# 65 Deluxe - no heaters - resolved



## Greg Ellis (Oct 1, 2007)

I've been playing this amp regularly for several hours a day without issue.

Suddenly, this morning, it's dead. No sound at all.

I took a look at the tubes, and only the rectifier tube is lighting up. It's rather on the hot side too, but maybe that's normal enough, I don't really know.

None of the heaters are coming on, in the power tubes or the preamp tubes.

There's one obvious fuse I can find, on the back panel, and a continuity tester says that fuse is just fine.

I took a quick look inside the chassis, and I don't see any other fuses that could be responsible.

The heater wires and all their socket connections appear to be intact, and I'm getting positive continuity all the way down that line.

Any ideas?

Should I suspect that the rectifier has gone bad, as a first step?


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## cboutilier (Jan 12, 2016)

Doesn't the heater supply come right off the power transformer? I'd start at the PT and look for heater voltage down the line from there.


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## Greg Ellis (Oct 1, 2007)

PT is a Hammond 290BX.

Expecting 6.3V AC at 3A on the green wires.

Using my super-awesome cheap-as-dirt multimeter...

2.8 to 3.0V AC between each ONE of those green wires and a chassis ground.

6.2V AC if I measure between one green wire and the other green wire.

I checked each tube socket, and if I measure across the heater wires, I see about 5.7V AC at each socket.

So.. I'm wild guessing that this is ok, and the PT is fine.

And now I'm looking for a bad tube?


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## Greg Ellis (Oct 1, 2007)

SMH. I don't know what to think now.

I pulled each tube and checked for continuity across the heater pins, to see if I had burnt filament or something. 

Everything checked out. There was one preamp tube that didn't get a good result at first, but when I checked it again later, it was fine.

Then I put all the tubes back in their sockets and powered up and suddenly I've got heaters again.

Hooked it all up and now I've got sound. The amp seems to be working as normal.

I don't know what to think. Sketchy preamp tube? Would that actually kill the heaters on all the tubes?

It doesn't make a lot of sense to me.


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## LexxM3 (Oct 12, 2009)

Maybe just a dirty tube socket pin.

Not quite the same, but I recently had reverb "fail". In the end it was the tank input and moving it in/out and some contact cleaner fixed it up and no issues now. That amp and tank were 35 years old. Even aluminum oxidizes enough to open circuit.


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## jb welder (Sep 14, 2010)

If they were all out (except rectifier), then a bad connection somewhere between the transformer and the first tube that gets supplied.
Assuming this is the re-issue? If they are wired like the old ones, maybe at the pilot lamp socket?


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## Greg Ellis (Oct 1, 2007)

Not a reissue. This amp was born in 1965. 

Weird thing is that I was getting continuity on the heater circuit all the way from the pilot lamp to the end of the string of heaters. I checked every tube socket.

I didn't try that with the tubes pulled - maybe that would have show me a problem.

It's working now, I'm just not sure I can trust it.


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## nonreverb (Sep 19, 2006)

Make sure the heater wires at the pilot light aren't shorting to the chassis. It's a known problem.


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## loudtubeamps (Feb 2, 2012)

You may want to check your heater center tap (Green -Yellow) for a secure connection to ground.


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## sammyr (May 7, 2013)

It's funny I have a canadian jcm 800 and I went to play the other day and turned it on and got no sound. Took a look and the preamp heaters werent lighting up. Checked for continuity across the heater socket pins found no issues. Cleaned the tube pins and sockets with de-oxit and the heaters came back. So far so good. on top of the previously mentioned suggestions, hows the tension on your tube sockets?


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## alwaysflat (Feb 14, 2016)

It's been a while ... hopefully all is still well. No drop-outs or weird other noises ? 
Your rectifier is on a different (5 vac) winding , right ? (yellow leads) so don't suspect the rectifier just yet. It has nothing to do with 6.3 vac.

I'd be doing some gentle vibration tests on the tubes. Gently tapping on the tubes with like the rubber end of a pencil. 
If there are any jumpers/connectors in the 6.3 vAC signal path, certainly re-seat those. 
I don't believe there is a CT on 6.3 heater winding ( anywhere I've ever seen ), just for 12.6 and that doesn't apply for this tranny.
Opening any tube to socket heater connection should not cause loss of heaters with the exception of the one affected tube.

Follow the twisted 6.3 heater wires to make sure its not strained or stressed against any component, i.e. well isolated from contact anywhere. 
As far as reliability, I might suggest have your output tubes (or all ) checked (leakage) and/or have another set of op tubes handy.


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## Greg Ellis (Oct 1, 2007)

I opened it up again after it had miraculously started working again, and I was poking around the spot where the heater wires meet the pilot lamp when I noticed a huge glob of solder rolling around loose in that corner of the chassis.

I have to guess that was the problem. Totally random. It was big - like a chunk of split shot that you'd use to weigh down a fishing line.

Best guess is that roaming glob of solder had been shorting the heaters to the chassis somehow, just randomly, sometimes. I fished it out and it's all been fine ever since. At least so far.

Thanks all for you advice


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## nonreverb (Sep 19, 2006)

Best guess is it arced at the pilot light. That has always been a trouble spot. Keep your pilot light assemblies good and tight!


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## Greg Ellis (Oct 1, 2007)

Well, I'm bewildered, but this problem has come back.

The amp has been sitting unused for almost a year. Unplugged too.

I'm starting to wonder if it could be a capacitor problem? Unfortunately I don't have a variac to 'reform' the caps.

I haven't tried anything yet; haven't even pulled the chassis yet, but I'll get to that stage soon.


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## jb welder (Sep 14, 2010)

Greg Ellis said:


> 6.2V AC if I measure between one green wire and the other green wire.
> 
> I checked each tube socket, and if I measure across the heater wires, I see about 5.7V AC at each socket.


Was that 6.2VAC between the greens with all the tubes installed? Yet it's down to 5.7VAC at the sockets? See if you can find where it is dropping the missing .5V, you may find some kind of intermittent connection. 
Is this an original 65 Blackface Deluxe Reverb?


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## Greg Ellis (Oct 1, 2007)

jb welder said:


> Was that 6.2VAC between the greens with all the tubes installed? Yet it's down to 5.7VAC at the sockets? See if you can find where it is dropping the missing .5V, you may find some kind of intermittent connection.
> Is this an original 65 Blackface Deluxe Reverb?


Thanks. I'll pull the chassis soon and see what I can see.

It's a 65 Deluxe. There is no reverb in this amp.

It is a real 1965, although I wouldn't call it "original". It has certainly been messed with in the past. And later "restored". 

Some of the parts are not original. The output transformer is definitely a replacement, and there's a 4, 8, 16 ohm selector switch on the back panel beside the speaker jack. There's a three prong power cable, and the ground switch on the back doesn't do anything any more. One of the pots in the Vibrato channel has a switch at the zero position that hard-bypasses the whole Vibrato circuit. I don't think the accessory plug is connected to anything. Aside from those changes I think it's pretty close to the original circuit now.

I'll try to grab some pictures later.


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## jb welder (Sep 14, 2010)

I'll share a similar one with you that is probably not the same but might offer some insight. Heaters take a fairly hefty current and need a real solid connection. A connection can look pretty good and the current can flow and then just quit. Sometimes it's easier to just go through all the heater connections and resolder them. 
I had a re-issue that the owner said had been in for repair elsewhere several times and always came back and worked awhile, then quit. Turned out that one of the spots where more than 1 heater wire goes into the socket pin, the top (visible) wire was soldered but the one underneath was not. Right from the factory. It worked because the other soldered wire was holding it in there fairly snug. But sometimes it just couldn't carry the current and would cut out. You could pull on it with pliers and it stayed in place, but there was enough wiggle room for it to be very occasionally intermittent. I got lucky with that one and sure couldn't fault the other guys for not finding it.


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## dtsaudio (Apr 15, 2009)

Good point JB. Re-soldering all the filament connections as a matter of course is not a bad idea in these old amps. Solder will crystallize under fairly heavy current and over time. There may be enough resistance at the joints to cause a significant voltage drop, or a bad connection.


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## Greg Ellis (Oct 1, 2007)

Thanks guys. I really should have spent more time on this when it happened a year ago.

I'm pretty sure that .5 V drop was happening between the pilot light and the first tube socket, so I'll focus in that area first.

I just need to find the time and energy. Way too exhausted last night because Monday.


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## Greg Ellis (Oct 1, 2007)

Getting some pics together so you can see what I'm dealing with here:















I'm guessing that choke is original, although the PT and OT both seem to be replacements.

I haven't found a date code de-coder to tell me what 606-5-39 means, but I did get some google hits showing the same code on some Hammond components in a 1965 Vibrolux and a 65 Princeton Reverb.


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## Greg Ellis (Oct 1, 2007)




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## Greg Ellis (Oct 1, 2007)

Gah, it's tough getting the camera to focus on stuff this close. Here's the first tube socket in the heater chain, and I can see that someone has replaced the wires between the pilot light and this socket, whereas the rest of the heater wiring seems to be much older.

I'll start here I think, and see if touching up these solder joints gets us anywhere.


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## Greg Ellis (Oct 1, 2007)

Heaters are alive again after touching up all the connections in the heater chain at the tube sockets and at the pilot lamp.

I wish I had paid more attention to which of the preamp tubes were in which socket. I just realized that one of them is a 5751 and I'm not sure which position it was in. Maybe first stage on the Vibrato channel, but I really don't recall.

I think this is an AA763, and although I can only find schematic and layout for a non-reverb model in AB763, I THINK the tube layout is the same. 

V1 is the normal channel preamp 12ax7 (7025 on the old schematics)
V2 is the vibrato channel preamp 12ax7 (7025 on the old schematics)
V3 is for the vibrato circuit 12ax7
V4 is the phase inverter - 12at7 

Huh, so maybe that 5751 belongs in the phase inverter position. I'll give that a try.


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## jb welder (Sep 14, 2010)

Normally guys will put them in the first stages as you say. For whichever channel you prefer, either in V1 or V2 slot.
Can you check those resistors off the pilot socket? One pic looks like orange black orange, but another pic looks like the correct brown black brown.


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## Greg Ellis (Oct 1, 2007)

jb welder said:


> Can you check those resistors off the pilot socket? One pic looks like orange black orange, but another pic looks like the correct brown black brown.


Yeah it's a weird orangey-brown color. I compared those resistors to some others in the amp that have stripes which are CLEARLY orange, and I'd have to say that those two coming off the pilot socket are brown-black-brown-silver. What is that, 100 ohms +/-10%?

I don't see these resistors on the schematics or layout diagrams I can find, but then again I don't have a lot of experience in reading schematics and layout diagrams.

What are they for?

As far as the tubes go...

There's a major volume drop when I put that 5751 into a channel preamp position. As I suppose one might expect. 5751 is only gain factor 70 compared to the gain factor of 100 for a 12AX7.

When I put the 5751 into the phase inverter spot and use 12AX7's in both preamp spots, the amp sounds a lot more ballsy like I'm used to. 

I think the 5751 is probably an ok sub for a 12AT7, right? I see 12AT7 in the phase inverter spot on all the old schematics.


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## dtsaudio (Apr 15, 2009)

5751 is not a sub for a 12AT7. It is basically a lower gain 12AX7 and cannot handle the current of the phase inverter. 
Those resistors on the pilot/filament wiring form a center ground between the two 6.3v wires. They're in there to reference the filament to ground. This is a modification. Fenders normally just ground one leg of the filament wiring and leave out those resistors. 
Did you re-cap the amp (just curious)?


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## Greg Ellis (Oct 1, 2007)

I did not recap the amp myself. It came to me in this condition approx 4 years ago. 

I can tell that the caps in the doghouse are relatively recent. Some others on the tag board look a lot older.

That's good info about the PI tube. I dug through my tube stash and wouldn't you know it, the only sign of a 12at7 is an EMPTY 12at7 box. LOL.

There's another project to put on the list.


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## greco (Jul 15, 2007)

Greg Ellis said:


> the only sign of a 12at7 is an EMPTY 12at7 box.


That is about the same as finding the cookie tin or chocolate box empty when you were a kid...LOL


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## Greg Ellis (Oct 1, 2007)

I think I might have given away that 12at7 with the Blackheart Little Giant I swapped for a guitar a couple of years back. That amp changed character quite a lot with different preamp tubes, and if I remember right, most of the higher gain tubes I tried were just too gainy and harsh.

I kinda lost interest in the Little Giant when I got the Deluxe, so it sat idle for a while and then I got rid of it.


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## dtsaudio (Apr 15, 2009)

Greg Ellis said:


> I did not recap the amp myself. It came to me in this condition approx 4 years ago.
> 
> I can tell that the caps in the doghouse are relatively recent. Some others on the tag board look a lot older.


Looks like all the electrolytic caps have been replaced, both in the "doghouse" and on the board. Not much else though other than the transformers.
If I were you, I would go back and check all the wiring and solder joints to those transformers. The ground connection from the power transformer doesn't look too good (but it could just be the picture. But there is some sloppy work there.


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## Greg Ellis (Oct 1, 2007)

Grin. My soldering skills are not great. Touching up the heater connections yesterday confirmed that for me. One of these days I think I might pay a pro to go over the amp.

I had a question about solder joints, actually. 

In my (very limited) experience with soldering, I've always tried to make a solid "mechanical" connection first, by wrapping the wire around the post, or folding it back on itself, or whatever.

A lot of the joints at the tube sockets in this amp have been made just by slipping the wire through the hole in the lug. The solder is the only thing holding the wire in place.

I'm not really sure which technique is preferred, or why.

Is it overkill to try to secure the wire mechanically first?

Any thoughts?


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## jb welder (Sep 14, 2010)

You're right, good mechanical connection first is preferable. Just don't overdo it and assume you are the one who will have to undo the joint if ever necessary. 
Those resistors at the pilot lamp form a 'virtual center tap' for the heater winding of the power transformer. The original PT would have had a center tap, the replacements often don't. If there is not some kind of ground reference for the heaters, they will cause bad hum.
As DTS mentioned, some of the earlier Fenders didn't even have a CT for the heater winding, and ran one side of the winding straight to ground.


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