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Messages - billyjoe24

#1
Okay it's working! :)
I must have screwed up something when I was taking out the silver mica caps I put in.
I resoldered the speaker wires and input jack and it's working.Whew!
#2
Well if their tube amp wasn't bad enough,
now my Hiwatt bulldog 30r has gone kaput. :'(

I am not getting any sound when I plug in to either the high or low inputs or
use the distortion.Tried different cables, guitars etc.The spring reverb control is making some sound, which I hear through the speakers with nothing plugged in. The tone controls are not making any sound.
The whole amp works off the tl072 chip which is on a separate little pcb.
There are a couple of 4558 chips in there as well.The power light lights up as well.

Was working yesterday. Don't know what happened.
If it wasn't for bad luck I wouldn't have any luck at all with Hiwatt.
Any ideas?
#3
There is a problem with the wiring on tube 2.
There is a grey wire which has a blackwire on one end and a black and white wire on the other. The black wire goes to the Ground on tube 2 and the white to 7.
The ground was on very flimsily. I managed to recrimp it, but I am not getting a
continuity beep when I check the black wires. When I check the black and white I get a beep. Is that normal?  I think someone mentioned an open electro as a possible source of hum.
Is that what this is? What kind of wire did they use here?
It looks like someone attempted to repair these by soldering but they have come loose.
#4
Just on a side note. I have been able to move the OT a little further sideways away
from v1.  Probably can go a little further too.If I could find a mounting bracket with longer slots I could get at least 1/2 inch of separation. Gonna have to look around.
#5
The board is accurate.Don't worry about that. I should repost it with the cap numbers finalized.
I can take out the cap and resistor, but I will get it done to avoid getting fried.
And that's no laughing matter.
But I am pretty sure the hum will still be there.
Can this amp be modified to be even more like the sa412? Dumb question?

Is it a waste of time messing with the transformers then?
I think you mentioned putting a metal piece there with an alligator clip to see if it does anything.
I am having a devil of a time getting two of the bolts loose on the PT.
I can move the OT way back using two of the existing holes, but the laminate will touch the baffle. Or I can drill 4 new holes.

Can this be of any use,like you said before:
QuoteThe only other way is to lift the CT of heaters to a reference voltage but I doubt this is done on this amp.
Definitely no resistors under tube board. This is proving very difficult to unscrew though.
Of all the things they did wrong, this they had to do right!

One thing I would like to ask is , is there any info you need regarding plate voltages and so on? Let me know.
I could get it checked for a very small fee and get some written answers once and for all.
So you , and myself included,know exactly what is what with the bias and everything else.

The only odd things  that have come up was too much voltage on one of the tubes.Tube 3 I think.
I think tech  2 mentioned something about the power tubes.
One wasn't dissipating as much as the other?
Can't remember.I asked him twice the next day about it but I didn't get an an answer.
I made him do the pin to ground test on the sockets and there was something he mentioned that didn't make sense. He said the noise on the a tube was 1 point something instead of 3 point something.Can't remember.
And do caps have to be removed from the board to be checked?
Certainly, these were not.
One thing the last guy said was the tubes felt hot.
"Imagine if they were running at 220 like fender." ???
#6

If there is info you need I could ask someone to check that and just go with a list:
this is the info we need.
There are some guys who don't charge or charge very little for looking it over.
Do the caps have to be removed from the board to be checked?




You're right there is a lot of gain here :)
(stop laughing) :) I admit defeat.
In my defense I haven't heard the thing in months.
For me it's not a super high gain amp, but you don't need a distortion pedal.
Perhaps it's high gain 7- 7.5 out of 10? with 10 being out of control hi gain monster?
Maybe I can post a power chord so you can hear it.Or the hum.
But it's the crap tubes they put in too.
Sovtek wb are not helping. Yuk.

The clean sound is (from 0 to 10)
Mv at 3 gain at 3.
Going up with MV control gets more hum. Gain up, some buzz.
Can the buzz be filtered out as before with filters,rather than hunt down the cause?

You could use the amp with mv very low (below 1 really) and use the gain at whatever setting. Not very loud but no buzz or hum.

I'm trying to get the transformers out of there but the one thing they did right was glue the bloody bolts on like there's no tomorrow! How do these bolts work?
If moving the transformers has no effect then :-\
But now I can't get them out.


What about a 470k resistor on tube 2 where the trace was cut?
I'm going to try this.The solder is there.
I see it on a lot of Hiwatt amps including the sa412.
This should cut down the gain somewhat?
I'm going to try it tomorrow just to see what happens.
Dumb idea maybe but what the hell.Why not?
What about a 68 k resistor on tube one? A grid stopper. What exactly is that?
#7
Is it possible to change the mounting bracket on these transformers?
I f the bracket had longer slots I could move the shielded transformer further from v1, probably a good 1/2 inch.There's plenty of room on that side.
What about flip flopping the transformers? Changing sides?

Changing value of gain or master volume have any effect?
The other transfomer is a bit more of a problem, but I think I can get bell ends.
It's really  a last try, after that...

A 12ay7 in v1 lowers the hum somewhat, about same effect as cutting traces.
Zero effect on buzz.
#8
How about getting the ceriatone 504 head and using it with the amp?
I don't think i can fit the chassis in here.
It's too big. The board alone is not expensive.
But can it fit in the existing chassis?
Can the wattage be lowered on it from 50?
#9
I certainly appreciate your help and everyone else who's chipped in.
It's a frustrating amp this thing.
I think the amp had a somewhat better sound at -14.
Could the bias affect the loudness?
It seems louder than before.
But the output transformer is very, very close to tube 1.
I think the hum is tube 1 position, buzz from tube 2 position.

You know the problem with the guy who has the amp, he's way over in California.
If he could check the parts on the board and shoot some photos maybe you could see something but  I don't think he can.
I have one last fellow lined up, who is a retired tech,
so I think he's the best man for this troubleshooting job.
After that :'(

#10
Checked it again; still hums and buzzes.
With gain high and master volume pretty low it's okay. The guitar covers it and it's a ral rocking sound.
Should I leave the pot in or put back in the resistor?
The resistor would make  -14 again.
Did some tests.
Pulling v3 and v4 nothing connected to input,
no buzz hum or anything.
V2 pulled out, no buzz, some hum.
V1 out, buzz some hum.
Plug a guitar cable to  input but not to guitar buzz goes up.
Could the input jack be part of the problem here as well?
#11
What's going on here?
I was told this amp is not cathode biased according to the schematic and is class ab.
Pushpull. -14 was too low and now it's -30.
R38 was replaced with a pot and higher voltage cap for c23. Does this make sense to anyone?
I'm getting mighty confused and angry.
What exactly is the bias type originally and now?
#12
The amp sounds terrible! There is no clean sound now.
With the master at 9 am and the gain at 9 am I get distortion.
This was not the case before.
There is no dynamic response from the tubes either.
Chords seem to be cutting off. Especially at low volumes.

He told me the bias is set at -30. Is that too low or too high?
He told me it's the right bias for the circuit.
Maybe it's a speaker or connection etc.
I think I might have been had here.
What should the bias be for el 84?
It was -14, sounds right to me.I'm going there tomorrow,

A  pot was installed where the resistor was for the bias and a higher voltage cap was installed just before it.
There are absolutely no resistors that I can see under the tube pcb.
Would a 68k resistor on tube 1 get rid of hum?
Should I make him put the bias back where it was?



#13
I'm hoping I didn't get screwed here!
Just got the amp back so I will test it.
I heard it at the tech's place and it sounded okay,
but it wasn't a super thorough test.
I will shoot a picture as well.

He told me it was biased too low.
He changed a capacitor for the higher voltage. Does that sense ?
Perhaps he was talking about the current per tube?
If it was 14ma would it make sense then?
I will check it out further tomorrow, it's winter here so the amp is a little frozen from the 45 minute drive back.

He told me the input jack is not a shorting jack as well.
Can this be replaced? Any reason why it can't be changed?
#14
I believe the amp has been fixed!
I'm going to pick it up tomorrow and hopefully no surprises.
He put in a trim pot to adjust the bias and replaced one of the caps with a bigger one.
I can't remember the details, but with the standby on the voltage was -24 and with it off -14.
He adjusted it to 35 and the hum and buzz were reduced or eliminated.
Not sure. Something along those lines.
I'll know for sure tomorow.
So far so good I think.