Pioneer RG-1 Refurb Project

Possible dumb question - using the Chinese tester in post #6 above, do I need to continue pulling the transistors to measure it properly to determine if the transistor is faulty? I think I know the answer but looking for confirmation really - Pulling the transistors is what I have done in the past and it has worked marvels in identifying bad transistors on a few other projects I have done with great effectiveness. Also a great tool to ID what leads are B, C or E plus PNP or NPN I have found. I have done it this way because I have been concerned that measuring it installed on the board with the fine clamp probes would measure backward in the circuit and could give a false reading. I am not so concerned in the resultant numerical values as I am whether it tests good or bad. The Tester with three leads clamped onto the transistor will normally tell me which leads are the B, C and E leads among other numerical values or it will simply tell me if the component is faulty. I measured a couple Q's directly on the board yesterday and did get B,C and E info which would indicates to me that the transistors I tested in-situ are (probably) good despite the fact the values obtained are likely skewed by the fact it is reading other components in line/in the circuit. I am thinking the best confirmation though is to continue pulling the transistors off the board to be sure I am getting a good indication that the transistor is functional or not. Regardless I will be swapping out the known problematic Q devices as discussed in the thread above. Just wanted to conform my logic is somewhat sound. Thanks for any advice on this one...
 
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your chinese tester tests how many bjt parameters?
the complaint with those old devices is noise, remember that, it is only one of the operating parameters for bjt operation.
I am listening to Pioneer qx-9900 using those same parts, it is still op okay, I can hear those noisy bjts, they settle down when they warm up.
think of your RG-1 as the test jig to test to see if the bjts and assoc comps are operating properly. but you need proper instruments to do so, enter the shell game
I frown on the idea of changing every bjt in an attempt to fix the problem.
if I told my boss that was my method on the factory test floor, I'd be in trouble :) I know it is not the exact same comparing new vs aged, but try to find the problem child without the madness of puling every bjt and testing it on a Chinese tester. if you pull certainly put new ones back in and test for op at every stage.

Good luck Tim
 
your chinese tester tests how many bjt parameters?
the complaint with those old devices is noise, remember that, it is only one of the operating parameters for bjt operation.
I am listening to Pioneer qx-9900 using those same parts, it is still op okay, I can hear those noisy bjts, they settle down when they warm up.
think of your RG-1 as the test jig to test to see if the bjts and assoc comps are operating properly. but you need proper instruments to do so, enter the shell game
I frown on the idea of changing every bjt in an attempt to fix the problem.
if I told my boss that was my method on the factory test floor, I'd be in trouble :) I know it is not the exact same comparing new vs aged, but try to find the problem child without the madness of puling every bjt and testing it on a Chinese tester. if you pull certainly put new ones back in and test for op at every stage.

Good luck Tim

Thank you. Will do a screen capture when I get home from work. I do think I have a solid method. I have essentially ruled out the right channel side (save for troublesome transistors {BJT} which will be switched anyway as a preventative measure). I am pretty confident all my mech switches are good as well as control dials given the meter deflections appearing to operate nominally, I have a good idea on the Left channel part of the board which BJTs are the suspect failures given that a good chunk of the left channel side of the board is functioning good judging by the fact both expansion meters are reacting both left and right channel to source material equally well and in sync with controls reacting equally well on both meters. Looking at the schematics I believe I have a pretty good place to start with maybe 3 maybe 4 BJTs to be tested to isolate if it is a BJT or multiple BJT failure. If any fails are found I will replace with transistors on order (when they arrive) plus the problem child ones as noted previously. IF BJTs are not the culprits I will simply go to other components in the area I think is being affected before expanding the investigation outward. Troubleshooting is always a PITA. The good news is it is working all of the way up to both meters given their behaviour when operating the controls so the problem pretty much exists only on the left side between there and the Left output thus significantly reducing the number of components to test out I believe. Re-capping doesn't happen until the very end which simply needs to occur anyway given the age of the electrolytics.
 
your chinese tester tests how many bjt parameters?
the complaint with those old devices is noise, remember that, it is only one of the operating parameters for bjt operation.
I am listening to Pioneer qx-9900 using those same parts, it is still op okay, I can hear those noisy bjts, they settle down when they warm up.
think of your RG-1 as the test jig to test to see if the bjts and assoc comps are operating properly. but you need proper instruments to do so, enter the shell game
I frown on the idea of changing every bjt in an attempt to fix the problem.
if I told my boss that was my method on the factory test floor, I'd be in trouble :) I know it is not the exact same comparing new vs aged, but try to find the problem child without the madness of puling every bjt and testing it on a Chinese tester. if you pull certainly put new ones back in and test for op at every stage.

Good luck Tim

Well, got home from work and had a go at simply testing the left channel Transistors straight off the board. I thought it wouldn't hurt...
Interesting results since they were still in circuit. However, with the results I got I think I identified 3 bad Transistors and 2 other possibles. 3 read as straight up non ID, bad or damaged parts while two read as either a paired diode or a single diode which is not surprising considering what a transistor is and may read this way if one part of it was working. Nevertheless those two transistors did not read as transistors thus making them candidates for a pull and a test like the three BJTs that read bad (maybe that will change when pulled and tested due to testing on the board - will see how that pans out). So here is a link to the results on the left channel side of the board:

https://timothyflath.smugmug.com/Stereo/Pioneer-RG-1/

Will go ahead and do the right side just because I am curious to see if I get similar results. The two final board shots show the 5 suspect transistors marked with yellow masking tape (frogtape).
I believe they are:

Q20 - No, unknown or damaged part
Q19 - No, unknown or damaged part
Q13 - No, unknown or damaged part
Q9 - Read as single Diode
Q7 - Read as 2 Diodes

More to follow
Tim
 
Here are the results of the Right side testing (note that Q20 and Q19 are not truly left channel according to the schematics)
https://timothyflath.smugmug.com/Stereo/Pioneer-RG-1-Right-Channel/

This has generated some interesting results with two readings as NIFETs, one as damaged, and one as 2 X Diodes so these will be checked off board as well. Suspect that the NIFET ones are simply measuring surrounding circuitry so will see if they pan out as good....
 
Just pulled Q20 and off board it checks out as per (sorry hard to read and I already soldered it back in but good result as PNP transistor:

20181009_200712.jpg
 
Holy smokes!:yikes: Changed out all the 725 and 1312 transistors and Pow! Works like a charm now - both channels are strong and sounding great. Still going to press forward with the recap and ultimately calibration (when I get the right test gear - working on it). Thank you for all the help folks - This is why I love AK so much. Just a great bunch of hobbyists who care - My hat goes off to all who provided their sage advice! I will of course follow up with any additional work and report on how the recap etc goes with a sound check video at the end when all is buttoned back together.:beerchug::rockon::rflmao::music::thumbsup::)
 
Restoration complete, obey all further alarms!;)


Unless I get any further questions or advice I will consider this thread a wrap. Things to work on (I know) are my diagnostic techniques (hence the shotgun technique) but also remembering I am a newbie completely self taught but unafraid to ask questions or do further research - Big Yeah to Youtube and AK for being two wonderful resources among many:music:
 
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