lowe_caps.pdf

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1、Lowe HF-125, HF-225, HF-235 and HF-250 (HF-150?) Common Electrolytic Capacitor Failures Even with the HF-250s extremely cool operation, there are TWO electrolytic capacitors on the main board that should be replaced in EVERY Lowe HF-125, HF-225, HF-235 and HF-250 (HF-150?) receiver on the planet. Th

2、is is a very common failure trait. Voltage stressed electrolytic capacitors C156 and 157 (both 100 uf at 10 volt rating) go bad or we should say are BAD. These should both be replaced with 100 uf ones having a 16 volt rating. Of course this is for the electronic savvy person and be sure NOT to use t

3、oo much heat and a small soldering iron tip and proper de-soldering device (otherwise damage will happen to the board), WARNING : Uses plated through holes. Be sure and use QUALITY replacement capacitors (nichicon etc) and some TLC. Both test samples suffered from these capacitor failures. Can lead

4、to strange wooshy-rumbling sounds in the audio to total receiver dropouts (including totally DEAD) and weird Sync operation. With the later sample the 8 volt regulator capacitor vented with some electrolyte oozed out (thank goodness no damage to the PC Board in this case, but it can happen). These a

5、re NOT surface mounted capacitors (standard radial lead type). With the front of the cabinet facing you C156 is located on the far left side, just right of the 2 voltage regulators ICs. C157 in located right in the middle of the PC board FRONT edge. Its a bit tight with the front panel metal shield

6、cut out area. Or see the HF-225 service manual for the detailed board location (its in the same location and part numbers). Another possible part failure is L46 (a 100 uh choke that becomes open). Receiver goes totally DEAD (display works). Dan Walkley in the UK reported this on You Tube. To properl

7、y disassemble the HF-250s cabinet (at your own risk) first one removes the 3 front panel knobs (volume and tone knobs: 1.5 mm, main tuning knob: 2.0 mm Hex type). Then carefully remove the 2 large Hex screws at each end on the FRONT panel (3.0 mm). The front panel then can be carefully removed. Next

8、 the interlocked piece on the top panel can be removed (slid out of its rear panel slot, use a PLASTIC screwdriver to get it started) along with its internal speaker and access to the PC boards. Do NOT remove the rear panel. IMPORTANT: Bottom cover removal has just 4 screws, but be careful as with o

9、ne of our test samples there were plastic (nylon) washers in between the cabinet and rear cover screws that can be very easily lost. I will NOT be held responsible for any info that is listed here ALL DONE AT YOUR OWN RISK ! Version 2.0 2021 Dave N9EWO, all rights reserved (This information / pdf not for distribution to other web sites or to be stolen / sold. thank you)