new build: 50w Bluesmaster HRM combo

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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

martin manning wrote: Tue Jun 20, 2017 11:51 am I recommend changing the board resistor to raise the mid point of the bias range. The pot and ground resistor together set the range and current so you should keep them the same.
thanks Martin, I looked at the Ceriatone layout for a bluesmaster HRM and they use 1k2 and a 10k bias pot with a 15k ground resistor which is why I tried it after writing my post. Seems to work fine, any reason to change it?

Need to work out why I've no pre amp sound going on now.

is there a way to bypass the signal traveling through the relays? I've a hunch that might be the issue as everything else is checking out fine.

marcus
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

doing some probing around the relays as that was the area I wasn't 100% when building as the relays seemed to be wired differently from my #102,124 builds, not sure why when it's switching the same things.

I have continuity here,
Bluesmasterrelay.png

I have the same continuity on the other relay board pins which is putting both sides of the 22m to ground

does this mean the relays are wired correctly?

edit I've just powered up to check these connections and they do switch open and closed here, so the relays are working. also after prodding around on those connections I got sound.

I now have sound, the clean volume control doesn't seem to work along with the tone stack and switches, the OD will switch in and the two OD controls work as expected. kicking in the boost kills both the clean and OD.

I think my hunch about the relays is correct...not sure what it is though.

marcus
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

OK,

summary;

clean: volume control has no effect, I have a clear signal though. Engaging boost kills everything, not sure if the mid and bright switches are working and the tone stack is very weak.

OD: again the first volume has no effect so the OD isn't what it should be, the two OD controls work as expected, again the boost kills everything.


here's my relay wiring.
BM_No_Jazz.png

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erwin_ve
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Re: new build: 50w Bluesmaster HRM combo

Post by erwin_ve »

On your last picture I can't see a wire coming from the middle lug volume pot to the grid of v1b, is it there?
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

erwin_ve wrote: Tue Jun 20, 2017 1:29 pm On your last picture I can't see a wire coming from the middle lug volume pot to the grid of v1b, is it there?
Irwin,

well spotted....I had it going to the master volume not the volume. however looking at the layout, it's confusing.
Bluesmaster Rev6.jpg


Marcus
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Last edited by norburybrook on Tue Jun 20, 2017 1:50 pm, edited 1 time in total.
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erwin_ve
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Re: new build: 50w Bluesmaster HRM combo

Post by erwin_ve »

Edit; you did an edit :D

The layout maybe confusing but the middle lug of the volume pot has to go to the v1b grid. If not all my builds were wrong....
And use shielded wire on that spot!
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

Erwin :D ,,I didn't use shielded cable but it sounds great :D

of course it has to go from the volume to the v1b grid :D

rooky mistake.


All sounding very good here now....only issue is the OD switch is the wrong way round, i.e. it's on when it should be off and vice versa.

whats the simplest way to swap this behaviour?

and while we're on the subject;

why does the switching of the OD channel have so many different relay wiring schemes on the various amps I've built? the circuit is pretty much the same so why all the different relay wirings to achieve the same thing? on my last build I remember hard wiring a jumper between certain pins for example.

m
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erwin_ve
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Re: new build: 50w Bluesmaster HRM combo

Post by erwin_ve »

All sounding very good here now....only issue is the OD switch is the wrong way round, i.e. it's on when it should be off and vice versa.
whats the simplest way to swap this behaviour?
Reverse the diode on the od relay? (and the wire that feed the diode!!)
why does the switching of the OD channel have so many different relay wiring schemes on the various amps I've built?
Bluesmaster and HRM have seperate master compared to the #102, #124 and #183 and Mr. Dumble doesn't want it easy for us pirates and bootleggers :evil:

Pls reconsider on the shielded v1b connection. You might get lucky but it is a very sensitive spot.
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

thanks Erwin,


I'm away on tour again in the morning so will have a look at the changes needed when I'm back after this leg.

I'm surprised at the amount of gain on the clean channel on this build, it goes into OD on the clean channel if you turn it up, just like my JTM45, it's not as bright as my last BM either. Interesting stuff, I wonder what the EL34's are doing for the sound? they're old Mullard ones that came out of an old Marshall, they might be knackered for all I know. Sounding mightily raucous at the moment for a 50w amp.
DSC_1298.JPG
DSC_1296.JPG


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rogb
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Re: new build: 50w Bluesmaster HRM combo

Post by rogb »

Nice work Marcus!!!
Glad it is sounding good too.
This is Martin's relay diagram that I followed on my #183 preamp build, it worked just fine.
Like you say, they are all a bit confusing.
Taylor_OD_Relay_R1.jpg
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

Ok finished off with some tweaking today and some cabinet work as the chassis wouldn't go in the cab due to the OT being to near the front of my chassis and the fact that the peavey combo had a sloping baffle. Jig saw to the rescue.
DSC_1304.JPG


Now back to the last thing to do, the OD relay which is acting in reverse.

Is there a simple way of rectifying this behaviour without swapping the diode and wiring round? It
s going to be a PIA to do this as it's all tightly wired in there.

Can I jumper or move any of the wires on top of the board to switch the behaviour round?


TIA

Marcus
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martin manning
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Re: new build: 50w Bluesmaster HRM combo

Post by martin manning »

If by backwards you mean that the LED is on in clean mode and off in OD mode, then you should be able to fix it by swapping the Ground and Clean Out leads and swapping the leads going to the Clean Volume and the OD Volume pot wipers.
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

Martin, no it's the switch on the back as I haven't made a footswitch yet.


When it's on pedal it's on rather than off and when it's on manual its off rather than on :D


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martin manning
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Re: new build: 50w Bluesmaster HRM combo

Post by martin manning »

Check to see which switch position grounds the relay coil (should be the manual setting), and/or determine if you have the pedal switch wired correctly. Looks like the BM layout drawing (Rev. 6) is showing incorrect wiring for slide switches as the relay coil wires are grounded in the position labeled "Pedal."
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

Martin I haven't labelled the chassis rear yet so as long as both switches work the same it doesn't matter which is which, however the boost works as expected and the OD is the opposite. If it's easier to rewire the boost then that's OK too.

edit; if I swap the wiring of one of the switches round then that will achieve what I want as its basically the switch that's the wrong way round.


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