On the workbench, a
Fender Blues Deluxe
Reissue
tells us it’s an amplifier re-released by Fender with the idea of releasing a modern version of an older model.
There are pros and cons to this.
I won’t enter into that debate; what I do know is that this Fender Blues Deluxe Reissue is completely useless.
First impression:
A nice amplifier with a great vintage look in a tweed jacket with a beautiful chrome chassis and chicken head knobs.
The 40-watt amplifier with a 12-inch speaker is quite well-regarded and certainly a good all-purpose amplifier for the guitarist who plays a lot of gigs.
The problem with this Fender Blues Deluxe:
The disassembled transformer as it looked before the transformer inspection.
It doesn’t work at all.
It receives no working voltage at all, although it does receive a voltage (220 volts).
The secondary windings of the transformer seem to be good when I measure their ohms.
When I re-measure the primary windings, the transformer appears to be open there.
I removed the transformer and, in consultation with the owner, examined it more thoroughly. It turns out there’s a thermal protection device between the windings.
The thermal protection device trips permanently when a mechanically “pre-programmed” temperature is exceeded.
The transformer was “dissected.” The thermal protection device is located between the transformer windings at the arrow.
Unfortunately, this cannot be reset.
It’s unknown what temperature the protection device is set to, but it’s suspected to be somewhere between 75 and 90 degrees Celsius. This would be closer to 90 degrees Celsius than 75 degrees Celsius, as a tube power transformer can easily reach temperatures between 65 and 80 degrees Celsius.
To Quick Fix or Not to Quick Fix?
These types of safety devices are certainly helpful, but also annoying, as the transformer seems otherwise perfectly fine. In theory, I could bypass the safety device and get the transformer working again. A dirty little quick fix…
However, there’s a risk involved.
If something goes wrong with the transformer after the repair, I’m responsible for the damage. After all, the device wasn’t repaired as instructed and therefore not up to spec.
As a private individual, I can’t justify delivering such work and risking my reputation. So, no quick fix!
The owner is completely understanding, so I’m looking for a new, original specification transformer for this Fender. I’ve since found one in Germany.
The reason for the defect in the Fender Blues Deluxe
There is of course a reason that this transformer has reached such a high temperature.
So I will have to test all the tubes and diodes.
It is good that I have a tube tester and a semiconductor tester! 🙂
The Tube Test:
Testing tubes is always a challenge… what do you find important: two tubes that draw the same number of milliamps, equal tone, equal slope?
If I tell you that Fender deliberately runs this amplifier “cool” to allow for the use of cheaper, tightly sized transformers, you’ll immediately realize that they paid less attention to tone and probably didn’t even consider milliamps, but only function.
It may sound a bit cheesy, but they’ve truly launched a very price-conscious amplifier.
This comes at the expense of build and sound quality, and yet this isn’t a bad amplifier at all.
Anyway, we’re going to test tubes purely functionally for internal short circuits, gas/vacuum, and finally, whether they’re too far apart in milliamps.
Installing the Transformer:
Replacing the power transformer isn’t rocket science. A set of wires and four screws. And the new transformer comes with good instructions on how to connect it.
After the transformer was in place, I started checking the peripheral components and found a “grilled” section of the PCB next to the 6L6 output tubes.
After milling this out and refilling it, it looks healthy again.
Time to check the Output Transformer.
That was a major disappointment. It also turned out to be defective… I wish I had done so sooner… and then I blamed myself for not providing the owner with a complete list of defects right away.
This means I have to adjust my process to prevent communication disruptions during these kinds of exceptional situations. We keep learning!!!
I quickly searched and luckily found a new output transformer, and after discussing this disappointment with the client, I ordered one.
It arrived quickly and was installed even faster.
That said, it sounds easy peasy, but there’s a bit of build quality involved here that makes it more difficult for me to quickly swap out a transformer.
Anyway, I now seem ready to finish disassembling the board and take further measurements.
And during the test, I found another defective diode.
The board was heavily contaminated with a greasy substance, which I cleaned with IPA and dried. I cleaned the regulators and reassembled the board.
Reverb:
During the last check, the reverb didn’t seem to work anymore either. What happened
to this amplifier?
Everything that even remotely resembles a coil is defective! Now, the reverb tank’s input coil.
After consulting with the owner again, they finally got the green light… and ordered a model-correct reverb tank.
All in all, a complex repair with many different facets.
Now I’ve matched and installed a new set of 6L6 power tubes, in this case a set of cleartop Tungsols. A beautiful tube from EHX (USA), produced in the Sovtek factory.
Now I’ll wait and see what the owner thinks of the sound. But the Fender Blues Deluxe is ready again.
A quick update… the owner is super happy with how the Fender turned out. In his own words: More than worth it!
Now that makes me happy… and the client aswell
Tell me you saw it on Vintage-Audio.nl