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February 25, 2024, 02:17:13 PM

Author Topic: Ecc81 red plating. [resolved]  (Read 649 times)

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Online Paul Birkeland

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Re: Ecc81 red plating.
« Reply #15 on: February 10, 2024, 10:35:34 AM »
If the zener diodes fail, I think the 90.9 ohm resistor can pop, so having some spares of that wouldn't hurt either.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Rob Capizzi

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Re: Ecc81 red plating.
« Reply #16 on: February 10, 2024, 11:09:49 AM »
Yes back in November the led and mje popped, so I replaced thoes along with the zener string. I didn't know the 90.9 would suffer.  I will check mine and order some. Thank you.

Offline Rob Capizzi

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Re: Ecc81 red plating.
« Reply #17 on: February 10, 2024, 12:31:31 PM »
The 90.9 is reading 32.7 and looks Blown underneath. 

Online Paul Birkeland

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Re: Ecc81 red plating.
« Reply #18 on: February 10, 2024, 01:44:46 PM »
Yeah, so definitely pull that, probably best to replace the zener diodes under that board.  With the transistors out, you can set your meter to diode mode and check that the LEDs read about 1.5V in the correct direction and nothing in the other.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Rob Capizzi

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Re: Ecc81 red plating.
« Reply #19 on: February 12, 2024, 03:29:48 AM »
Back in November I replaced those zener diodes already I just didn't notice that 90.9 was burnt I will check the zener diodes again also should I replace the 431 on B3 as well?

Online Paul Birkeland

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Re: Ecc81 red plating.
« Reply #20 on: February 12, 2024, 04:38:08 AM »
It wouldn't hurt to do that while you're in there.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Rob Capizzi

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Re: Ecc81 red plating.
« Reply #21 on: February 18, 2024, 05:35:59 AM »
Hi, so on amp B,  I replaced the 90.9 and the 431 on both the nine pin socket and the board. The tube is not red plating anymore.  I'm glad I asked about stocking up on Parts because I should have checked that resistor. Maybe that was the issue thank you for all your help. Here are my voltage readings for amp B and A
Terminal
Amp (B).      ( A)
1.     447.       446
5.     64.          68
6.     64.          68
9.     231.        220
10.   0.            0
11.   282.        285
12.   207.        213
13.   0.            0
14.   133.       141
15.   60.          69
16.   467.       463
17.   0.            0
18.   0.            0
19.   232.        214
20.   0.            0

4pin
1.  67.             72
2.  446.           445
3.  0.               0
4. 62.             67
9 pin
1.  229.          220
2.  0.               0
3.  2.48.          2.49
4. 3.1ac.        3.1
5.  3.1ac.       3.1
6.  356.          357
7.  0.              0
8.  4.              4.7
9.  3.1ac.       3.1

« Last Edit: February 18, 2024, 06:33:58 AM by Rob Capizzi »

Online Paul Birkeland

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Re: Ecc81 red plating.
« Reply #22 on: February 18, 2024, 06:16:48 AM »
Paul "PB" Birkeland

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Offline Rob Capizzi

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Re: Ecc81 red plating.
« Reply #23 on: February 18, 2024, 06:35:14 AM »
Oops. Yes. I fixed it and also added the voltages from amp A.
The majority of the work was done on AMP B the only thing I've done so far to amp a is replace the mje because I did it on AMP B

Online Paul Birkeland

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Re: Ecc81 red plating.
« Reply #24 on: February 18, 2024, 07:43:02 AM »
Those look like working voltages.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Rob Capizzi

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Re: Ecc81 red plating.
« Reply #25 on: February 20, 2024, 02:07:15 PM »
All seems and sounds great!  Thanks so much.