Fender Blues Deville

[Big chief]

1995? Blues Deville with very low volume. Have replaced all the tubes did not help.
Any help would be great.
It has a pc board  Thanks

[sluckey]

Could be almost anything. Probably not tubes. Check input/output jacks, especially power amp in and speaker jacks.

Check dc voltages.

The schematic has signal voltages listed throughout the schematic. Insert a 4mV 1KHz sine wave signal into jack 1. Use a scope to check signal level at each test point indicated on the schematic.

[Big chief]

Thank you very much

[jjasilli]

Ditto.  Make sure a single speaker is plugged into the Main Spkr Jack.  If a single speaker is plugged into the Extn Jack, there will be low volume.  This is rather unique to this line of amps which cleverly use a complex switched jack circuit.  But this can be a trap for the unwary.

[Raybob]

1995, look at the filter caps to be sure they are not originals.

[Big chief]

Ran voltage on pre amp tubes
V1 pin 1-6 voltage 108
V2 pin 1-6 voltage 252
V3 pin 1-6 voltage 008
5881 power tubes voltage pin 2-7 voltage 6.2 both tubes
Any help please

[pompeiisneaks]

Pictures of the board may help, I've got a blues deluxe, which is the same amp but with 1x12 intead of 2x12 I think.  I've done some mods to mine, I'd agree at looking at the filter caps if it's an original, (mine was like '96 so it def needed new caps). 

~Phil

[Big chief]

Have replaced caps c34 has 50 Vdc  c 41 275 Vdc
Any help please

[pompeiisneaks]

Again, pictures of the board may help.  There were several other suggestions, did you perform them?  what was the outcome?  The voltages you list are a bit confusing.  Is voltage identical on both pin 1 and 6?  (It could be, but usually people list each pin separately) did you trace the signal or do you have the means to?  voltage being 008 on V3 sounds really wrong, if you're getting the anode voltages on that one, it should be.  Make sure you're reading the schematic correctly and the notes, it says to measure the AC volts at those Test Points in the schematic (it does have DC volts at the cathodes). 

Basically, if we don't have the normal troubleshooting data, we can't guess at what's wrong.   The suspicion is that you may have off voltages, meaning something isn't sending voltages correctly. 

You also mentioned 'caps c34' that's caps plural and a single cap.  The main electrolytics are well past their age, I replaced mine, the general life span of electrolytics is 10-15 years, if its a 95 that's a 22 year old set.  You should replace all of the main electrolytics for the power filtering at a minimum: C34, C35, C41, C42, C45 and C46 as well as potentially all of the smaller ones, like the bias supply, C37 and C40.

Also check the bias voltage that should be -46.7 at that C point.

~Phil

[Big chief]

Replaced electrolytic  caps voltage C 34-20vdc C35-441vdc C41 -342vdc C42-224vdc C45-410vdc C46-370 Vdc

Voltage on preamp tubes
V1 pin 1-230 Vdc  Pin -6 238 heater pins 6.0  No pop on pin5
V 2 pin 1-245vdc.  Pin 6 O.0 heater pins 6.1. No pop on pin 5
V 3 pin 1-235 Vdc. Pin 6 242 Vdc  heater pins 6.0

Power tubes
V 4 pin 3 470 pin 4 466 heater pins 6.0
V 5 pin 3 468 pin 4 468 heater pins 6.1
Thanks for all your help

[pompeiisneaks]

Seems like all the voltages look good, did you look at the second speaker jack issue that was mentioned by jjasili, also make sure the reverb is off, to see if there's something there causing problems, limit it down to the bare minimum.  That 0 volts on the second half of V2 is normal, they left a triode unused on one of the 12AX7's.  (I plan on modding mine soon to use that for better drive).  Validate that the power tubes are about the right plate current.  It's possible that for whatever reason the bias circuit negative voltage has drifted (check it to see if it matches the expected schematic value) and maybe they're really cold biased.  maybe one or both of the bias resistors has drifted seriously.  Again, pictures may help.

[Big chief]

Repaired broken circuit near the 470 resisters and replaced the resisters circuit board has been very hot at some time
Amp powered up and sounded good for about 5 min. Then power tubes got a red glow and the fuse blew also
Replaced caps C 36,37,38,39,40
Current limiter shows short after standby switch is on

Please help

[pompeiisneaks]

That means your bias voltage is likely off.  You need to adjust the bias to ensure things are at the right range (again look at the schematic for the expected negative voltage.  (Did you replace the capacitor(s) in the bias circuit too?  If so maybe one doesn't have a good ground or positive connection, or maybe the resistors in the bias circuit have drifted.  Again, pictures would help.

Also, pictures would help.

If you could take some pictures, and post them, that also might be helpful.

:D

~Phil

[Big chief]

Photo

[Big chief]

Please review photos as I found an old camara to post photos

look at the repairs on the board

any help or should I just quit
thanks

[Ambugaton]

It is hard to tell but it looks like maybe a couple of the jumpers you installed are crossing lanes (overlapping into another part of the circuit)

Looks like too much solder and maybe not the most confident joints (don't worry... I am still learning how to properly solder each time I pick up the iron)

I don't work with PCB... but I can't imagine why you are trying to make jumpers on the underside of the board. The PCB circuit itself should provide these jumpers.

I strongly suggest watching some soldering videos, make sure you have a decent iron with a good clean tip. Take your time with it. Clean the tip with a damp sponge, tin the tip with solder - the tip should be shiny and clean just like a good solder joint will be.

[sluckey]

You can quickly destroy a delicate PCB such as that if you don't have proper soldering/desoldering equipment and experience.

[Big chief]

The reason for the jumpers is the board as been hot and melted the strands.
So I tried to repair

Something is getting hot as the current limiter glowes from dim to bright as the amp heats up have removed power tubes and no change. Have cleaned up the joints

[Ambugaton]

Somebody with experience will chime in, but you have to identify the short by process of elimination. You checked power tubes... not the short. What about rectifier? The damage/melting appears to be centered around the two diodes and 470ohm 5w resistors. Not familiar with the amp but maybe start identifying what part of the circuit they are in and start there?

[pompeiisneaks]

One other area to look at (Thanks for the pics), the ribbon cables are known to fail in their connections sometimes or be partially broken.  If you test continuity from one end to the other, sometimes it won't be open and have some resistance, and that can cause some pretty bad behavior. I'd check to make sure they're all still solid, or replace them with dedicated better wires.  It is possible, as sluckey said, with those traces messed up, that they're causing some excess resistance and lowering the overall signal.