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where can I buy ribbon cable?

ruger9

Member
Messages
9,779
Fender Super-sonic 22. Noise issue with reverb. Long story, but suffice it to say I think I've determined a ribbon cable is the issue... when the cable is BARELY touched, the hum comes and goes.... and the way the lead dress was zip-tied together, it doesn't surprise me...the cable is folded over flat on itself to make a 90 degree turn, then zip-tied flat to the top of a bunch of other cables.

Actually, when the chassis is in the cab, and it's humming (sometimes it doesn't), if you just push down on the top of the cab, it apparently moves that cab;e enough for the hum to go in & out.

I realize it may not be the issue, and I am willing to take the amp to a tech, BUT I'd like to replace this ribbon first, because that means I won't be without my amp for who knows how many weeks...

 

ruger9

Member
Messages
9,779
Found the part in the service manual

Fender part# 0079115000 9CKT 14" ribbon cable

Now, to locate one.... found the Belden ribbon cable, but I guess now I need the connectors too...

Maybe I'll call Fender and see if they'll sell me one, even tho I'm not an "Authorized Repair Center"...
 
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xtian

Gold Supporting Member
Messages
2,585
A new ribbon cable is not going to solve this issue, because the ribbon cable itself isn't faulty. But you are correct that it's a lead dress issue, and the ribbon is at the heart of it. Clip those zip ties, and continue to move the ribbon and the other wires around until you've minimized the hum. Don't forget to test often with the rear panel in place, because it provides shielding, and the whole EM environment changes when you put the rear panel on.
 

ruger9

Member
Messages
9,779
The hum doesn't get more or less, it exists or it doesn't- like a ground hum. LOUD. Similar to when you touch the end of a guitar cable.

Again, I'll try to explain it better, if you have any ideas...

Sometimes, the reverb works fine. Occasionally, it will emit a loud hum... that gets louder as you turn up the reverb control. Sometimes I can hit the top of the amp, and it disappears. Not today.

While the amp was humming, I leaned heavy on the top of the combo cabinet... I can't imagine it flexes much, but it apparently it flexes enough to move something a HAIR... and create (or fix) the hum. I literally stood there, doing this over and over, hum, no hum, hum, no hum....

With the chassis removed, I pushed down on that ribbon cable, which of course moves the whole bundle of wires, but it took VERY LITTLE - almost none- on that ribbon cable, to "toggle" the hum "on & off"...

I basically kept pushing on that bundle until the hum seemed to be gone (for now), and put the amp back together, and right now it's not humming. But I could wake up tomorrow, and it will be- the amp not having been moved or even touched.

I called Fender, and while they usually don't sell this part to a consumer, the guy thinks he can get it done- but the part has to be re-keyed in the system to accept a consumer order. He doesn't think it'll be a problem. The guy who needs to do the re-keying is out until May 9 tho, LOL We'll see.
 
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Jeff Gehring

Gold Supporting Member
Messages
6,796
That is an IDC type header on the cable. Quite possibly in the ribbon cable itself the wires are solid, rather than stranded. IDC stands for "insulation displacement connector"; the metal contacts in the header have split fork ends into which the wire is crimped. The crimping action of the wire being pushed down into the fork slices the wire insulation and bites into the metal conductor in the wire. I don't think you would want to clean out and re-use a header, as the spring tension in the forks is kind of a one shot deal.

Gazing into a PCB Fender always brings this movie scene to mind, in particular, Sally's words...

 

xtian

Gold Supporting Member
Messages
2,585
With the chassis removed, I pushed down on that ribbon cable, which of course moves the whole bundle of wires, but it took VERY LITTLE - almost none- on that ribbon cable, to "toggle" the hum "on & off"...
Ah, thanks for the clarification. I agree, you've got a dodgy connection. Finding one can be tough! A wooden chopstick is a good tool to use--you can prod the connectors and other areas difficult (and dangerous!) to get at with your fingers.
 

ruger9

Member
Messages
9,779
Well, I didn't use a chopstick, but as I said MINUTE movement of that ribbon cable APPEARS to cause it. I know that's far from conclusive. The Fender part will come with the connectors on it, hopefully the connectors ON THE PCBs will be alright to re-use. I know there's a proper way to remove those connectors from each other to prevent damage/lifting traces.

I WILL go in with a chopstick for more reconnaissance before making the swap.

Yes, PCB amps aren't much fun. Believe me, I'd love a handwired amp. It's on my bucket list, just have to scrape up the dough to buy the one I want, which isn't cheap. At least the PCB Fenders do sound good (I love the Super-sonic 22), as did my PRRI. Actually, never had any issues with my old Peavey Classic 50 either!
 

ruger9

Member
Messages
9,779
Fender got back to me, and won't sell me the part, the bastards. Only to Authorized Service Centers. And IDK if a service center will even sell me the part- they'll no doubt want to do the work, which is what I'm trying to avoid because that means WEEKS without this amp (it's the only tube amp I own).

Can anyone tell me what connectors those are? IDC (like stated above?) If I can identify the connectors, maybe I could find an assembly someplace else like Mouser...

I found the Belden 9 connector flat ribbon cable, but I like to get the assembly with the connectors, if I can.
 

gldtp99

Member
Messages
4,060
I don't like Ribbon Cables in tube guitar amps------ they do make assembly (snap-it-together) possible for low cost unskilled workers----- this keeps the cost down so that the unit can be sold for a reasonable price (hopefully).
But what a PITA to deal with when they start to go bad----- not always the wire itself-- it can be the connectors both on the cable or the PCB itself------ not fun when the whole mess arcs over and heat damages/carbonizes everything.

And the manufacturer won't even sell the part directly to the owner.

I hand wire the amps that I build----- They almost never come back for service other than worn out tubes.

Maybe the OP could find a good tech near him who could hard wire a replacement for that ribbon cable ?

But sometimes junk can't be fixed.
 

Jeff Gehring

Gold Supporting Member
Messages
6,796
Well it looks like the return feed from the reverb pot is connected via pin 9 on that cable to the grid input resistors for V4B, and the FEED to the reverb pot is on pin 8. If when it is humming, you can turn down the hum using the reverb pot, I'd recommend looking at the pin 8 connection as being intermittent. If you can get it to hum, then GENTLY exercise the pin 8 connection (with an insulated probe, ideally something like a telco spudger that has an insulated hard wire hook on one end) to see if it affects things, you may be able to determine which end of the cable has the bum connection (if that's what is going on). If you get confidence that you know which connection it is, you MAY be able to gently remove the whole cable, and then be able to try to press down on the wire in the IDC header to try to re-seat it. NO guarantees, and the problem may come back even if you get it stable. But, it's something to try, that doesn't require you to get a part out of Fender. Definitely be gentle with removing/installing that cable; handle it like it is made of glass.
 

HotBluePlates

Member
Messages
12,013
Gazing into a PCB Fender always brings this movie scene to mind...
I was at a repairman's home-based shop this past weekend. He'd had an electronic repair business from the 50's through the late-80's. Now in retirement he's still fixing amps at home & building clones.

He's gotten to the point of telling people with new Fender amps that he won't work on them. One small thing breaks, and it is cheaper (though not cheap) to simply replace an entire board or section of an amp. The labor time to disassemble multiple items to get in and fix a single faulty part would cost more than replacing an assembly or two.

He came to the conclusion the amps were designed for easy mass-production, then to be thrown away when they break down, and that they're not designed to be repaired. He said modern TV's are the same way (and I can tell you from fixing one that cell phones aren't far off).
 

ruger9

Member
Messages
9,779
Well it looks like the return feed from the reverb pot is connected via pin 9 on that cable to the grid input resistors for V4B, and the FEED to the reverb pot is on pin 8. If when it is humming, you can turn down the hum using the reverb pot, I'd recommend looking at the pin 8 connection as being intermittent. If you can get it to hum, then GENTLY exercise the pin 8 connection (with an insulated probe, ideally something like a telco spudger that has an insulated hard wire hook on one end) to see if it affects things, you may be able to determine which end of the cable has the bum connection (if that's what is going on). If you get confidence that you know which connection it is, you MAY be able to gently remove the whole cable, and then be able to try to press down on the wire in the IDC header to try to re-seat it. NO guarantees, and the problem may come back even if you get it stable. But, it's something to try, that doesn't require you to get a part out of Fender. Definitely be gentle with removing/installing that cable; handle it like it is made of glass.
Thanks Jeff! Worth a try, the worst that can happen is I lose my amp to a service center for weeks anyway...

I love the way this amp sounds- I think it's one of Fender's best current-production (not vintage reissue, etc) models- tonally- but this is the last PCB amp I buy. I've had enough of them over the years, and I'm done. I'm a DIY guy, I work on my own stuff, and PCBs are a PITA.
 

Jeff Gehring

Gold Supporting Member
Messages
6,796
Now in retirement he's still fixing amps at home & building clones.
You were over to my place?? :D

Just the fact that you have to remove every stinkin' knob (as a minimum) to do any work on those PCB amps frosts my cupcake extremely. And then you're treading on egg shells hoping something else doesn't break while you wrangle the circuit boards around -- I don't work on those any more either.
 

HotBluePlates

Member
Messages
12,013
You were over to my place?? :D.
:rotflmao

... Just the fact that you have to remove every stinkin' knob (as a minimum) to do any work on those PCB amps frosts my cupcake extremely. And then you're treading on egg shells hoping something else doesn't break while you wrangle the circuit boards around ...
Were you stalking him??

He had a Super Champ XD in, one of the pot shafts sheared off in a fall. Couldn't repair the single pot without taking out the whole front panel board, but to do that he would have to remove other boards just to gain clearance. He decided the labor time to fix the one pot would force him to charge the owner too much to fix a single pot, but also that he wasn't willing to cut his labor rate and get paid for less time than he spent working on it.

He also had a Twin Amp (Fender Pro Series) in for something or other. Same solid-core ribbon cable running down the center of the chassis. First thought for both of us was, "2nd or 3rd time moving that thing, and the wire will break in the middle of the cable."

Fender got back to me, and won't sell me the part, the bastards. Only to Authorized Service Centers. ...
Hopefully an Authorized Service Center would be willing to take easy money to mail you the cable.

I worked a summer in a p.c. board manufacturing plant. We had a special tool/fixture for installing the end on those ribbon cables. I wouldn't want to try to fake it by hand, as you're just bound to break the small solid-core wire inside at some inconvenient point.
 

Tony Bones

Member
Messages
1,212
I completely appreciate what you guys are saying, but I also appreciate that this manufacturing method is the reason that Fender can sell the amps at a price that ordinary middle class people can afford. The good news is that we have options and alternatives when it comes to guitar amps. Hand wired p2p amps are available for a lot more money. That's not the case with most electronics today. Nobody repairs TVs anymore. If yours breaks under warranty you get it replaced with a new one for free. If it's not under warranty then you pay for a new one. Either way, the broken one gets recycled. You can't buy a repairable TV even if you want to.

And don't get me started on the general quality of computers. I have a 9 year old Thinkpad that I use everyday. I don't replace it because, well, it just keeps going (and even after nine years it's still not completely obsolete [quad core i7, 16GB]), but mostly I don't replace it because NOBODY makes a laptop with a decent keyboard anymore. Nobody. They can't be had for any amount of money. Every new keyboard feels like rubbery mush.

So yeah, the cheap Fender amps are hard to repair, but they're cheap and there are other options, so whatever.
 

mattball826

Senior Member
Messages
20,798
If you are fairly sure it is that ribbon, there is plenty of length to pull the wires in the connector, and then cut them back 3/8" and then press fit them back in. Use a meter to ensure the connection is made when done. That's what I'd do.

OTOH, you can also have a fracture solder joint on the bottom of the board where that connector is soldered to. Seen it on a bunch of Peavey amps. Worse case, remove the connector and solder the wires directly to the board. I also do that with Peavey and Bugera amps.
 






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