# CT-605 Accompaniment Not Working—ISO service manual

**URL:** <https://forums.syntaur.com/t/ct-605-accompaniment-not-working-iso-service-manual/9240>\
**Category:** Synth Repair\
**Tags:** casio, ct-605, no-audio\
**Created:** [December 2, 2025, 2:24pm UTC](https://forums.syntaur.com/t/ct-605-accompaniment-not-working-iso-service-manual/9240 "2025-12-02T14:24:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![nomadicrust](https://forums.syntaur.com/letter_avatar_proxy/v4/letter/n/7bcc69/32.png) [@nomadicrust](https://forums.syntaur.com/u/nomadicrust)\
**Post date:** [December 2, 2025, 2:24pm UTC](https://forums.syntaur.com/t/ct-605-accompaniment-not-working-iso-service-manual/9240/1 "2025-12-02T14:24:58Z")

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[CASIO] [CT-605] – [No Accompaniment/Bass/Rhythm Audio]

Hey y’all,

Does anyone have a Casiotone CT-605 Service Manual?

I’ve got a CT-605 where the whole accompaniment section is not playing audio (chords/bass/rhythm). I have been working from a CT-405 schematic and I have confirmed that the LSI handling the accompaniment section is good—but I have also determined that the tempo fader is faulty. Would replacing that fader be enough to fix the problem? If the 605 is the same as the 405, then I have narrowed down the other two potential culprits to be either the “Mixer 3” op amp or the accompaniment “Start/Stop” switch.

Has anyone run into this issue and does anyone have any other ideas? Thanks!

• Model & revision/OS:  
• Symptoms (what changed, when):  
• Tests already done (voltages, parts replaced):  
• Photos / audio clips:

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**Author:** ![jeremy](https://forums.syntaur.com/letter_avatar_proxy/v4/letter/j/82dd89/32.png) [@jeremy](https://forums.syntaur.com/u/jeremy)\
**Post date:** [December 19, 2025, 6:46pm UTC](https://forums.syntaur.com/t/ct-605-accompaniment-not-working-iso-service-manual/9240/2 "2025-12-19T18:46:31Z")

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Hey @nomadicrust, though I can’t help with your problem. Here is a link to a pdf of the Casio CT-605 owners manual.

> **[Casio\_CT-605\_Owners\_Manual.pdf](https://static.wikitide.net/circuitbendingwiki/e/ee/Casio_CT-605_Owners_Manual.pdf)**
>
> 2.05 MB

Hope it helps!

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<div class="post-metadata">

**Author:** ![nomadicrust](https://forums.syntaur.com/letter_avatar_proxy/v4/letter/n/7bcc69/32.png) [@nomadicrust](https://forums.syntaur.com/u/nomadicrust)\
**Post date:** [December 20, 2025, 4:35am UTC](https://forums.syntaur.com/t/ct-605-accompaniment-not-working-iso-service-manual/9240/3 "2025-12-20T04:35:11Z")

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Thanks Jeremy! Appreciate that. I have (most likely) narrowed it down to a faulty tempo fader—but unfortunately have had no luck sourcing the slide pot i need to replace it. Updated post is available here:

> [@Seeking: 1MOhm "C" (Reverse Audio/Log) Taper Slide Potentiometer](https://forums.syntaur.com/t/seeking-1mohm-c-reverse-audio-log-taper-slide-potentiometer/9270):
>
> [CASIO] [CT-605] – [Seeking Replacement Tempo Fader] Hey y’all, Seeking a slide potentiometer with the following specs, as used on the Casio CT-605 and the Korg DW-6000: Resistance: 1MOhm Physical length: 45mm Travel distance: 30mm Taper: Reverse Audio (C) Gang: Single I have reached out to a few different places (including Syntaur) and unfortunately no dice, beyond buying a whole PCB from the Korg model to desolder the slide pot from. Does anyone have a suitable replacement part? Thank …