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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Sun Mar 29, 2009 6:38 pm Post subject: Amp schematic. Infinity SSW-10 |
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I know, wrong forum but it is posted there but not to much traffic in the audio forum so I thought I'd also ask here.
There is a couple of scorched resistors on the circuit board that need changing but I can't visually identify them.
Thanks,
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Chip
A Barco is only a AmPro with training wheels
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Heywood Jablome
Joined: 12 Mar 2006
Posts: 1548
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| Posted: Sun Mar 29, 2009 8:55 pm Post subject: |
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http://eshop-manuals.com/product_info.php/cPath/13/products_id/201435 is the service manual for ten bucks.
Could not find a free one in a quick googling (but did manage to drop the price from 25 to 15 to 10!)
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-- Baron Alexander von Humboldt: 1769-1859
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macgyver655
Joined: 22 Aug 2007
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| Posted: Sun Mar 29, 2009 10:01 pm Post subject: |
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I dont have the manual but if you want to post the location id's I might be able to get you the values.
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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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| Posted: Sun Mar 29, 2009 11:37 pm Post subject: |
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Everything is put away for now. I'm cleaning the house for company tomorrow night. Tuesday after work (assuming I still have work)  I will take it apart and look at it some more.
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Chip
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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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| Posted: Tue Mar 31, 2009 9:09 pm Post subject: |
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| macgyver655 wrote: | | I dont have the manual but if you want to post the location id's I might be able to get you the values. |
The resistor locations ar R2 and R3
I only looked at this briefly without my glasses on. Now I can see that someone has butched about in here. The good news it the power supply transformer is good. There is however some trace damage on the circuit board between R2 and C7. Like it's ripped off completly. I guess I'll have to guess  I can't break it anymore than it is
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Chip
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macgyver655
Joined: 22 Aug 2007
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| Posted: Wed Apr 01, 2009 2:54 am Post subject: |
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I put in a request. I'll let you know what I hear back.... 
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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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| Posted: Wed Apr 01, 2009 3:26 am Post subject: |
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Got pissed and bought the manual. They are both 430 ohm 1 watt resistors. However that is not what someone tried to butch in. The manual states that those two resistors burn for one of two reasons,
1. IC1 and IC2 on the signal input board require replacement
2. One or both Zener diodes on the power supply (ZD1 and ZD2) require replacement.
I wouldn't have a clue on how to test the IC's but I should be able to pull one leg of the diodes to test them out of circuit.
The diodes are 1N5246B (NTE 5075A)
IC1 is LF347 (NTE859)
IC2 is LF353 (NTE 858M)
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Chip
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macgyver655
Joined: 22 Aug 2007
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| Posted: Wed Apr 01, 2009 3:34 am Post subject: |
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On the ic's you want to check for a short to gnd. On ic 347, check for short between pins 4 and 11. On ic 353 check for short between pins 4 and 8. Have fun......
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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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| Posted: Wed Apr 01, 2009 10:07 pm Post subject: |
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| macgyver655 wrote: | | On the ic's you want to check for a short to gnd. On ic 347, check for short between pins 4 and 11. On ic 353 check for short between pins 4 and 8. Have fun...... |
No shorts on both. Any other test for them? Note: I did check them in-circuit. Is that OK?
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Chip
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macgyver655
Joined: 22 Aug 2007
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| Posted: Wed Apr 01, 2009 10:42 pm Post subject: |
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I would think that would be the only thing that would take out those resistors if the zeners checked ok also. I would need to look at that print to give you any more suggestions. Or just replace the resistors and see what happens.
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
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Location: Langley, BC
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| Posted: Wed Apr 01, 2009 11:31 pm Post subject: |
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I haven't seen the schematic, but typically small op amps don't cause large (relatively speaking) resistors to smoke. The rare exception is the Barco convergence board, but those chips smoke due to HV arcing onto the board.
In a sub amp, I'd look for faults more towards the output section, but that's my $.02.
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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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| Posted: Wed Apr 01, 2009 11:40 pm Post subject: |
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Curt, that suggestion comes directly from the Infinity service manual. And it applies to only those two resistors. I'm unsure how to correctly test Zener diodes. If I lift a leg from the pcb and test with my dmm set to it's lowest range (400), I show open in both directions. If I set the dmm to diode test, I show open in one direction and 0.749V in the other.
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Chip
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stefuel
Joined: 07 Mar 2006
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| Posted: Wed Apr 01, 2009 11:44 pm Post subject: |
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Curt, do you want a zip-file of the service manual? Just tell me which e-mail address to send it to.
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Curt Palme
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| Posted: Wed Apr 01, 2009 11:44 pm Post subject: |
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Yup, I know it did, I'm guessing the resistors drop voltage to those chips. It's just rare that they would blow. Check Zeners exactly as you have, continuity one way, none the other. Sounds like they are fine. Can you scan the schematic, or at least the power supply/op amp section and post it?
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macgyver655
Joined: 22 Aug 2007
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| Posted: Thu Apr 02, 2009 1:52 am Post subject: |
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Your posted readings for the zeners look good. I'm changing your testing on those ics. IC1-LF347 with meter set to diode, test from pins 4 to 5 and then 11 to 5. post readings. Then on IC2-LF353 with meter on diode, test from pins 4 to 3 and then 8 to 3. Post readings.
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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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| Posted: Thu Apr 02, 2009 10:21 am Post subject: |
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I have to work a double shift today but have tomorrow off, so it might not be until late tonight before I get a chance to
re-test those IC's. Thanks,
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stefuel
Joined: 07 Mar 2006
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Location: Green Harbor MA USA
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| Posted: Thu Apr 02, 2009 9:46 pm Post subject: |
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| macgyver655 wrote: | | Your posted readings for the zeners look good. I'm changing your testing on those ics. IC1-LF347 with meter set to diode, test from pins 4 to 5 and then 11 to 5. post readings. Then on IC2-LF353 with meter on diode, test from pins 4 to 3 and then 8 to 3. Post readings. |
OK, I had a couple of minutes to kill between shifts
LF347N
4 to 5 both ways = 0.057V
11 to 5 with red on 11 = 0.598V with black on 11 = 1.022V
LF353N
4 to 3 with the red on 4 = 0.593V and with the black on 4 = 1.018V
8 to 3 both ways 0.056V
This is with the two Zener diodes and the two burned resistors out of circuit if it makes a difference.
Thanks,
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Chip
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macgyver655
Joined: 22 Aug 2007
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| Posted: Thu Apr 02, 2009 10:53 pm Post subject: |
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Well it looks like your +16v line is shorted to gnd. This line feeds IC1, IC2 and IC3. The manual says there are 2 versions of your board and one version has these ic's socketed. Are yours socketed? If not then you may have to unsolder 1 at a time to see which one is shorted. Sometimes you can try to unsolder just the leg your checking but sometimes the leg will break off. So you may be better off removing the whole chip. I would probably start with IC2 (LF353) since its only an 8 pin chip. What would you like to do?
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stefuel
Joined: 07 Mar 2006
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| Posted: Fri Apr 03, 2009 2:12 am Post subject: |
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| macgyver655 wrote: | | Well it looks like your +16v line is shorted to gnd. This line feeds IC1, IC2 and IC3. The manual says there are 2 versions of your board and one version has these ic's socketed. Are yours socketed? If not then you may have to unsolder 1 at a time to see which one is shorted. Sometimes you can try to unsolder just the leg your checking but sometimes the leg will break off. So you may be better off removing the whole chip. I would probably start with IC2 (LF353) since its only an 8 pin chip. What would you like to do? |
I have the un-socketed version. The manual says (assuming it's not the diodes) it would be IC1 or IC2. My thinking at this point is to locate the all the parts listed (including installing the sockets) and swap them all out and be done with it.
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macgyver655
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