A happy new year to all of you, and thank you to all the help and good advises I have gotten on this BL/BM 5000 restoration.
The system has now been playing several hours with the BG 5000 pizzabox connected and several hours with the BM playing on different radio stations.
The sound is clear from low to high and comparing to my BM 4400 it is like a little livelier, the BL gets warmer (not hot) than the BM 4400 I didnt measure the temp so by feeling I will say around 50°C where the left side is a little warmer (4 big resistors) than the right (transformer side), this after several hours of continued playing.
The BM 4400 has better FM reception than the BM 5000, I didnt do any adjustment in the BM 5000 except for the simple voltage adjustments, so I will have to open it again and try to adjust it with the help of a good tone generator (still on the way) and the scope after learning how to.
Restoration:
Would I do it again, oh yes, I had a lot of fun and learned a lot.
I mounted 2 TRs with wrong pin assignment, in afterthought I can put that to a unclear tech sheet from, I think Farnell, when ever I changed a TR I called up a tech sheet on the web and the sheet in question shows the pin assignment seeing the TR from then top and not like others in a 3D drawing.
I took the BL apart as far as I dared and I will do the same with the next one if it is as dirty as this one, it is also easier to change components with the PCBs out
The biggest problem with this amp is the switch assembly, all incoming signals are going through 2-5 contacts before they goes to the different preamps, all switches are in a semi closed housing and to clean them is nearly impossible without desoldering (some 20 solder points), I am still thinking about how to do that in a better way, I still have a scratchy sound when changing input, good advises will be highly appreciated😁
I used axial caps as in the original, I will use radial where possible in the next one, with radial caps it is easier to get nearer to the original values.
Here the time sheet, a lot of time was used on the web and thinking about how to find failures until I got the scope, I bought some items from Mouser included in the price but I still have some of these in stock as I bought more than needed.
| BL/BM 5000 calculation |
| Date |
Work done |
Hours |
Spare parts |
Price USD |
| 8/01/15 |
Pre check |
2.50 |
Buying price S and H |
450.00 USD |
| 8/01/15 |
Photos |
1.00 |
|
|
| 8/02/15 |
Dismantling |
3.00 |
|
|
| 8/02/15 |
Photos |
2.00 |
|
|
| 8/03/15 |
Desoldering components |
4.00 |
|
|
| 8/04/15 |
Desoldering TR Check |
4.00 |
|
|
| 8/05/15 |
TR Check, Dism. BM |
3.00 |
|
|
| 8/05/15 |
Photos |
2.00 |
|
|
| 8/06/15 |
Engraver visit |
1.00 |
|
|
| 8/07/15 |
Transformer |
1.50 |
|
|
| 8/08/15 |
Transformer, Cleaning, caps |
3.00 |
Paint and screws |
17.50 USD |
| 8/09/15 |
Wood BL |
1.00 |
|
|
| 8/24/15 |
Wood BM |
1.50 |
Caps, lamps Martin |
60.00 USD |
| 8/24/15 |
Photos |
3.00 |
Frede Fronts |
489.00 USD |
| 9/28/15 |
New caps and clean |
2.50 |
|
|
| 9/29/15 |
New caps and clean |
3.00 |
|
|
| 10/05/15 |
Checking transistors |
1.00 |
Mouser caps and Trs |
40.00 USD |
| 10/08/15 |
New caps BM |
2.50 |
|
|
| 10/12/15 |
Change transistors (Bl drop) |
3.00 |
|
|
| 10/13/15 |
Change transistors (Bl drop) |
1.50 |
|
|
| 10/14/15 |
Asmb. Trs to cooling |
3.00 |
|
|
| 10/15/15 |
Asmb. Transf. Side |
3.00 |
|
|
| 10/16/15 |
Sold. PCB 03, + caps, Sw.asmb. |
|
|
|
|
Mount. PCB 01, sold. To Sw.asmb |
4.00 |
|
|
| 10/27/15 |
Chassis front, V and Bal sliders |
3.00 |
|
|
| 10/28/15 |
Bass and Treble sliders, PCB 2 |
4.00 |
|
|
| 10/28/15 |
Photos November |
3.00 |
|
|
| 10/31/15 |
Sold. PCB 2 and placed wirebundles |
2.00 |
|
|
| 11/01/15 |
Adjust and failure finding |
3.00 |
|
|
| 11/02/15 |
Failure finding |
1.00 |
|
|
| 11/04/15 |
Test and adjust, Front on |
3.00 |
|
|
| 11/10/15 |
Failure finding |
2.00 |
|
|
| 11/17/15 |
Failure finding |
3.00 |
|
|
| 11/18/15 |
Failure finding |
4.00 |
|
|
| 11/26/15 |
Oscilloscope ordered |
|
|
|
| 12/09/15 |
Failure finding w/Osc. |
2.00 |
|
|
| 12/11/15 |
Polarity BC 154, Test w/tuner |
3.00 |
|
|
| 12/26/15 |
Phono input, swithch |
2.00 |
|
|
| 12/27/15 |
End assembly |
2.00 |
|
|
|
|
|
|
|
|
|
93.00 |
|
1,056.50 USD |
One more pic because I am proud of it
