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Techman · 2nd Jul 2020, 12:45 am

The original ones could be OK.

Don't jump to conclusions regarding their state until you've gone through the reforming process with them - this will very soon show whether it's one of them that has caused the problem with the transformer.

The best thing to do is to replace the two coupling capacitors to the output valves and use the lamp limiter in series with the mains input to test the state of play when you re-fit the mains transformer. With a 'lamp' in series with the mains supply, very little damage can be done if anything goes wrong and you can assess the unit for potential faults and take readings - particularly the HT voltage, remembering that it will be a bit on the low side due to the series 'lamp', but it gives you a rough idea of any problems. Assuming that it has a valve rectifier, it would be a good idea to power up first with the limiter with this valve removed, obviously there will be no HT at this stage, but it tests the heater circuit etc.

If the amplifier originally had 500 volt rated smoothing, then that's what it needs - and NO less, so test and reform the originals if possible.

2nd Jul 2020, 12:45 am	#23
Techman Dekatron Join Date: Nov 2009 Location: Lincolnshire, UK. Posts: 5,000	Re: Linear L50 Mains transformer Fault The original ones could be OK. Don't jump to conclusions regarding their state until you've gone through the reforming process with them - this will very soon show whether it's one of them that has caused the problem with the transformer. The best thing to do is to replace the two coupling capacitors to the output valves and use the lamp limiter in series with the mains input to test the state of play when you re-fit the mains transformer. With a 'lamp' in series with the mains supply, very little damage can be done if anything goes wrong and you can assess the unit for potential faults and take readings - particularly the HT voltage, remembering that it will be a bit on the low side due to the series 'lamp', but it gives you a rough idea of any problems. Assuming that it has a valve rectifier, it would be a good idea to power up first with the limiter with this valve removed, obviously there will be no HT at this stage, but it tests the heater circuit etc. If the amplifier originally had 500 volt rated smoothing, then that's what it needs - and NO less, so test and reform the originals if possible.