Pioneer SX-1250

Anyone have a full list of components, resistors, transistors, caps, diodes and anything else I'll need for the awh-048 amp boards rebuild?
 
Sorry for bumping this thread, but I need an updated Tone Amp and Flat Amp parts list for my 1250 if anyone has one. Thanks in advance.
 
I finally got around to working on the old SX-1250 recently. I've done all boards except AWF-021 EQ board, one cap on the AWS-094 Function Switch board and the AWR-107 Power Supply board. The EQ board looks like a pain to do and gonna do the power supply board soon. It is sounding good again.
 
I finally got around to working on the old SX-1250 recently. I've done all boards except AWF-021 EQ board, one cap on the AWS-094 Function Switch board and the AWR-107 Power Supply board. The EQ board looks like a pain to do and gonna do the power supply board soon. It is sounding good again.
Quick question:
Do the 215 Cerwin Vegas sound any better than the AT15's ?
 
Mouser is out of stock with 512-KSC1845FTA (lead formed on paper tape), so use a different option, ksc1845bu (bulk) are in stock.
 
They have 56k 512-KSC1845FTA ready to ship. I was just wanting to know a substitube in case they may not have any in the future. I have some 512-KSA992FBU, 512-KSC1845FTA ,512-KSC2383YTA ,512-KSA1013YBU, 512-KSC2690AYS and some more.
 
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Modern day subs in THT? Well slim pick'ns. I say stock up, if you anticipate a need, you never know when they will decide to stop production, esp after Onsemi bought Fairchild. It is demand that is the driving force. They may want or force every one to go smt, FJV992(1845) :)
 
Got the receiver back together, has a pop on right side when relay kicks in and out. I don't have a 5.1k ohm resistor at the moment to set DC offset the right way and when I adjust without the resistor it doesn't seem to move on the DMM. I have some 5.1k ohm resistors on the way, guess I'll have to wait till then to set the offset. I got the caps and transistors from mouser today instead of Saturday.

I tested the sound with headphones and the bass seems to be equal on both sides. I'm gonna hook it up to my big speakers and see how it sounds in a bit.
 
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I got my 5.1k ohm resistors, put them on the power in jacks and still not having any luck with the DC offset adjustment. The multi-turn pots in my opinion are crap and annoying. To make sure, am I supposed to do this is DC or MV? I just want to make sure.

Update: Finally got the DC offset between -0.5 - +0.5 on both sides and still get a popping noise on the right channel when I turn it on or off. Could the 4 big filter caps be suspect or something on the right channel AWH-048 P. amp board?
 
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popping noise when turned off means the protect relay isn't releasing quickly enough.
THAT means the protect system is probably not working, the 100uf timing cap in the protect circuit is not being discharged by the q4 controlled by the 992 pnp transistor. Part of the 2383 biasing arrangement. remove q3, then make sure that pulling out Fu5 (awr-107) 1.5 amps toggles the protection in and out.
 
I just got around to replacing the 4 caps on AWR-107 and the 4 big electrolytic filter caps today. I tested and set the 65v and -65, which was barely off. I am letting the 1250 warm up to set the left and right AWH-048 mV. Will update about the popping issue once I have it hooked back up to speakers.

Still has the damn pop. Which board is q3 and q4 on?
 
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popping noise when turned off means the protect relay isn't releasing quickly enough.
THAT means the protect system is probably not working, the 100uf timing cap in the protect circuit is not being discharged by the q4 controlled by the 992 pnp transistor. Part of the 2383 biasing arrangement. remove q3, then make sure that pulling out Fu5 (awr-107) 1.5 amps toggles the protection in and out.
Can you be more specific which boards Q3 and Q4 are on that way I can look into it? I have a new problem with the 4 lights behind the tuner dial, they work and are weak, but every now and then they'll brighten up.
 
Can you be more specific which boards Q3 and Q4 are on
AWM-094
I have a new problem with the 4 lights behind the tuner dial, they work and are weak, but every now and then they'll brighten up.
Would that not be a power supply or connection problem, try rotating fuse FU5 (1.5A) on AWR-107 or removing the fuse and squeezing the fuse hold tabs together for better contact with the fuse after it is re-inserted.
 
Sorry, but my sx-1250 doesn't seem to have an AWM-094 board. Did you mean AWM-091?

The AWM-091 board IS the SX-1250's protection board.

PLEASE try the AWR-107 FU5 test (on/off). FU5 is the one all by itself. Use it like a knife switch.
Chosen due to it's ease of accessibility, prominent in the bottom of the chassis, between the bottoms of the big capacitors.

It HAS to work like that in order for ALL THE OTHER PROTECTION FUNCTIONS TO WORK!!
 
I just noticed last night that the SX-1250 only pops on the right channel when turned on and when turned off is has a different kind of sound on both channels.
 
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@markthefixer which 100uf cap would be part of the Q3/Q4 in case I need the change it? After this winter storm is over I am going to remove Q3 and try the FU5 thing.

Are the phono selection lights ran off of the power supply board like the dial lamps? I changed the bulbs a while back and all work except the 2 phono and speaker C. Could just be bad bulbs, not sure at the moment.
 
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