Shocking

[lowell]

Thanks Nickb.

I always feel a bit hesitant when asking if they wanna sell their gear to me for cheap since it's broken. But I am honest, and explain the hourly rate and parts cost to them, and then explain my time is money but I don't have to pay myself to do the work so it makes sense for me to buy it. It goes without saying that they can take it to someone for a second opinion and then decide if they wanna sell it to me.

[lowell]

I suppose I can at least figure out where the EL90 and 6EU7 go by checking the heater wiring. Probably use 12ax7 for all other.

[pdf64]

I suggest being wary of Weber iron; there's a recent thread on TAG reporting that they're having a recurrence of the 'B+ winding not being correctly center tapped' issue.
They were very helpful when that happened to me, but it was a PIA and must have cost them a heap in shipping.
Then after eventually getting a good one (#4) from a new batch, a tube short killed the PT and OT, even though I'd put a fuse in the B+ line.
Maybe just bad luck, but their spec may be such that they're not as resilient to expected fault current as other makes.
Their price makes them attractive, but I suggest they're best used for personal projects, rather than for paying customers.

[Alex R]

On the buying-in broken gear thing - I've always avoided it for reasons already stated. I do offer to retain the amp in lieu of payment if they think my bill is more than the amp is worth, on the grounds that I am then the loser, having spent more time fixing it than it is worth. However this is rhetorical only so far, just my way of making a point. In truth I often bend a little further than my own advantage requires, as a happy customer is a valuable asset not just a source of cash. I am very much of the view that this is a personal matter as you soon fall back on your own value system and your own way of seeking happy outcomes.

The point I was going to make before I got all philosophical was that to offer a customer money for a broken amp is likely to appear either pointless if the true repair cost is higher than the amp's value, or dishonest if it's not as the customer would be best served by having the amp repaired for a fair price. Professional ethics ain't easy!

[lowell]

Thread revival!

Ok, so I got the new Weber PT in there. Installed 3-prong cord. Recapped all filters. Replaced broken 6v6 socket. Biased it. It's alive and sounds really awesome! I am surprised at how good it sounds honestly. However, only one channel works. This should be easy though at this point. Just wanted to report my results and say thanks for the help. BTW the tubes: 6n1n(EL90), 6EU7, 12AX7 x5, 6V6 x2, 5Y3.

[lowell]

My previous post says 6N1N in first position...this is wrong, it's an EL90(6AQ5)

[lowell]

Ok so both channels work. I'm trying to fix the no-reverb issue now. It's an EL90 driver tube with a reverb driver transformer. The primary is open, yay. I need some help with figuring out what is the correct transformer to use here. This is an OLD amp.. there is a schematic here, but it doesn't have these specs as someone hand drew it (kindly).

Best I can do on the tank without any kind of lettering on it is measuring DC resistance of the coils. (Tank was made by Gibbs Mfr and is a long type with 2 springs)

Tank specs:
OUTPUT: 165ohms
INPUT: 1.2ohms

EL90 output resistance/impedance:
Ra 52k
Za 5k

There is 235v on the plate of the EL90. At 5k primaryZ the max current for the transformer primary is 47ma. Would a reverb 12at7 style reverb driver transformer work for this? I'm thinking NO. Thoughts? Any ideas on a transformer sub? Thanks!

[Enzo]

So it has a low impedance input coil, like any Fender, so a 4AB2C1B equivalent, more or less. This ain't rocket science, wire in a plain old fender reverb transformer and see how it works.

47ma? Well, only if the tube could bring the plate to ground.

[lowell]

Thanks Enzo I think I may have one around here somewhere.

[lowell]

Alright! Reverb is working. Replaced the transformer, still didn't work but it ended up being the tube itself. The transformer was definitely bad, but so was the tube.

Now, had to replace the tube socket for V5 as pin6 was completely missing. I wired it all up. Everything seems wired correctly. I'm not sure the schematic is correct in regards to the Tremelo. Can someone please advise what to check here?

There is a footswitch for the reverb and tremelo. The tremelo footswitch connects/disconnects the junction of the 47M/220k/220k (that go to the bottom of the SPEED control and V6 Rk) and the supply labeled F. I don't think this is right.

The SPEED and DEPTH controls, when turned to max, greatly reduce the volume. So they're doing something, but acting more like volume controls.

Here's the schem so you don't have to dig for it. http://music-electronics-forum.com/a...r_120r_sch.pdf

Thanks!