Re: Harman Kardon receiver model hk680i (30+ years old): bad caps



Thanks for the confirmation that 1SR35-200 is equivalent to 1N4003.

Using flashlight and magnifying glass to peer into all the dark crevices of this receiver, I have identified 8 or so additional caps with this dark brown old glue at their bases--with corrosion visible on nearby component leads. I have my work cut out for me....

Re: Harman Kardon receiver model hk680i (30+ years old): bad caps

I was able to remove the old glue by carefully scraping with a modified wooden chopstick and then using a cotton swab dipped in acetone to remove glue residue that did not respond to scraping.

In addition to the diode near the corrosive glue shown above, I have found two more identical diodes on another board affected by corrosive glue. So I have three diodes I should replace.

But finding a replacement diode has not been easy.

These diodes are identified as “1SR35-200”...

Re: Harman Kardon receiver model hk680i (30+ years old): bad caps

Thanks for the input.

I didn't know that could happen with the glue. Nasty stuff.

When I first saw that brownish material, I thought it might be glue rather than cap leakage. But then I spotted the corroded screw (1 of 4 that fasten that circuit board to the receiver frame) just behind and between the two caps and the end of that resistor that appears crumbly so I figured it must be the corrosive cap leakage doing that. I have attached another photo that shows a better view of this corroded...

This 30+ year old Harman Kardon hk680i has a pair of identical caps (C23 & C24) that appear to have both leaked. These two caps sit on a board identified as the “power supply p.c. board.” I want to find equivalent or better new caps and replace these bad original caps.

Here is what I know about those two caps so far:

TK brand
2200uF +50% -10%
16V
85 deg C
“C-340” ?
height: 1”, 25mm
diameter: 5/8”, 16mm
lead spacing: 5/16”, 8mm

My problem is that I don't think I know enough about the...

Re: Sony telephone IT-B9 (15-yr old circuit board w/ Rubycon YK caps)

Good catch! So I resoldered those 12 points on CN1. Then scanned the rest of the board with a magnifying glass for other similar faulty solder connections but no others obvious to me anyway. Reassembled the phone and it tests good! The background white noise is gone. And a few test dials on the keypad worked as they should.
Thanks.

I have a 15-year old corded Sony telephone model IT-B9. This phone started exhibiting some flakiness. For one thing, it developed a relatively loud background white noise. The other thing, when I punched in a phone number on the keypad, it would not consistently complete the call.

Anyway, I decided to open it up to see if there was an obvious problem.

There are 17 radial electrolytic capacitors on the circuit board (all Rubycon YK). However, none show any obvious signs of leaking or bulging.

1 x 0.22uF 50V (C91)
4 x 2.2uF 50V (C94,C95,C97,C98)...

Re: New Members - please post your introductions here

I decided I have discarded/recycled too many electronic items that had degraded due to bad caps. I have had a couple of motherboards with bad caps fixed by pros. But since I have had some soldering experience over the years, I thought I would make an effort to take on the task myself where a bad cap is obvious and the situation is not too complicated.