HARMAN KARDON AVR235 repair

[budm]

Got this one in on Saturday, power up with display but no sound.
Blown open fusible resistor (2.2 Ohms) due to shorted out ceramic cap (0.1uf 50V).
The cap is connected across the 34VAC (48V Peak) winding of the transformer through the fusible resistor, the 50V (34VAC) rating of the cap is too low. I replace all the ceramic caps on the PCB with 100V rating instead (there are four 0.01uf, two 0.1uf for two windings of the transformer).
An easy fix with $5 worth of parts.

[newbiesat]

Re: HARMAN KARDON AVR235 repair

Thank you budm for your info and congrats. Have a question about those replace caps .... Are those caps located in the same board ??? CUP 11747-4 or CUP 11747-5 in schematic ??

[budm]

Re: HARMAN KARDON AVR235 repair

They are all on the same board mounted on the transformer. The service manual shows 0.47 and 0.33 Ohms but all 4 (R104, 105, 106, 107) on that board are 0.22 Ohms.
Post 1 was typo as 2.2 Ohms, it should be 0.22 Ohms.
Sch CUP 11747-5

[newbiesat]

Re: HARMAN KARDON AVR235 repair

Budm,
Where do you get those fuse resistor ? Do digikey or mouse have it ? What is the specs on those resistor ? Thanks.

[budm]

Re: HARMAN KARDON AVR235 repair

I have the fusible flame proof years ago, they are really have to find them in stock, you can use the flame proof MOX type instead, it will still blow open if there is shorts circuit and not catching on fire.
http://www.digikey.com/product-detai...0TR-ND/2021716

[retiredcaps]

Re: HARMAN KARDON AVR235 repair

Good work and thanks for sharing.

I attempted to fix a H/K receiver, but I couldn't get the bloody boards apart and I eventually gave up.

The person who received it works on AV equipment as was able to repair it quickly.

[budm]

Re: HARMAN KARDON AVR235 repair

BTW, if you cannot find 0.22 Ohms, you can use 0.33, or 0.47.

[Moreno83]

Re: HARMAN KARDON AVR235 repair

Is it ok to use electrolytic capacitors for those caps?

[Andrew F. Ali]

Re: HARMAN KARDON AVR235 repair

Nice work BUDM. It is an easy fix for one who knows where to look. Great job!!