Fixing Negative DC Voltage on Cassette Deck Output: Nakamichi RX-505 Example

In this video, I tackle a surprising issue: negative 300 mV on one channel at the RCA output of my Nakamichi RX-505. Follow along as I investigate and successfully fix this problem, sharing my step-by-step approach to troubleshooting and repair. This issue turned out to be more complex than expected, requiring two attempts to resolve.
🔧 Troubleshooting and Repair Process:
Diagnosis: Discover how I identified the root cause of the negative voltage, pinpointing a failed transistor in the output stage.
First Attempt: Replacing the failed transistor with a regular NPN transistor resulted in high noise levels, leading to further investigation.
Successful Fix: Learn how I found the correct component and implemented a reliable solution to restore the output to proper working condition.
🎶 Key Takeaways:
Technical Insights: Understand the symptoms and causes of voltage issues in vintage cassette decks.
Practical Solution: See how proper diagnosis and persistence can resolve challenging problems in audio equipment.
Useful Guide: This video can serve as a valuable resource for anyone encountering similar issues with their cassette decks.
👂 Share Your Experience:
Join the Discussion: Have you faced voltage or noise issues in your audio gear? Share your troubleshooting methods and solutions in the comments below!
Don’t miss this detailed guide to fixing negative voltage issues on a cassette deck output. Like, share, and subscribe for more audio repair tutorials and vintage gear insights.
🔍 Tags: #NakamichiRX505 #CassetteDeckRepair #AudioTroubleshooting #VintageAudio #NegativeVoltageFix #RCAOutputIssue #AudioRepairTutorials

[@Nakamichi_Service_UK]

I have had this issue on many Nak decks so now replace all muting transistors in every Nak I restored

[@m80116]

Mutating transistor

[@From_the_mil]

Do you have any recommendation on how to learn how to a service cassette deck? Much appreciated, thank you for all your videos

[@Nakamichi_Service_UK]

Watch all sarhei’s video’s to gain expertise

[@profscanltd2935]

Прежде всего надо выучить закон Ома...

[@DJNeiloSF]

While I understand that this negative dc output is undesirable and needs to be fixed, I presume that most amp inputs are AC coupled so it shouldn't make a difference?

[@hifirulezzz]

@@DJNeiloSF it depends on how badly that transistor failed. It may start distorting the sound. Also, in some decks it is coupled with Dolby IC, making situation even worse.