Harmon-Kardon TA-230 Stereo Festival baseline.

[electra225]

While I wait for the procedures to play out on the record player cabinet I'm working on, I thought I'd take the opportunity to do a baseline on projects I have on the back burner. I needed to move this receiver, so I decided to do an inspection to see if I wanted to service and use it, or just sell it. I've had this thing 35 years or more, never used it much and was not impressed with its performance when I did use it. I've never done anything to it.

Codes I have found indicate this thing is probably a late 1959 or early 1960 model. It does not have built in stereo decoder. All the tubes I saw were H-K branded Amperex except the output tubes. The original 7408 quad of output tubes has been replaced with GE 6V6GT's, coded the 39th week 1961. The Astron filter caps are coded the 34th week of 1959. Most of the small tubes are coded the 46th week of 1959. I checked several of the resistors in the chassis and found all but three that I checked had drifted more than 20% high. There are five electrolytic cap cans on the chassis. All but one checks good. There are four .047@600 volt bumble bee caps that should probably be replaced. I'll have to dig up service literature for this if I decide to go thru it.

[Firedome]

7408s maybe?
I had one and was not impressed either.

[Hi-Fi-Mogul]

Greg,
Would you give us a quick primer on how
to read date codes on vacuum tubes ?
Thanks !

[electra225]

Yes, Roger, sorry. Senior moment. 7408 is what I intended and will change the text to reflect that. Thanks for the better eyes than mine.

Mr. Mogul, in "Getting Started" there is the EIA codes. These codes, typically three numbers, tell the manaufacturer. Another code, typically two digits, tell the week, then a hyphon, then another two digit code that tells the year. So the output tubes were coded 61-39 then under that "188". Not only were the tube bases printed the the GE logo, but it was also coded in ink on the bakelite base. So the "61" would indicated 1961, and the "39 would indicated the 39th week. The "188" is the EIA code for GE. The filter caps in this receiver were coded with three numbers such as "935" The "9" would be for 1959, and the "35" would be for the 35th week. The codes were in ink on the body of the filter caps. Probably best until you get your feet wet with codes to just post them on here and let somebody help you until you become more familiar. It takes some practice to learn how to read codes, but once you get the hang of it, it makes sense. Maybe somebody else can jump on and explain it better than I did.

Are any of you aware of any tweaks that can be made to this receiver to improve its audio performance? Why would this receiver not sound at least as good as a Magnavox 88 series with similar components?

[TC Chris]

Maybe because you haven't recapped it yet???? Or replaced the drifted resistors???

Chris Campbell

[electra225]

I'm wondering how much affect drifted components actually have on this receiver design. One side of me says it's not worth putting the effort into, the other side of me says how do I know that for sure?

[TC Chris]

H-K was a higher-end brand back in those days, so it would probably be worth the effort. And if you didn't like the results, you could sell it, stating "all capacitors and out-of spec resistors replaced."

Chris Campbell