Starting a Bluesmaster 100 HRM

[Beach247]

Thanks for the responses.

The bad news. I finished up my build, or thought I had, and tested it without tubes. All voltages looked good. Put tubes in and tested with a limiter and all appeared good. Plugged straight in and no signal out

I will get some pictures up later with some voltages. probably going to have to do some audio probing.

[norburybrook]

Thanks for the responses.

The bad news. I finished up my build, or thought I had, and tested it without tubes. All voltages looked good. Put tubes in and tested with a limiter and all appeared good. Plugged straight in and no signal out

I will get some pictures up later with some voltages. probably going to have to do some audio probing.

well it looks a tidy build so I bet it will be something stupid. Check all your grounds with a continuity tester and then voltages on the valve socket pins will be a good start. I once forgot to wire back from V1 to the volume pot as I was looking at a layout where it wasn't actually drawn in so it had slipped my mind.
….


M

[Beach247]

Don't have much time for tinkering because the wife left me home alone with the 4 kids. However, I saw your reply and thought to myself, "self, did you connect grid 2 to the volume pot?"

Ran downstairs with baby in hand and saw a terminal strip with no wire running to volume Great minds think a like, or are absent minded alike.

Let's hope that's the only trouble.

I'll get back to it tomorrow

[Beach247]

Yep

[norburybrook]

Yep

LOL, how funny.


Is everything OK now?



M

[Beach247]

Everything but no signal from the FET input. Looking at the Bluesmaster layout it looks like the tip is grounded and the shunt is wired to the output. Thinking that should be the other way around. I’m using a switchcraft 14b jack.

[Beach247]

Nope that wasn't it..

[Beach247]

So the amp doesn’t sound as dirty as I expected. Even the Overdrive channel is fairly clean unless I flip up the rock switch. Only the normal input works and not the FET. Here’s a couple finished photos and some voltages.

B+ 454v
1 454v
2 452v
3 431v
4 318v
5 311v

6l6 plates 456v

V1:
pin 1 202v
pin 6 199v

V2:
pin 1 187v
pin 6 186v

V3:
pin 1 252v
Pin 6 276v

FET B+ 313v

[xtian]

Even the Overdrive channel is fairly clean unless I flip up the rock switch.

The Jazz tone stack cuts quite a bit of gain, so you can definitely expect more gain in the Rock setting.

[norburybrook]

I'd start with it set in the rock setting as default and make judgements/settings with regards to the OD from that. The OD is gainy on the bluesmaster and you shouldn't need to turn up the OD trim pot that much to have a good OD sound. Also it sounds better with PAB on as it cut's the clean tonestack so you can fine tune the HRM OD tonestack to suit. with the PAB and OD you should be able to dial in a strong OD tone.


FET? can't help I'm afraid as I've only ever built them as switchable with the gain pot on the front, I Know that the original FET jack is a strange and mythical beast by all accounts.

M

[Guitarman18]

So the amp doesn’t sound as dirty as I expected. Even the Overdrive channel is fairly clean unless I flip up the rock switch. Only the normal input works and not the FET. Here’s a couple finished photos and some voltages.

B+ 454v
1 454v
2 452v
3 431v
4 318v
5 311v

6l6 plates 456v

V1:
pin 1 202v
pin 6 199v

V2:
pin 1 187v
pin 6 186v

V3:
pin 1 252v
Pin 6 276v

FET B+ 313v

You may have got your B+4 and B+5 wires swapped over, by the looks of things.

Cheers,

Paul.

[talbany]

So the amp doesn’t sound as dirty as I expected. Even the Overdrive channel is fairly clean unless I flip up the rock switch.

That's pretty vague?

Get the amp working then move to the fet.
The signal path first!
1. Do all of your controls function properly?
2.Do both relays work and does the OD switch in properly including PAB
3. Do all of the controls on the OD circuit function properly. (Trim,HRM stack,Level, gain.Mstr etc)
This might give us a clue as to what might not be wired properly or it could be the amp is working fine but you don't have it set up properly yet?
As far as voltages everything looks good accept V2 looks to be 20v lower than what it should be. This might be the problem or it could be just the tube drawing more current Check the cathode voltages and let us know what you get there.



Tony

[Beach247]

You're right it was vague. It wasn't so much a complaint or concern but it just wasn't exactly what I expected as far as the gain.

Everything control wise works as it should including relays and HRM trim pots.

Cathode Voltages

V1
Pin3 - 1.607v
Pin 6 - 1.594v

V2
Pin 3 - 1.888v
Pin 6 - 1.976v

V3
Pin 3 - 28v
Pin 6 - 27.5v

I should also note that I set up the output with a half power switch also which works great.

Thanks!

[amplifiednation]

Did you use audio or linear taper pots for the OD?

[amplifiednation]

And those are 10-32 pem nuts.