- 2024
- Nov
- 2
A Westinghouse H-636T6 AA5+1 Radio - It lives*
This one was a nice example of a 6 tube AA5 - it has a tuned RF front end which amplifies the RF before it’s brought down to it’s IF signal that the radio demodulates the audio from. That gives it the ability to hear more stations - without any further tuning I was listening to a station 115 miles away during the day, something other radios have a hard time doing during the quieter night period.
Radio came to me not working, seller said “Won’t warm up.” I think the guy just didn’t know that the power was pull on, not turn on. Plugged it in, and bad filters - the characteristic loud 60Hz buzz said that immediately. The replacements are the two cylinders standing up in the upper right corner. Two 47μF @ 160V replaced the 40/40@150 there previously. That device was dead, high ESR and loss, and cracked potting.
That brought the radio back to life, but the across-the-line capacitor had to be changed as well. That’s a .047μF @ 630V that literally sits across the AC line, and helps reduce noise in the system. That’s the orange-red rectangle in the middle, a brand new film cap with it’s leads covered in spaghetti to keep it off of the AC below.
These go bad just because they have a lot of voltage on them, and age - the part in there was a type of capacitor called a bumblebee. They’re BumbleBombs now because they like to pop. Fine for the time, but they crack and leak and get moisture in the paper capacitor material, and pop.
The radio with all of its new parts. I tried to not disturb anything else. (That recent spaghetti purchase has been used a lot!)
The old parts. The bumblebee measured ok, but I didn’t do leakage. The electrolytic was dead, however. Notice how the leads on the ‘bee are bent weird? That’s how it was in the circuit. Someone hand-inserted the part decades ago and said “eh…good enough!”
The only thing it really needs at this point is a little bit of penetrating oil on the tuner, as it’s gritty - a flush clean with DeOxit helped, but some Kroil is in order here. It probably needs an alignment, not a big deal but that’s after the tuner is cleaned, and it needs the dial lamps replaced. Power cord could be changed as well, but since it’s one of those in-the-case style it’s going to need a bit of doing. I may just solder a new cord in the board and run it out the hole.
In all, it was a good find in my opinion, a nice clean example of a AA5, late enough that silver mica disease hasn’t taken over yet. It’s getting harder to find this kind of radio in good shape, so as soon as the lubricant arrives and I get it tuned up, it goes on the shelf in the living room for use.
I don’t know that there will be much for a third part, except to talk about how far off the alignment is. We’ll see, stay tuned!
Next part of this series: Coming evenutally.
Previous part of this series: https://wereboar.com … -h-636t6-aa51-radio/