UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Trio W-38 servicing process

qualityten · 19th Aug 2010, 10:03 am

Following the advice of Michael and Station X, here are my measurements:

There is no resistance at the mains plug (with a 3A fuse in place and a 2A in the amp fuse socket).

With rectifier removed, the heaters and bulbs do light up. With 40W lamp limiter bulb in circuit the lamp is 'quite bright'.

Emboldened, and still with rectifier out, I switched on full power to measure the transformer (sorry Kat). Heater circuits provide 5.6V to the MPX decoder and 4.6 to the heaters.

I then measured the other power taps. Here is where my knowledge of transformers is limited. From left to right there are four numbered 0 -115 - 0 -115. Numbering these a (0), b (115), c (0) and d (115), I get:
a-b 119V; a-c 119V; b-c 0V; c-d 119V.

I didn't leave the transformer on longer than necessary to take these readings. Here's hoping they don't mean it is damaged. I fear that the a-c and b-c ones are not what they should be?

19th Aug 2010, 10:03 am	#19
qualityten Octode Join Date: Feb 2009 Location: Wallasey, UK. Posts: 1,314	Re: Trio W-38 servicing process Following the advice of Michael and Station X, here are my measurements: There is no resistance at the mains plug (with a 3A fuse in place and a 2A in the amp fuse socket). With rectifier removed, the heaters and bulbs do light up. With 40W lamp limiter bulb in circuit the lamp is 'quite bright'. Emboldened, and still with rectifier out, I switched on full power to measure the transformer (sorry Kat). Heater circuits provide 5.6V to the MPX decoder and 4.6 to the heaters. I then measured the other power taps. Here is where my knowledge of transformers is limited. From left to right there are four numbered 0 -115 - 0 -115. Numbering these a (0), b (115), c (0) and d (115), I get: a-b 119V; a-c 119V; b-c 0V; c-d 119V. I didn't leave the transformer on longer than necessary to take these readings. Here's hoping they don't mean it is damaged. I fear that the a-c and b-c ones are not what they should be?