Arp Quartet problems.

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Arp Quartet problems.

Postby Europanaut » Sat Feb 15, 2014 3:13 am

Hi all!

I have a broken Quartet that is finally getting some attention.

At first, all the lights worked, but no audio was getting out. We replaced the CD4069 IC, and now we have quiet organ, slightly louder piano, and VERY quiet brass. The attack and sustain sliders also work. So progress is being made.


Here are the remaining issues.

Honky Tonk doesn't work.
Celeste doesn't work.
Strings don't work.
Vibrato doesn't work.
Brilliance doesn't work.

My tech has a (pretty sketchy) pdf of the service manual, but it doesn't seem to match this particular Quartet. So we are kind of stumped.

Are there different versions of the Quartet?
Do any of these problems sound familiar to anyone here?
Are there better manuals available online?


Thanks!
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Re: Arp Quartet problems.

Postby rhino » Sat Feb 15, 2014 4:43 am

Welcome to the board!

Had one on the bench several years ago.
1) MANY dead ICs - all 4000 series.
2) check the flat cables from board to board for bent wire ends not going into the socket correctly.
3) I got a nice print copy of the service manual from: http://www.markglinsky.com/ManualManor.html
4) check the power supply carefully for correct voltages
5) IIRC, the honky-tonk, celest and strings all use the chorus circuit. Check there.
"A thing may seem impossible...until it's done."
--Nelson Mandela
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Re: Arp Quartet problems.

Postby Europanaut » Sun Feb 16, 2014 12:20 am

Thanks for your help! I'll pass the info to the tech, and report back.
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Re: Arp Quartet problems.

Postby Europanaut » Sun Mar 09, 2014 7:20 am

Small progress to report.

I've swapped out quite a few 4016's and 4013's, with no success.....except for one. When another new 4069 was installed, the trombone came back to life. But only the trombone, not the trumpet.

I've been trying to find equivalents for these chips. (I don't mind ordering new chips, but I have quite a few spare 7400 series ic's in my parts supply, so if there are some equivalents to the 4000 series, I'd like to use them up. Sometimes I get lucky! )

909 (op amp)
TDA1022 (bucket brigade delay)
3600
4011 (2 input quad NAND gate)
4082 (4 input AND gate)
4071 (OR gate)

Here's a few more details on the Quartet's misbehaviours.

There's a fairly fast "ticking" sound that is always present. Around 200 bpm, I'd estimate.
The strings and trumpet are heard, but barely. Like, I didn't even know they were playing until the room was silent.
Nothing at all from Honky Tonk piano or Celeste.
Organ, Trombone, and Piano are fine. Probably not the best idea for a band though. ;)


Thanks
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