Text preview for : WurlitzerManual.pdf part of . Various WurlitzerManual . Various WurlitzerManual.pdf
Back to : WurlitzerManual.pdf | Home
Troubleshooting the Wurlitzer 200 Series Amplifiers
Troubleshooting the Wurlitzer 200 Series Amplifiers
This text is directly taken from the Wurlitzer 200 Service Manual notes.
Electronic Piano Note #23
April 15th, 1971
200 Series Amplifiers
1. Dead Amplifier (Pilot light does not light) A
2. Blows line fuse B, C, D
3. Blows output transistors J, L, M, N, O, P - See Note #1
4. Distortion D, E, S
5. Low Volume E, S
6. Static E, F, H, I, J, K, T
7. Hiss and noise (can control with volume control) E, F, H, I, J, K, T
8. Hiss & noise (cannot control with volume control) C, I, J, K, U
9. Hum C, E, F
10. Tremelo dead Q, R
A. AC line fuse open
B. Shorted rectifiers D-2, D-3
C. C-6
D. Shorted output transistors
E. Cracks or poor solder joints on PC board
F. Poor ground on input cable
G. TR-1 (use GE style 11-0778 or 651891 yellow or green)
H. R-40, R-36, R-45, R-66 (replace with deposited carbon)
I. R-14, R-7, R-8
J. C-9
K. C-18 too close to R-14
L. R-14 (noisy)
M. R-10 high in value
N. D-4
O. Burr on heat sink puncturing mica washer
P. Use one mica under output and driver transistors with heat sink compound on both sides
Q. TR-4
R. C-53, C-46, D-5
S. Open or shorted coupling capacitors
T. Reed striking pickup
U. TR-5, TR-6
http://www.oldschool-sound.com Page 1
Troubleshooting the Wurlitzer 200 Series Amplifiers
Note #1. Inspect C, J, L and follow P prior to turning piano on after replacement of output
TR'S.
ELECTRONIC PIANO 200A
Before ordering a new AC power cord for a model 200A, check to see which type of pins is
used in the receptacle of your piano. Recently, a new connector has been introduced which
features rectangular shaped pins rather than the traditional, round ones. Including the
description "round pins" or "square pins" on your parts order will insure the proper type of
cord to be sent.
Model: 200, 203, 206, 207
Subject: Failure Output Transistors
References: Schematic - Piano Amplifier (11-0783)
When called upon to change output transistors in the Electronic Piano, check the following
items to ensure they are in good functioning order. Check for the following:
C-6 1000 mfd. 50 VDC Intermittent
C-9 500 mfd. 50 VDC Intermittent
R-14 200 mfd. 5 watt resistor Noise
R-8 .68 ohms 5 watt resistor Noise
R-7 200 ohms 5 watt resistor Noise
R-10 2.7 ohms 1 watt resistor Open
MODEL: 200 Series Electronic Pianos
Subject: Connecting external amplifiers
Reference: 200 Series amplifier Schematic No. 11-1305-S-1
The most satisfactory point to obtain a signal for driving an external amplifier is at the
auxiliary output jack. As the piano is wired, this signal is taken from point 7 (signal) and
point 1 (ground). It has been noted that in some cases this circuit does not supply sufficient
drive signal to the external amplifier input. In other cases a hum is introduced into the
external amplifier. The following circuit has been found to correct these conditions. Change
the 100K resistor between points 6 and 7 to a 6.8K and the 15K resistor between points 1 and
7 to a 2.2K. The maximum signal is approximately .5 volts peak to peak. If there is no D.C.
voltage at the external amplifier input, a cleaner drive signal can be obtained by removing the
5MFD capacitor between pins 5 and 6 and replacing it with a jumper wire.
http://www.oldschool-sound.com Page 2
Troubleshooting the Wurlitzer 200 Series Amplifiers
Model: 203-203W, 214
Subject: Baffle Board Wiring
If you should encounter a piano which has apparent low volume, check speaker wiring to
ensure they are all in phase. The orange wires should be connected to the speaker terminal
with the color dot. The black wires to the unmarked speaker terminals.
http://www.oldschool-sound.com Page 3
Troubleshooting the Wurlitzer 200 Series Amplifiers
The 200 series seems to be the most popular model amongst collectors and players alike.
It's the latest of the reed-based pianos, the lightest in weight, and probably has the best
action and sound amplification of all the models. I won't dwell on this aspect much,
since it's merely opinion.
According to the schematic dates of the 200 series, they were being made in 1981 (200-B)
and beyond. Below is an excerpt transcribed from the original manual.
MODEL 200, 200A (PROFESSIONAL PORTABLE)
Keyboard Range 64 Notes, A-13 thru C-76
Height (From Floor to Keys With Legs) 28 5/8"
Height of Case (Less Legs) 7 1/8"
Height (From Floor to Top of Case, Not
33"
including Music Panel)
Overall Width 40"
Overall Depth 18 9/16"
Weight (Less Legs and Pedal) 56 lbs.
Removable chrome plated steel legs, two of
Legs
which have leveling glides.
MODELS 203, 203W, 206, 207, 207V, 214, 214V, 215V & 270
The Models 203 and 203W are home consoles. For Group Piano Instruction, the Model
206 is the student console and the Models 205V, 207 and 207V are teacher's consoles.
The Models 214, 214V and 215V are classroom consoles. The Models 207V and 214V
have the switches, wiring and plugs installed for use with the Model 208 Key/Note
Visualizer. The Models 205V and 215V are similarly equipped to operate the V-500
key/Note Visualizer. The Model 270 is a Butterfly grand using similar internal
assemblies as the model 200.
Keyboard Range 64 Notes, A-13 thru C-76
Height (From Floor to Top of Keys) 28 5/8"
Height (From Floor to Top of Keys) Model 270 27 1/4"
Overall Height (Not including Music Panel or Casters) 32 7/8"
Overall Height (Not including Music Panel) Model 270 34"
Overall Width 40"
Overall Width Model 270 41"
Overall Depth 18 9/16"
Overall Depth Model 270 37 1/2"
Weight Model 270 Approx. 150 lbs.
http://www.oldschool-sound.com Page 4
Troubleshooting the Wurlitzer 200 Series Amplifiers
Weight (With Legs and Lyre) Model 270 160 lbs.
Note: The following Information applies to all Models Except as Noted.
Bench