- Harman Kardon 930 lost channel. Hoe to trouble shoot ? - 2 Updates
- Can I remove the choke? - 3 Updates
| Steff <e-post.nu@gmx.com>: Oct 05 05:54PM +0200 Well just lost a channel at my Harman Kardon 930 Vintage geek as I am I want to keep my great Reciver and repair it.. What I done sofaar Check Fuses ( They are OK) Moving the speakers between the channels left-Right And A and B speaker outlets. With this info I understand that the left Channel is ALMOST dead turning the balance to Left channel I can hear a faint OK sound. (Like the tiny transistors trying their best before the end power transistors do their job. My conclution. 1 Not enough power to the end transistors on the left channel. 2 Broken End Trasistors (two 2SC897 according to the scematics) 3 End of preamp broken on left channel. Most likely End transistors.. Is my thinking OK or did I miss something ? I am a beginner in HiFi electronics but have basic skills in electricity as an electrician for 25 years and do know how to solder.. |
| John-Del <ohger1s@gmail.com>: Oct 05 09:11AM -0700 On Friday, October 5, 2018 at 11:54:11 AM UTC-4, Steff wrote: > Is my thinking OK or did I miss something ? > I am a beginner in HiFi electronics but have basic skills in electricity > as an electrician for 25 years and do know how to solder.. Normally, blown outputs (is this what you mean by "end"?) will open fuses or low value resistors. You really need a meter to go farther. If you get one or have one, you can compare voltages and resistance from the good side to the bad. If the receiver has a pre-amp out and in (or tape monitor) arrangement, you can reverse those to see if the problem trades sides. If it uses metal U shaped jumpers, remove them and use RCA patch cords to cross swap. |
| Terry Schwartz <tschw10117@aol.com>: Oct 04 02:03PM -0700 If you want to restore the functionality of the original "choke" which is actually a ferrite bead, you'd need to find the equivalent of the original part. And it's not like they are marked. Just cut it off, it'll work fine. Those are placed on there to meet regulatory requirements. The radiated emissions levels from common equipment are very low, and the susceptibility of adjacent equipment is very good. You'll have no issues. I spent several years running an EMC lab. I had a hand in putting those ferrites on many pieces of equipment, not to solve a real problem, but to get the equipment to comply with regulations. There were a very few cases where the ferrites were installed to solve a susceptibility problem, one that happened at ridiculously high field strengths in every case. On Thursday, October 4, 2018 at 3:15:21 AM UTC-5, Clifford Heath wrote: |
| oldschool@tubes.com: Oct 04 05:44PM -0500 On Thu, 4 Oct 2018 10:09:32 -0400, Ralph Mowery >include the wireless mouse and keyboard or wifi modem that is used with >the computer you are using. Mostly rare cases, but can hapen. >FM radios may not work well that are near by. Thanks for everyone's help!!! |
| Look165 <look165@numericable.fr>: Oct 05 10:02AM +0200 Indetails : In DC annd LF (50/60 Hz), cooke doesn't change anything In HF it make the impedance od the cale higher so, HF in return is blocked to comply EMC rules. It is a common mode dual inductance. It is easy to create one with a suitable toroid and somes turns of the 2 wires in //. The ferrite must be high Q and high µ values. |
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