100w Bluesmaster- I've made a start

[norburybrook]

yes the pre amp valves had no glow at all, they looked dead.

any ideas what this might be Martin?



marcus

[martin manning]

A hidden break in the filament wiring, perhaps? Sometimes twisting them too tightly can cause that. It's not likely that they were shorted out, as that would take down all of the filaments and cause a lot of other trouble, like overheating the PT and/or blowing the mains fuse.

[norburybrook]

ah, so I should replace the pre amp heater wiring then ?

I did wind them with my drill to get them nice and tight. I used stranded cable for this job though, would that still suffer from the same problem?

after some more testing I'm still getting the distortion when the amp is on the floor it's just less pronounced.

something's not quite right...


so close yet so far


marcus


p.s. after it's been on now for half an hour its clean a whistle sat on the floor.

[martin manning]

I think I would replace the entire filament wring harness. Stranded wire will still fail, but it's more likely to go intermittent (at least at first) as you are seeing. I don't know if that would cause your static, but maybe it could since there is a lot of current flowing through those wires.

[norburybrook]

I think I would replace the entire filament wring harness. Stranded wire will still fail, but it's more likely to go intermittent (at least at first) as you are seeing. I don't know if that would cause your static, but maybe it could since there is a lot of current flowing through those wires.

my least favourite job

could it be the sockets, or a socket?


I'll see if I have enough wire left over to do it this week. I'll leave it looser this time then.

Marcus

[martin manning]

Looking at your photos, the twist doesn't look overly tight; about right I'd say. Before you tear it all out maybe take a close look at the V3 and V4 sockets. Cut the cable ties off so you can check the solder joints carefully, and see if the leads between those two tubes are sound. I don't know what else could cause all of the preamp tube filaments to go dark. A bad socket (broken lug, e.g.) would affect only the filament of the tube plugged into it.

[norburybrook]

Looking at your photos, the twist doesn't look overly tight; about right I'd say. Before you tear it all out maybe take a close look at the V3 and V4 sockets. Cut the cable ties off so you can check the solder joints carefully, and see if the leads between those two tubes are sound. I don't know what else could cause all of the preamp tube filaments to go dark. A bad socket (broken lug, e.g.) would affect only the filament of the tube plugged into it.

I'll do that tomorrow if I get a chance. I didn't think I'd over done it with the twisting. It's also heavy duty stranded wire as I'm aware of the high current flowing on the heaters.

the only other thing I've noticed compared to my #102 is, until a guitar is plugged in to the BM amp it's a lot noisier than the 102. Once a guitar is plugged in it's OK.

don't now if that's of any relevance.


Marcus

[martin manning]

That could be a faulty input jack, where the switching contact isn't making a good connection with the tip contact.

[norburybrook]

That could be a faulty input jack, where the switching contact isn't making a good connection with the tip contact.

it's a switchcraft I think, but I'll swap that out as well as I think I've another and it's a quick swap.

the #102 once I sorted the relays has been a 100% reliable amp, this is proving to be tricky for no apparent reason. I'm sure I'll learn something from this trouble shooting too in the end, just frustrating at the moment.

It's a great sounding , powerful amp and speaker combo when working so would like to sort it out.


thanks Martin.

[norburybrook]

so today I have.

1: replaced the heater wiring from V4 back to V1

2: replaced the input jack

3:replaced every valve with known working ones.

4: tightened and checked every earth point.


I've chop sticked around 'till I'm blue in the face but nothing makes any difference.


No change


so to sum up;

when the amp is on top of the speaker, any note around the B,C,C#,D on the 'A' string will cause horrible crackly distortion.

when the amp is NOT on top of the speaker it's fine.


Marcus

[norburybrook]

ah ha................



so I started chop sticking around the output valves and got a bit of noise around the bias resistor pins of V5. I only tried removing the outer 2 valves but this time removed the inner 2, valves 5 and 6 and the noise has gone


so that narrows it down.

I know it's not the valves, I'll re-solder all the pins first and then see how it is...


TBC



Marcus

[norburybrook]

.............


Success, re-soldered the 2 connected pins with the bias resistor and it's now fine


I'll leave the other posts up just in case they're helpful to anyone.


so 2 bad solder joints on this build. I've never had a bad solder joint on anything I've built until this build, don't know what's different.

something for me to watch next time............and you all know there will be a next time.....


Marcus

[martin manning]

Good to hear you have it sorted, Marcus!

When you replaced the input jack did the noise problem with nothing plugged in go away?

Any changes to your tools or materials related to soldering on this one?

[norburybrook]

Thanks Martin.

Input jack change didn't do much, I did put another earth from the socket to the buss bar for belt and braces ( along with the one direct to the chassis earth)

It's definitely quieter with a guitar plugged in , and that's obviously how I'll use it . so no big deal.


Regarding tools/methods etc; same tools/solder I think I was trying this time to be as neat as possible with this build and maybe didn't put as much solder as before, and or perhaps didn't hold the iron on for as long. Perhaps I should go back to instinctual method of old


I'm always very impressed with the gut shots of everyone's amps here, they always look so neat and tidy compared to mine. I suppose that comes with practice and this is only number 4 in my entire life so I've a long way to go.



Marcus

[martin manning]

It's a good idea to run a wire from the input jack's sleeve terminal to the input ground lug. That way you are not relying on any mechanical connections which can oxidize over time.

You definitely need to hold the soldering iron tip in contact until the solder flows out and permeates the connection. Keep the tip clean by wiping it on a damp sponge and applying some fresh solder after each use. An occasional plunge into tip cleaner/tinning compound helps too.