Completely Out of My Depth - Modulus 50w 69 Build

[kingfredward]

All done. Godamn I am anxious now haha

I know caps are what kill me so I have a discharge took what do you reckon?

 

[PelliX]

I know caps are what kill me so I have a discharge took what do you reckon?

The amp is looking good! I can't exactly make out every solder joint from those pics due to the resolution, but overall it seems fine. You mentioned that you checked for continuity in various places. I often do the inverse, too - just make sure that certain points have plenty of resistance to ground where I expect it. I'd rather have a component float than short - generally.

You have an LBL, I believe, and you know the basics of firing it up without valves first, etc. Start with a low wattage bulb, etc.

The cap discharger looks like... many of them. If it's rated for the voltages you're dealing with I guess it should be fine.

 

[kingfredward]

So got some good news and some bad news …





Started up fine nothing went pop and stayed stable

However



When it came to putting in the preamp tubes …. There was solder weirdly between the holes . So couldn’t get the tube in. I put the soldering iron to get rid of it and f*cked it up.

This meant that the middle preamp tube didn’t heat up and glow

So I didn’t hit standby for fear of something going bang. I guess I buy a new socket and wire that in?

 

[NickKUK]

So. learning experience.

1. Sparklies = bad news
2. Carbon = bad
3. Slow step by step = good.

Back to check the connections, step by step.

 

[BlueX]

Looks good, except for the hickup.

I guess I buy a new socket and wire that in?

Yes, get a new one. That one's toast.

Solder blobs and strand cutoffs can cause a lot of problems. Magnifying desk lamp and inspection mirror, together with tweezers and brush, are useful.

 

[BlueX]

Started up fine nothing went pop and stayed stable

B+ 319 VDC seems low. When you start up again, you could measure VAC before rectifier (at red arrows in pic below). You measure from each pin to ground/chassis, one at the time. Don't short between these, very high voltage!

PT MOD002 should have 345 - 0 - 345 VAC (if that's the PT you're using).

Edit: Could of course be that the amp is connected after LBL, that would explain.

 

[NickKUK]

Looks good, except for the hickup.

Yes, get a new one. That one's toast.

Solder blobs and strand cutoffs can cause a lot of problems. Magnifying desk lamp and inspection mirror, together with tweezers and brush, are useful.

View attachment 158262

Worth using some iso

Next time start up without tubes and check voltages - the unloaded transformer will result in a higher voltage (check the caps can handle it first). If they’re not high then there’s a problem.