Early 90's Fender Hot Rod Deluxe

[rgdr]

I have a HRD on the bench with the following voltages:

1 2 3 4 5 6 7 8 9
V1 209 -- 1.7 2.8AC 2.8AC 214 -- 1.6 2.8AC
V2 208 -- 1.7 2.8AC 2.8AC 210 -- 1.7 2.8AC
V3 -- 13.3 27.5 2.8AC 2.8AC 153 5.1 27 2.8AC
V4 -- 2.8AC 426 427 -37.8 -- 2.8AC --
V5 -- 2.8AC 426 426 -37.9 -- 2.8AC --
When the amp came to me, there was no sound. Now there is signal getting to the speaker however with a ton of hiss and low volume. I have known good tubes in it and am currently at a loss for where to try and track down the problem(s). Any feedback is greatly appreciated.

** So, the voltages are meant to be a spreadsheet looking chart, though when I post it, I don't believe they are. The '--' are for no voltage on the corresponding pin. I hope this helps.

[Haze13]

Isn't a heaters are a bit low? 2.8 - that's 5.6 in total...
Try to connect some signal between the stages, from a signal generator (PC sound card will do the job if you don't have one). This way you should find the problem very quickly... Start from the PI and move to the Inputs.
Do you have a scope?
What tubes are there?

[rgdr]

No, I don't have a scope. The tubes are 12AX7 in V1 and V2, 12AU7 in V3, 6L6 in V4 and 5. Thanks for the insight though, I'll start looking. I didn't make much of the heater discrepancy as I thought that they should be 3.15. But 5% of that is 3.00... So they are a little low. Would that maybe a power transformer thing?

[Haze13]

If you are using the the wrong primaries of the power transformer that the voltage can drop. If the primaries are for 120 volts, but you connected to 110 voltage source, than secondaries will be lower than they should.
If you are dealing with amps often, or experimenting with some electronic stuff the scope is a must! Don't look for these expansive scopes, an old analog will do the job and they are even cheaper than small hand-held DSO's from ePay...

If you don't have one... You can listen to the signal that you connect in different locations of the preamp, with scope it's just "noise free"

[Haze13]

strange that you have voltage on both sides of the PI. There should be caps on the grids, and no DC should be present on them, I think... Don't have a schem so can't be shure on that. Is it a 4X10 combo?

[rgdr]

There is a schematic at http://amparchives.com/Amp%20Archives/F ... ematic.pdf
I'll check the grid resistors on V3 to make sure that they are not open. The plates are off as well. V3 pin 6 reads 153 VDC and per the schematic should be 11.5 on pin 1 and pin 6. I suspect to find something there...

[Haze13]

They can't be 11.5, it's not a DC voltage. Just like a 66.5 volts on the plates of the power tubes. It's an AC signal. In the Ampeg shems there are some times 2 voltages are shown. One for the DC and the other for the AC.
I remember that amp... The C9 or C9 had a loose solder join:)

[rgdr]

I think I found it. Maybe... R57-one leg is not soldered and there looks to be no trace intact on the PCB. I was going through and hitting all of the solder joints with some heat to reflow and noticed this. I attempted to solder the leg however the board wouldn't take the solder. My plan is to jumper to the next intact pad. My question is, could this explain the low volume and added hiss? Per the schematic R57 is the V3A plate resistor. Thanks.

[Haze13]

Well it's a Phase Inverter. You wrote a list of the voltages on the pins of the tubes, the V3 had no plate voltage at all on the first pin. So I think it can be a problem:) Make a good connection and check for the voltages w/o the tubes. There must be a B+ on the first pin and the pin number 6. If they are there, put back the tubes and check the voltages again. It should work.