I’m working on an Aiwa HS-PX30 that constantly goes into fast-forward as soon as power is applied. None of the transport buttons respond. The capacitors have already been replaced; no leaking. I’m still checking traces but nothing around where the old capacitors were located Key symptoms Unit instantly enters FF whenever powered. Controls are unresponsive. Constant popping in headphones when powered. Behavior does not change even with the front-panel ribbon disconnected. I wanted to get some guidance from others that may have dealt with a similar issue. I’ve started testing IC6 with some interesting results. I’m not sure if this is a sign of bad things but when testing the pins. The pins on the left all show 2.4v instead of the suggested 2v in the manual. I’m also a little short on hands so I’m buying some clamping prongs for my multimeter so I can test button inputs while powering on.
Ok just took a quick look at the schematics and i think your problem is in IC5 BA3818F. The control buttons are in a series resistance string (R104 to R106 on operation flex pcb). They exit through connector 'B' and is applied through the remote switch (check this switch) and R86 (3K9). When the correct resistance is apllied to IC5 this ic will activate the correct pin (4 = FWD) to send to the MCU IC6. So check the components around ic5 to see if correct voltages appear. You already said that it even happens with the flex cable disconnected so we could rule out the resistance string of the control buttons. Problem could also be Q14/Q15 which turns the comparator on or off....if one of these is in short circuit the B+ voltage is directly applied to IC5 and the machine will start running. ps Great looking walkman these PX30/50, been looking for one
@Alt_ht Before proceeding...how are you powering the Aiwa when testing? With two batteries? If yes what is the B+ voltage you get at the exit 'a' from the regulator pcb? It should read 2V. You can also measure it at R89 100Ohm resistor (measure its resistance) or emitter of Q15. You're saying you get 2.4V readings on left side IC6 so could be that the regulator pcb isn't putting out 2V. If the voltage is to high it will mess up the input to IC5. Look up what a comparator does Did you also swap the 470uF on the reg. pcb? The popping you hearing is travelling on the ground line, as soon as you find the problem and replace the broken part this will disappear most of the times.
I have an after market battery that feeds 2.4v to the unit. I was wondering if this would affect performance. I do have the battery compartment as well but even after replacing the 470 uf cap it feeds 2.3v. Yes those have been replaced. I'm hoping this whole auto ff issue resolves this as well. I also tested the components around IC5 with some mixed results. R89 & R86 both read the correct resistance values. Q14/Q15 on the other hand I am not to sure how to really test. I did a simple resistance check from c to e just to make sure it wasn't open. I had the flex cables disconnected & measured pins 2-8 (excluding 6) to GND while it was powered & it read ~0.08v. I think before I go any further I'll invest in a dc bench just to make my life easier. Thanks for the help so far I'm slowly understanding how this unit works.
Ok so you're using a BP4 replacement. If you look at the schematic the BP4 is directly feeding the B+ voltage line. Can you try powering the Aiwa with 2x AAA in the external holder? The 3V from these two are passed through the regulator to get 2V. Then measure the voltages on the IC's again. The fact that you're feeding it 2.4V and you're seeing 2.4V on the pins of the ic's makes me believe that0.4V is to much. But better try to see if it makes a difference. Transistors can be tested using the diode test function on your DMM. On google you will find how to do this, where to put the positive and negative lead of your DMM on the base, collector or emitter. Transistors can also function as a diode. If the transistor is working you will get a reading, when its open no reading, and continues beep when in short. Best is to test them out of circuit but mostly can be tested in circuit, depends how they are implemented.
Small update. Motor still running in FF after supplying 2v from my DC bench. Suspicious of the path to PIN 1 on IC5 as it only receives ~.2 v when it’s supposed to get ~2v. Removed Q14 & running tests but as the size of the part is small it’s becoming a real pain to do. I also removed IC5 just to make sure everything is clean underneath. Also considering removing IC6 to do the same. I’ll keep you guys posted!
Update 2: looking good It seems like I had to reflow solder into Q19 & Q17 because now the motor is not spinning on powering. ( could have been open vias that also got cleaned in the process as I blasted the area with flux. Currently I have IC5, IC6, & Q14 which, if understand the logic correctly means the motor should not be spinning. Going to install those parts 1 at a time to see if everything is in order.
Testing IC5 & Transistors: Everything was looking okay motor did not move on powering Testing IC6: To GND IC6 pin15 DIR Jumps between .5v to 2v IC6 Pin 16 motor Similar issue here ( Jumps between .5v to 2v ) I'm afraid to say but the Ctrl might be fried Edit: Yeah lifted the pins seems voltages are stable across the pads & the lifted dir & motor pin's keep exhibiting the jump mentioned. IC5 send signals perfectly to the right side of IC6 but don't change anything in IC6 Oh well the units on Ebay for anyone that wants a for parts unit
Hello everyone, I bought this unit specifically and managed to fix it. I’d like to share the solution in case it helps others facing similar issues: IC6 replacement – I swapped IC6 with one taken from a scrap PL-30. The logic circuit of the PL-30 is very similar, so it works perfectly as a donor. Clutch repair – The clutch was broken. I used the well-known solution shared here in the forum: securing the clutch with small wires to hold it firmly in place under pressure. Capacitors – Some of the previously replaced capacitors were of poor quality. With aluminum SMD capacitors, especially at low capacitance values, it’s important to be extra careful since good ones are hard to find. After replacing them with better parts, the sound improved significantly. I also had to thoroughly clean the entire board, as the original capacitors had leaked and left residue. Finally, after the usual calibrations, the unit is working beautifully again. I’m very happy with the result and I hope this helps someone restore other PX-30 units — they are definitely worth saving.
