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Harman Kardon HK430 tuner dead silent

M

mqtthiqs

New Member
Hello AK,

I am seeking help with my recently bought HK 430. FM reception suddenly stopped working after a couple months of perfectly fine reception. Now FM (stereo or not) is dead silent; the rest of the receiver works perfectly, including AM. Surprisingly the tuning meter moves correctly when I turn the tuner jog dial.

I opened the receiver, checked power supply voltage going into the FM board (~12.5V, ok), looked around for burnt components, reheated a few dodgy looking solder joints... still nothing.

Is there a good soul around here to help me troubleshoot this?
Thanks in advance,
-m
 
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Did you engage the FM Muting button by accident? There's a trim pot on the back of the receiver to adjust sensitivity of that function, as well. So if you engaged it by mistake, disengage it or adjust the sensitivity so you can continue to receive stations without static in between them.
 
And nothing changed with your antenna? It's still good, solidly plugged in and positioned properly?
 
Nope. It cut intermittently 1/2 weeks before turning completely silent (a few seconds/minutes of silence) so I strongly suspect a dead component in the muting circuit...
 
mqtthiqs said:
so I strongly suspect a dead component in the muting circuit...
Click to expand...

Certainly beginning to sound that way. Fortunately, the service manual (free at hifiengine.com) lists voltages for most if not all transistors and IC's in there, so it shouldn't be too hard to track down - I'd start by taking a look at the Q205 & Q206 & Q301 voltages, and work from there. It does have a few 40 year old tantalums in there, so probably worth keeping an eye out for them.
 
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Thanks @Goldie99. I just checked the voltages: all seem to be within reasonable error (+/- 0.8V), except for Q205's collector. It should drop to 0.08V when Mute is On but it is unstable between 1V and 4V.

Sorry, I can't interpret the schematics. Is Q205 the culprit? Should I replace it?
 
Does wiggling or turning the selector switch do anything? I thought if the selector switch was dirty it would attribute to your problem. It has been problematic in other receivers/integrateds that have come through my fingers.
 
I can imagine dirty switches would be an issue, but with both channels affected, and completely silent (?), I'm a bit more inclined to think it's maybe losing the FM signal further back - but that's just based on the schematic & logic, not experience with HK.

What values are you actually measuring on Q205 & Q206 - Base, Emitter, Collector (Mute ON), and the same Mute (OFF) ? +/- 0.8V is not really accurate enough.
 
Hello,
Thank you again for your help. Here are the exact values:

Q205 w/ Mute OFF: E 0.0V C 7.4V B -0.34V [Expected: 0.0V 7.97V 0.07V]
Q205 w/ Mute ON: E 0.0V C 0.12V (yesterday was 1.0-4.0V...) B 0.62V [Expected: 0.0V 0.08V 0.63V]

Q206 w/ Mute OFF: E 5.90V C 5.25V B 7.32V [Expected: 6.06V 6.05V 7.97V]
Q206 w/ Mute ON: E 5.90V C 5.87V B 5.20V [Expected: 6.05V 6.05V 5.36V]
+B3: 12.4V [Expected: 12.5V]

A few other power measurements that are a bit off (I didn't measure them all):
-B2: -30.4 [Expected: -28.5V]
+B4: 24.2 [Expected: 25.4V]

@cademan it is not a problem of selector switch: I cleaned it, tried to bypass it temporarily, controlled with the Aux input...
 
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Just off out for a few hours, but will check this afternoon.

Later...

Q205 looks OK to me; it seems to be turning 'off' when muting is off, and 'on' when muting is on. Regarding the variable value - maybe you didn't get a good contact on it yesterday ? or possibly VR1 might need cleaning ?
Q206 I think is OK as well; it's 'off' when muting is off, and 'on' when muting is on, but I'm not seeing why the collector voltage is varying with muting on / off (Anyone ?). I'd probably check C228 & C301.

Could I ask - how is C301 actually installed ? e.g., does it have the +ve or -ve side connected to Q301(B) ?

-B2 voltage - shouldn't be relevant here. It's the unregulated -ve supply to the right main amp. I can't see it involved anywhere else.
+B4 voltage - I think +24.2V is fine. The +25.4V shown in the manual may actually be a misprint. As far as I can see, it's essentially set by D8, which is a 25V (nominal) zener, so I'd expect the +B4 value to be below 25V (quite possibly 24.5, not 25.4).

Not seeing yet why you've lost FM. Maybe keep checking at Q301, and IC301 (carefully), unless anyone else wants to join in ?
 
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Hello, and sorry for the long reply time...
Here are some more measurements, if you would be kind enough to interpret them @Goldie99:

Goldie99 said:
Q205 looks OK to me; it seems to be turning 'off' when muting is off, and 'on' when muting is on. Regarding the variable value - maybe you didn't get a good contact on it yesterday ? or possibly VR1 might need cleaning ?
Click to expand...

Yes, the variable value... varies with VR1, which I was not caring about the other day. When it is fully CCW I get the expected value.

Goldie99 said:
Q206 I think is OK as well; it's 'off' when muting is off, and 'on' when muting is on, but I'm not seeing why the collector voltage is varying with muting on / off (Anyone ?). I'd probably check C228 & C301.
Click to expand...

I don't think I have the equipment to test capacitors unfortunately... (just a plain voltmeter)
Out of curiosity, how do you do this? Do you have to unsolder them first?

Goldie99 said:
Could I ask - how is C301 actually installed ? e.g., does it have the +ve or -ve side connected to Q301(B) ?
Click to expand...

The -ve side, like on the reproduced PCB and unlike on the schematics. Do you think the error is on the PCB and mounting, or on the schematics?

Goldie99 said:
Not seeing yet why you've lost FM. Maybe keep checking at Q301, and IC301 (carefully)
Click to expand...

Q301 seems ok: B 1.54V, E 1.07V, C 4.04V [Expected: 1.75 1.11 4.03]
IC301: ok except Pin 8: 2.62V [should be 0.12V]

Then I started probing randomly and might have discovered a few anomalies:
Q201: ok
Q202: drain at 6.43 [should be 4.89]
Q203:B 6.23 [should be 4.89], E 5.58 [should be 4.19]
Q204: B 6.22 E 5.59 C 8.96 [should be 4.89 4.19 6.25]
Q303, Q304: ok

Thanks again for your help.
 
OK - the easy bit - the C301 orientation shown on the schematic seems to be wrong (which is why I asked). Stay with the orientation shown on the pcb drawing & as it's installed at the moment.

The rest of it is not so easy....

Pin 8 of IC301 could be relevant, but I don't have a decent datasheet for the IC, so I'm not sure what it is.

I'm not seeing anything obvious in the DC values you've measured: the V(base-emitter) drop on Q301 seems a little low, but with the expected voltage at the emitter it appears to be working. I think the voltages around Q203 & 204 also depend on the setting of VR201, so I'm not sure they're relevant here (don't change VR201, or the other VR pots in the tuner area).

I do wonder if a failed cap might not be an issue here, but can't be sure... I check electro caps with an ESR meter, initially in circuit, and repeat after removal if I find a problem.

I see other HK owners have reported similar issues in the past (e.g., search BA1310, or HK FM problems, on the AK forums) - it would be worth reviewing those threads if you haven't already.

I do think you probably need someone more familiar with tuner circuits and/or similar HK models to come onboard... I know my limits...
.
 
Hey team, resuscitating this thread hoping for a miracle!

Picked up a 430 at a great price, seller mentioned that FM was not working but I took a chance and you know what, the FM is dead silent, crap...

But, the rest of the unit is in good shape, Aux and Phono work fine, AM is, well, AM, and the case and faceplate are in relatively good shape.

I'm assuming this fix will involve the testing that was mentioned earlier in this thread - tracking down potentially bad components in the muting and FM systems - BUT, I thought I'd still reach out to see if anyone has discovered something to get me over the hump, the "fix your 430 FM" magic pill!

Again, shot in the dark here but I'd love to revive that velvety FM sound I know this model is more than capable of producing.

Thanks in advance for any assistance you can afford.
 
JB8 said:
Hey team, resuscitating this thread hoping for a miracle!

Picked up a 430 at a great price, seller mentioned that FM was not working but I took a chance and you know what, the FM is dead silent, crap...

But, the rest of the unit is in good shape, Aux and Phono work fine, AM is, well, AM, and the case and faceplate are in relatively good shape.

I'm assuming this fix will involve the testing that was mentioned earlier in this thread - tracking down potentially bad components in the muting and FM systems - BUT, I thought I'd still reach out to see if anyone has discovered something to get me over the hump, the "fix your 430 FM" magic pill!

Again, shot in the dark here but I'd love to revive that velvety FM sound I know this model is more than capable of producing.

Thanks in advance for any assistance you can afford.
Click to expand...

Hey JB8 - Hope you got the FM working on your HK-430. Got the same issue on a recent acquisition 430 and just started a new post, looking for help. Let me know if u fixed yours.
 
Hey @MBondo , sorry to hear about your 430 but I'm certain there's a solution!

Based on how old this thread is I'm sure I got it fixed but I can't remember what the issue was on that specific unit. I have, however, struggled with dead FM on other HK's from this era and have done everything from exercising the FM capacitors (very gently after marking a starting point if that makes sense), I've replaced the main chip on the FM board, replaced VR's, etc. Most coaches will start with the classic and strong advice of cleaning switches - function and pushbutton - but after that you're left staring at the FM board, or at least I was. If you've started a new thread and stated your level of technical ability, tools on-hand, etc. I'm sure someone will hop in to walk you through some of the troubleshooting steps.

The last time I dealt with this, a few months ago, was on a 330C and it ended up being the chip, easy fix, worked out great and I would likely still be scratching my head if not for @dlucy steering me in the right direction.

As long as you stick to the coaching you'll get via your thread you should have no problems getting it working again if you have some experience in these waters.

Have fun!
 
JB8 said:
Hey @MBondo , sorry to hear about your 430 but I'm certain there's a solution!

Based on how old this thread is I'm sure I got it fixed but I can't remember what the issue was on that specific unit. I have, however, struggled with dead FM on other HK's from this era and have done everything from exercising the FM capacitors (very gently after marking a starting point if that makes sense), I've replaced the main chip on the FM board, replaced VR's, etc. Most coaches will start with the classic and strong advice of cleaning switches - function and pushbutton - but after that you're left staring at the FM board, or at least I was. If you've started a new thread and stated your level of technical ability, tools on-hand, etc. I'm sure someone will hop in to walk you through some of the troubleshooting steps.

The last time I dealt with this, a few months ago, was on a 330C and it ended up being the chip, easy fix, worked out great and I would likely still be scratching my head if not for @dlucy steering me in the right direction.

As long as you stick to the coaching you'll get via your thread you should have no problems getting it working again if you have some experience in these waters.

Have fun!
Click to expand...

Thx JB8 - I’m not experienced at electronic repair, only some work on my turntable and a few guitar tube amps over the years. But no solid state circuit boards like my receiver.
I’m a good direction follower and capable…but no diagnostic skills. I’ll start with a thorough deox/cleaning; hopefully that’ll fix the issue.
 
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