Bill M mods Blues junior.

allicio

How do you stop the oscillation?

jpfamps

allicio said:

How do you stop the oscillation?

Normally be pushing the grey ribbon cable above the power valves into the corner of the chassis.

The key is moving this cable away from the blue cable to the output transformer to reduce the stray capacitance between them. 

NB the blue wire to the transformer is connected to the HT and so potentially could have a very high voltage on it (especially as Fender don't use bleeder resistors in this design).

If this doesn't cure the oscillation (and I've come across a few amps where this doesn't) then you will need to add snubber caps.

Sessionman

jpfamps said

To quote from elsewhere on this forum "Whichever is best no longer matters. What is adequate to meet regulations, give a useful life and keep them competitive is what does matter... and all that matters!".

Except in this case, no one in their right mind would put a product on the market knowing full well that it will break so easily (pots fastenings - lack of - therefore an unreasonably short life).

On the other hand, I would not agree with anyone over-engineering something to pedant levels when it's just not required.  And then, perhaps, making electronically uneducated people feel bad, weary about buying a perfectly acceptable product, for the use it will be put to, as we see some 'booteek' makers do so often.  Confused customers buy nothing!

Taking advantage of musicians engineering ignorance in either way is, to my mind, unacceptable.

As revealed so often on any forum... price is usually the deciding factor in many potential purchases, so, making products that are adequately engineered for the job makes 100% sense and essential for self preservation in a highly competitive market place.  Like it or not, sadly, the customer ultimately decides. That's why my old 'cheap' amps sold so many and are still running strongly!

Thankfully, bad practises have a habit of bighting dubious manufacturers on the bum, eventually!

Faff

My BJr mods saga... 

I have a  BJr mk2 and I have done most of the Billm mods. Installed Canabis Rex speaker. Revalved. Biased. Moved chassis into a custom made 5E3 size tweed cab. Looks great and sounds great. 

 It's hard to say what was the best mod as it's not possible to A/B before and after. The most recent thing was the cab upgrade. This definitely made the amp sound bigger. I think the billm power cap mods and transformer gave the amp more bass definition. The presence mod gives a good range of options. Overall no hiss and quiet. It's still a BJr - but more so.

 I like tinkering and it has cost a lot. Too much. I never started out intending to spend so much but I have done it a bit at time and after every strep thinking "well I've spent so much so far I might as well do another bit". 

The amp was 2nd hand and cost £240. I have spent another £400. Now it's a good amp and I'm very happy with it but it's still 'only a BluesJr' . I do enjoy playing it. 

Now I need to keep it due to the labour of love and no-one will get even close to covering my costs if I try to sell. It's easier to spend bits at a time, but if I'd had my time again I would certainly just buy a Deluxe Reverb RI for the £650 which is what I really wanted!

Gagaryn

I had been going to do something similar to you with mine but stopped myself in time, bit the bullet, flogged it and bought a PRRI.

randomhandclaps

Loobs said:

What does sterility sound like? 

WHY WON'T YOU GIVE ME A BABY, PETE?  DO YOU NOT REALLY LOVE ME?  :-<