Egnater Rebel 20 let out the magic smoke !

[digitaldrummer]

I've got an Egnater Rebel 20 amp head (and 1x12 cabinet). I've had it for 5-6 years probably and I think I got it from the original owner. Seems like these were made 2008-2014, so I'm sure this one is at least 10 years old (and they were made where everything else is made cheaply).

Anyway, was minding my own business and recording some guitar the other night, stopped to listen back and smelled that smell (no, not that smell. The burning silicon smell) and saw that the pilot lamp was off... so I ran over and powered off, unplugged, etc. Egnater is now a fried egg & tater.

After looking it over several times, I finally noticed that there was a little of that blackened chicken residue next to one of the rectifier diodes (D102 = 1N4007), so I plan to replace both of those. Of course the fuse popped. Have a spare but ordered a few more just in case it's more than the diodes (like a tube - although they look fine). One the upside, these diodes are just on the north side of the power transformer (meaning power gets through the transformer) so I'm hoping that means the PT is OK. Mercury Magnetics has a replacement but it's >$250 + tax + shipping and that will make this unfixable - at least for me, since I only paid $300 for the head and cabinet. There is a secondary 0.5A fuse after the standby switch and it is still good. Also found schematics online which is helpful (as I hear Egnater is NOT helpful - and it sounds like Bruce sorta split with them and they are now defunct, or at least the partnership with Boutique Amps Distribution is).

I miss the days then I could run down to Radio Shack or Fry's Electronics, but unfortunately both have closed all stores near me. Mouser is only about 3 hours from me, so I can get next day ground delivery, but that still adds about $10 to the cost, so I usually only do that when I'm ordering lotsa parts. So Amazon it is. I thought I had a bunch of these, but I only had 1N4003 (1N4003 would be OK for 115V, but this has the capability to switch to 230V, so I want to put in the correct values just in case it lives a long a fruitful life and gets to travel to Europe some day) ... Anyway, supposed to get a pack of 25 generic (or at least a brand I don't recognize) 1N4007 tomorrow sometime for ~ $5. I'll buy some extra real one's next time I order from Mouser.

[floid]

Are these the diodes for the B+ rectifier? I'd suspect something downstream pulled too much current and that's the real issue. A dim bulb tester is useful for when you don't want to endlessly replace fuses while hunting down a problem like this

[digitaldrummer]

when I disassembled the unit (lots of wires to remove before you can pull the board out), it looks like the first big electrolytic filter cap (C127) is the culprit. there is a big skid mark next to it - while it kinda looks like a shadow in the photo, it's not. Anyway, I had to order from Mouser.com after all and those parts are coming later today... I may replace the diodes, but they don't seem to be shorted (or open) so they may be ok still. plan to replace a few other caps in the power supply area too (3 x 47uF/450v) as a preventative (they are cheap, "Secon" brand). Coulda ordered some F&T's but didn't want to wait.

cap_blowout.png (869.5 KiB) Viewed 6513 times

[floid]

If I'm reading the schematic correctly, it looks like the only load that cap sees when in standby is r116, so there's probably quite the difference in voltage at that node when on vs in standby. That cap's probably had a rough life.
What brand/ type replacement did you order?

[digitaldrummer]

I ordered a Kemet - which I know is not the best out there, but it was availability for a similar size and even then I'm hoping it fits height-wise as it has to fit when the chassis is installed back in the cabinet. I don't like the 2000 hour life for sure... (vs say a Nichicon with 12000)

https://www.mouser.com/datasheet/2/212/ ... 101279.pdf

[digitaldrummer]

Success! It is working again. The 100uF cap was about 1mm taller than the original, and then the lead spacing was 7.5mm instead of 10, so it didn't sit completely flush on the board. I was afraid it might be slightly taller than the chassis, which means when it was actually mounted (upside down in the cabinet), it might have the weight of everything pressing against the bottom of the cabinet... So I jacked the chassis up on a coupla washers and it holds it up high enough I can see light - in other words nothing touching the top of the cap. a bit of a hack but it works fine.

I replaced the diodes (even though they were probably fine) and the 3 x 47uF caps. Probably coulda waited, but hopefully these extend the life a bit. I did manage to pull off one solder pad - and even though I cut the caps out and then tried to de-solder, it's difficult to get them hot enough to melt the solder (with big ground planes) and not melt off the pad... So I soldered 2 of the legs together on the ground side. Not the prettiest but it also works fine.

[floid]

Excellent! Lead space, radius, and height are every bit as important as electrical specs often enough that I like to pull out the calipers to make sure -try recapping a tektronix or 70s Japanese power amp without those specs.
I used kemet caps in my valco national and it's held up well for over a decade. These days i prefer Nichicon or Panasonic with at least an 8K hr rating for radial caps, and am constantly impressed with the footprint, but a successful recap is always worth celebrating.

[digitaldrummer]

you don't always notice it until you get a project like this, but "miniaturization" is still happening. Even in the last 15-20 years or so since these amps were in design/production, the components have shrunk. it was pretty easy to find caps that still have the 7.5mm spacing, but getting 10mm spacing was difficult (at least Mouser did not stock many options for me) so I had to go to the 7.5mm spaced cap, which I suspected was going to cause trouble. So many radial Electrolytics have even gone to 5mm spacing or smaller (for smaller values/voltages). So while going smaller generally makes it easier to fit, sometimes it can make it more difficult too!

[floid]

It's happening to resistors as well - the new line of vishay 1 watt resistors are the same size as 1/4 watt resistors, the 3 watters from the same line aren't much bigger.

[digitaldrummer]

It's happening to resistors as well - the new line of vishay 1 watt resistors are the same size as 1/4 watt resistors, the 3 watters from the same line aren't much bigger.

I don't usually have trouble fitting resistors since they are 99.9% "axial" lead so you can stretch them out a bit -- but yes, they are getting a lot smaller too and it's difficult to read any writing on any them anymore too! Sometimes a magnifying glass is not even enough. I just bought some 4x readers (to use as magnifiers- otherwise wow they hurt my head) and sometimes I have to take a picture with my phone, if it will focus, and then zoom/blow it up to read the markings! But I'm kinda glad they put number codes on some of the resistors now because I'm color blind and that's always been a problem when trying to figure them out in-circuit...

[vvv]

... sometimes I have to take a picture with my phone, if it will focus, and then zoom/blow it up to read the markings!

I gotta do that to see my ...


... bank balance.

[floid]

... sometimes I have to take a picture with my phone, if it will focus, and then zoom/blow it up to read the markings!

I gotta do that to see my ...


... bank balance.

Don't we all these days.

[floid]

It's happening to resistors as well - the new line of vishay 1 watt resistors are the same size as 1/4 watt resistors, the 3 watters from the same line aren't much bigger.

I don't usually have trouble fitting resistors since they are 99.9% "axial" lead so you can stretch them out a bit -- but yes, they are getting a lot smaller too and it's difficult to read any writing on any them anymore too! Sometimes a magnifying glass is not even enough. I just bought some 4x readers (to use as magnifiers- otherwise wow they hurt my head) and sometimes I have to take a picture with my phone, if it will focus, and then zoom/blow it up to read the markings! But I'm kinda glad they put number codes on some of the resistors now because I'm color blind and that's always been a problem when trying to figure them out in-circuit...

The vishay line I referred to are impossible to read. They picked the perfect shade of brown to ruin color contrast for red, orange, brown, gray, purple.

[digitaldrummer]

getting way OT now, but sometimes I use an app on my phone - it's called "color grab". For Android (only I think). anyway, you point the camera at something and it tells you the color. it works OK, although for resistor bands it's touch and go since it's difficult to hold it steady on such a tiny thing, and the colors bleed on these things anyway. but it works well on bigger things.

[vvv]

I bought one of those reading assist magnifriars onna stand - lens is like 9x11" and it mags ... 5x?

Got lights and shite, it was for moms but didn't help her so I took it back to repair pedals and solder cable, etc.

Got it back at the end of Spring, and haven't heated a iron all summer.

But bright lights and the blow-up factor may make it a option for this kinda stuff ...

https://www.amazon.com/gp/product/B00GY ... asin_title