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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 11th Dec 2016, 3:00 pm   #1
cliofreak
Retired Dormant Member
 
Join Date: Dec 2016
Location: Derry, Northern Ireland, UK.
Posts: 17
Default Marantz CP430 - Delay/Echo Machine

Hi folks,
I have a Marantz CP430 that I have converted into a tape delay. It was working fine for a few weeks but then stopped working. Ive stripped most of it down and disconnected the 'new' circuit that I added (for repeats, feedback mixer etc).

So, essentially it is in an original state.

1. It records to tape just fine via stereo Line IN and Mic IN (Ive tested playback on a Sony Walkman)
2. It wont playback the tape correctly. Its just a humm/noise.
3. Hovering my hand over the playhead causes and 'interference'.

Here it is when it was working. Well worth the effort! And well worth the effort to get it working again - https://www.youtube.com/watch?v=ZQ7ee62Eqj0

So, Ive used an audio probe. I sourced the most direct point of contact with the play head and tested both L and R channels. I got no audio, just a mixture of hum and hiss. I tried grounding the probe on the frame, the Line in, the power in and directly on the ground on the plug that goes to the head.

No audio.

Any ideas? Surly the tape head can't be dead or can it?
There is an intermittent issue with the tape wanting to auto shut off too. Every 3/4 secs or so it clicks off. Must be connected to the issue. Thoughts welcome.

Im getting continuity from the ground on the head to the ground on the 'Tape In' so I think the head is getting ground.
I should also say that when using the audio probe, Im getting a solid audio signal from the tape head (both play side and record side) BUT its only the 'monitor' audio, NOT the actual tape's audio.

Measured resistance. Im getting:

Playhead L = N/A (no reading)
Playhead R = 30 + Megohm

RecordHead L = 127.9 ohm
RecordHead R = 127.8 ohm


To sum it up, the machine records perfectly.
The machine doesn't playback.

Any help welcome! Thanks.
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Old 11th Dec 2016, 4:15 pm   #2
ronbryan
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Join Date: Jan 2003
Location: Guildford, Surrey, UK.
Posts: 1,958
Default Re: Marantz CP430 - Delay/Echo Machine

Tape replay heads are wound with very fine wire and can go open circuit due to corrosion (green spot) or even excess current in the case of a modification.

Your meter reading appears to confirm open circuit replay heads.

Ron
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Old 11th Dec 2016, 5:19 pm   #3
cliofreak
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Join Date: Dec 2016
Location: Derry, Northern Ireland, UK.
Posts: 17
Default Re: Marantz CP430 - Delay/Echo Machine

Thanks Ron. That makes sense! I wonder if a replacement rec/play head is available for this model. I can't see anything on eBay.
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