What is on your workbench right now?

[restorer-john]

Is it difficult to operate?

Nah, they're easy enough. Nulling can be fun, especially in the presence of noise, but they are old skool. My old Leader is still my goto for quick tests and I hardly use the auto nulling setting.

You always have to remind yourself to switch back to the highest range ACV or the SET function before turning them off, otherwise you'll turn them on in the most sensitive range from last time whe you were digging down in THD on something you just fixed. Nothing like pinning a meter when you don't want to.

 

[Doodski]

Leader

When I worked part time at the metrology lab after my daytime job as a techy they sold used gear and I saw many pieces of Leader gear. Respectable stuff for sure. I bought a buncha gear and I never bought a Leader but they all said why not? I just wanted HP, GR, Tektronix, Power Designs, Sorenson, Wavetek, Lambda and the old classics that I saw in old post WW2 science/physics videos ...LoL... My buddy bought Leader and Sencore and he loved them to death for sure. The Sencore had nice features for TV service but I never serviced TVs or microwave ovens. I was considering a Leader oscillator because it was very nice and I went with the HP because it had multiple output Z and was single ended and balanced too. It was CDN $1200 buckeroos in the mid 90s. I used the HP oscillator a lot. The Leader looked like a classic HP oscillator. I like that look and the dimensions.

 

[Doodski]

Nah, they're easy enough. Nulling can be fun, especially in the presence of noise, but they are old skool.

Sounds good.

You always have to remind yourself to switch back to the highest range ACV or the SET function before turning them off, otherwise you'll turn them on in the most sensitive range from last time whe you were digging down in THD on something you just fixed. Nothing like pinning a meter when you don't want to.

Yeah, the sound of the limit stops being impacted does sound scary at times. The Meguro W&F meter reallly made noise that way.

 

[Jaxjax]

It is a Tandberg model 845.

Got one on the closet shelf. I used to get them for the Mullards I use in my guitar amps...I see a Tele in that one.. Such a finely crafted piece of gear. Super cool ya got it back up & running !!!

 

[Jaxjax]

Nothing crazy, just an early 80s Marshall JCM800 2204. Incredibly, it still has its stock GE 6550As!

Lucky you !!!!!!!! That amp changed the world again for more then a minute.

 

[LTig]

My old KEF PSW2000 sub (which I got broken many years ago for a Pizza and could fix by replacing an opamp) failed again. Power came up but no output and no switch on/off noise.So I took out the electronics. See front and back side:

A visual inspection shows something I haven't seen outside a battery chamber or in a device flooded by salt water:

Everything else just looked fine:

So I replaced the opamp (BF4560) in the preamp section by a NE5532. Checking the output pin revealed that it was oscillating at 360kHz, so I removed the 220 nF cap between output and ground (the dark monster in the pic 2nd above which was soldered across the board) to check it. It was fine but then I saw that the oscillation was gone without it. So I left it out:

The sub still didn't work although the new opamp now worked fine - the scope showed the expected signal I fed into the input of the sub. So I checked the power amp and - OMG - its output (before the protection relais) sat at 50V DC. Checked voltages at the output transistors, the drivers, the VAS stage - everywhere clinging to one of the voltage rails. And then - oh wonder - I measured a good voltage (close to 0V), checked again and now the sub was working. How could this happen? Had I touched somewhere stupid and the opamp in the input stage had latched up? Anyway, several power cycles showed the amp in working order so I put it back into the box and hope it lasts. Phew ...

 

[DonH56]

My old KEF PSW2000 sub (which I got broken many years ago for a Pizza and could fix by replacing an opamp) failed again. Power came up but no output and no switch on/off noise.So I took out the electronics. See front and back side:

View attachment 363578

View attachment 363579

A visual inspection shows something I haven't seen outside a battery chamber or in a device flooded by salt water:

View attachment 363581

Everything else just looked fine:

View attachment 363582

So I replaced the opamp (BF4560) in the preamp section by a NE5532. Checking the output pin revealed that it was oscillating at 360kHz, so I removed the 220 nF cap between output and ground (the dark monster in the pic 2nd above which was soldered across the board) to check it. It was fine but then I saw that the oscillation was gone without it. So I left it as is:

View attachment 363583

The sub still didn't work although the new opamp now worked fine - the scope showed the expected signal I fed into the input of the sub.

So I checked the power amp and its output (before the protection relais) sat at 50V DC. OMG. Checked voltages at the output transistors, the drivers, the VAS stage - everywhere clinging to one of the voltage rails. And then - oh wonder - I measured a good voltage (close to 0V), checked again and now the sub was working. How could this happen? Had I touched somewhere stupid and the opamp in the input stage had latched up? Anyway, several power cycles showed the amp in working order so I put it back into the box and hope it lasts. Phew ...

Think I'd pull it apart again and go over all solder joints and connections with a fine-tooth comb before it decides to glitch and fry things.

 

[LTig]

Think I'd pull it apart again and go over all solder joints and connections with a fine-tooth comb before it decides to glitch and fry things.

You're certainly right. But I'm close to order a Neumann KH750. The Kef is not a SOTA sub, and I'm not in the mood right now to invest more time into this "Pizza" sub. I'd rather try my luck to write a Python GUI to control the Neumann DSP (there is a command line project on Github I could use) once I have it.

 

[Timcognito]

FWIW, when my old Def Tech sub had a hissy fit and died. I got a plate amp from Parts Express on sale for $150 and routed a bigger opening. My son says it is working fine after 2+ years.

 

[Berwhale]

My Logitech G604 is still suffering from double clicks. I suspect that there is some debris in the left microswitch. It is possible to clean inside the switch by carefully removing the cover, but given that I had to remove 37 screws to get to it, I might as well just replace the whole switch.

Update: I am glad I did not take up soldering as a career! I had to completely destroy the old switch to get it off the board (which was not unexpected). I just hope I haven't put too much heat through the replacement to shorten it's life. Anyway, all 37 screws are back in place and button seems to be working fine *click*

If there is any kind of audio angle here, it's that the Omron switches rated for 50 million operations (50M) are quite a bit louder than the ones rated for 10M, so my left mouse button is now louder than the right!

 

[Hipocrates]

My good old AVR kicked the bucket, but I'm sure is the regulated PS.

 

[restorer-john]

6 variable bench supplies to give just about any combination of rails for repair/design work. Inexpensive, accurate, very compact and pretty noise free (SMPS). Temperature controlled fans that very rarely come on and when they do, they quickly cool the unit and turn back off.

2x 0-30V@10A
2x 0-60V@5A
2x 0-120V@3A

 

[Doodski]

6 variable bench supplies to give just about any combination of rails for repair/design work. Inexpensive, accurate, very compact and pretty noise free (SMPS). Temperature controlled fans that very rarely come on and when they do, they quickly cool the unit and turn back off.

2x 0-30V@10A
2x 0-60V@5A
2x 0-120V@3A

View attachment 365021

I thought I died and went to heaven after I assembled the first analogue AC Volts and Amps meter box that I made for winding amps up on the variac. These DC supplies are wonderful.

 

[restorer-john]

These DC supplies are wonderful.

You can never have too many power supplies they say.

 

[Andysu]

top secret shhh is not yet on the bench only in theory at the moment , shhh top secret coming soon
i give you a hint , you are looking at it and it has ears

 

[Andysu]

I am curious what what is on your workbench right now. I am testing a "small" power amplifier module .

View attachment 47899

someone has there JBL control 1 priorities in order

 

[Doodski]

You can never have too many power supplies they say.

The bright red LEDs work very well for me...LoL. Does not get better for digital display down to high resolution thermal tracking under soak.

 

[egellings]

6 variable bench supplies to give just about any combination of rails for repair/design work. Inexpensive, accurate, very compact and pretty noise free (SMPS). Temperature controlled fans that very rarely come on and when they do, they quickly cool the unit and turn back off.

2x 0-30V@10A
2x 0-60V@5A
2x 0-120V@3A

View attachment 365021

3 different brands that look the same.