Wonky Voltages on Hot Rod Deluxe (2009)

[TubeJunkie]

Hi All,

Need some  with a HRDx (2009) I purchased at a great price.  The previous owner did some mods, and in his words "broke it good."  The price was good enough that I felt it was worth bringing home to see if I could get it running.  When turned on, the amp has very little volume, and that's only if the amp is turned all the way up, as well as the guitar.  I opened up the amp and got the following readings:

       Test
      Point  Measured   Spec
     ==========================
        1     0.2mV    4.0mV
        2     156.1V   180mV
        3     2.58V    +1.93Vdc
        4     -0.2mV   13.0mV
        5     154.5V   354mV
        6     2.46V    +1.93Vdc
        7     0.0mV    58mV
        8     209.3V   1.49V
        9     1.59V    +1.93Vdc
        10    0.0V     1.0V
        11    210.6V   23.6V
        12    1.56V    +1.93Vdc
        13    0.0V     1.45V
        14    0.0V     78mV
        15    3.4mV    78mV
        16    0.0V     78mV
        17    5.4mV    1.54V
        18    0.0V     1.37V
        19    17.4mV   1.32V
        20    19.2mV   13.8V
        21    0.0mV    12mV
        22    -4.7V    1.22V
        23    0.0V     920.mV
        24    252.9V   11.5V
        25    241.5V   11.5V
        26    31.46V   +42.8Vdc
        27    410.9V   66.5V
        28    412.4V   66.5V
        29    0.0V     5.34V
        30    76.4mV   60mV
        31    1.32V    +1.39V
        32    0.55V    +0.54V
        33    16.12V   +16.0V
        34    -12.25V  -12.5V
        35    -0.56mV  +0.52V
        36    -15.7V   -15.5V
        37    408.9V   431V
        38    406.8V   430V
        39    367.8V   392V
        40    313.3V   345V
        41     ----    -106V
        42    45.7V    +48Vdc
        43    -45.8V   -48Vdc
        44     ----    39Vac



Here are some additional readings I took:

TP42 and TP43 are for one side of resistors R78 and R79 respectively, and the reading on the other side is:
R78 = +16.9V   +16V (spec)
R78 = -16.9V    -16V (spec)

Speaker1 = 405.1V   431V (spec)
Speaker2 = 403.8V   430V (spec)

R76 = -100.7V   -53V (spec)
R97 = 37.8Vac   39Vac (spec)


Here's the readings from the Power Transformer:
 ______________
( Red
(
(
(
(   331.5Vac   330Vac (spec
(
(
(
(Red___________

 ______________
( Green
(
(   6.94Vac   7Vac (spec
(
(Green_________

 ______________
( Brown
(
(
(   40.3Vac   40Vac (spec
(
(
(Brown_________


Here's a link to the schematic:
https://el34world.com/charts/Schematics/files/Fender/Fender_hotrod_deluxe.pdf


As you can see, many of the reading are way off, and all the B+ voltages are off by about 30Vdc.

(info continued on next post)

[TubeJunkie]

(part 2)

Here's a list of the mods the previous owner said he did:

•   Replaced resistors: R78, R79 470Ω 5W Cement
•   Replaced filter cap: C31 to 100uf 500V F&T
•   Replaced filter cap: C33, C35, C36 to 22uf 500V F&T
•   Replaced Master Volume pot: 250k Audio
•   Replaced Reverb pot: Use old 100k Linear from Master Volume
•   Replaced Plate Load Resistor: R57 to 82kΩ (1/2 watt Carbon Comp)
•   Replaced Plate Load Resistors: R4, R11, R16, R22, R58 to 100kΩ (1/2 watt Carbon Comp)
•   Replaced power tube screen resistors: R61, R62 1kΩ 5W 750V High-Temp
•   Replaced Bass control resistor: R105 100kΩ (1/2 watt Carbon Comp)
•   Replaced coupling caps: C2, C10 to .047uf Orange Drop
•   Replaced coupling cap: C11 to 1000pf Silver Mica
•   Fixed Mid pot: Jumper from Wiper Leg to Bass Leg (What would this look like?)
•   Fixed reverb issues: Remove R103 & C52
•   Replaced: R1, R2 to 68kΩ Carbon Comp
•   Less Bass Gain: C1 47uf to 22uf 25V (electrolytic)
•   Highs & Gain Boost: R9 220kΩ to 100kΩ (1/2 watt)
•   Tone Slope Resistor: R12 130kΩ to 56kΩ (1/2watt)
•   Harsh Drive & More Max Gain: C8 1uf to 22uf 100V (electrolytic)
•   More Bass to Drive: C23 1.5nf to .01uf (Orange Drop)
•   Treble Tone Cap: C7 500pf (Silver Mica)
•   Bass Tone Cap: C5 .1uf to .047uf (Orange Drop)
•   Mid Tone Cap: C6 .022 to .047uf (Orange Drop)
•   Less Muddy Tone @Low Volume (Vol Pot): 220pF (Silver Mica) Middle Leg to Right Leg  (From Wiper to Input?)
•   Less Muddy Tone @Low Volume (Drv Pot): 360pF (Silver Mica) Middle Leg to Right Leg (From Wiper to Input?)

   I appreciate any and all input that can help me resolve these issues.  Thanks in Advance!!!

Sorry about the length, but wanted to include as much important info as I could.

[sluckey]

I'm guessing you did not inject a test signal (4mV, 1KHz, Sine wave) into input jack J1? Until you do that, all of your "oval" test point readings are meaningless. You need a sig gen and a scope to make those readings. You also need to read all notes so you can set the knobs to the required setting to make those signal readings meaningful.

[MakerDP]

Gut it and do this...

https://ampgarage.com/forum/viewtopic.php?f=8&t=31844

At least, that's what I would do and I am actively looking for broken HRD's to do just that.

[TubeJunkie]

Problem fixed . . .  . . . found a couple bad components and a few bad solder joints.  Everything's back together, voltages all look good, and I just made a $75 purchase worth about $450 . . . not bad for a few days work.