2330B Faux Pas...

newguytom · Dec 18, 2014

So, long story short, while the unit was on and playing in am, I removed the cover to show a buddy the inside of this beast, a paper clip fell out of my pocket and landed on the MPX decoder panel. Two quick "Zaps" later, I have no sound on any setting. I thought maybe that I had blown a fuse, but I can't seem to find the culprit.
Do you guys feel like giving me a hand with the quest?
I included a pic of the area where the paper clip landed.

rBuckner · Dec 19, 2014

Awww, mannnn! Does the relay click a few seconds after power on?

First step, if not already done, is to download the service manual. Next it's time to measure the power supply output(s). Meter black "-" lead to chassis ground and red "+" to the power supply pins.

J807: +36Vdc
J808: -36Vdc
J809: +20Vdc
J810: -20Vdc
J811: +14Vdc

newguytom · Dec 19, 2014

rBuckner said:
Awww, mannnn! Does the relay click a few seconds after power on?

First step, if not already done, is to download the service manual. Next it's time to measure the power supply output(s). Meter black "-" lead to chassis ground and red "+" to the power supply pins.

J807: +36Vdc
J808: -36Vdc
J809: +20Vdc
J810: -20Vdc
J811: +14Vdc

Hey pal, thanks for answering my plea!
I have no relay, forgot to mention that in the original message. I'll test those pins after work today, maybe I'll even leave the farm early to get a look at them.

That's a hell of a way to discover that you have a hole in your breast pocket...paper clip escaping and creating an electrical event!

newguytom · Dec 19, 2014

Im not getting any readings on any of those points. Meter stays at all zeros.

newguytom · Dec 19, 2014

rBuckner said:
Awww, mannnn! Does the relay click a few seconds after power on?

First step, if not already done, is to download the service manual. Next it's time to measure the power supply output(s). Meter black "-" lead to chassis ground and red "+" to the power supply pins.

J807: +36Vdc
J808: -36Vdc
J809: +20Vdc
J810: -20Vdc
J811: +14Vdc

EEEK- I have no readings on any of those points. The meter is in fact working, it properly gauges the voltage for the bulbs

EchoWars · Dec 19, 2014

Not a great PS design...no fuse protection at all that I can see.

You'll need to backtrack in the PS to confirm that the rectifiers are at least functional. Need to measure the voltage at the '+' pin of C801, and the '-' pin of C802. Should be around +/-54V or so. Also check the voltage at the '+' pin of C817.

rBuckner · Dec 19, 2014

Also make sure your meter is on DC volts , especially if you just finished measuring the AC on the bulbs.

newguytom · Dec 20, 2014

EchoWars said:
Not a great PS design...no fuse protection at all that I can see.

You'll need to backtrack in the PS to confirm that the rectifiers are at least functional. Need to measure the voltage at the '+' pin of C801, and the '-' pin of C802. Should be around +/-54V or so. Also check the voltage at the '+' pin of C817.

Positive C801 53.5 vDc
Negative C802 -54.4 vDc
Positive C817 53.9 vDc

newguytom · Dec 20, 2014

rBuckner said:
Also make sure your meter is on DC volts , especially if you just finished measuring the AC on the bulbs.

Copy that - good reminder for me to double check that.

newguytom · Dec 22, 2014

EchoWars said:
Not a great PS design...no fuse protection at all that I can see.

You'll need to backtrack in the PS to confirm that the rectifiers are at least functional. Need to measure the voltage at the '+' pin of C801, and the '-' pin of C802. Should be around +/-54V or so. Also check the voltage at the '+' pin of C817.

So now that these voltages are verified, do I need to test the transistors on the board?

mech986 · Dec 22, 2014

sorry to hear about this mishap.

newguytom · Dec 22, 2014

mech986 said:
sorry to hear about this mishap.

Thanks for the empathy. I don't even know why I had a paper clip in my pocket!

rBuckner · Dec 22, 2014

Sorry Tom, I had a busy weekend and didn't get back to this. If you don't have the Service Manual, go to the AK database and download it, that will help you a ton! Link:Here

So EW had you look at the front of the power supply after I had you look at the ends. Rather strange that ALL those pins were at 0 volts which made me suspect your meter was on AC. So assuming they are all at 0 volts, let's measure some DC voltages. Report back your measurements.

First, the +36 supply get the three voltages from transistor Q801:
C (expecting +53Vdc)
B (expecting +36.6Vdc)
E (expecting +36Vdc = the output at pin J807)

Second, the -36 supply and transistor Q803:
C (expecting -53Vdc)
B (expecting -36.6Vdc)
E (expecting -36Vdc = the output at pin J808)

newguytom · Dec 22, 2014

rBuckner said:
Sorry Tom, I had a busy weekend and didn't get back to this. If you don't have the Service Manual, go to the AK database and download it, that will help you a ton! Link:Here

So EW had you look at the front of the power supply after I had you look at the ends. Rather strange that ALL those pins were at 0 volts which made me suspect your meter was on AC. So assuming they are all at 0 volts, let's measure some DC voltages. Report back your measurements.

No need to apologize - I'm sure that you are a busy man and I had a dog scare over the weekend with one of the farm hounds... must have chased a rabbit a little to hard into a bramble bush, knocked herself silly and came away looking like a cactus... thankfully she's ok.

I have the manual downloaded and I have printed several copies of the various boards for notations. Thanks for clueing me into that link, what a great resource.

I am 99% positive that my DMM was on DC, but I'll poke around on them again while Im checking those transistors. I think that B C E is printed on the board so that should make my life easier. Once my work on the farm is done, I'll head back to town and try not to mess up anything else!!

rBuckner · Dec 22, 2014

Thanks Tom! Glad to hear the pup ended up okay, as you can tell I'm a softy for dogs. What general area do you live and work in?

newguytom · Dec 22, 2014

rBuckner said:
Thanks Tom! Glad to hear the pup ended up okay, as you can tell I'm a softy for dogs. What general area do you live and work in?

I live in west central Illinois, not far from Peoria near Pekin. Im an independent agriculture specialist, most of my jobs come fron the farm bureau's of Mo and Il.

newguytom · Dec 22, 2014

rBuckner said:
Thanks Tom! Glad to hear the pup ended up okay, as you can tell I'm a softy for dogs. What general area do you live and work in?

Well, you were right. I must've had the meter set to AC. These of the readings that I get now that I have that straightened out.
j807 = 37.5
808= -36.8
809 = 19.8
810 = -19.4
811=13.1

I am not real fond of that placement for J811, it took me forever to lasso that pin
And almost by request, the battery in my DMM is dead. I could build a house out of all the AA and AAA. Guess what I dont have....

rBuckner · Dec 22, 2014

Been there, did both things... the AC setting and running out of batteries. :yes: So it looks like the supplies are good. I asked about the relay and you said you had none. If you meant it doesn't click that either means the outputs fried or the circuit that is there to detect excess dc voltage fried. Weird but it could be! Check the dc voltage on pins J813 and J814 = the amp outputs, they should be somewhere near zero volts if the amps are okay. If so then check the voltages on transistors Q810-812 against the values on the schematic and see what we have.

Now if the relay is clicking on, have you tried the Aux input? Or even the phono input? If those are dead too try patching into the main amp inputs with another receiver's preamp outputs. I'd think this might get it going pointing to a toasted preamp.

I was hoping for Az. or Calif. so you could bring it by, oh well. My Mom spent her early years in Springfield, Ill. then moved on to Ohio during the Depression. Some people say I have a bit of an accent from that area still even though born and raised in Calif. For sure I know a passel of hillbilly sayings!

newguytom · Dec 23, 2014

rBuckner said:
So it looks like the supplies are good. I asked about the relay and you said you had none. If you meant it doesn't click that either means the outputs fried or the circuit that is there to detect excess dc voltage fried. Weird but it could be! Check the dc voltage on pins J813 and J814 = the amp outputs, they should be somewhere near zero volts if the amps are okay. If so then check the voltages on transistors Q810-812 against the values on the schematic and see what we have.

Thanks for the fast reply - I'll check those points and report back with my findings.

Also, I can't thank you enough for your offer to take a look at it. I found a really good tech in St Louie, but the guy is busy building something called a blue stripe compressor. He promised someone that he'd have two of them done by the new year. I hate to disturbed him while he is under a timeline.

newguytom · Dec 24, 2014

rBuckner said:
Thanks Tom! Glad to hear the pup ended up okay, as you can tell I'm a softy for dogs. What general area do you live and work in?

OK, I found another issue. The resistor at R809 looks toasty. I'll include a picture.

2330B Faux Pas...

Active Member

Attachments

Luv 2 Restore

Active Member

Active Member

Active Member

Hiding in Honduras

Luv 2 Restore

Active Member

Active Member

Active Member

AK Subscriber

Active Member

Luv 2 Restore

Active Member

Luv 2 Restore

Active Member

Active Member

Luv 2 Restore

Active Member

Active Member

Attachments

Similar threads