Harman Kardon 330 B troubleshooting

[Jpkwd]

Looking for specialists advices on a couple of challenges with my newly acquired receiver.

Just bought one HK 330B to pair with Dynaco A25 after a long period of research throught AK threads.
once i fix the couple of little issue with the receiver, i,m hoping i will be happy with it.

Btw, i am really a newbie at fixing receivers but i am here to learn. This is my second project, the first one being a yamaha CR-1040. thats my experience to date And i havent succeeded in fixing it yet, but one day i will !

Ok, so here it goes : the 330B has the following issue.
The left channel has static. Also, when the volume is completely turned down, i can still hear whatever source is sending signal to it. Raising the volume affects both channels, turning it down only lowers right channel.

I also have this issue which was covered in another thread and discussed between Dlucy, captouch and others


http://audiokarma.org/forums/index....se-harman-kardon-330b-resistor-values.476040/

i would replace each of these resistor with 1K 1W (R2) and 2.2K 1W (R4) if this is an acceptable replacement value. I think increasing the value to 1W would make it a better fit based on the feedback in the thread above.

Schematics can be found here :
https://www.hifiengine.com/hfe_down...ardon/harman_kardon_330b_service_addendum.pdf

I am wondering if the dried up resistors (if not dried up resistor then almost fried resistors) on the main and sub rectifier board could be the cause of the static and persistent volume on the left channel. dont hesistate to school me on this topic, i am here to learn.

Also, there seems to have been some tampering with one of the fuse holder. Not completely sure this is totally safe so any advice welcome.




Production code and serial of the receiver are the following : 4343 22936 A which, according to info i have seen on AK makes it a taiwan made receiver. With luck, this is the best production run

Hoping someone with expert knowledge can help

Regards
Jpkwd

 

[captouch]

Looking for specialists advices on a couple of challenges with my newly acquired receiver.

Just bought one HK 330B to pair with Dynaco A25 after a long period of research throught AK threads.
once i fix the couple of little issue with the receiver, i,m hoping i will be happy with it.

Btw, i am really a newbie at fixing receivers but i am here to learn. This is my second project, the first one being a yamaha CR-1040. thats my experience to date And i havent succeeded in fixing it yet, but one day i will !

Ok, so here it goes : the 330B has the following issue.
The left channel has static. Also, when the volume is completely turned down, i can still hear whatever source is sending signal to it. Raising the volume affects both channels, turning it down only lowers right channel.

I also have this issue which was covered in another thread and discussed between Dlucy, captouch and others
View attachment 1000411View attachment 1000412

http://audiokarma.org/forums/index....se-harman-kardon-330b-resistor-values.476040/

i would replace each of these resistor with 1K 1W (R2) and 2.2K 1W (R4) if this is an acceptable replacement value. I think increasing the value to 1W would make it a better fit based on the feedback in the thread above.

Schematics can be found here :
https://www.hifiengine.com/hfe_down...ardon/harman_kardon_330b_service_addendum.pdf

I am wondering if the dried up resistors (if not dried up resistor then almost fried resistors) on the main and sub rectifier board could be the cause of the static and persistent volume on the left channel. dont hesistate to school me on this topic, i am here to learn.

Also, there seems to have been some tempering with one of the fuse holder. Not completely sure this is totally safe so any advice welcome.


View attachment 1000409 View attachment 1000410

Production code and serial of the receiver are the following : 4343 22936 A which, according to info i have seen on AK makes it a taiwan made receiver. With luck, this is the best production run

Hoping someone with expert knowledge can help

Regards
Jpkwd

Have you cleaned the controls with DeOxit for similar?

When you say the left channel has static, it's only static, or it has music but also has some static? And when you lower the volume, how loud is the left channel?

It likely won't solve all your problems, but I would clean and exercise the controls thoroughly (volume, balance, all of them really), as well as trying to spray cleaner into the push buttons and exercising them (pushing them in/out repeatedly) as well. Do this with the unit powered off, btw, and give the cleaner some time to dry before you power back up. There's an excellent thread on using Deoxit if you haven't already found it. A lot of really strange things can be resolved by cleaning the controls.

If the problem is still there after cleaning the controls, you can try to replace the resistors, but unless the resistors are channel specific (and I don't recall if they are), I wouldn't expect the resistors alone to solve a channel dependent issue. But if this is something you're comfortable doing, you might as well get that out of the way.

IIRC, the 330B has pre-out/main-in jacks on the back. This is good. This can help you isolate the problem to the pre-amp section or the amp section. We can walk you through that after you clean the controls.

The 330B with A25's will make an excellent pairing.

 

[Jpkwd]

Good to hear both the a25 and 330B are a good match,
I did read there is a good compatibility between them so i picked the 330B version based on feedbacks i'Ve seen. Seems that the B had that tubish kind of sound that the A25 would emphasize a lot.

I did a quick clean of the controls with Deoxit yesterday, and i'll give them another clean tonight and report back any improvement. Hopefully this will solve the issue or other potential issues.

If it doesn't change anything then i`m guessing i should try and move the problem to the right channel with a preamp connection swap : left pream out to right amp in to see if the static and volume issue move to the right channel. If so then the issue would most probably be at the preamp level. if not should be in the amp section.

after all that, then i could change the R2 and R4 resistors.

Have you seen the change at the AC fuse level ? not sure about that one, i think the ac outlet fuse has been bypassed, and replaced with a huge resistance. Wonder if this thing would serve as a fuse and blow up in place of the fuse... Still pretty mysterious to me. I'm guessing it's not too much of an issue, i will not use the outlet in the back of the receiver. Really not too sure my reading of this change is the right one. Perhaps the fuse was constantly blown and required this change...?

The static is sporadic and always comes back
volume completely down, i hear music in the left channel only + static.
cranking the volume up the right channel comes out of silence and raises the overall volume.

Thanks for the guidance Captouch,really appreciated.

 

[captouch]

Are you sure the fuse is for the AC outlet only? I haven't heard of that being done in a design. Usually, the fuse is for the entire unit, and you may have some additional fuses (not sure on this model) for the speakers or internal fuses. Fuses are good - they protect the gear many times. But substituting the fuse with anything else is not good. The fuse functionality should be put back, otherwise you're not getting the protection that was meant to be there.

Will wait to hear back after the additional cleaning. Good luck!

 

[Jpkwd]

Thanks captouch,
reading the schematics a little closer, the fuse might be for the power transformer, not the outlet.

Why the change was performed is weird science to me. not sure i get it

 

[dlucy]

View attachment 1000409 View attachment 1000410

Production code and serial of the receiver are the following : 4343 22936 A which, according to info i have seen on AK makes it a taiwan made receiver. With luck, this is the best production run

Sorry to be late to the party!

One of your photos shows *almost* which of the B series this unit is. It'll say "B-1 series" or "B-2 series". B-1 just means you have a later "true 330B" design and B-2 just means you have a "mostly 330A design with a 330B label". Both are great, neither are bad. They are really, REALLY similar. The 330C is where the big change, from cap-coupled (like the 330, 330A and 330B) output to direct-coupled (like the 330C) output.

Which series do you have?

 

[dlucy]

i would replace each of these resistor with 1K 1W (R2) and 2.2K 1W (R4) if this is an acceptable replacement value. I think increasing the value to 1W would make it a better fit based on the feedback in the thread above.

It sounds like you have a "better safe than sorry" approach like I do. For the price difference between a 500 mW metal film resistor and a flameproof 1W or 2W resistor, my opinion is $0.30 for twice the wattage is money well spent.

For the 2.2K R4 500mW on the Main power supply board, I like Mouser PN 71-CPF12.2K2%T1 which is a Vishay CPF flameproof series 1% 2.2K 1W metal film resistor.

For the 1K R2 500mW on the secondary (SAB) power supply board, I like Mouser PN 71-CPF11K0000FKEE6 which again is a Vishay CPF flameproof series 1% precision 1K 1W metal film resistor.

For me, taking those boards off and replacing all five is the best plan. I've rebuilt a bunch of these nice HK 330's and I always replace all the components on both power supply boards. They are very few to buy, they are cheap, they guarantee smooth operation for a long time, and I find it a better use of my time to get it all replaced while I'm in there. I'm not saying everyone should follow the same crazy approach I do, but rather pointing out the reasoning behind what I do.

 

[dlucy]

Good to hear both the a25 and 330B are a good match,
I did read there is a good compatibility between them so i picked the 330B version based on feedbacks i'Ve seen. Seems that the B had that tubish kind of sound that the A25 would emphasize a lot.

The circuit design of the HK three thirty, the HK 330A and the HK 330B uses a final large electrolytic capacitor between the output transistors and the speaker terminals. This is the "cap-coupled" part of the design. This introduces a style or character to the sound the receiver puts outs. If I understand it correctly (since I'm just a tinkerer and not an E.E. or audio tech) the characteristic sound comes from a curve or bandpass filtering effect based on the capacitance and the resistance of that final cap.

Other designs where the output transistors have no such cap between them and the speakers are "direct-coupled" designs and allow more bandwidth through and no or less filtering than a cap-coupled design.

For me, "tube-like" or "warm" is what I'd call the cap-coupled sound and "neutral" or "harsher" is what I'd call the direct-coupled sound, but only in comparison to a cap-coupled unit.

The output caps in the HK 330B:

 

[Jpkwd]

Sorry to be late to the party!

One of your photos shows *almost* which of the B series this unit is. It'll say "B-1 series" or "B-2 series". B-1 just means you have a later "true 330B" design and B-2 just means you have a "mostly 330A design with a 330B label". Both are great, neither are bad. They are really, REALLY similar. The 330C is where the big change, from cap-coupled (like the 330, 330A and 330B) output to direct-coupled (like the 330C) output.

Which series do you have?

Hi Dlucy, nice to meet you and thanks for all the info
the series is the B1 Series, so i guess i got the *real* B deal

Beautiful pictures and i appreciate the explanation on the tone the 330B has from it's cap couple design.
Can't wait to hear it with proper speakers. right now i'm using some cheap speakers for testing.

for the power supply, i took advice from your initial thread and i think i'll use the parts you are mentionning above. i'm saving this for the final touch when i get the volume issue cleared on the left channel.
weird thing that perhaps you might have insight on : i'm kind of new to such a vintage receiver and i have some behavior close to my bass amp
is it normal that closing the power when music is playing kind of chokes the sound until it finally stops agonizing and dies could this be linked to the defective resistors or just plain normal for a receiver of this age ?

I followed captouch's advice on cleaning the pots real good with deoxit. that had some positive effects:

A) i don't hear the crackle and static (kind of like in the dark side of the moon sometime when some bombs explodes)
B) i'm not hearing anything from the left channel when volume is turned completely down, which wasnt the case before.

with Tuner, AUX and PHONO input, the volume of the left channel when the stereo switch is on is about half the volume of the right channel.
A) switching to mono, both channel are of equal volume.
B) Switching to stereo, left channel drops by half if not more
C) using the Tape input, A and B disappears :| this is intriguing me. No more volume difference from left to right channel, the mono/ stereo switch behaves as one would expect

let me know your thought on what could be causing this,
might be something you have seen as a behavior in one of your 330 projects

 

[dlucy]

For right now I can only answer the first part of your question.

In this design, the big capacitor on the top side of the receiver is the power supply's reservoir cap. To a great extent it stores power and temporarily continues to supply that power to the amp even after you throw the power switch to off. That dying off performance you hear is the power stores in that reservoir cap being used up and the exhausted.

The other caps in the power supply are mainly for smoothing ripple but they too store some power which then is used after you turn off the power switch.

It's normal.

I know there are bleeder resistors in some designs which are there to quickly bleed off the power stores in these caps. I'm not sure when they are used versus when not to use them. Perhaps an EE or better-educated AK'er can explain why there isn't a bleeder in this design.

 

[dlucy]

Hi Dlucy, nice to meet you and thanks for all the info
the series is the B1 Series, so i guess i got the *real* B deal

Beautiful pictures and i appreciate the explanation on the tone the 330B has from it's cap couple design.
Can't wait to hear it with proper speakers. right now i'm using some cheap speakers for testing.

for the power supply, i took advice from your initial thread and i think i'll use the parts you are mentionning above. i'm saving this for the final touch when i get the volume issue cleared on the left channel.
weird thing that perhaps you might have insight on : i'm kind of new to such a vintage receiver and i have some behavior close to my bass amp
is it normal that closing the power when music is playing kind of chokes the sound until it finally stops agonizing and dies could this be linked to the defective resistors or just plain normal for a receiver of this age ?

I followed captouch's advice on cleaning the pots real good with deoxit. that had some positive effects:

A) i don't hear the crackle and static (kind of like in the dark side of the moon sometime when some bombs explodes)
B) i'm not hearing anything from the left channel when volume is turned completely down, which wasnt the case before.

with Tuner, AUX and PHONO input, the volume of the left channel when the stereo switch is on is about half the volume of the right channel.
A) switching to mono, both channel are of equal volume.
B) Switching to stereo, left channel drops by half if not more
C) using the Tape input, A and B disappears :| this is intriguing me. No more volume difference from left to right channel, the mono/ stereo switch behaves as one would expect

let me know your thought on what could be causing this,
might be something you have seen as a behavior in one of your 330 projects

When you switch to tape input, you are using two transistors in the preamp (control amp) board that aren't normally used. It sounds like these are working properly.

When you are not listening to tape input, you are instead listening to the 1-2 transistors just before the tape loop transistors in the preamp board. It sounds like one of them or a cap has failed or is dying.

When you switch to mono, I believe, you are summing the left and right channels in the early half of the preamp board and therefore overcoming or masking the failure of one channels transistors/caps.

The transistors we are talking about are all 2SC458 which are known to go bad or produce lots of staticky noise. I would suggest you buy 10-20 KSC1845F transistors and go ahead and replace all the 2SC458 ones on the preamp board. It'll sound better and might solve your problem(s).

 

[dlucy]

Looking at the schematic for the control amp (the preamp circuit in the 330B) I'm thinking more and more your first transistor in the circuit is bad or starting to fail.

Q501 and Q502 are the first bit of gain for all input sources except TAPE. So, your symptoms suggest that part of the preamp, the part prior to Q503 and Q504, is failing.

It could also be one of the electrolytic caps in that area going bad. C501, C502, C503 or C504... or several of them.

 

[Jpkwd]

For right now I can only answer the first part of your question.

In this design, the big capacitor on the top side of the receiver is the power supply's reservoir cap. To a great extent it stores power and temporarily continues to supply that power to the amp even after you throw the power switch to off. That dying off performance you hear is the power stores in that reservoir cap being used up and the exhausted.

The other caps in the power supply are mainly for smoothing ripple but they too store some power which then is used after you turn off the power switch.

It's normal.

I know there are bleeder resistors in some designs which are there to quickly bleed off the power stores in these caps. I'm not sure when they are used versus when not to use them. Perhaps an EE or better-educated AK'er can explain why there isn't a bleeder in this design.

Good to hear that this is normal. It really isn't that bad. I came to realize this behavior while testing and was wondering if there was any other problem to solve.
thanks for sharing your experience on this

 

[dlucy]

When you switch to tape input, you are using two transistors in the preamp (control amp) board that aren't normally used. It sounds like these are working properly.

When you are not listening to tape input, you are instead listening to the 1-2 transistors just before the tape loop transistors in the preamp board. It sounds like one of them or a cap has failed or is dying.

When you switch to mono, I believe, you are summing the left and right channels in the early half of the preamp board and therefore overcoming or masking the failure of one channels transistors/caps.

The transistors we are talking about are all 2SC458 which are known to go bad or produce lots of staticky noise. I would suggest you buy 10-20 KSC1845F transistors and go ahead and replace all the 2SC458 ones on the preamp board. It'll sound better and might solve your problem(s).

When you replace the 2SC458 transistors with KSC1845F, just remember to check the pinouts of the new transistors and get them in the right E, C and B holes in the board. If I remember correctly, the pinout is a different order between the 2SC458 and the KSC1845.

 

[captouch]

Good to hear that this is normal. It really isn't that bad. I came to realize this behavior while testing and was wondering if there was any other problem to solve.
thanks for sharing your experience on this

It sounds like you're in good hands with dlucy.

Sometimes channel imbalances like you're continuing to see can be related to still-dirty controls. Replacing problematic transistors like the 458's is always a good idea, and if it's a keeper, you'll likely want to recap at some point anyway. Ideally, you resolve all known problems before doing a wholesale recap though. Maybe place an order for those parts mentioned by dlucy, but while you're waiting do another through cleaning of the controls (push buttons included) making sure to spray into the open part of the controls as best as you can. Sometimes this requires removing the faceplate to really get into the proper spots, though I don't recall if the 330B required this.

 

[Jpkwd]

Looking at the schematic for the control amp (the preamp circuit in the 330B) I'm thinking more and more your first transistor in the circuit is bad or starting to fail.

Q501 and Q502 are the first bit of gain for all input sources except TAPE. So, your symptoms suggest that part of the preamp, the part prior to Q503 and Q504, is failing.

It could also be one of the electrolytic caps in that area going bad. C501, C502, C503 or C504... or several of them.

View attachment 1000912

that really helps Doug

so Q501 and 503 are linked to tape out, they should be fine
Q502 and Q504 are linked to the aux, phono and tuner, and are the usual suspects.

are both transistor impacting left and right channel or are they channel specific ? say 502 is left and 504 is right ?

 

[dlucy]

that really helps Doug

so Q501 and 503 are linked to tape out, they should be fine
Q502 and Q504 are linked to the aux, phono and tuner, and are the usual suspects.

are both transistor impacting left and right channel or are they channel specific ? say 502 is left and 504 is right ?

Q501 and Q502 amplify the tuner, aux and phono inputs. One of those amplifies the left and the other amplifies the right.

Q503 and Q504 amplify the tape in. Again one does the left and the other does the right.

the signal comes in to the preamp on the left side of the schematic and flows toward the right.

 

[Jpkwd]

Q501 and Q502 amplify the tuner, aux and phono inputs. One of those amplifies the left and the other amplifies the right.
Q503 and Q504 amplify the tape in. Again one does the left and the other does the right.
the signal comes in to the preamp on the left side of the schematic and flows toward the right.

ok, that makes sens, i'll try and test both Q501 and Q502 that amplify the tuner. Perhaps i could identify if one is defective.
Probably will get busy on this shortly when i receive parts.Makes me think I need to find a good place to order parts you mention here in canada.

Sometimes channel imbalances like you're continuing to see can be related to still-dirty controls. Replacing problematic transistors like the 458's is always a good idea, and if it's a keeper, you'll likely want to recap at some point anyway. Ideally, you resolve all known problems before doing a wholesale recap though. Maybe place an order for those parts mentioned by dlucy, but while you're waiting do another through cleaning of the controls (push buttons included) making sure to spray into the open part of the controls as best as you can. Sometimes this requires removing the faceplate to really get into the proper spots, though I don't recall if the 330B required this.

Will do another thorough clean of the pots and controls, can't hurt.
Thanks for the support Captouch, it is appreciated.

 

[Jpkwd]

When you replace the 2SC458 transistors with KSC1845F, just remember to check the pinouts of the new transistors and get them in the right E, C and B holes in the board. If I remember correctly, the pinout is a different order between the 2SC458 and the KSC1845.

One question, i find the following part on mouser, that must be an equivalent to the KSC1845F ?

search KSC1845F =
http://ca.mouser.com/_/?Keyword=KSC1845FTA

 

[dlucy]

For testing transistors:

If you have an Atlas Peak DCA55 or DCA75 transistor tester, you can test a transistor quickly, but they are expensive: http://audiokarma.org/forums/index.php?threads/new-transistor-tester.684329/#post-9141141

If you have a cheap component tester $20 USD, that is a quick way to do basic testing on a transistor: http://audiokarma.org/forums/index.php?threads/cheap-component-tester.749729/

If you don't have a cheap component tester, then you can still do basic testing with a digital multimeter or DMM: http://www.audiokarma.org/forums/index.php?threads/bipolar-junction-transistor-testing-basics.43186/