Recent content by wattsabundant

I'll bet they don't publish any time/current curves.

If you read the troubleshooting section off the service manual, and do exactly what it says, you'll likely find the trouble. Note that the manual was written before we had digital meters. You can invest in an analog meter like a Simpson 260 and follow the manual verbatim.

Try slowly opening a knife switch with 100 VDC and watch the fire ball. With care you can sustain a very nice arc, right up until it melts down into a puddle. My bleeder resistor is hard wired to test probes. When you make the connection to the charged cap, jam it on there and leave it for a...

For discharging caps there are plenty of options available. If some kind of a mechanical switch is to be used, the contacts must be rated for the DC voltage applied. Any ice cube relay is rated for 250 VAC and 32 VDC. The reason for only 32 VDC? When the contacts open, arcing occurs as any...

Here's an EBAY link for the switches I used. EBAY link To clarify the listing appears to be the same as what I used. Have to be careful using a switch on the bleeder resistor. Contacts rated for 100 volts DC are rare. I don't have a switch on my bleeder.

A few things to consider: Ideally, the fins would be facing inside so the fans push air across them. A switched 1:1/10:1 voltage divider that feeds the scope. The first time I did that I used 1k and 10K. WRONG! 10K and 90K or some multiple of that. You mentioned you will have two monitor...

Unlike electrolytic caps, which becomes open as the electrolyte dries out, the failure mode of tantalum is a short. The attached document discusses tantalums on page 5.

Yep, same here. That is one of few exceptions to my rule that semis are run to fail. I see people buying these repair kits on EBAY and change out every transistor and diode. Changing out diodes and transistors that haven't failed does not improve reliability. The potential damage to the...

Did this thing take on water? Otherwise, it's not common to see rust on transformers. The Luxman I'm working in has the same glue/resin all over the place. I don't think it's glue because the same gunk is under 1/4 watt resistors. There is none under the electrolytic cap, just around the...

One of my post retirement gigs is doing repairs (amplifiers/receivers) at Stereo Lab in Columbus Ohio. Although the facility is relatively large, consoles take up a lot of space so I usually pick up the unit, fix it at home and drop it off when it's done. What's wrong with these photos...

The data sheet tells it all. Who knows what it sounds like, but it does protect itself.

As one of my post retirement jobs, I'm doing repairs here and there for a local shop, Stereo Lab, In Columbus Ohio. Many years ago there were Japanese data manuals for semiconductors. One that is very beneficial for vintage gear is the Transistor Substitution Manual. The latest version I have...

Every time you replace the fuse you do at least $50 more damage. With both output modules removed, bring it up with a 60 watt bulb or so and a 5 amp fuse. If successful discharge the caps and install one module and bring it up on a 100 watt bulb. If the bulb doesn't dim then switch to the...

I have the drop-in relay board. Also have a few of the power switches. Highly recommend my triac power switching board to avoid switch failure.

Jump on it. URIE is high quality pro gear. If you don’t like it, I’ll buy it.