Just my thoughts of fixing those old Browning 180 amps. About 1/2 of them I have had, the transformer itself was blown. Most often if the trannie is blown, it has overheated, spilled its guts, smells bad and if you plug it in, will pull a lot of amps and blow the fuse. When bad, I replace it with this heavy duty Toroid from Ebay. [ Ссылка ]
That Ebay Trannie has all the voltages the amp requires with more than enough amps. The High Voltage needs 600v center tapped which this has with the 2 300v taps in series. Plus the torroid has two 6.3v 2a filament power that would be hooked in parallel giving you 6.3 at 4a.
The other thing that goes is of course those HV electrolytic caps. Originally called for 500V at 40Uf. The power supply in this runs at around 850V so the more common 450V caps (2 used in series would give you 900V) the tolerance or headroom would be too close. I use 500V or even 600v if I can find them at a good price, or since I often have plenty of 450V laying around, I have used 3 of them in series instead of 2. In series increases the voltage rating, but reduces the total capacitance. Original with 2 in series the UF's would be 1/2 the 40 so 20UF. Actually upping the UF's to a certain point is a good thing. Better filtering and lower voltage drop. When I go with 2, I use at least 68UF or sometimes even 100uf. When I go with 3, and the Uf's are at 1/3, I go with at least 100uf or preferred 150uf's. With electrolytics in old tube equipment, I do not test nor attempt to refurb caps, especially with the HV. I replace them.
The HV also uses a bridge Diode circuit. The Bridge Diode circuit in the amp is originally in 1 package. The Black thing with 4 legs. All that is is 4 diodes configured in a common bridge circuit and encased in one package. Like a chip with many circuits in a single package. Sometimes 1 of the Diodes in the bridge will go and since diodes nowadays are very small and very cheap, its easier to just replace the original 1 package bridge with 4 (or 8 if you want more safety headroom) common 1a or 3a 1kv diodes. I use 3a 1kv as I have a lot of them on hand already for bigger amps.
That old open frame relay, the contacts get dirty and need cleaning. I take apart the relay and burnish the contacts with a burnishing tool. I have seen a few where the relay coil is open. Note that the relay is a high voltage 120vdc relay if it needs to be replaced.
Last, note that this amp when the power switch is in standby the HV to the amp is turned off. However when the amp is in the On position, the HV is applied and the tubes/ transformer and everything else are cooking a little. Don't leave this old classic running for long periods of time with the power switch in the On position. I believe that will also contribute to the cooking of the tubes and transformer.
