Venturing out into domestic radio repair,had to happen to progress - Page 1
Forum section: electronics / repair

author: M0BSW
author_rank: Frequent Contributor
timestamp: November 04, 2012, 05:39:49 pm
content: Well I'm expanding my radio repairing out of my comfort zone, I just bought a Pure DAB radio off E-Bay, which will be a change from my usual amateur radio stuff which I'm really comfortable with, it's supposed to power up, with dim back light and a faint buzzing, can't wait for it's arrival.Paul

author: SeanB
author_rank: Super Contributor
timestamp: November 04, 2012, 05:46:49 pm
content: 90% likely this has power supply capacitor issues. Built down to a price and using as cheap a cap as possible that hopefully will last the warranty.

author: M0BSW
author_rank: Frequent Contributor
timestamp: November 04, 2012, 06:05:09 pm
content: Quote from: SeanB on November 04, 2012, 05:46:49 pmHi Sean that's the first thing that crossed my mind too, I had a ham radio receiver in here Sat, similar fault , it was those two big smoothing cap, the ESR meter picked up huge resistance, replaced caps job done. Easiest £20.00p I made in a long time, I think this sucker is out of warranty ,I'll let my wife have it when I fixed it she's always wanted a DAB radio.

author: M0BSW
author_rank: Frequent Contributor
timestamp: November 04, 2012, 06:08:37 pm
content: Also if it has switching power I'm going to check not only the caps but the switching transistors and clamping diodes, also the resistors, i figure it to has to be the power end.

author: SeanB
author_rank: Super Contributor
timestamp: November 04, 2012, 06:30:54 pm
content: With a switching supply change all the secondary caps, any small 50v electrolytics 9 always suspect0 and any small electrolytics near the power devices on the primary side. Works in most cases.Just did an order to RS for a few parts, and went trawling through the 105C caps for cheap ones as stock. 100 on the way........ A few resistors as they go with the chip I ordered, so only a few cents more anyway, and a few MOV's and some tantalum caps to round things off. All local stock, so should be here Tuesday. 105 RS branded caps, and 10 Rubycon, and 10 Kemet, all in MOQ lots. All I wanted was the 10 Microchip Liion controllers to add to battery packs. Needed to get the order to a higher amount, even though RS does offer free delivery on Web orders.Surcharge on the phone, but the same online free.

author: M0BSW
author_rank: Frequent Contributor
timestamp: November 04, 2012, 06:42:28 pm
content: Sean think I just found the answer, I phone a friend of mine repairs TV's ect mains filter capacitor they are using is 15volts the power in rail is 18volts, that was the problem on his, and Capzons were fitted , doesn't look good, he replace them all with higher working voltages. he also reccomended RS.

author: SeanB
author_rank: Super Contributor
timestamp: November 04, 2012, 06:51:22 pm
content: Reminds me of an Everready branded radio I bought cheap ( it was cheaper than the battery next to it) and made a power supply out of an old phone power supply. Turns out they used a 10V cap on the input side of the radio and the PSU I used gave 12V unloaded. After 10 mins a pop and it carried on. Never bothered to change it though, too much bother and it works anyway. I looked in the other and saw they used a 220uf 10v cap in that position. Next wall wart gave 11V and the cap is still holding. genuine no name brand light pale blue Chinalytics.

author: M0BSW
author_rank: Frequent Contributor
timestamp: November 04, 2012, 06:58:49 pm
content: Quote from: SeanB on November 04, 2012, 06:51:22 pmThat's interesting these are supposed to freeze, unplug them , plug in again and they work , sound familier, can't wait for it to get here now, I wnt to get at it.