boss Tone?

So, a guy brings me this thing to work on... seems to be a somewhat rare bird? Couldn't find really much of anything on the web.
I don't know if anybody cares too much about it.. it just seems to be a Distortion+ copy...
but it came with the original box & warranty card, and I'm pleased to be able to contribute something to the forum!

Can someone confirm for me: is that IC a 4558 or a 741? I'm assuming 4558.

oh yeah, you're seeing it pretty much as I first saw it... someone's been in there already, installed a new LED, backwards... not a great sign.

Dunno if I can get it running, I know just enough to be dangerous...

[aron]

Seems to be a dual op amp - 6458 like it says. Thanks for the pics!

[Johan]

I would check that I have roughly half the batteryvoltage on pin 1 on the opamp...
..then..that scratch over the pcb traces on the lower photo, specificaly the one over B+/in/G ( lower part of pcb)...do you actualy have a signal going in to the opamp at that point? or os the trace cut?...

j

[SG6505]

From what I can see in the picture, it seems to be at least three cold solder joints. Is it completely dead?

[Sir H C]

Not liike the bosstone but those are pretty rare and I have yet to see one come up on the 'bay with original box.  I always first check that the battery is working and you see the +v on pin 8 and -v on pin 4.

[c.wright]

OK... lemme think where I'm at... I worked on it all day yesterday, without too much luck.

Replaced the LED, correctly oriented (!), and now it will light up when i click the switch. But it will not pass signal when the effect is engaged.

It will light up with battery power or DC.
Both sides of DPDT switch are good.

Checked the voltages on that 6458 chip... and they didn't look good from my untrained eye -
Pin 1 seemed ok at 8 or so volts, but everything else was reading weird very LOW numbers, at a volt or less.

I pulled the original chip, and installed a socket  - (yeah, i know, shame, it's not stock anymore... but i just wanna get it working)
I dropped in a JRC4558 - still no signal
Checked those new voltages, and they all seemed more reasonable, at 9v on pin 1 and about 4.5 on everything else that would read.

I've swapped out a couple of caps too - the electrolytics, and a couple ceramics... nothing there either.

NOTE: I am keeping the original parts handy and intact, and if i can nail down the problem, i'll re-install the stock pieces. I do have SOME couth.

Eh, as for the scratch(es) on the board, they appear superficial, but i'll double check for continuity to be safe.
And cold solder joints - I re-melted everything yesterday, also to no avail - but if you point out the suspicious bits, i'll go back and pay extra special attention.

A last note, before i go back to get you guys some concrete numbers... I've been poking at it with a cheesy audio probe, and you can hear it in different places in the circuit when the pedal is off, but when it's engaged, you can't get signal ANYWHERE... sometimes not even on the amp cord's tip!! So, is there just maybe a BAAAAD short somewhere?

I'll come back with real pin voltages later today -


and thanks for all your help!!!!

[Sir H C]

On the right, bottom of the PCB shot, to the right of Artek, are those two solder pieces shorting (think it is the battery connector).  And, voltage from Pin 4 to pin 8, ground on pin 4.  What is it?

[Johan]

unless I'm wrong, it is biased through a 1Mresistor to the +input (pin 3) and the bias is two 1M and a cap...I would try a TL072 instead of a 4558. I dont think it can pull enough current through that 1M to bias properly. also, I think you should have 9volt on pin 8, 0volt on pin 4 and 4.5v on pin 1
what measurements do you get in the socket if you pull the IC?

j

[tiges_ tendres]

A last note, before i go back to get you guys some concrete numbers... I've been poking at it with a cheesy audio probe, and you can hear it in different places in the circuit when the pedal is off, but when it's engaged, you can't get signal ANYWHERE... sometimes not even on the amp cord's tip!! So, is there just maybe a BAAAAD short somewhere?



and thanks for all your help!!!!

Is the input jack corroded?  check the jack wiring and check for corrossion.  Also, some of those solder joints look really sloppy.  I'd want to clean those up a little bit just to make sure that wasnt what was causing the problem.

[aron]

Check your voltages like Johan said, then assuming they look good, use the audio probe to trace the signal into the op amp (pin 3 or pin 5). Next verify that the signal is coming out of the op amp (pin1 or 7) - assuming a dual op amp.

Verify pin 4 is connected to ground and that pin 8 has power.

The output of pin 1 or 7 should be loud if you crank the drive level. Assuming it is, then it is an easy debugging task to the output using the audio probe.

[SG6505]

The suspicious looking joints I noticed in the picture are; The "G" pin on the power supply jack, lower right side close to the last zero in the PCB number(?) are two joints close together, the left one looks cold and as sir HC pointed out, they look shorted. On the left side of "artek" there is a 5pin connector footprint, the middle pin has an extension downwards with a joint with burnt flux wich looks bad. If you measure resistance on the input and output, do any of them short when you engage/disengage the button? Can you take some pictures of the outboard aswell?

[Ice-9]

I have put a schematic together from the photos you have posted, as i cant see the the offboard wiring the pots are an educated guess/ best try wire trace. I think its quite acurate and possibly the 3rd wire on the gain pot may go to ground. I hope this might help you out.



If anyone spots any errors please say.

[Ice-9]

I have labelled c103 with a question mark for 2 reasons.
1. They lettering is slightly obscured by onother component
2. it is a ceramic disk value 10n but it is between ground and +v. Doesnt seem the right type/value to be there.

[Ice-9]

Wow, It's taken some searching but here is the datasheet for the 6458ds chip

http://pdf1.alldatasheet.com/datasheet-pdf/view/108362/SANYO/LA6458D.html

[Ice-9]

I have one thing that was bugging me with the schematic and its the gain pot, i now think that the centre of the pot goes to ground instead of to pin 1 as in my diagram. Sorry for all the posts , here is the schematic that i think is 100% correct. (it makes more sense to me now)



So there you go , its just a mxr dist+ clone

[c.wright]

Ok, sorry, I have this pesky thing called a family sucking my time today - 
below (bottom) is an external wiring photo, should've included that in the first place...

quick notes... the scratch at the input was superficial, not a problem. the possible cold joint on the DC jack is OK, i'll re-melt anyway.
The burny-flux bit at the battery connector was ok, as was the other similar bit pointed out, uh, on the input i think.

uh other bits - the 'LEVEL' pot is a 50K, the DISTORT a 500K...
did I mention i've popped 2 LEDs since i pulled the backwards one out? Does that mean something, or have i just been careless knocking that board around? I know at one point i inadvertantly jumpered across that resistor with my vise, and got a MUCH brighter LED for a bit, but it didn't burn it out.
Both times it seems like I was maybe poking around with the audio probe... i'll swap it and try again, maybe a bad batch of chinese stuff?

and here are some pin voltages: (1-8, counterclockwise around chip, right?)
-- circuit w/o IC, AND circuit with 6458 installed--
1  .025ish and drops
2  .025ish and drops
3  4.2
4  0
5  0
6  0
7  0
8  9.6

-- circuit with 4558 -- (lemme guess, this pinout is incompatible with the 6458? need to look at that datasheet...)
1  4.8
2  4.8
3  4.25
4  0
5  0
6  9.1
7  9.1
8  9.6


Again let me say how much I appreciate everyone taking interest in this - I REALLY appreciate your help, and even though it is just an MXR Dist+ clone, I'm happy to be documenting/working on a fairly obscure piece.

[SG6505]

NTE778 is a replacement for 6458 and the datasheet for that one is easier to find. The pinout is the standard dual-op. In my last post I asked about resistance on input/output I ment from input/output to GND. ( I am new to this forum and I haven't found the edit button yet)  I'll take a look at the new pics and ice-9 schematic and be back if I get any :s

[Ice-9]

Hi, Thanks for the pot's and wiring photo. Everything traces corectly to my schematic so things should not be too hard to trace the problem.  The pin out is the same as a 4558  and the voltages your getting 6458 on the look about right. not sure of pins 1 +2 though. (should ber about 4.5v pin 1)

With a guitar input and using a probe do you get a signal at pin 3 of the op amp.
Then test for a signal at pin 1 of the op amp. If you hacve a signal here,
Check C102 cap for problems.
Also do a continuity test on the traces (there is damage but looks ok)
Check the pots and wiring as well if all else seems ok.

post your results

Ps  I wasn't being funny when i said it was just a MXR dist+ clone. It was just i've not seen one of these pedal and couldn't resist working out the schematic from the excellent quality photo's, just surprised when it traved out to be the same.

regards
Mick

[Sir H C]

Voltages look right for the 4558.  It is just using 1 side of a dual op-amp, weird.  1, 2 and 3 are all at the right point for operation.

[slacker]

Could be as simple as a dodgy switch, with the switch in the on position test for continuity between the lugs with the red and brown wires attached. Or just temporarily jumper them together and see if that gives you any sound.

Apart from that probe away like Mick suggested hopefully that will isolate the problem.