• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

BGW Model 410 Stereo Power Amplifier no longer working

N

numba1killa

New Member
http://imgur.com/a/XzV12

Hello AK. I have a BGW Model 410 amp, and BGW model 203 Stereo Control Center. The BGW 203 currently works and works well. The 410 however no longer works. For the past 2 months, the BGW 410 would require numerous attempts before the relay would *click* to let me know it turned on. Well, just a couple days ago, I was listening to music, and the 410 decided to turn off and turn right back on, and scared the crap out of me, as it put a ton of noise to my left channel. I immeditly turned it off, and after that, it would no longer *click* on. It now wants to just remain off.

I am at a loss. I am not the most tech savy, but I can see when something doesn't look right on the inside... and the inside looks good. I will include pictures. I will also note, that the 410 has 10 LEDs to show how much power is being driven to each channel, sometimes when I would turn on the amp, it would show, up to, 50 watts of power being given to the left side, with nothing being sent to the 410 (no record playing, or cassette tape).

I heard these BGW pieces of equipment are built like tanks and by looking at the inside craftsmanship, is true. I am bringing this in for a repair next week, but I don't want to be wasting my money for something that I can fix, or not fix at all by a professional. Any ideas guys? Thanks for the input and for a great website.
 
Last edited:
Register to hide this ad
Yep, got some ideas. How much are you willing to dig into it?

Schematics will be helpful for the 'arm chair bench techs' here at AK. We're flying blind without your test readings and a schematic.

Cheers,

David
 
dshoaf said:
Yep, got some ideas. How much are you willing to dig into it?

Schematics will be helpful for the 'arm chair bench techs' here at AK. We're flying blind without your test readings and a schematic.

Cheers,

David
Click to expand...
Thank you very much for the quick reply David. I have uploaded all the schematics I found in the BGW 410 manual that BGW sent me a few months ago. I cannot do any tests I have no equipment to do so. All I can say is, it will not turn on... I know thats pretty vague but I have no voltage reader or anything like that. Im not giving you guys much to work with here and for that i apologize. I hope the schematics help a bit... please let me know If i can take additional photos once someone looks over the schematics. Thanks again for your time.

I am unsure how far I can dig into the unit as I am not techsavy at all. I have soldered a few wires here and there but nothing major like this.

Also, the schematics state they are from a unit made in 1978. Mine was made in 1977, not sure if they changed anything between that time... so i am unable to tell how accurate the schematics are.

Schematics to BGW 410 amp:

http://imgur.com/a/4AEYX
 
Thanks for the schematic link although that hosting site is pretty nasty with the intrusive ads.

No testing meter means there's only so much you can do, then. "Not turning" on is too vague, for sure.

You'll first need to distinguish between whether there is AC power getting to the unit and whether the speaker relay is kicking in. From the sound of the symptoms leading up to a more complete failure, I'd suggest it may be getting AC power.

If not, however, there appears to be 2 fuses in the primary side of the power transformer. Check them first. You _really_ need an ohm meter to determine if they're good or not. Replace them if there's any doubt with the exact amperage called for.

If there is AC power getting to the amp, then, the speaker protection relay is not engaging. This means there's a problem with DC Offset (find the Sticky Note on that topic here at AK), which it appears that the relay board checks for. If this proves to be the case, plan on taking the amp to a good vintage tech now as I doubt you'll have the tooling to deal with it.

The BGW amps are worth the investment if you plan on keeping it long term. Otherwise, I'd recommend it be sold as is and allow someone else to deal with the problem.

Hope that helps.
 
dshoaf said:
Thanks for the schematic link although that hosting site is pretty nasty with the intrusive ads.

No testing meter means there's only so much you can do, then. "Not turning" on is too vague, for sure.

You'll first need to distinguish between whether there is AC power getting to the unit and whether the speaker relay is kicking in. From the sound of the symptoms leading up to a more complete failure, I'd suggest it may be getting AC power.

If not, however, there appears to be 2 fuses in the primary side of the power transformer. Check them first. You _really_ need an ohm meter to determine if they're good or not. Replace them if there's any doubt with the exact amperage called for.

If there is AC power getting to the amp, then, the speaker protection relay is not engaging. This means there's a problem with DC Offset (find the Sticky Note on that topic here at AK), which it appears that the relay board checks for. If this proves to be the case, plan on taking the amp to a good vintage tech now as I doubt you'll have the tooling to deal with it.

The BGW amps are worth the investment if you plan on keeping it long term. Otherwise, I'd recommend it be sold as is and allow someone else to deal with the problem.

Hope that helps.
Click to expand...


I do plan to keep this long term as it does sound pretty good. I am bringing it to a repair shop either tomorrow or Wednesday.

Thanks for the help :)
 
So, I brought in my amp to a local gent, and he told me that prior to me owning the amp, (July 7th 2015) someone replaced a bunch of pieces in it. The right channel has a newer board on it, with newer transistors, and the left channel (that has failed according to my guy) is an older style board. He also stated to me that it's probably going to be a little costly to fix, but he is unsure until he progresses further into the unit.

HE did indeed say there was something wrong with the DC Offset, as it was only engaging on 1 rail? If I heard him correctly.

Thanks for the comments David. I will post back once we get further into the project.
 
You must log in or register to reply here.
Back
Top Bottom