Ok I see what you mean. They appear to be ok. I have heard of the ten ohm smoke but didn't know what it was. Haha.
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X-Force 600HD Smoked
- Thread starter Shadetree Mechanic
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- x-force
Gotcha - not meaning to send you on a wild goose chase, lol. I’ve managed to blow up a couple amps (doing stuff I shouldn’t have been) and the little 10ohm was a tattle-tale every time.
Haha, no problem at all on the goose chase. I appreciate you taking a look and giving your input. I wonder if the transistor can go open without burning the 10 ohm?
I like posting pictures because I hate reading stuff without them and the pictures help to put everybody on the same page. Looking for a set of HG and will probably change all 4. Do all 4 need to be matched or just the pairs?
My opinion on that won’t go far...haha.
Back in the Toshiba days, I never replaced anything but the offending transistor and I didn’t have any issues.
I don’t believe I’ve ever owned an amplifier with an all matched set...and I highly doubt my DX500 has them.
That said, DEIs and HGs probably aren’t as consistent as the Toshibas were. If you were going to do any matching, I suppose a matched quad is what you’d really want...any difference in the two sections would be felt across that combiner resistor.
Back in the Toshiba days, I never replaced anything but the offending transistor and I didn’t have any issues.
I don’t believe I’ve ever owned an amplifier with an all matched set...and I highly doubt my DX500 has them.
That said, DEIs and HGs probably aren’t as consistent as the Toshibas were. If you were going to do any matching, I suppose a matched quad is what you’d really want...any difference in the two sections would be felt across that combiner resistor.
It was doing about 450 average and 600 peak on my Autek WM-1. I think someone built a 16 pill from those plans and he had to do some more work to get it going. I don't remember if it was the combiners or transformers or what. There was a thread on it but I didn't think to link it to the plans thread.
Here’s the 5 watt Vienna sausage sized resistor they used in the “Powerplate” amps.
Shadetree, typically when that combiner resistor fails its due to output issue or SWR. Considering that you antenna SWR is likely fine, I would look into not replacing the 2w with a 5w resistor , but more likely your issue is that ceramic disc capacitor failed creating a matching issue on output. You will likely have to replace that and preferably tune the output with a capacitance tube that offers variable Capacitance. Not sure what Voltage rating is on that cap but, my guess that's the culprit . I wouldn't cover underlying issue with bigger resistor . GL
Thanks for your input 44, I thought that I would see the trombone tube capacitor when I took the lid off and was surprised that it didn't have one. I will have to pull the disk capacitor out and check it. Would the output be tuned for peak output like a tube amp?
The brass trombone cap is generally used on 6 pills and larger. It is part of the LC circuit that tunes the combined 2 or 4 pill sections.
I have saw some dud pills not burn the 10 ohm resistors from collector to ground. I would lift the tabs on each one and test them. I would also check the caps as 44 mentioned.
Those big sandbar resistors are part of the bias circuit.
You are correct about the balancing resistors. They should not heat up. If they do, there is an imbalance. A 5w resistor might make it run. When I reworked my 16 pill I used half watt resistors and hammered if for a few minutes. Then touched each resistor with a dab of heatsink compound on my finger to make sure they weren't. After that I put the 2 watts back on.
I am anal about balance. Matched pills and hand picked caps that test the same. With the price of Toshiba 2879s we have to be less picky or move on. Fortunately I have all the pill amps I'll ever need.
I've also heard the non Toshiba's tune differently and most builders just keep connecting the dots and use the same value caps. I haven't played with any so I can't say.
I have saw some dud pills not burn the 10 ohm resistors from collector to ground. I would lift the tabs on each one and test them. I would also check the caps as 44 mentioned.
Those big sandbar resistors are part of the bias circuit.
You are correct about the balancing resistors. They should not heat up. If they do, there is an imbalance. A 5w resistor might make it run. When I reworked my 16 pill I used half watt resistors and hammered if for a few minutes. Then touched each resistor with a dab of heatsink compound on my finger to make sure they weren't. After that I put the 2 watts back on.
I am anal about balance. Matched pills and hand picked caps that test the same. With the price of Toshiba 2879s we have to be less picky or move on. Fortunately I have all the pill amps I'll ever need.
I've also heard the non Toshiba's tune differently and most builders just keep connecting the dots and use the same value caps. I haven't played with any so I can't say.
Nice amp. Yes that is a class B TnT built by X-Force. Before that they came in a redish maroon case and were called Magna Force.
Yes it is a TNT.
Dog gone it Man! That sucks. Hope you get it up a running soon.
Dog gone it Man! That sucks. Hope you get it up a running soon.
Too much DK for DEI's....need to keep the carrier @ 100w or less...150w a bit high...I've got a XForce 1x4 base amp with DEI's and no problems even after 3 years...but, I keep the carrier at 100w and let it swing from there.
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