Sinclair ZX Spectrum +2 Datacorder Azimuth Adjustment
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When the Datacorder in a grey Sinclair ZX Spectrum +2 plays at a steady speed but programs will not load, the usual causes are a dirty tape head, capstan and pinch roller, or a head whose azimuth (its angle to the tape) has drifted. The +2's case has a small hole for adjusting the azimuth without opening the computer.[1]
Symptoms
[edit | edit source]- "R Tape loading error" while the tape plays at a steady speed.[1]
- Playback that sounds muffled. The T.I.S. field-service notes for the Spectrum say that if the note is "in the least muffled sounding then there is no chance of the Spectrum loading from it".[2]
Faults that look similar:
- Speed that wavers, or slow winding: the belts. See Sinclair ZX Spectrum +2 Datacorder Belt Replacement.[1]
- A constant hum or buzz on the sound, present even when the deck is stopped: the tape PCB's ground path through the mechanism frame. See the Sinclair ZX Spectrum +2 Troubleshooting Guide.[1]
- Poor sound that cleaning and azimuth adjustment do not improve: the capacitors on the tape PCB. See the Sinclair ZX Spectrum +2 Capacitor Replacement Guide.[1]
Tools and parts
[edit | edit source]- Isopropyl alcohol and cotton buds.[1]
- A No. 0 jeweller's screwdriver for the azimuth screw.[1]
- A tape known to load on another machine.
- Optionally, the ZX Diagnostics test ROM. Its ULA test screen shows the EAR input as black and white loading stripes in the border while a tape plays, and its author suggests using them to set azimuth for more even stripes.[3]
Procedure
[edit | edit source]Cleaning
[edit | edit source]- Open the cassette door and remove any cassette.
- Clean the tape head, the capstan and the pinch roller with isopropyl alcohol on a cotton bud. These parts collect dirt and particles shed by the tape over the years.[1]
- Let them dry, then try loading again. If loading is still unreliable, adjust the azimuth.[1]
Azimuth adjustment
[edit | edit source]- Insert a tape and set it playing.[1]
- Pass the No. 0 jeweller's screwdriver through the hole in the case moulding to the head's azimuth screw (see the photograph).[1]
- Turn the screw slowly while listening to the tape, and stop where the sound is clearest.[1] The T.I.S. notes describe the same adjustment on external recorders as turning for "the sharpest possible sounding note".[2]
- If you are using ZX Diagnostics, run its ULA test screen while the tape plays and adjust for the most even loading stripes in the border.[3]
- Clean the head again and recheck the setting, as the T.I.S. notes advise.[2]
Testing
[edit | edit source]- Load a program from tape. It should load without "R Tape loading error".
- Try a second tape, recorded on another machine.
Revision notes
[edit | edit source]This adjustment is described for the grey +2. The black +2A and +2B use a different cassette mechanism.[1]
Related pages
[edit | edit source]- Sinclair ZX Spectrum +2
- Sinclair ZX Spectrum +2 General Maintenance
- Sinclair ZX Spectrum +2 Troubleshooting Guide
- Sinclair ZX Spectrum +2 Capacitor Replacement Guide
- Sinclair ZX Spectrum +2 Datacorder Belt Replacement
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 "Servicing your +2's Datacorder", Spectrum for Everyone, February 2017. Cleaning the head, capstan and pinch roller with isopropyl alcohol, the azimuth hole and No. 0 screwdriver, adjusting with a tape playing, and the other Datacorder faults.
- ↑ 2.0 2.1 2.2 ZX Spectrum Servicing Manual, prepared by Thorn (EMI) Datatech for Sinclair Research, March 1984, with T.I.S. "Repair Data" appended, PDF p. 60 onwards (adjusting a cassette recorder's azimuth). Hosted as ZX Spectrum Servicing Manual (Thorn EMI Datatech, 1984) (PDF). Written for external recorders used with the 48K Spectrum.
- ↑ 3.0 3.1 Brendan Alford, "Firmware", ZX Diagnostics wiki, GitHub, edited 18 August 2021. ULA test screen: EAR bit shown as loading stripes in the border, for checking azimuth on a connected or built-in cassette recorder.