My EL34s in my Klemt S100 are drawing too much current

[overtone]

The Atom is not original and probably looks like the stick of dynamite below. You have a 40uF + 40uF? Perhaps there was a cap-can originally.

Usually I would replace the caps exactly as shown in the schematic with standard 500V axials, 33uF or 47uF in this case.

I did not understand the underlined part your description:
"Should I use 2 47uf caps tied together at the neg and routed individually to the end points of the current positive leads (one of which is gnd, or, use 1 cap and connect both wires from the positive to the single lead?"
I would expect one +ve lead to go to point 1 and the other to point 2 in the schematic ampgeek posted. Is that not the case?
If not, maybe you could you draw us, e.g. in the schematic from ampgeek, how that stick of dynamite is wired in?

[Structo]

Not sure where you live but AES carries F&T electrolytic capacitors.
I have used them in several builds and they seem to work fine.

http://www.tubesandmore.com/products/ca ... nd%3DF%26T

[El_ThirtyfFour]

Replaced the big old ATOM Dual cap with 2 47uF capacitors. First put them in backwards and that blew the fuse, then turned them around. When I turned on the amp, the tubes did the same climb up in ma draw to >200, as I was observing this, the power resistor suddenly smoked and melted. This is a 1K ohm tubular resistor, anyone have any ideas the watt rating I should use for the replacement?


I have purchased a number of capacitors to replace the most likely suspects.
There is another capacitor, pictured, that I plan to replace next.

[El_ThirtyfFour]

I hadent seen your replies above. Correct that it is a 40 40 and I replaced it as I mentioned with 2 47uFs which should be OK according to other info I looked at saying that the 40 40 was the same as 2 40uF caps, so replacement with 2 47uf s might have worked, but, the problem still persists and the power cap was roasted. Also, I agree the ATOM doesnt seem original.

Im not sure what to do, also the schamtics seem to differ from what was posted. This board is marked 205, and I am having trouble relating it to the schematics presented. I am exploring this board a bit with my voltmeter now that I have my probes back but the burning of the power resistor mage live reading impossible I think.

p.s. the amp still powers on but the tubes only get up to about 4.5ma now. The power resistor measure infinity.

[El_ThirtyfFour]

Yes, the capacitors I replaced connect at points 1 and 2 for the positive leads, similar to the schematic.

I am replacing the 2 caps with one F&T : http://www.tubesandmore.com/products/C-EC32-32-500FT

As a kind fellow suggested above. This is a 32 32uF 500V which seems more similar to the schematic. THe power resistor that fried is the one which connects points 1 and 2.

Any ideas as to why this happened are welcome.

Also, this orginal resistor is 1k ohm and tubular, I dont know the wattage, but it is about 1.25 inches long. Any ideas on wattage? Should I replace this with a tubular type, or can I use other types of resistors such as a wire wrapped or other?

[tictac]

Looks like at least a 10 watt resistor to me....

[El_ThirtyfFour]

I purchased some 25W wire wrapped that seem like they will work.

I am wondering why it fried since it spans the 2 caps I just replaced.

Ideas welcome

[overtone]

As I understand it, you refitted the E-caps after running them with the wrong polarity. Even though the fuse kicked in before they exploded, these E-caps are probably worse than useless now. Notice how the 1k dropping resistor smoked after you made re-fitted them. Looks like the 1k dropping resistor was shorted to ground.

These are simple mishaps and many of us have made them at one time and learn. But right now I am getting uneasy because it reads like you are getting in above your head. As stated in the article I linked to these amps demand a level of experience. This could be something very simple for a tech to sort out quickly.

To make progress you need to isolate the sections of the amp to find where the trouble is. We call this divide and conquer. The suggestions of ampfab and ampgeek on page one are spot on.

[Structo]

I agree, the caps are likely compromised.

[El_ThirtyfFour]

Yes, the possibility that the caps are dust has occurred to me, I already ordered a new, more suitable cap, (more like the caps in the schematic than that old atom was) see above link, to replace both with, an F&T 32 32 500V, this should arrive before the new power resistors.

I agree with the divide and conquer, when I get this new cap and power resistor this is what I intend to do, and actually, what I was aiming for when I turned it on and smoked the resistor.

When I get these parts, I will put up pics so I can be sure I am testing at the right points.

I am somewhat new to tube amps, though I successfully recapped a Tube amp radio a few years back, but I regularly fix hydrogen generators, gas chromatographs and process control equipment, - all solid state stuff with pumps and solenoid valves, but quite complex, and very dangerous, so things like resistors smoking and mistakes (like backwards caps) are not quite so scary and I take them in stride. I also wear rubber gloves and sometimes a wrist ground strap, plus use a very sensitive surge protector on the ac side. Unfortunatley my programmable power supplies I use to isolate individual subsystems dont handle enough current or high enough voltage for this amp, or the task would be easier as I could simulate the power supply as I do to test and repair individual boards.

Note: the transformer is set up to be adjustable for 6 or so different voltages, which are 150, 220, 130, 250, 110, 230 in the order they appear on the selector on the back of the amp. There is a sticker on the back which says : "In USA leave voltage setting on 130". I have it set on 130.

[Kazooman]

I suggest that you contact Bobby Staedel.

http://bobbysreparaturen.de/

He is THE go-to guy for all vintage German gear, especially things like the Klemt Echolettes. He might have a schematic for your Klemt amp and/or some very good advice.

[overtone]

...Unfortunatley my programmable power supplies I use to isolate individual subsystems dont handle enough current or high enough voltage for this amp, or the task would be easier as I could simulate the power supply as I do to test and repair individual boards.
...

I often test an unknown amp, tubes out, with a 2,3V supply from an old signal generator. (230V mains here) It is enough to locate goofy shorts etc, before running higher voltage.

Not sure if you have read the Ampgarage current-limiter sticky thread?
https://tubeamparchive.com/viewtopic.php?t=20341

tony

[El_ThirtyfFour]

Hi Everyone and thanks for your help.

I now have afully functioning - except for some dusty pots, Klemt S100 amp.

I replaced the 47uf caps I had blown by wrong orientation with the one Structo suggested: F&T 2x32uf http://www.tubesandmore.com/products/C-EC32-32-500FT

I replaced the 1K power resistor with one of these:
http://www.ebay.com/itm/390650110983?ss ... 1439.l2649
A 25W 1K,

This brought me back to the original problem where when turned on everything seemed fine but as things warmed up the amp began to distort and then fade out.

I replaced this ugly cap next pictured below, with one of these:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 1213282319

Now it works - and in fact - works really well.

Thanks everyone. This amp spent 15 years in my garage non functional and at least 10 in the backroom of the store where I bought it for 50.00 15 years ago. Now it lives again!

[Structo]

That is great that you were able to fix that.
Can you tell us where that cap was in reference to the amp?

This will help our data base about the amps we have been able to successfully given advice that resulted in a fix.

[overtone]

Yes good news!
I wonder if that was a coupling cap to one of the output tubes?
Voltage ratings seems a bit low though.