Amp/Preamp Asylum

Quad 405 amp resistor question

184.102.104.44

Story

A

I've heard a few pops here and there when I turn it on after 5 minutes in my Quad 405 left channel so I decided to take a peak. The original boards were replaced about 8 years ago with aftermarket boards that have worked perfect ever since.

I found one burnt 1/8 watt resistor, it measures 10 ohms and looks like a military type with blue body (no color code now), but beneath it on the board it says 22 ohms. I put a 1/8 watt 22 ohm regular resistor in its place but the channel has a very slight distortion.

Now I'm not sure if it was a value change during production and I'm using the wrong approach

Any suggestions on what else to look at or try? Thanks in advance

Follow Ups:

RE: Quad 405 amp resistor question - airtime 06:47:14 09/29/24 (1)
If that's an 80's amp you really should have it restored. It's well past it's burn out date.
- RE: Quad 405 amp resistor question - Story 09:50:22 09/29/24 (0)
  If I did not mention it, it was already rebuilt years ago
RE: Quad 405 amp resistor question - Jonesy 20:32:09 09/19/24 (1)
Sending you this link to Keith Snooks site. Not sure if it will help with after market boards, but it also includes a link to a service manual with several pcb itinerations. In fact there are many links throughout that may be helpful, including the mods he describes.
I think I may have sent it to you (or someone here?) once before but here it is again.

Jonesy

"I know just enough to get into trouble. But not enough to get out of it."
- Quad 405 (Open in New Window)
Edits: 09/20/24
- Thanks Jonesy /nt - Story 03:11:17 09/20/24 (0)
Just a thought... - mlsstl 09:21:54 09/19/24 (3)
... that if a resistor was burnt there are good odds that another component (or more) on the circuit board is (are) also bad.
- RE: Just a thought... - 6bq5 11:15:14 09/19/24 (2)
  Absolutely-
  and could be from another board also...
  the 405 is an older SS amp- and may well need the replacement of a number of components...
  Happy Listening
  - RE: Just a thought... - mpcrnc@aol.com 05:39:51 09/22/24 (1)
    Any reliable shops that repair/upgrade Quad 34 and 405?
    - RE: Just a thought... - Cycler2 16:59:28 09/22/24 (0)
      I recommend amplifiersurgery.com They refurbished my Quad 303 and did a great job at a reasonable price.
      Rich

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