Output Impedance error

[Snicksound]

... all fuses are fine, I dont get it... HT and Mains (and I know what the burnt ones look like as I kept them haha!)

A failed fuse can appear fine.
Please check them with a meter.

This. I've been tricked before. Check continuity before assuming.

[desertmouth90]

All Voltages are fine and Output tubes are drawing current, but the reamp valves are not getting warm, the Current limiter has a slight glow.

I can hear the faintest of signal from my guitar.

edit:
I really dont know what to say, I changed the preamp valves and it was feint then I messed with the volume knob, and the master and played a Low E chord and then it came back to life! I dont understand!!!

[Roe]

All Voltages are fine and Output tubes are drawing current, but the reamp valves are not getting warm, the Current limiter has a slight glow.

I can hear the faintest of signal from my guitar.

edit:
I really dont know what to say, I changed the preamp valves and it was feint then I messed with the volume knob, and the master and played a Low E chord and then it came back to life! I dont understand!!!

check heater wiring and the volume and master

[Stevem]

Just do a simple grid tap test with a small screw driver starting at the output tube grids and then going back up stream into the PI and then then the main preamp section.

For every step back that pop you hear should get louder, if not then you found your bad gain stage.


Be sure to have the master wide open.

[desertmouth90]

Just do a simple grid tap test with a small screw driver starting at the output tube grids and then going back up stream into the PI and then then the main preamp section.

For every step back that pop you hear should get louder, if not then you found your bad gain stage.


Be sure to have the master wide open.

With the amp on you stick a screw driver into it?

[martin manning]

All Voltages are fine and Output tubes are drawing current, but the reamp valves are not getting warm, the Current limiter has a slight glow.

I can hear the faintest of signal from my guitar.

edit:
I really dont know what to say, I changed the preamp valves and it was feint then I messed with the volume knob, and the master and played a Low E chord and then it came back to life! I dont understand!!!

check heater wiring and the volume and master

Ok so the power supply seems ok, so it’s a signal path intermittent. Hard to track down as long as it’s working. Chopsticking can sometimes flush it out. A dodgy heater connection occurred to me too, based on the report of it “fading out.”

[desertmouth90]

All Voltages are fine and Output tubes are drawing current, but the reamp valves are not getting warm, the Current limiter has a slight glow.

I can hear the faintest of signal from my guitar.

edit:
I really dont know what to say, I changed the preamp valves and it was feint then I messed with the volume knob, and the master and played a Low E chord and then it came back to life! I dont understand!!!

check heater wiring and the volume and master

Ok so the power supply seems ok, so it’s a signal path intermittent. Hard to track down as long as it’s working. Chopsticking can sometimes flush it out. A dodgy heater connection occurred to me too, based on the report of it “fading out.”

Could this have been caused by the 4ohm to 16ohm discrepency?

[Roe]

check heater wiring and the volume and master

Ok so the power supply seems ok, so it’s a signal path intermittent. Hard to track down as long as it’s working. Chopsticking can sometimes flush it out. A dodgy heater connection occurred to me too, based on the report of it “fading out.”

Could this have been caused by the 4ohm to 16ohm discrepency?

no, it seems independent

[desertmouth90]

Ok so the power supply seems ok, so it’s a signal path intermittent. Hard to track down as long as it’s working. Chopsticking can sometimes flush it out. A dodgy heater connection occurred to me too, based on the report of it “fading out.”

Could this have been caused by the 4ohm to 16ohm discrepency?

no, it seems independent

Nothing is ever simple is it?

[Stevem]

You haven’t seen the hard problems yet!

Especially if there’s multiple problems.

[desertmouth90]

You haven’t seen the hard problems yet!

Especially if there’s multiple problems.

I thought that as soon as I mentioned it haha!

Best thing to do is keep testing it then get it back to my friend for research testing in the field - or studio!

This is a prototype I guess

I have a 50w one I used single core cloth wire in that I feel is more stable somehow, im torn between silicone strand wire and single core!

[Phil_S]

I have a 50w one I used single core cloth wire in that I feel is more stable somehow, im torn between silicone strand wire and single core!

Solid wire is more likely to break with excessive flexing and this can include excessive movement due to vibration while using the amp. Stranded wire is typically more flexible and less likely to break. If you have an intermittent fault, it is possible that the wire is the problem. Unless you mishandled the wire during the build, I suggest this is not a likely cause. Given a choice, I'd choose stranded wire in most cases. Use of solid core is more convenient because it tends to stay where you put it, whereas, it can be more of a challenge to get stranded to stay put. Silcon jacketed wire is nice because it doesn't melt if you get careless with the soldering iron.

On Stevem's suggestion to use a screwdriver, he's suggesting a traditional "pop test." You can also use your meter probe with the ground to the chassis. When you touch various connections, you'll hear an audible pop. Yes, stick a fine point screwdriver in a live amp to do the pop test.

Edit: I don't know what I was thinking -- I guess I wasn't. I wasn't thinking about silcon wire, I was thinking about Teflon/PFTE. I can't say that I've ever seen silicon.

[martin manning]

A lot of people (including me) are sold on top-coated wire, stranded but lightly tinned to hold it together and so it will hold a shape. Typically 22 AWG with 600V PVC insulation, but not hard to deal with wrt melting if your technique is good.

[Guy77]

I also like the top coated stranded 22AWG 600v wire a lot. It is quick to work with since it handles like solid wire when you are trying to loop it around preamp vacuum tube solder lugs.

What I find interesting is that some commercial boutique amp company's are using 20 AWG solid core in their preamps that is 600v rated.
It has the same thick insulation as the 22 AWG top coated 600v wire. Two Rock has been using this.
This is also a nice wire to work with but it seems to be hard to find for sale anywhere.

Cheers
Guy

[desertmouth90]

I bought a tonne of that 20awg solid core wire and the coating is laquered. It doesnt bend and i cant push it back to wire up!