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Yamamaya42 04-04-2026 03:48 PM

Quote:

Originally Posted by timmy (Post 3266873)
Looks similar to the vt71 series Motorola

Most likely a clone of it,

And that's a Sansui 1000EA in the background.

Yamamaya42 04-04-2026 03:54 PM

Question is, what to replace that ugly 18 ohm sandbar resistor with once I replace that selenium rectifier with modern diode, random guess is 180 ohms, but what does people who have done these sets think?

Yamamaya42 04-06-2026 09:01 PM

the HV transformer look OK

http://suzaku.live-evil.org/20260406_202205.jpg

Except for the wire to the Rect tube broke.
It's very brittle

http://suzaku.live-evil.org/20260406_202224.jpg
that cap down there is shot.

timmy 04-07-2026 10:34 AM

Quote:

Originally Posted by Yamamaya42 (Post 3266902)
the HV transformer look OK

http://suzaku.live-evil.org/20260406_202205.jpg

Except for the wire to the Rect tube broke.
It's very brittle

http://suzaku.live-evil.org/20260406_202224.jpg
that cap down there is shot.

Looks don’t always mean good until it works

timmy 04-07-2026 10:36 AM

Those black caps were probably the best back in the day

Yamamaya42 04-07-2026 11:27 AM

resistance check of where that wire SHOULD go, to ground, checks OK, meaning the main HV coil is good.

For lack of any better idea, I will try a 180 ohm resistor in place of the 18, when I replace the selenium rect with a modern diode.

bandersen 04-07-2026 11:40 AM

No, that's much, much too large. I'd leave the 18. It's there for surge protection.

timmy 04-07-2026 11:42 AM

Quote:

Originally Posted by Yamamaya42 (Post 3266908)
resistance check of where that wire SHOULD go, to ground, checks OK, meaning the main HV coil is good.

For lack of any better idea, I will try a 180 ohm resistor in place of the 18, when I replace the selenium rect with a modern diode.

So you’re going to add a resistor while replacing the selenium so why don’t you check the voltages without putting a resistor in if you do need it ok you may not. All my Motorolas got silicon diodes and none of them have a resistor the voltages are all where they should be. You never know with the resistor it may be low.

Yamamaya42 04-07-2026 12:01 PM

Quote:

Originally Posted by timmy (Post 3266910)
So you’re going to add a resistor while replacing the selenium so why don’t you check the voltages without putting a resistor in if you do need it ok you may not. All my Motorolas got silicon diodes and none of them have a resistor the voltages are all where they should be. You never know with the resistor it may be low.

Replacing a selenium with silicon diodes always causes a raise in voltage, due to the better rating of the silicon diode.

I have 20 ohm 10w I will try, it should be ok, with the higher voltage from the SI diode.

timmy 04-07-2026 12:27 PM

Quote:

Originally Posted by Yamamaya42 (Post 3266911)
Replacing a selenium with silicon diodes always causes a raise in voltage, due to the better rating of the silicon diode.

I have 20 ohm 10w I will try, it should be ok, with the higher voltage from the SI diode.

Well yes voltage usually goes up with the change but all my sets never did

Yamamaya42 04-07-2026 08:58 PM

Most places say to add 100 ohms when you remove a selenium and replace it, anyway, I'm out of large adapt-A-caps T_T, I used 4 in my sansui, need more now.
Oddly enough, the 18 ohm sandbar was OK, still gonna replace it with a 20, and the 680 ohm was bad, REALLY bad, 1.2k ohms bad.

timmy 04-08-2026 09:44 AM

How many watts is the old 18 ohm

Yamamaya42 04-08-2026 10:45 AM

SAMS says 5w for the 18, and 1w for the 680, though they look to be bigger due to they are old dogbone sand types.

Yamamaya42 04-08-2026 07:57 PM

first cap done.
http://suzaku.live-evil.org/20260408_194417.jpg
http://suzaku.live-evil.org/20260408_194444.jpg

Waiting for more adapt-A-Caps

Yamamaya42 04-09-2026 01:02 PM

On the front of resistors, not sure yet, but there's prob goanna be a lot bad in the set, a random check of R64, which sams says to be a 150 ohm 1w, power to audio out, (brown, red, brown, silver 120 ohms 1/2 w) tested at 187 ohms. :(

Not sure why a 1/2w was in there, 6L6GTs (25V version) like their power for output, gonna replace it with at least a 1w 120 ohm when I do that cap.


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