Well here is some issue....I took the cover off and the board for the left channel has two small fuses on it and they are blown....how was the left channel even playing??? I'll attach a zoomed out pic with them circled in red as well as a zoomed in pic with them circled in red. What are those fuses doing? What would be bad that caused them to blow?
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Is that something bad I see on the upper left side of that first picture?
Might want to let a tech work on those instead of using them…
Would be a shame to have them go poof!
Edit; second picture…
Might want to let a tech work on those instead of using them…
Would be a shame to have them go poof!
Edit; second picture…
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Those are the rail fuses for one channel, that channel cannot work if those are blown.
Have you measured them for continuity?
Have you measured them for continuity?
The only paired fuses I see are the rail fuses down towards the lower right of the schematic. Best check output transistors q405-417 or the ones on the other channel, depending on which channel the load side of the fuses connects to the collectors of. Vbe and Vce .5 to .7 volts forwards, differrent polarities for pnp versus npn. Make sure amp unplugged and rail caps are discharged before you check anything with diode scale. Sorry I said ohms, 2010 meters checked transistors on 2000 ohms scale, but 2020 meters have too low a voltage on regular ohms scale, have to use diode+beep scale.
If output transistors are bad, drivers and emitter resistors usually go too.
Warning, Vce in mid .4 volts is an overstressed transistor. They will blow up later if rail voltage if put on them. Sending schrapnel to the ceiling if you don't have a load in the AC feed line to the power cord. Say on this huge of an amp, a 1500 w heater core from a blown room heater (which is what I used on a PV-1.3k. 100 w bulb series power cord was too small to allow the op amps to work).
If output transistors are bad, drivers and emitter resistors usually go too.
Warning, Vce in mid .4 volts is an overstressed transistor. They will blow up later if rail voltage if put on them. Sending schrapnel to the ceiling if you don't have a load in the AC feed line to the power cord. Say on this huge of an amp, a 1500 w heater core from a blown room heater (which is what I used on a PV-1.3k. 100 w bulb series power cord was too small to allow the op amps to work).
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Yes, I was JUST fixing to post a good pic of that area. What section of the sound does this affect? How was the left channel still playing??? Well I'll be trying to find someone in the Birmingham, AL area to look at it but so far no luck. Wont turn this one back on though....I'm fixing to pull the cover of the other one and look at it real close.
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Maybe they were supposed to be blown, but failed to open. Vaporized metal inside the glass, but still conducting. Possibly from a shorted speaker wire which didn’t do any damage other than “trying” to blow the fuses. It can happen if somebody used 32 volt fuses. If the amp is working it’s ok, but I would be inclined to put in fresh fuses.
It looks like dried electrolyte from the capacitor(s), unless someone spilled brown water on it.
At this point it (they) should be in the hands of a tech who will use a light bulb circuit/variac to start it after replacing the capacitors, and then see what has been damaged. Caps like those fail open, so there’s highly likely an issue beyond that.
At this point it (they) should be in the hands of a tech who will use a light bulb circuit/variac to start it after replacing the capacitors, and then see what has been damaged. Caps like those fail open, so there’s highly likely an issue beyond that.
There arent any good shops locally, they have all gone out of business. I checked around in my local electronics FB groups and most people mail stuff off. I like to fix things, I've done a lot of high end work on cars, building turbo cars, tuning them with a laptop, etc. Also Ive done a lot of computer work and have a server I built that's in my living room...I stream my own music from it. So I'm pretty handy and like to learn how things work....might as well start repairing electronics lol.
I think since I have two of these, one being a spare, I'd like to try repairing it myself. I think while I'm at it I may also do the mods John Curl spoke of for this amp (theres good how to write ups online).
Plus I have a Sansui reciever with a slight crackle in the high end so maybe I can repair that too!
Question......what are good tools to use? I'll want to get a soldering iron (mine sucks and the tip isnt small enough for this work). Do I need a oscilloscope and signal generator? I'll prob just look on FB marketplace or Ebay for some used stuff. Do you guys have any suggestions? I dont do this every day, so not like I need pro grade equipment.
I think since I have two of these, one being a spare, I'd like to try repairing it myself. I think while I'm at it I may also do the mods John Curl spoke of for this amp (theres good how to write ups online).
Plus I have a Sansui reciever with a slight crackle in the high end so maybe I can repair that too!
Question......what are good tools to use? I'll want to get a soldering iron (mine sucks and the tip isnt small enough for this work). Do I need a oscilloscope and signal generator? I'll prob just look on FB marketplace or Ebay for some used stuff. Do you guys have any suggestions? I dont do this every day, so not like I need pro grade equipment.
This is DIY audio, learning how to repair class AB amps is better than doing crossword puzzles IMHO. I'm up to switcher supplies now, some simple ones.
First you need a DVM. Since Sears crashed out, I've found the house brand from newark, tenma, to be accurate. I don't like auto-ranging, those waste a lot of time trying to measure 200 mv when you know the range needs to be 20 v or 200 v. This one looks okay: https://www.newark.com/tenma/72-13440/dmm-handheld-manual-2000-count/dp/52AC3273?st=dvm
If you want temperature too it is $1 more.
Close work with power on, pamona grabbers are less likely to short two things togetter. Buy the lead with banana plug.
I don't use oscilloscope, used ones are full of expired e-caps and new ones <$100 only have 60 or 80 v range, too small for this amp. 10x probes solve that problem but are $30-$50. Easy to break if stepped on. I use a simpson 266XLPM analog meter for tracing music, but $15 analog meters with a 20 vac scale would be fine. Cheap DVM produce random numbers on music, only accurate for 50-60 hz. RMS DVM can see music but find anything >7000 hz invisible, so they would miss an ultrasonic oscillation. For analog vom you'll need .047 uf 250 v up capacitor to block it from reading DC on AC scale, and a couple of alligator clip leads. Parts-express has the alligator clip leads in package of 10 sometimes. On music, beats of a rock station make pointer dance, whereas oscillation is high & steady. You can prove an AC voltage ultrasonic with VOM by checking again with 390 pf cap instead of .047. 1 mhz will go right through a 390 pf cap, music will not.
I use a $6 FM radio instead of a signal generator, with a 1/8" stereo phone plug to dual RCA plug adapter. Amps with 1/4 mono phone input, use that adapter or add two RCA jack to 1/4 phone male adapters.
Soldering iron, I find the parts-express.com vari-temp one the best bargain but if you get it from newark they carry hakka. You'll need a 1/8" wide or 3/16" wide chisel tip to remove power transistors quickly. Faster work lifts fewer lands off the pcb. 40 w is adequate. Solder, tin/lead 60/40 or 63/35 with rosin core is correct. I find squeeze bulb with teflon tip from parts-express best solder sucker, although others like the spring type and some use solder wick. You need a pick to push solder out of the tip.
Safety glasses to keep splashing solder out of your eyes.
47 k resistor with 2 clip leads can do a Iceo test at 12 or 25 volts on used power transistors to see if they are leaky or not. 12-24 v wall transformer for $1, a $3 barrel socket, works. Also a 12 v 2 amp car battery charger. Iceo test detects counterfeit transistors, too.
5 x 20 mm .5 amp fuse in same box will save you frustration when you blow the fuse in the meter checking amps the wrong way.
On the west coast, arrow & jameco are closer than newark in SC. I get stuff from SC sometimes in 1 day for surface rate if I get order in by noon.
Digikey is popular, but they don't have the extensive QA program in china for house brand stuff farnell (parent of newark) has. I find multicomp resistors & capacitors transistors & farnell test equipment are okay even from the land of forgeries.
Happy shopping. Maybe later repairing.
Keep repair questions on this thread, I'll watch it.
First you need a DVM. Since Sears crashed out, I've found the house brand from newark, tenma, to be accurate. I don't like auto-ranging, those waste a lot of time trying to measure 200 mv when you know the range needs to be 20 v or 200 v. This one looks okay: https://www.newark.com/tenma/72-13440/dmm-handheld-manual-2000-count/dp/52AC3273?st=dvm
If you want temperature too it is $1 more.
Close work with power on, pamona grabbers are less likely to short two things togetter. Buy the lead with banana plug.
I don't use oscilloscope, used ones are full of expired e-caps and new ones <$100 only have 60 or 80 v range, too small for this amp. 10x probes solve that problem but are $30-$50. Easy to break if stepped on. I use a simpson 266XLPM analog meter for tracing music, but $15 analog meters with a 20 vac scale would be fine. Cheap DVM produce random numbers on music, only accurate for 50-60 hz. RMS DVM can see music but find anything >7000 hz invisible, so they would miss an ultrasonic oscillation. For analog vom you'll need .047 uf 250 v up capacitor to block it from reading DC on AC scale, and a couple of alligator clip leads. Parts-express has the alligator clip leads in package of 10 sometimes. On music, beats of a rock station make pointer dance, whereas oscillation is high & steady. You can prove an AC voltage ultrasonic with VOM by checking again with 390 pf cap instead of .047. 1 mhz will go right through a 390 pf cap, music will not.
I use a $6 FM radio instead of a signal generator, with a 1/8" stereo phone plug to dual RCA plug adapter. Amps with 1/4 mono phone input, use that adapter or add two RCA jack to 1/4 phone male adapters.
Soldering iron, I find the parts-express.com vari-temp one the best bargain but if you get it from newark they carry hakka. You'll need a 1/8" wide or 3/16" wide chisel tip to remove power transistors quickly. Faster work lifts fewer lands off the pcb. 40 w is adequate. Solder, tin/lead 60/40 or 63/35 with rosin core is correct. I find squeeze bulb with teflon tip from parts-express best solder sucker, although others like the spring type and some use solder wick. You need a pick to push solder out of the tip.
Safety glasses to keep splashing solder out of your eyes.
47 k resistor with 2 clip leads can do a Iceo test at 12 or 25 volts on used power transistors to see if they are leaky or not. 12-24 v wall transformer for $1, a $3 barrel socket, works. Also a 12 v 2 amp car battery charger. Iceo test detects counterfeit transistors, too.
5 x 20 mm .5 amp fuse in same box will save you frustration when you blow the fuse in the meter checking amps the wrong way.
On the west coast, arrow & jameco are closer than newark in SC. I get stuff from SC sometimes in 1 day for surface rate if I get order in by noon.
Digikey is popular, but they don't have the extensive QA program in china for house brand stuff farnell (parent of newark) has. I find multicomp resistors & capacitors transistors & farnell test equipment are okay even from the land of forgeries.
Happy shopping. Maybe later repairing.
Keep repair questions on this thread, I'll watch it.
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Dang theres a lot of info in that post!....much appreciated! If you dont mind I'll just take one bite at a time....Let me start with soldering iron supplies. Is this the variable temp one you mentioned that would be good? They have a $20 one but you adjust the wattage not the temp...where this one you set the temp and it adjusts the wattage to keep it temp stable. They have a digital one that's $10 less but it's less powerful, I thought the extra power for $10 is good. Im not sure if this is actually the one you were refering too or not. Its 48w and up to around 840 degrees. Is this one overkill?.....
Stahl Tools TCSS Temp Controlled Soldering Iron Station ESD Safe
The desoldering pump and bulb are cheap like $3-$5 so I'll just get both and see what I like.
Do you use some kind of stand to hold things in place while your trying to solder/desolder? If so, what tends to be good when working on boards?
I like the vari-temp. I turn temp up for big parts like connectors or to3 packages. That's the one but I paid $42. They had a close out on non-esd safe vari-temp for $12 or something if they still have it. BJT's are not very static sensitive. I have an 80 w weller for 12 ga wires on speaker connectors & the like.
I used to be flexible enough to hold things between my feet, but bought a panavise 2 years ago. Last year it was stolen along with 45000 of tools parts wire LP's CS's. Mostly I leave things on the coffee table I work on. I'm short, tall backs & necks may complain.
Only parts express has the cheapo alligator clip leads, IMHO. good for about 60 volts. Other vendors sell 600 v rated ones at $25 each or something. We're not working on 480 vac panels.
Parts express used to have a $40 C meter, useful, but now only an LCR meter @ $100. Thinking long & hard about that.
I used to be flexible enough to hold things between my feet, but bought a panavise 2 years ago. Last year it was stolen along with 45000 of tools parts wire LP's CS's. Mostly I leave things on the coffee table I work on. I'm short, tall backs & necks may complain.
Only parts express has the cheapo alligator clip leads, IMHO. good for about 60 volts. Other vendors sell 600 v rated ones at $25 each or something. We're not working on 480 vac panels.
Parts express used to have a $40 C meter, useful, but now only an LCR meter @ $100. Thinking long & hard about that.
Hope I you mind that I replied to your post with multiple posts....I thought it might be easier
Okay, you kind of lost me in this section. I'm looking at the Simpson meter you have but cant find much about it. Do you know if it's similar to a Simpson 260 series 6? I can get one of those local from someone asking $75.
insights within the thread.
indianajoe knocks em out of the park regularly!! I have written him in a personal message, in so much to thank him for the REALLY REALLY solid guidance in these forums.
Of course "others" contribute in many ways as well... not meant to slight them.
I have a growing list of DIY favorites and IJ is pretty amazing among them! I am grateful to some outstanding mentors in life, my close friends and engineers, backing my efforts. We all need help along the path, fortunately some of my friends do the heavy lifting [load lines and math] so I can do what I am the best at.
indianajoe knocks em out of the park regularly!! I have written him in a personal message, in so much to thank him for the REALLY REALLY solid guidance in these forums.
Of course "others" contribute in many ways as well... not meant to slight them.
I have a growing list of DIY favorites and IJ is pretty amazing among them! I am grateful to some outstanding mentors in life, my close friends and engineers, backing my efforts. We all need help along the path, fortunately some of my friends do the heavy lifting [load lines and math] so I can do what I am the best at.
I did my DH120 with Exicons. Took out Dynaquad, Many changes to the ccs, bias, and of course, changing from dominate pole to transient miller compensation. End result is very sweet. Might just add a DC sense and output mute to bring it up to current use.
Not sure there is that much to "POOGE" in a 2200 Mk II. New caps. It already was a very good architecture. Only other amp I wish I had was a Nak Stasis. Or maybe an Aragon.
~ image that comes to mind ~ LOLS
I am often outside (on my deck, in the sunlight and fresh air) clutching gear any ways I can. Installing an IEC jack, using a rat-tail file, to finish the square hole, with chassis pan tightly gripped between my feet, the rubber soles of my shoes. *to not do damage to, or scratch the chassis.
I digress, you made me laugh... I can relate.
I struggle admitting (publicly) how much work gets done on the floor, on the carpet, in living space(s), Kitchen island in one home (where the light was good) or even in my music rooms ~ as well as shop space. The music never sounds as good in my shop / compared to music rooms, as a incentive.
I am often outside (on my deck, in the sunlight and fresh air) clutching gear any ways I can. Installing an IEC jack, using a rat-tail file, to finish the square hole, with chassis pan tightly gripped between my feet, the rubber soles of my shoes. *to not do damage to, or scratch the chassis.
I digress, you made me laugh... I can relate.
I struggle admitting (publicly) how much work gets done on the floor, on the carpet, in living space(s), Kitchen island in one home (where the light was good) or even in my music rooms ~ as well as shop space. The music never sounds as good in my shop / compared to music rooms, as a incentive.