I am repairing an Aiwa HS P505 - and originally it wasn't listening to the play button. (I don't have a service manual for this unit) The play button was indeed dead and has been replaced. However... it still doesn't listen to the play button. I suspect that the hold switch is faulty, but I have no idea how to test this. Here is the switch... it has three positions (for this purpose) - left (remote on) - middle (hold) - right (remote off) I have a feeling that this switch is deceased. I was getting spurious readings from it (in the hold position, the centre and right pins were reading... but in the other two positions, nothing was happening.) Can anyone advise please?
I did get a step further. There is a safety mechanism that will allow forward and rewind while the lid is open... but it won't allow play while the lid is open. Managed to fix that... but the unit still isn't running. Only forward and reverse.... no play. I'm 99.999% sure I've got a problem with the hold switch, but with no schematic, I can't even work out the correct combination to run without hold.
YES - YES - YES - YES - YES - GOT IT !!! ... wow... nothing quite like that feeling of getting it working. Well... at least I've got the mechanism listening to the buttons. Now to take a large, long swig of tea and try to see if I can get any sound out of it.
Now fully working. Well, you know about the caps. That much is taken for read. Three problems... 1) The play button microswitch was dead 2) The hold switch was broken 3) I'm an idiot. I didn't realise that there was a safety switch for only allowing the unit to play, while the cover was closed. That hampered my testing. Not having a service manual for this unit, I was running off manuals for other units, and this hold switch is wired differently. It seems to need to be open on the "off" pins (which is, remote off, and hold off) in order for the unit to listen to commands. I was going by another diagram and I was wiring it closed. Thus... hold was engaged. The unit probably won't last long though. There is so much leakage that I can't clean it all up. :-( ... but, it's such a great feeling to get it working.
Thank you ... and now for the next challenge... assembling the sodding thing again !!! ... that's tomorrow's job.. but I'll probably swap the case with the other P505, as that one's dented. ... depending on how much corrosion I find in that one, of course.
Did you clean the leakage off with baking soda paste and isopropyl alcohol? Take a picture of the board with the old caps removed. If there is crusty solder remaining, you must slowly scrape it off. For the hold switch, it it is broken, I would just desolder it and jump it to "Remote Off".
Yes, the procedure was followed. I cleaned it as best I could, but some of the solder is refusing to come clean. I need some better brushes ... small, but stiffer, if you know what I mean. Some of the larger joints, I just de-soldered, and re-soldered. I didn't expect to get this working, to be honest. I thought it would be a sacrificial unit to get my hand and eye in. But... it works - I have another P505 to do, and that will probably be this weekends project. The P505's will be of limited use, because they only go to Dolby B, and I'll be using C for my recordings. I haven't made plans for them yet ... but the P505 will probably die during the next phase in a month or two... which is when I start putting together LiPo batteries in old gumstick shells. I'm bound to make something go pop at that point.
Congrats on a first success! To better clean off the crud, I just scrape it off with a tiny flat screwdriver. I do not really recommend recording Dolby for Walkmans, especially C, as most Walkmans do not have accurate enough azimuth, and some do not have Dolby Level adjustment. Unless everything is perfect, and the Dolby level of your recording matches your Walkman, you will likely get artifacts, like pumping. And if you eventually have a big Walkman collection, it becomes even harder... The exception is the D6C, which is closer to a full size deck in performance. Even then...
I had been using an unserviced aiwa pc202 for a while which surprisingly had a 1:1 picture prefect dolby C system. How can one tell if there are incompatibilities between the deck and a walkman? I am assuming you would need to fiddle with the dolby potentiometers in your walkman until the sound matches that of the deck, but then you mention azimuth which i've never really dealt with either on my deck or my walkmans. Thanks
My first problem is actually going to be getting a working decent walkman and tape deck first. Killed my BS705 attempting to service it yesterday, and I still haven't found the fault with the PX303 units yet. Still working on them.
You'll know what misaligned Dolby sounds like almost immediately, the PC202 is a rare machine that has a accurate mechanism and adjustable dolby level. What do you mean killed a deck?
Well, I tried to change the belt on my Technics RS B705. Managed to do it... first time on that unit... and when I put it back together, it didn't listen to the controls. I have a feeling that, given that all the cables are stiff... that I've worked something loose. I'll have to take the circuit board out, re-work all the joints and check all the cables for continuity. But given my low standard of electronics knowledge, I fear I won't be able to fix it, because I can't diagnose very well. I usually end up destroying the first unit of anything I repair... while I learn the lessons I need for the second one.
I'd recommend you give fixing your deck a try. Do the basics, check the solder joints, power rails. The B705 is a good deck worth fixing. The techs on Tapeheads can help you with specific problems.
I've done the basics, and no joy. I have the service manual, and reached my limit. It is picked up by a friend this afternoon, and will be winging its way to Brighton for someone else to have a look at.
