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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Tue Dec 10, 2013 5:03 pm
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shimmilou wrote:
Art1 wrote:
T...The schematic shows a link going from the grid(and plate) of V1B to the plate of V2B (TP9 to TP16) which does not exist on the 65RI. You might look at that for bad solder joint. Also, the small link between plate of V1B TP11 and grid of V1B TP9....


That wire only connects the two Plates (V1B and V2B), and it only crosses the grid wire of V1B it is not connected to V1B grid.

That connection is where the two channels are connected together so that both have reverb. On the originals, the Plate of V1B would have connected to the PI after the reverb, so no reverb on the normal channel.


Correct. The schematic is not the clearest that I have seen and I missed the cross over.
:shock:
Art


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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 1:08 am
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:lol:

I thought the same thing at first glance. :oops:

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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 6:24 am
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Does the schem. show voltages?


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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 7:26 am
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Yes, most modern schematics do.

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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 9:18 am
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Quote:
="shimmilou"]Look at this picture, in the upper left corner, where the wires come from the first two tubes to the circuit board. Each tube has six wires that go to the circuit board, labeled "3, 2, 1, 8, 7,and 6". The right-most wires for both tubes, marked "6" on the board, should have continuity between them, maybe a trace on the bottom of the circuit board. Be sure that the amp is off and caps discharged before checking for continuity. By continuity, I mean close to zero ohms, very low resistance, as if the two wires are connected (they should be).


Using a mulitmeter between V1 tube pin 6 – V2 tube pin 6 set at 200M I get a reading of 1.2, set at 20M 0.19 ?
Solder joints on V1, V2 and V3 looks fine.


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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 9:42 am
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To repeat, you are looking for very low resistance, so put your meter on a very low scale, like maybe 200 ohm or 20 ohm scale and read again. It appears that you are reading approx 200K ohms, which is the two Plate resistors, meaning that you do not have a connection between the two points as it should be.

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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 10:54 am
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shimmilou wrote:
To repeat, you are looking for very low resistance, so put your meter on a very low scale, like maybe 200 ohm or 20 ohm scale and read again. It appears that you are reading approx 200K ohms, which is the two Plate resistors, meaning that you do not have a connection between the two points as it should be.


Sorry, got it. I think you are right, putting the meter at 200 ohm (lowest setting on mine) reads nothing. I will to try solder a jumper wire between the two tube pins (6&6).


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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 11:15 am
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Waiting with eager anticipation!

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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 12:04 pm
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shimmilou, that did it ... but, now the overall output volume is lower and the reverb and tremolo "mix" is higher – the trem is really throbbing, the rev is stronger too ?

I disconnected the jumper wire again. Lost the reverb and tremolo on the customs channel, but output volume back to normal as is rev+trem on the vintage channel ...


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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 5:47 pm
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It's as if you have a '65 DRRI, and not a '68 CDR..........? Are you sure that your front panel inputs are labeled "Custom" and "Vintage"? Or are they labeled "Normal" and "Vibrato"?

Looking over your pictures again, I see that you have the C5 cap, which should not be on the '68. C5 is on the circuit board just below where the V2 wire labeled "7" connects to the board. Anyway, put the jumper back between the two pins 6 as you just had, then clip one leg of the C5 cap and try again. If you want to be able to put the amp back like it was, you can pull the circuit board and unsolder C5, although it would be easy enough to get a new C5 if needed. C5 is a .047 µF, 400 volt, coupling cap, inexpensive and available almost anywhere.

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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 5:52 pm
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What color is the front panel? I did notice that his circuit board had the 2002 copyright. Not sure what mine is. I haven't opened her up.

Art


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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Wed Dec 11, 2013 11:51 pm
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It's most certainly the 68 silver face, drip edge custom – the channels are label custom and vintage.

shimmilou, I will try the mods when I get home tonight and report back.

Thanks again!


Last edited by SunKing on Thu Dec 12, 2013 10:17 am, edited 1 time in total.

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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Thu Dec 12, 2013 1:14 am
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Putting in the jumper to connect the pins 6 of V1 and V2, along with clipping the C5 cap, is the same way that the '65 DRRI would be modified to get reverb and vibrato on both channels.

It appears that you might have the regular '65 DRRI circuit inside the '68 CDR cab, or the factory just didn't modify it for some reason.

The schematic says that R72 (added resistor on the Custom channel tone stack) is installed on the solder side of the board near R8 (the bass pot for the Custom Channel). The addition of the jumper, removing C5, removing R12, the addition of R72 in the tone stack of the Custom channel, and a different cap value in the tone stack of the Custom channel, would be the only differences in the circuits between the '65 DRRI and '68 CDR (that I can see). Either way, adding the jumper and clipping the cap should fix it up for you, and no need to remove R12, as clipping the C5 cap will take R12 out of the circuit anyway.

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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Thu Dec 12, 2013 1:52 pm
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Nice work on sorting this out, but I have to say if I was the buyer I'd be fairly peeved about this. I mean the wrong faceplate on the wrong chassis/circuit, then that chassis/circuit goes into the wrong cabinet, so essentially the buyer gets the wrong amp, although it is in the cabinet he ordered and now does a manual wiring conversion to a different model amp and now has zero warranty.

Sounds like a royal cock-up by Fender for which the buyer shouldn't have had to shoulder any cost whatsoever, shipping or otherwise. This amp should have been shipped back to Fender on Fender's dime.

Snowy


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Post subject: Re: 68 Custom Deluxe Reverb problem
Posted: Thu Dec 12, 2013 2:42 pm
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No457 Snowy wrote:
Sounds like a royal cock-up by Fender for which the buyer shouldn't have had to shoulder any cost whatsoever, shipping or otherwise. This amp should have been shipped back to Fender on Fender's dime.


+1

It's certainly looking that way at this point.

And it showcases perfectly the reason why it does not pay to buy a new amp sight unseen (or unheard).

Arjay

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