Pioneer SX-1250 recap and restoration thread!
- Thread starter mattsd
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top gun
oldstuffer55
Runaway voltage
Hi, well I have done the sx 1250 recap and refurbish as per the bom list supplied by Matt, and things went quite well thank you Matt, unfortunately after several hours of playing music at moderate volume the left channel is getting very hot, so I checked the voltages again only to find out that it's running at about 265 volts and I am unable to lower the voltage with the new vr2 on that channel, I'm not sure where to go next. Please Help
Hi, well I have done the sx 1250 recap and refurbish as per the bom list supplied by Matt, and things went quite well thank you Matt, unfortunately after several hours of playing music at moderate volume the left channel is getting very hot, so I checked the voltages again only to find out that it's running at about 265 volts and I am unable to lower the voltage with the new vr2 on that channel, I'm not sure where to go next. Please Help
start a new thread please.
and please include what you posted above - thank you
and please include what you posted above - thank you
Howdy, I am in the middle of a 1250 using your parts list, many thanks, and just noticed you don't list replacements for Q1-3 on the protection board(AWM-091). I assume Q1 and Q2 can be replaced with 512-KSC2383YTA? But what about Q3? It is a 2SA733. Unfortunately I cleaned the board before I checked the parts list. I have a spare board to steal from but was hoping to replace all I could with new. I need help:scratch2:
They rarely present problems. Rarely enough that I usually just leave them alone. The a733 also presented enough confusion between ecb and ebc versions that the additional online problems weren't worth mentioning it for replacement. It is a "logic" position and is not stressed in the least bit.
q1 and q2 are ksc1845, high gain, low noise,
q3 can be an a992
ksc2383 is when we want to handle some current, which isn't the case here.
q4 is the current dump transistor, which is stressed, and the original is marginally undersized.
q5 is the relay drive transistor, which is stressed
q6 is a voltage regulator, which can be heat stressed, although most of the heat is supposed to be shed by R23 (which can handle it).
q1 and q2 are ksc1845, high gain, low noise,
q3 can be an a992
ksc2383 is when we want to handle some current, which isn't the case here.
q4 is the current dump transistor, which is stressed, and the original is marginally undersized.
q5 is the relay drive transistor, which is stressed
q6 is a voltage regulator, which can be heat stressed, although most of the heat is supposed to be shed by R23 (which can handle it).
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Schooling appreciated....
Looks like a SX-1250 to me...
The Patient
Well, I am about to turn the juice on to this 1250 that came to me a month or so ago. It was very dirty and going into protection. I got it for $485 and thought it might be good for parts at least. After opening it up and cleaning a ton of grime away it appeared all original. No replaced parts, no heat stress marks on the driver boards, no evidence that anyone had ever taken an iron to it. So, I recapped everything but the tuner section. I also replaced all transistors and diodes on the stabilizer and protection boards, in addition to new on-semi outputs. Here are some pics of BEFORE I put power to it. Any suggestions or warnings would be much appreciated!!
Well, I am about to turn the juice on to this 1250 that came to me a month or so ago. It was very dirty and going into protection. I got it for $485 and thought it might be good for parts at least. After opening it up and cleaning a ton of grime away it appeared all original. No replaced parts, no heat stress marks on the driver boards, no evidence that anyone had ever taken an iron to it. So, I recapped everything but the tuner section. I also replaced all transistors and diodes on the stabilizer and protection boards, in addition to new on-semi outputs. Here are some pics of BEFORE I put power to it. Any suggestions or warnings would be much appreciated!!
Attachments
I cannot give any advice however after a heap o reading I recall two things that really stick out to me. One, use a dim bulb tester to power them up. Two, check and re check the orientation of the main filter Caps to make absolutely sure that they are installed correctly. I have limited experience with total re caps so waiting for resident Gurus to chime in may well make for a happy Christmas.. To me just having an SX 1250 makes for a happy Christmas. With best regards, vsat88.
DBT is needed, but you should of checked the set at each board restoration. (Maybe you did).
What was your restoration process? List the steps you took from start to finish. No detail required. (Please :yes
You might want to start your own Thread.
First answer the above questions.
What was your restoration process? List the steps you took from start to finish. No detail required. (Please :yes
You might want to start your own Thread.
First answer the above questions.
The Patient
I did not test each board. I went in, cleaned it up as much as practical then recapped the boards, one by one starting with the equalizer amp, then function board, filter amp, control amp, stabilizer, protection, drivers, power supply. Only one of the wrapped wires broke off during all this and I took a replacement from my donor carcass to replace it, same color and all. Pic of my DBT and 5.1kohm tester plugs(if I get that far!)
I did not test each board. I went in, cleaned it up as much as practical then recapped the boards, one by one starting with the equalizer amp, then function board, filter amp, control amp, stabilizer, protection, drivers, power supply. Only one of the wrapped wires broke off during all this and I took a replacement from my donor carcass to replace it, same color and all. Pic of my DBT and 5.1kohm tester plugs(if I get that far!)
Attachments
OK. We will call you "The one with big Kauna's"
Did you double check all the component placements? Trace connections on the back of the boards (A million times?) The Thread you posted on is the bible for the 1250 restoration. Did you use this as a guide?
Plug the set in the DBT with a 100 watt bulb. Don't flip the switch until instructed.
Unplug the amp boards top and bottom plugs.
Set the +-65 regulated stabilizer trimmers VR1 and VR2 to center. If they are the multi turn, they come centered from the factory (Mouser).
The large caps look installed correctly. A close up pic of the big caps (one side is good. And for later a shot of the outputs on the heatsinks (for later).
It might be a little of a pain but: I would like to see a top shot of the Stabilizer (PS) picture as well. (This could save many hours later)
Did you double check all the component placements? Trace connections on the back of the boards (A million times?) The Thread you posted on is the bible for the 1250 restoration. Did you use this as a guide?
Plug the set in the DBT with a 100 watt bulb. Don't flip the switch until instructed.
Unplug the amp boards top and bottom plugs.
Set the +-65 regulated stabilizer trimmers VR1 and VR2 to center. If they are the multi turn, they come centered from the factory (Mouser).
The large caps look installed correctly. A close up pic of the big caps (one side is good. And for later a shot of the outputs on the heatsinks (for later).
It might be a little of a pain but: I would like to see a top shot of the Stabilizer (PS) picture as well. (This could save many hours later)