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AKAI GX630D - Normal playback, slow recording

Halisson

Halisson

Member
I'm having trouble listening to the recording I make on this equipment. What I reproduce is perfectly fine, but what I record on it, reproduces slow. I heard what was recorded on other equipment, but now I do not have any other equipment to test. The speed variation is intermittent, on average recording 1khz, playing 948hz, both channels.
Both measures in 7in or 10in persist.
Changing the 7 1/2 or 3 3/4 switch does not change.
I demagnetized the heads,
I forced the Pinch roller arm more or less pressure, just noticed that it is in the best position. I noticed that the voltage is the same as the recording or playback of the solenoid of the inverter, the loose impedance roller and the axis of the loose winch are adjusted.

It stood in front of the air conditioning at 16 ° C for 4 hours, rewound the entire reel to the beginning persisted in slowness, changed its original capacitor, persisted the problem. (In Brazil, AC 220v 60Hz, then the capacitor I used is 3,5uf)
When I am recording, I repair the TAPE Switch (source) mode, which automatically adjusts the speed (at the time I am recording), even adjusts if I continue to switch between 7 1/2 and 3 3/4 during recording Stabilize accordingly With the selected Speed, advancing a little or delaying, for example.
The variation of speed trimpots of 3 or 7, does not change.
Tests with 7 or 10 coils do not change.
I'm lost to do.
Thank you for any help.
 
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I have this same problem with my Akai GX-400D and Pioneer RT-1020H. I have 2 7" reel only RTR and don't have this problem. Since no one replies on this thread, I guess it's not a popular issue. Funny thing is it happens on both of my RTRs that can play 7" and 10" reels :dunno:
 
Clean the variable tape speed control and switch. The control and switch are bypassed in record mode, so if the switch is dirty, which is very common, you will get speed variations in playback mode, compared to record mode. After you clean the controls, adjust the internal adjustment for playback speed using a calibrated speed tape and a frequency counter. Then all should be correct.
 
I don't think the GX-630D has a variable tape speed control, just a 3.75 / 7.5 IPS tape speed selector switch which works in both record and play modes.
 
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Does the 984Hz drift at all? Record 1k for 10 minutes and see if the 984 Hz playback drifts at all for the 10 minutes

See if power supply voltages on pins 6 and 7 change between play and record modes.
 
tapetech said:
Does the 984Hz drift at all? Record 1k for 10 minutes and see if the 984 Hz playback drifts at all for the 10 minutes

See if power supply voltages on pins 6 and 7 change between play and record modes.
Click to expand...

tapetech,

I saw your answer now, and I was right back here to tell you what I discovered, and I saw your help! Thank you anyway, you were on the right track. After switching D6, D7, D8, D9, C3, C4 and C6 on the relay board and have already done replacing components with some variation in the servoboard, I had not yet set the VDC value to pin 6, it was always 23.9 vdc Even when moving VR1. By the time I was going to record, the voltage of pin 7 remained at 38.9vdc but pin 6 (which should be 24vdc) dropped to 18.9 in REC mode and 21.1 play mode. After checking, I replaced TR3 and received the adjustment, but remained the voltage did not reach above 23.9. After switching the TR2 which had no normal HFE problem - possible wrong pinout - fakes components from Brazil (2sc1247a) and everything went well. The voltage stayed on 24vdc in any mode, and recording and playback remain perfect. Thanks for all the help!
 
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