1968 Fender Deluxe Reverb - any help/insight on an issue?

[Chuck D. Bones]

Bad filter caps might do that. I strongly recommend replacing ALL of the electrolytics because if they're original, then your amp is living on borrowed time. When they fail (notice I don't say "if") it makes a mess with hot electrolyte spewing out and if the bias supply cap fails, then you might cook the output tubes before the fuse pops.

I don't know the history of your amp. Is it all original or has it been worked on? Without photos and some measurements, I can only guess what's going on.

A knowledgeable tech should be able to test tubes out of the amp. He/she should know how to assess the amp's condition and troubleshoot problems. The tech replaced a cap to cure the Vibrato tick and now the Vibrato doesn't work? Mighty suspicious to me. The Vibrato's neon bulb & LDR should last forever. BTW, the tick fix I'm familiar with (Fender Service Bulletin #9) involves adding a 10nF 600V cap and rerouting some of the wiring. I can't guarantee that this service bulletin is relevant to a 1968 model, but it's worthwhile for you or your tech to find out.

Even the best techs can have a bad day. The really good ones will make it right.

 

[mkstewartesq]

Bad filter caps might do that. I strongly recommend replacing ALL of the electrolytics because if they're original, then your amp is living on borrowed time. When they fail (notice I don't say "if") it makes a mess with hot electrolyte spewing out and if the bias supply cap fails, then you might cook the output tubes before the fuse pops.

I don't know the history of your amp. Is it all original or has it been worked on? Without photos and some measurements, I can only guess what's going on.

A knowledgeable tech should be able to test tubes out of the amp. He/she should know how to assess the amp's condition and troubleshoot problems. The tech replaced a cap to cure the Vibrato tick and now the Vibrato doesn't work? Mighty suspicious to me. The Vibrato's neon bulb & LDR should last forever. BTW, the tick fix I'm familiar with (Fender Service Bulletin #9) involves adding a 10nF 600V cap and rerouting some of the wiring. I can't guarantee that this service bulletin is relevant to a 1968 model, but it's worthwhile for you or your tech to find out.

Even the best techs can have a bad day. The really good ones will make it right.

Thanks, @Chuck.

Yes, all of the caps and tubes are original (except for the one cap that got replaced to cure the vibrato ticking). Sorry if there was some misunderstanding – the vibrato does work, although we had to replace the optocoupler (the little “bug”). In any event, I’m sure the caps are on borrowed time. I think the preamp tubes are OK based on testing but I don’t have spares of the rectifier and power tubes to check those, nor the equipment to bias them even if I did.

Backstory: I was given this amp and a 1977 Strat for Christmas in 1985; my parents bought them as a package off some local friend of my sister for a couple hundred dollars. Being a dumb teenager (and still not a terribly smart adult), I honestly had no idea what I had until just a few months ago when a more knowledgeable friend advised me. Before that, for 40 years, I just assumed it was some bargain basement Fender amp from around 1977, not worth much.

Once I figured it out what I had, I went to work on cleaning it up and I really just asked the amp guy to go over it and make sure everything was working (since the amp didn’t come with the footswitch, in 40 years, I’d never even fired up the vibrato). So he took that mandate literally and charged me a very small amount to make sure everything works – which is not the same as saying everything works “like new”. He said that he fixed what absolutely needed fixing (power cord and reverb cables, one cap and the optocoupler) and left all of the rest vintage since everything was original on it. So I’m not going to ding him as if he had charged me $500 and not done $500 worth of work. I really should’ve just been more specific that what I wanted was a refurbishment to replace everything that was getting near the end of its (almost 60 year) service life. This would’ve been the one time in my life when I would’ve actually appreciated someone trying to upsell me on work to be done.

Thanks again,
M

 

[Chuck D. Bones]

Here's how my friend's 66 DR looked when I was done refurbing it.

I installed a grounded AC cord and removed the "killer cap." Is it 100% original now? No. Did I do anything to reduce the value? No.

Bias Board (new cap, resistor & diode)


Main Board (arrows point to things I changed, mostly replaced electrolytic caps)


Cap Bank (all new caps & resistors)


Output Tube Grid Resistors

 

[Chuck D. Bones]

BTW, you parents got a helluva deal in 1985. These amps have always held their value. They sound great, are loud enough for a small club, aren't to heavy and are very reliable if you take care of them. Not sure I buy the idea that carting an amp around town is bad for it. Working musicians do it all the time. The tubes had better be able to survive vibration because they're mounted in a speaker cabinet. Having a roadie throw it off of a truck, sure, that's bad.

 

[Nostradoomus]

I'd be pissed if I took an amp that old to a tech and he told me he replaced one cap.

But, I mean, I'd message Chuck before I even bothered.

 

[RetiredUnit1]

I refurb'ed a friend's 1966 DR a few years ago. I replaced ALL of the electrolytic caps. I tested the original tubes and they were all still in-spec. Not too surprising since A) the tubes were all made in the US in the '60s and B) the amp spent most of its life in storage. One of the screen resistors was out of spec, so I replaced both. Also did the Tremolo Click Fix per the factory recommendation. What a sweet amp! I would have liked to buy it from him, but a fair price was out of my range. He ended up getting something like $2.4K on eBay.

What Chuck said ^^^

I have a vintage 68 sfdr with the bfdr circuit. About 20 years ago I changed all the electrolytic caps and the improvement in tone was amazing.

After that I replaced the old speaker with a Jensen P12N (50 watt alnico). I was playing outside with the Takamine 12 string acoustic, like David Gilmour's, and a friend came wandering into my backyard. "Duuuude, from the front yard it sounds like a F***ing concert hall bro"

You REALLY need to replace ALL those E-Caps. 40 years is the *maximum* time to use them. People talk about reforming them, but these WERE reformed. 2024 - 1966 = 58 years..... almost 20 years past the replace date.

 

[jimilee]

What Chuck said ^^^

I have a vintage 68 sfdr with the bfdr circuit. About 20 years ago I changed all the electrolytic caps and the improvement in tone was amazing.

After that I replaced the old speaker with a Jensen P12N (50 watt alnico). I was playing outside with the Takamine 12 string acoustic, like David Gilmour's, and a friend came wandering into my backyard. "Duuuude, from the front yard it sounds like a F***ing concert hall bro"

You REALLY need to replace ALL those E-Caps. 40 years is the *maximum* time to use them. People talk about reforming them, but these WERE reformed. 2024 - 1966 = 58 years..... almost 20 years past the replace date.

View attachment 83439

Wow!

 

[RetiredUnit1]

Wow!

This can also happen if the diodes fail, or the rectifier tube shorts. It's a REALLY GOOD idea to at least test the diodes, but even better to replace them. Backup diodes can also be added just before the rectifier tube so if the tube shorts you still keep A/C out of the polarized cap feed, because if it does get in {{{BOOM}}} !!!